Add vendored packages back

154 files changed, 41107 insertions, 0 deletions

diff --git a/lib/spack/external/_vendoring/_pyrsistent_version.py b/lib/spack/external/_vendoring/_pyrsistent_version.py
new file mode 100644
index 0000000000..5ec52a922c
--- /dev/null
+++ b/lib/spack/external/_vendoring/_pyrsistent_version.py
@@ -0,0 +1 @@
+__version__ = '0.18.0'
diff --git a/lib/spack/external/_vendoring/_pyrsistent_version.pyi b/lib/spack/external/_vendoring/_pyrsistent_version.pyi
new file mode 100644
index 0000000000..873cc62efd
--- /dev/null
+++ b/lib/spack/external/_vendoring/_pyrsistent_version.pyi
@@ -0,0 +1 @@
+from _pyrsistent_version import *
\ No newline at end of file
diff --git a/lib/spack/external/_vendoring/altgraph.pyi b/lib/spack/external/_vendoring/altgraph.pyi
new file mode 100644
index 0000000000..0d67a24e01
--- /dev/null
+++ b/lib/spack/external/_vendoring/altgraph.pyi
@@ -0,0 +1 @@
+from altgraph import *
\ No newline at end of file
diff --git a/lib/spack/external/_vendoring/altgraph/Dot.py b/lib/spack/external/_vendoring/altgraph/Dot.py
new file mode 100644
index 0000000000..f265a7121c
--- /dev/null
+++ b/lib/spack/external/_vendoring/altgraph/Dot.py
@@ -0,0 +1,321 @@
+"""
+altgraph.Dot - Interface to the dot language
+============================================
+
+The :py:mod:`~altgraph.Dot` module provides a simple interface to the
+file format used in the
+`graphviz <http://www.research.att.com/sw/tools/graphviz/>`_
+program. The module is intended to offload the most tedious part of the process
+(the **dot** file generation) while transparently exposing most of its
+features.
+
+To display the graphs or to generate image files the
+`graphviz <http://www.research.att.com/sw/tools/graphviz/>`_
+package needs to be installed on the system, moreover the :command:`dot` and
+:command:`dotty` programs must be accesible in the program path so that they
+can be ran from processes spawned within the module.
+
+Example usage
+-------------
+
+Here is a typical usage::
+
+    from altgraph import Graph, Dot
+
+    # create a graph
+    edges = [ (1,2), (1,3), (3,4), (3,5), (4,5), (5,4) ]
+    graph = Graph.Graph(edges)
+
+    # create a dot representation of the graph
+    dot = Dot.Dot(graph)
+
+    # display the graph
+    dot.display()
+
+    # save the dot representation into the mydot.dot file
+    dot.save_dot(file_name='mydot.dot')
+
+    # save dot file as gif image into the graph.gif file
+    dot.save_img(file_name='graph', file_type='gif')
+
+Directed graph and non-directed graph
+-------------------------------------
+
+Dot class can use for both directed graph and non-directed graph
+by passing ``graphtype`` parameter.
+
+Example::
+
+    # create directed graph(default)
+    dot = Dot.Dot(graph, graphtype="digraph")
+
+    # create non-directed graph
+    dot = Dot.Dot(graph, graphtype="graph")
+
+Customizing the output
+----------------------
+
+The graph drawing process may be customized by passing
+valid :command:`dot` parameters for the nodes and edges. For a list of all
+parameters see the `graphviz <http://www.research.att.com/sw/tools/graphviz/>`_
+documentation.
+
+Example::
+
+    # customizing the way the overall graph is drawn
+    dot.style(size='10,10', rankdir='RL', page='5, 5' , ranksep=0.75)
+
+    # customizing node drawing
+    dot.node_style(1, label='BASE_NODE',shape='box', color='blue' )
+    dot.node_style(2, style='filled', fillcolor='red')
+
+    # customizing edge drawing
+    dot.edge_style(1, 2, style='dotted')
+    dot.edge_style(3, 5, arrowhead='dot', label='binds', labelangle='90')
+    dot.edge_style(4, 5, arrowsize=2, style='bold')
+
+
+.. note::
+
+   dotty (invoked via :py:func:`~altgraph.Dot.display`) may not be able to
+   display all graphics styles. To verify the output save it to an image file
+   and look at it that way.
+
+Valid attributes
+----------------
+
+    - dot styles, passed via the :py:meth:`Dot.style` method::
+
+        rankdir = 'LR'   (draws the graph horizontally, left to right)
+        ranksep = number (rank separation in inches)
+
+    - node attributes, passed via the :py:meth:`Dot.node_style` method::
+
+        style = 'filled' | 'invisible' | 'diagonals' | 'rounded'
+        shape = 'box' | 'ellipse' | 'circle' | 'point' | 'triangle'
+
+    - edge attributes, passed via the :py:meth:`Dot.edge_style` method::
+
+        style     = 'dashed' | 'dotted' | 'solid' | 'invis' | 'bold'
+        arrowhead = 'box' | 'crow' | 'diamond' | 'dot' | 'inv' | 'none'
+            | 'tee' | 'vee'
+        weight    = number (the larger the number the closer the nodes will be)
+
+    - valid `graphviz colors
+        <http://www.research.att.com/~erg/graphviz/info/colors.html>`_
+
+    - for more details on how to control the graph drawing process see the
+      `graphviz reference
+        <http://www.research.att.com/sw/tools/graphviz/refs.html>`_.
+"""
+import os
+import warnings
+
+from altgraph import GraphError
+
+
+class Dot(object):
+    """
+    A  class providing a **graphviz** (dot language) representation
+    allowing a fine grained control over how the graph is being
+    displayed.
+
+    If the :command:`dot` and :command:`dotty` programs are not in the current
+    system path their location needs to be specified in the contructor.
+    """
+
+    def __init__(
+        self,
+        graph=None,
+        nodes=None,
+        edgefn=None,
+        nodevisitor=None,
+        edgevisitor=None,
+        name="G",
+        dot="dot",
+        dotty="dotty",
+        neato="neato",
+        graphtype="digraph",
+    ):
+        """
+        Initialization.
+        """
+        self.name, self.attr = name, {}
+
+        assert graphtype in ["graph", "digraph"]
+        self.type = graphtype
+
+        self.temp_dot = "tmp_dot.dot"
+        self.temp_neo = "tmp_neo.dot"
+
+        self.dot, self.dotty, self.neato = dot, dotty, neato
+
+        # self.nodes: node styles
+        # self.edges: edge styles
+        self.nodes, self.edges = {}, {}
+
+        if graph is not None and nodes is None:
+            nodes = graph
+        if graph is not None and edgefn is None:
+
+            def edgefn(node, graph=graph):
+                return graph.out_nbrs(node)
+
+        if nodes is None:
+            nodes = ()
+
+        seen = set()
+        for node in nodes:
+            if nodevisitor is None:
+                style = {}
+            else:
+                style = nodevisitor(node)
+            if style is not None:
+                self.nodes[node] = {}
+                self.node_style(node, **style)
+                seen.add(node)
+        if edgefn is not None:
+            for head in seen:
+                for tail in (n for n in edgefn(head) if n in seen):
+                    if edgevisitor is None:
+                        edgestyle = {}
+                    else:
+                        edgestyle = edgevisitor(head, tail)
+                    if edgestyle is not None:
+                        if head not in self.edges:
+                            self.edges[head] = {}
+                        self.edges[head][tail] = {}
+                        self.edge_style(head, tail, **edgestyle)
+
+    def style(self, **attr):
+        """
+        Changes the overall style
+        """
+        self.attr = attr
+
+    def display(self, mode="dot"):
+        """
+        Displays the current graph via dotty
+        """
+
+        if mode == "neato":
+            self.save_dot(self.temp_neo)
+            neato_cmd = "%s -o %s %s" % (self.neato, self.temp_dot, self.temp_neo)
+            os.system(neato_cmd)
+        else:
+            self.save_dot(self.temp_dot)
+
+        plot_cmd = "%s %s" % (self.dotty, self.temp_dot)
+        os.system(plot_cmd)
+
+    def node_style(self, node, **kwargs):
+        """
+        Modifies a node style to the dot representation.
+        """
+        if node not in self.edges:
+            self.edges[node] = {}
+        self.nodes[node] = kwargs
+
+    def all_node_style(self, **kwargs):
+        """
+        Modifies all node styles
+        """
+        for node in self.nodes:
+            self.node_style(node, **kwargs)
+
+    def edge_style(self, head, tail, **kwargs):
+        """
+        Modifies an edge style to the dot representation.
+        """
+        if tail not in self.nodes:
+            raise GraphError("invalid node %s" % (tail,))
+
+        try:
+            if tail not in self.edges[head]:
+                self.edges[head][tail] = {}
+            self.edges[head][tail] = kwargs
+        except KeyError:
+            raise GraphError("invalid edge  %s -> %s " % (head, tail))
+
+    def iterdot(self):
+        # write graph title
+        if self.type == "digraph":
+            yield "digraph %s {\n" % (self.name,)
+        elif self.type == "graph":
+            yield "graph %s {\n" % (self.name,)
+
+        else:
+            raise GraphError("unsupported graphtype %s" % (self.type,))
+
+        # write overall graph attributes
+        for attr_name, attr_value in sorted(self.attr.items()):
+            yield '%s="%s";' % (attr_name, attr_value)
+        yield "\n"
+
+        # some reusable patterns
+        cpatt = '%s="%s",'  # to separate attributes
+        epatt = "];\n"  # to end attributes
+
+        # write node attributes
+        for node_name, node_attr in sorted(self.nodes.items()):
+            yield '\t"%s" [' % (node_name,)
+            for attr_name, attr_value in sorted(node_attr.items()):
+                yield cpatt % (attr_name, attr_value)
+            yield epatt
+
+        # write edge attributes
+        for head in sorted(self.edges):
+            for tail in sorted(self.edges[head]):
+                if self.type == "digraph":
+                    yield '\t"%s" -> "%s" [' % (head, tail)
+                else:
+                    yield '\t"%s" -- "%s" [' % (head, tail)
+                for attr_name, attr_value in sorted(self.edges[head][tail].items()):
+                    yield cpatt % (attr_name, attr_value)
+                yield epatt
+
+        # finish file
+        yield "}\n"
+
+    def __iter__(self):
+        return self.iterdot()
+
+    def save_dot(self, file_name=None):
+        """
+        Saves the current graph representation into a file
+        """
+
+        if not file_name:
+            warnings.warn(DeprecationWarning, "always pass a file_name")
+            file_name = self.temp_dot
+
+        with open(file_name, "w") as fp:
+            for chunk in self.iterdot():
+                fp.write(chunk)
+
+    def save_img(self, file_name=None, file_type="gif", mode="dot"):
+        """
+        Saves the dot file as an image file
+        """
+
+        if not file_name:
+            warnings.warn(DeprecationWarning, "always pass a file_name")
+            file_name = "out"
+
+        if mode == "neato":
+            self.save_dot(self.temp_neo)
+            neato_cmd = "%s -o %s %s" % (self.neato, self.temp_dot, self.temp_neo)
+            os.system(neato_cmd)
+            plot_cmd = self.dot
+        else:
+            self.save_dot(self.temp_dot)
+            plot_cmd = self.dot
+
+        file_name = "%s.%s" % (file_name, file_type)
+        create_cmd = "%s -T%s %s -o %s" % (
+            plot_cmd,
+            file_type,
+            self.temp_dot,
+            file_name,
+        )
+        os.system(create_cmd)
diff --git a/lib/spack/external/_vendoring/altgraph/Graph.py b/lib/spack/external/_vendoring/altgraph/Graph.py
new file mode 100644
index 0000000000..8088007abd
--- /dev/null
+++ b/lib/spack/external/_vendoring/altgraph/Graph.py
@@ -0,0 +1,682 @@
+"""
+altgraph.Graph - Base Graph class
+=================================
+
+..
+  #--Version 2.1
+  #--Bob Ippolito October, 2004
+
+  #--Version 2.0
+  #--Istvan Albert June, 2004
+
+  #--Version 1.0
+  #--Nathan Denny, May 27, 1999
+"""
+
+from collections import deque
+
+from altgraph import GraphError
+
+
+class Graph(object):
+    """
+    The Graph class represents a directed graph with *N* nodes and *E* edges.
+
+    Naming conventions:
+
+    - the prefixes such as *out*, *inc* and *all* will refer to methods
+      that operate on the outgoing, incoming or all edges of that node.
+
+      For example: :py:meth:`inc_degree` will refer to the degree of the node
+      computed over the incoming edges (the number of neighbours linking to
+      the node).
+
+    - the prefixes such as *forw* and *back* will refer to the
+      orientation of the edges used in the method with respect to the node.
+
+      For example: :py:meth:`forw_bfs` will start at the node then use the
+      outgoing edges to traverse the graph (goes forward).
+    """
+
+    def __init__(self, edges=None):
+        """
+        Initialization
+        """
+
+        self.next_edge = 0
+        self.nodes, self.edges = {}, {}
+        self.hidden_edges, self.hidden_nodes = {}, {}
+
+        if edges is not None:
+            for item in edges:
+                if len(item) == 2:
+                    head, tail = item
+                    self.add_edge(head, tail)
+                elif len(item) == 3:
+                    head, tail, data = item
+                    self.add_edge(head, tail, data)
+                else:
+                    raise GraphError("Cannot create edge from %s" % (item,))
+
+    def __repr__(self):
+        return "<Graph: %d nodes, %d edges>" % (
+            self.number_of_nodes(),
+            self.number_of_edges(),
+        )
+
+    def add_node(self, node, node_data=None):
+        """
+        Adds a new node to the graph.  Arbitrary data can be attached to the
+        node via the node_data parameter.  Adding the same node twice will be
+        silently ignored.
+
+        The node must be a hashable value.
+        """
+        #
+        # the nodes will contain tuples that will store incoming edges,
+        # outgoing edges and data
+        #
+        # index 0 -> incoming edges
+        # index 1 -> outgoing edges
+
+        if node in self.hidden_nodes:
+            # Node is present, but hidden
+            return
+
+        if node not in self.nodes:
+            self.nodes[node] = ([], [], node_data)
+
+    def add_edge(self, head_id, tail_id, edge_data=1, create_nodes=True):
+        """
+        Adds a directed edge going from head_id to tail_id.
+        Arbitrary data can be attached to the edge via edge_data.
+        It may create the nodes if adding edges between nonexisting ones.
+
+        :param head_id: head node
+        :param tail_id: tail node
+        :param edge_data: (optional) data attached to the edge
+        :param create_nodes: (optional) creates the head_id or tail_id
+            node in case they did not exist
+        """
+        # shorcut
+        edge = self.next_edge
+
+        # add nodes if on automatic node creation
+        if create_nodes:
+            self.add_node(head_id)
+            self.add_node(tail_id)
+
+        # update the corresponding incoming and outgoing lists in the nodes
+        # index 0 -> incoming edges
+        # index 1 -> outgoing edges
+
+        try:
+            self.nodes[tail_id][0].append(edge)
+            self.nodes[head_id][1].append(edge)
+        except KeyError:
+            raise GraphError("Invalid nodes %s -> %s" % (head_id, tail_id))
+
+        # store edge information
+        self.edges[edge] = (head_id, tail_id, edge_data)
+
+        self.next_edge += 1
+
+    def hide_edge(self, edge):
+        """
+        Hides an edge from the graph. The edge may be unhidden at some later
+        time.
+        """
+        try:
+            head_id, tail_id, edge_data = self.hidden_edges[edge] = self.edges[edge]
+            self.nodes[tail_id][0].remove(edge)
+            self.nodes[head_id][1].remove(edge)
+            del self.edges[edge]
+        except KeyError:
+            raise GraphError("Invalid edge %s" % edge)
+
+    def hide_node(self, node):
+        """
+        Hides a node from the graph.  The incoming and outgoing edges of the
+        node will also be hidden.  The node may be unhidden at some later time.
+        """
+        try:
+            all_edges = self.all_edges(node)
+            self.hidden_nodes[node] = (self.nodes[node], all_edges)
+            for edge in all_edges:
+                self.hide_edge(edge)
+            del self.nodes[node]
+        except KeyError:
+            raise GraphError("Invalid node %s" % node)
+
+    def restore_node(self, node):
+        """
+        Restores a previously hidden node back into the graph and restores
+        all of its incoming and outgoing edges.
+        """
+        try:
+            self.nodes[node], all_edges = self.hidden_nodes[node]
+            for edge in all_edges:
+                self.restore_edge(edge)
+            del self.hidden_nodes[node]
+        except KeyError:
+            raise GraphError("Invalid node %s" % node)
+
+    def restore_edge(self, edge):
+        """
+        Restores a previously hidden edge back into the graph.
+        """
+        try:
+            head_id, tail_id, data = self.hidden_edges[edge]
+            self.nodes[tail_id][0].append(edge)
+            self.nodes[head_id][1].append(edge)
+            self.edges[edge] = head_id, tail_id, data
+            del self.hidden_edges[edge]
+        except KeyError:
+            raise GraphError("Invalid edge %s" % edge)
+
+    def restore_all_edges(self):
+        """
+        Restores all hidden edges.
+        """
+        for edge in list(self.hidden_edges.keys()):
+            try:
+                self.restore_edge(edge)
+            except GraphError:
+                pass
+
+    def restore_all_nodes(self):
+        """
+        Restores all hidden nodes.
+        """
+        for node in list(self.hidden_nodes.keys()):
+            self.restore_node(node)
+
+    def __contains__(self, node):
+        """
+        Test whether a node is in the graph
+        """
+        return node in self.nodes
+
+    def edge_by_id(self, edge):
+        """
+        Returns the edge that connects the head_id and tail_id nodes
+        """
+        try:
+            head, tail, data = self.edges[edge]
+        except KeyError:
+            head, tail = None, None
+            raise GraphError("Invalid edge %s" % edge)
+
+        return (head, tail)
+
+    def edge_by_node(self, head, tail):
+        """
+        Returns the edge that connects the head_id and tail_id nodes
+        """
+        for edge in self.out_edges(head):
+            if self.tail(edge) == tail:
+                return edge
+        return None
+
+    def number_of_nodes(self):
+        """
+        Returns the number of nodes
+        """
+        return len(self.nodes)
+
+    def number_of_edges(self):
+        """
+        Returns the number of edges
+        """
+        return len(self.edges)
+
+    def __iter__(self):
+        """
+        Iterates over all nodes in the graph
+        """
+        return iter(self.nodes)
+
+    def node_list(self):
+        """
+        Return a list of the node ids for all visible nodes in the graph.
+        """
+        return list(self.nodes.keys())
+
+    def edge_list(self):
+        """
+        Returns an iterator for all visible nodes in the graph.
+        """
+        return list(self.edges.keys())
+
+    def number_of_hidden_edges(self):
+        """
+        Returns the number of hidden edges
+        """
+        return len(self.hidden_edges)
+
+    def number_of_hidden_nodes(self):
+        """
+        Returns the number of hidden nodes
+        """
+        return len(self.hidden_nodes)
+
+    def hidden_node_list(self):
+        """
+        Returns the list with the hidden nodes
+        """
+        return list(self.hidden_nodes.keys())
+
+    def hidden_edge_list(self):
+        """
+        Returns a list with the hidden edges
+        """
+        return list(self.hidden_edges.keys())
+
+    def describe_node(self, node):
+        """
+        return node, node data, outgoing edges, incoming edges for node
+        """
+        incoming, outgoing, data = self.nodes[node]
+        return node, data, outgoing, incoming
+
+    def describe_edge(self, edge):
+        """
+        return edge, edge data, head, tail for edge
+        """
+        head, tail, data = self.edges[edge]
+        return edge, data, head, tail
+
+    def node_data(self, node):
+        """
+        Returns the data associated with a node
+        """
+        return self.nodes[node][2]
+
+    def edge_data(self, edge):
+        """
+        Returns the data associated with an edge
+        """
+        return self.edges[edge][2]
+
+    def update_edge_data(self, edge, edge_data):
+        """
+        Replace the edge data for a specific edge
+        """
+        self.edges[edge] = self.edges[edge][0:2] + (edge_data,)
+
+    def head(self, edge):
+        """
+        Returns the node of the head of the edge.
+        """
+        return self.edges[edge][0]
+
+    def tail(self, edge):
+        """
+        Returns node of the tail of the edge.
+        """
+        return self.edges[edge][1]
+
+    def out_nbrs(self, node):
+        """
+        List of nodes connected by outgoing edges
+        """
+        return [self.tail(n) for n in self.out_edges(node)]
+
+    def inc_nbrs(self, node):
+        """
+        List of nodes connected by incoming edges
+        """
+        return [self.head(n) for n in self.inc_edges(node)]
+
+    def all_nbrs(self, node):
+        """
+        List of nodes connected by incoming and outgoing edges
+        """
+        return list(dict.fromkeys(self.inc_nbrs(node) + self.out_nbrs(node)))
+
+    def out_edges(self, node):
+        """
+        Returns a list of the outgoing edges
+        """
+        try:
+            return list(self.nodes[node][1])
+        except KeyError:
+            raise GraphError("Invalid node %s" % node)
+
+    def inc_edges(self, node):
+        """
+        Returns a list of the incoming edges
+        """
+        try:
+            return list(self.nodes[node][0])
+        except KeyError:
+            raise GraphError("Invalid node %s" % node)
+
+    def all_edges(self, node):
+        """
+        Returns a list of incoming and outging edges.
+        """
+        return set(self.inc_edges(node) + self.out_edges(node))
+
+    def out_degree(self, node):
+        """
+        Returns the number of outgoing edges
+        """
+        return len(self.out_edges(node))
+
+    def inc_degree(self, node):
+        """
+        Returns the number of incoming edges
+        """
+        return len(self.inc_edges(node))
+
+    def all_degree(self, node):
+        """
+        The total degree of a node
+        """
+        return self.inc_degree(node) + self.out_degree(node)
+
+    def _topo_sort(self, forward=True):
+        """
+        Topological sort.
+
+        Returns a list of nodes where the successors (based on outgoing and
+        incoming edges selected by the forward parameter) of any given node
+        appear in the sequence after that node.
+        """
+        topo_list = []
+        queue = deque()
+        indeg = {}
+
+        # select the operation that will be performed
+        if forward:
+            get_edges = self.out_edges
+            get_degree = self.inc_degree
+            get_next = self.tail
+        else:
+            get_edges = self.inc_edges
+            get_degree = self.out_degree
+            get_next = self.head
+
+        for node in self.node_list():
+            degree = get_degree(node)
+            if degree:
+                indeg[node] = degree
+            else:
+                queue.append(node)
+
+        while queue:
+            curr_node = queue.popleft()
+            topo_list.append(curr_node)
+            for edge in get_edges(curr_node):
+                tail_id = get_next(edge)
+                if tail_id in indeg:
+                    indeg[tail_id] -= 1
+                    if indeg[tail_id] == 0:
+                        queue.append(tail_id)
+
+        if len(topo_list) == len(self.node_list()):
+            valid = True
+        else:
+            # the graph has cycles, invalid topological sort
+            valid = False
+
+        return (valid, topo_list)
+
+    def forw_topo_sort(self):
+        """
+        Topological sort.
+
+        Returns a list of nodes where the successors (based on outgoing edges)
+        of any given node appear in the sequence after that node.
+        """
+        return self._topo_sort(forward=True)
+
+    def back_topo_sort(self):
+        """
+        Reverse topological sort.
+
+        Returns a list of nodes where the successors (based on incoming edges)
+        of any given node appear in the sequence after that node.
+        """
+        return self._topo_sort(forward=False)
+
+    def _bfs_subgraph(self, start_id, forward=True):
+        """
+        Private method creates a subgraph in a bfs order.
+
+        The forward parameter specifies whether it is a forward or backward
+        traversal.
+        """
+        if forward:
+            get_bfs = self.forw_bfs
+            get_nbrs = self.out_nbrs
+        else:
+            get_bfs = self.back_bfs
+            get_nbrs = self.inc_nbrs
+
+        g = Graph()
+        bfs_list = get_bfs(start_id)
+        for node in bfs_list:
+            g.add_node(node)
+
+        for node in bfs_list:
+            for nbr_id in get_nbrs(node):
+                if forward:
+                    g.add_edge(node, nbr_id)
+                else:
+                    g.add_edge(nbr_id, node)
+
+        return g
+
+    def forw_bfs_subgraph(self, start_id):
+        """
+        Creates and returns a subgraph consisting of the breadth first
+        reachable nodes based on their outgoing edges.
+        """
+        return self._bfs_subgraph(start_id, forward=True)
+
+    def back_bfs_subgraph(self, start_id):
+        """
+        Creates and returns a subgraph consisting of the breadth first
+        reachable nodes based on the incoming edges.
+        """
+        return self._bfs_subgraph(start_id, forward=False)
+
+    def iterdfs(self, start, end=None, forward=True):
+        """
+        Collecting nodes in some depth first traversal.
+
+        The forward parameter specifies whether it is a forward or backward
+        traversal.
+        """
+        visited, stack = {start}, deque([start])
+
+        if forward:
+            get_edges = self.out_edges
+            get_next = self.tail
+        else:
+            get_edges = self.inc_edges
+            get_next = self.head
+
+        while stack:
+            curr_node = stack.pop()
+            yield curr_node
+            if curr_node == end:
+                break
+            for edge in sorted(get_edges(curr_node)):
+                tail = get_next(edge)
+                if tail not in visited:
+                    visited.add(tail)
+                    stack.append(tail)
+
+    def iterdata(self, start, end=None, forward=True, condition=None):
+        """
+        Perform a depth-first walk of the graph (as ``iterdfs``)
+        and yield the item data of every node where condition matches. The
+        condition callback is only called when node_data is not None.
+        """
+
+        visited, stack = {start}, deque([start])
+
+        if forward:
+            get_edges = self.out_edges
+            get_next = self.tail
+        else:
+            get_edges = self.inc_edges
+            get_next = self.head
+
+        get_data = self.node_data
+
+        while stack:
+            curr_node = stack.pop()
+            curr_data = get_data(curr_node)
+            if curr_data is not None:
+                if condition is not None and not condition(curr_data):
+                    continue
+                yield curr_data
+            if curr_node == end:
+                break
+            for edge in get_edges(curr_node):
+                tail = get_next(edge)
+                if tail not in visited:
+                    visited.add(tail)
+                    stack.append(tail)
+
+    def _iterbfs(self, start, end=None, forward=True):
+        """
+        The forward parameter specifies whether it is a forward or backward
+        traversal.  Returns a list of tuples where the first value is the hop
+        value the second value is the node id.
+        """
+        queue, visited = deque([(start, 0)]), {start}
+
+        # the direction of the bfs depends on the edges that are sampled
+        if forward:
+            get_edges = self.out_edges
+            get_next = self.tail
+        else:
+            get_edges = self.inc_edges
+            get_next = self.head
+
+        while queue:
+            curr_node, curr_step = queue.popleft()
+            yield (curr_node, curr_step)
+            if curr_node == end:
+                break
+            for edge in get_edges(curr_node):
+                tail = get_next(edge)
+                if tail not in visited:
+                    visited.add(tail)
+                    queue.append((tail, curr_step + 1))
+
+    def forw_bfs(self, start, end=None):
+        """
+        Returns a list of nodes in some forward BFS order.
+
+        Starting from the start node the breadth first search proceeds along
+        outgoing edges.
+        """
+        return [node for node, step in self._iterbfs(start, end, forward=True)]
+
+    def back_bfs(self, start, end=None):
+        """
+        Returns a list of nodes in some backward BFS order.
+
+        Starting from the start node the breadth first search proceeds along
+        incoming edges.
+        """
+        return [node for node, _ in self._iterbfs(start, end, forward=False)]
+
+    def forw_dfs(self, start, end=None):
+        """
+        Returns a list of nodes in some forward DFS order.
+
+        Starting with the start node the depth first search proceeds along
+        outgoing edges.
+        """
+        return list(self.iterdfs(start, end, forward=True))
+
+    def back_dfs(self, start, end=None):
+        """
+        Returns a list of nodes in some backward DFS order.
+
+        Starting from the start node the depth first search proceeds along
+        incoming edges.
+        """
+        return list(self.iterdfs(start, end, forward=False))
+
+    def connected(self):
+        """
+        Returns :py:data:`True` if the graph's every node can be reached from
+        every other node.
+        """
+        node_list = self.node_list()
+        for node in node_list:
+            bfs_list = self.forw_bfs(node)
+            if len(bfs_list) != len(node_list):
+                return False
+        return True
+
+    def clust_coef(self, node):
+        """
+        Computes and returns the local clustering coefficient of node.
+
+        The local cluster coefficient is proportion of the actual number of
+        edges between neighbours of node and the maximum number of edges
+        between those neighbours.
+
+        See "Local Clustering Coefficient" on
+        <http://en.wikipedia.org/wiki/Clustering_coefficient>
+        for a formal definition.
+        """
+        num = 0
+        nbr_set = set(self.out_nbrs(node))
+
+        if node in nbr_set:
+            nbr_set.remove(node)  # loop defense
+
+        for nbr in nbr_set:
+            sec_set = set(self.out_nbrs(nbr))
+            if nbr in sec_set:
+                sec_set.remove(nbr)  # loop defense
+            num += len(nbr_set & sec_set)
+
+        nbr_num = len(nbr_set)
+        if nbr_num:
+            clust_coef = float(num) / (nbr_num * (nbr_num - 1))
+        else:
+            clust_coef = 0.0
+        return clust_coef
+
+    def get_hops(self, start, end=None, forward=True):
+        """
+        Computes the hop distance to all nodes centered around a node.
+
+        First order neighbours are at hop 1, their neigbours are at hop 2 etc.
+        Uses :py:meth:`forw_bfs` or :py:meth:`back_bfs` depending on the value
+        of the forward parameter.  If the distance between all neighbouring
+        nodes is 1 the hop number corresponds to the shortest distance between
+        the nodes.
+
+        :param start: the starting node
+        :param end: ending node (optional). When not specified will search the
+            whole graph.
+        :param forward: directionality parameter (optional).
+            If C{True} (default) it uses L{forw_bfs} otherwise L{back_bfs}.
+        :return: returns a list of tuples where each tuple contains the
+            node and the hop.
+
+        Typical usage::
+
+            >>> print (graph.get_hops(1, 8))
+            >>> [(1, 0), (2, 1), (3, 1), (4, 2), (5, 3), (7, 4), (8, 5)]
+            # node 1 is at 0 hops
+            # node 2 is at 1 hop
+            # ...
+            # node 8 is at 5 hops
+        """
+        if forward:
+            return list(self._iterbfs(start=start, end=end, forward=True))
+        else:
+            return list(self._iterbfs(start=start, end=end, forward=False))
diff --git a/lib/spack/external/_vendoring/altgraph/GraphAlgo.py b/lib/spack/external/_vendoring/altgraph/GraphAlgo.py
new file mode 100644
index 0000000000..f93e73dcda
--- /dev/null
+++ b/lib/spack/external/_vendoring/altgraph/GraphAlgo.py
@@ -0,0 +1,171 @@
+"""
+altgraph.GraphAlgo - Graph algorithms
+=====================================
+"""
+from altgraph import GraphError
+
+
+def dijkstra(graph, start, end=None):
+    """
+    Dijkstra's algorithm for shortest paths
+
+    `David Eppstein, UC Irvine, 4 April 2002
+        <http://www.ics.uci.edu/~eppstein/161/python/>`_
+
+    `Python Cookbook Recipe
+        <http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/119466>`_
+
+    Find shortest paths from the  start node to all nodes nearer than or
+    equal to the end node.
+
+    Dijkstra's algorithm is only guaranteed to work correctly when all edge
+    lengths are positive.  This code does not verify this property for all
+    edges (only the edges examined until the end vertex is reached), but will
+    correctly compute shortest paths even for some graphs with negative edges,
+    and will raise an exception if it discovers that a negative edge has
+    caused it to make a mistake.
+
+    Adapted to altgraph by Istvan Albert, Pennsylvania State University -
+    June, 9 2004
+    """
+    D = {}  # dictionary of final distances
+    P = {}  # dictionary of predecessors
+    Q = _priorityDictionary()  # estimated distances of non-final vertices
+    Q[start] = 0
+
+    for v in Q:
+        D[v] = Q[v]
+        if v == end:
+            break
+
+        for w in graph.out_nbrs(v):
+            edge_id = graph.edge_by_node(v, w)
+            vwLength = D[v] + graph.edge_data(edge_id)
+            if w in D:
+                if vwLength < D[w]:
+                    raise GraphError(
+                        "Dijkstra: found better path to already-final vertex"
+                    )
+            elif w not in Q or vwLength < Q[w]:
+                Q[w] = vwLength
+                P[w] = v
+
+    return (D, P)
+
+
+def shortest_path(graph, start, end):
+    """
+    Find a single shortest path from the *start* node to the *end* node.
+    The input has the same conventions as dijkstra(). The output is a list of
+    the nodes in order along the shortest path.
+
+    **Note that the distances must be stored in the edge data as numeric data**
+    """
+
+    D, P = dijkstra(graph, start, end)
+    Path = []
+    while 1:
+        Path.append(end)
+        if end == start:
+            break
+        end = P[end]
+    Path.reverse()
+    return Path
+
+
+#
+# Utility classes and functions
+#
+class _priorityDictionary(dict):
+    """
+    Priority dictionary using binary heaps (internal use only)
+
+    David Eppstein, UC Irvine, 8 Mar 2002
+
+    Implements a data structure that acts almost like a dictionary, with
+    two modifications:
+
+        1. D.smallest() returns the value x minimizing D[x].  For this to
+           work correctly, all values D[x] stored in the dictionary must be
+           comparable.
+
+        2. iterating "for x in D" finds and removes the items from D in sorted
+           order. Each item is not removed until the next item is requested,
+           so D[x] will still return a useful value until the next iteration
+           of the for-loop.  Each operation takes logarithmic amortized time.
+    """
+
+    def __init__(self):
+        """
+        Initialize priorityDictionary by creating binary heap of pairs
+        (value,key).  Note that changing or removing a dict entry will not
+        remove the old pair from the heap until it is found by smallest()
+        or until the heap is rebuilt.
+        """
+        self.__heap = []
+        dict.__init__(self)
+
+    def smallest(self):
+        """
+        Find smallest item after removing deleted items from front of heap.
+        """
+        if len(self) == 0:
+            raise IndexError("smallest of empty priorityDictionary")
+        heap = self.__heap
+        while heap[0][1] not in self or self[heap[0][1]] != heap[0][0]:
+            lastItem = heap.pop()
+            insertionPoint = 0
+            while 1:
+                smallChild = 2 * insertionPoint + 1
+                if (
+                    smallChild + 1 < len(heap)
+                    and heap[smallChild] > heap[smallChild + 1]
+                ):
+                    smallChild += 1
+                if smallChild >= len(heap) or lastItem <= heap[smallChild]:
+                    heap[insertionPoint] = lastItem
+                    break
+                heap[insertionPoint] = heap[smallChild]
+                insertionPoint = smallChild
+        return heap[0][1]
+
+    def __iter__(self):
+        """
+        Create destructive sorted iterator of priorityDictionary.
+        """
+
+        def iterfn():
+            while len(self) > 0:
+                x = self.smallest()
+                yield x
+                del self[x]
+
+        return iterfn()
+
+    def __setitem__(self, key, val):
+        """
+        Change value stored in dictionary and add corresponding pair to heap.
+        Rebuilds the heap if the number of deleted items gets large, to avoid
+        memory leakage.
+        """
+        dict.__setitem__(self, key, val)
+        heap = self.__heap
+        if len(heap) > 2 * len(self):
+            self.__heap = [(v, k) for k, v in self.items()]
+            self.__heap.sort()
+        else:
+            newPair = (val, key)
+            insertionPoint = len(heap)
+            heap.append(None)
+            while insertionPoint > 0 and newPair < heap[(insertionPoint - 1) // 2]:
+                heap[insertionPoint] = heap[(insertionPoint - 1) // 2]
+                insertionPoint = (insertionPoint - 1) // 2
+            heap[insertionPoint] = newPair
+
+    def setdefault(self, key, val):
+        """
+        Reimplement setdefault to pass through our customized __setitem__.
+        """
+        if key not in self:
+            self[key] = val
+        return self[key]
diff --git a/lib/spack/external/_vendoring/altgraph/GraphStat.py b/lib/spack/external/_vendoring/altgraph/GraphStat.py
new file mode 100644
index 0000000000..577464b41e
--- /dev/null
+++ b/lib/spack/external/_vendoring/altgraph/GraphStat.py
@@ -0,0 +1,73 @@
+"""
+altgraph.GraphStat - Functions providing various graph statistics
+=================================================================
+"""
+
+
+def degree_dist(graph, limits=(0, 0), bin_num=10, mode="out"):
+    """
+    Computes the degree distribution for a graph.
+
+    Returns a list of tuples where the first element of the tuple is the
+    center of the bin representing a range of degrees and the second element
+    of the tuple are the number of nodes with the degree falling in the range.
+
+    Example::
+
+        ....
+    """
+
+    deg = []
+    if mode == "inc":
+        get_deg = graph.inc_degree
+    else:
+        get_deg = graph.out_degree
+
+    for node in graph:
+        deg.append(get_deg(node))
+
+    if not deg:
+        return []
+
+    results = _binning(values=deg, limits=limits, bin_num=bin_num)
+
+    return results
+
+
+_EPS = 1.0 / (2.0 ** 32)
+
+
+def _binning(values, limits=(0, 0), bin_num=10):
+    """
+    Bins data that falls between certain limits, if the limits are (0, 0) the
+    minimum and maximum values are used.
+
+    Returns a list of tuples where the first element of the tuple is the
+    center of the bin and the second element of the tuple are the counts.
+    """
+    if limits == (0, 0):
+        min_val, max_val = min(values) - _EPS, max(values) + _EPS
+    else:
+        min_val, max_val = limits
+
+    # get bin size
+    bin_size = (max_val - min_val) / float(bin_num)
+    bins = [0] * (bin_num)
+
+    # will ignore these outliers for now
+    for value in values:
+        try:
+            if (value - min_val) >= 0:
+                index = int((value - min_val) / float(bin_size))
+                bins[index] += 1
+        except IndexError:
+            pass
+
+    # make it ready for an x,y plot
+    result = []
+    center = (bin_size / 2) + min_val
+    for i, y in enumerate(bins):
+        x = center + bin_size * i
+        result.append((x, y))
+
+    return result
diff --git a/lib/spack/external/_vendoring/altgraph/GraphUtil.py b/lib/spack/external/_vendoring/altgraph/GraphUtil.py
new file mode 100644
index 0000000000..cfd6a34f3c
--- /dev/null
+++ b/lib/spack/external/_vendoring/altgraph/GraphUtil.py
@@ -0,0 +1,139 @@
+"""
+altgraph.GraphUtil - Utility classes and functions
+==================================================
+"""
+
+import random
+from collections import deque
+
+from altgraph import Graph, GraphError
+
+
+def generate_random_graph(node_num, edge_num, self_loops=False, multi_edges=False):
+    """
+    Generates and returns a :py:class:`~altgraph.Graph.Graph` instance with
+    *node_num* nodes randomly connected by *edge_num* edges.
+    """
+    g = Graph.Graph()
+
+    if not multi_edges:
+        if self_loops:
+            max_edges = node_num * node_num
+        else:
+            max_edges = node_num * (node_num - 1)
+
+        if edge_num > max_edges:
+            raise GraphError("inconsistent arguments to 'generate_random_graph'")
+
+    nodes = range(node_num)
+
+    for node in nodes:
+        g.add_node(node)
+
+    while 1:
+        head = random.choice(nodes)
+        tail = random.choice(nodes)
+
+        # loop defense
+        if head == tail and not self_loops:
+            continue
+
+        # multiple edge defense
+        if g.edge_by_node(head, tail) is not None and not multi_edges:
+            continue
+
+        # add the edge
+        g.add_edge(head, tail)
+        if g.number_of_edges() >= edge_num:
+            break
+
+    return g
+
+
+def generate_scale_free_graph(steps, growth_num, self_loops=False, multi_edges=False):
+    """
+    Generates and returns a :py:class:`~altgraph.Graph.Graph` instance that
+    will have *steps* \\* *growth_num* nodes and a scale free (powerlaw)
+    connectivity. Starting with a fully connected graph with *growth_num*
+    nodes at every step *growth_num* nodes are added to the graph and are
+    connected to existing nodes with a probability proportional to the degree
+    of these existing nodes.
+    """
+    # The code doesn't seem to do what the documentation claims.
+    graph = Graph.Graph()
+
+    # initialize the graph
+    store = []
+    for i in range(growth_num):
+        for j in range(i + 1, growth_num):
+            store.append(i)
+            store.append(j)
+            graph.add_edge(i, j)
+
+    # generate
+    for node in range(growth_num, steps * growth_num):
+        graph.add_node(node)
+        while graph.out_degree(node) < growth_num:
+            nbr = random.choice(store)
+
+            # loop defense
+            if node == nbr and not self_loops:
+                continue
+
+            # multi edge defense
+            if graph.edge_by_node(node, nbr) and not multi_edges:
+                continue
+
+            graph.add_edge(node, nbr)
+
+        for nbr in graph.out_nbrs(node):
+            store.append(node)
+            store.append(nbr)
+
+    return graph
+
+
+def filter_stack(graph, head, filters):
+    """
+    Perform a walk in a depth-first order starting
+    at *head*.
+
+    Returns (visited, removes, orphans).
+
+    * visited: the set of visited nodes
+    * removes: the list of nodes where the node
+      data does not all *filters*
+    * orphans: tuples of (last_good, node),
+      where node is not in removes, is directly
+      reachable from a node in *removes* and
+      *last_good* is the closest upstream node that is not
+      in *removes*.
+    """
+
+    visited, removes, orphans = {head}, set(), set()
+    stack = deque([(head, head)])
+    get_data = graph.node_data
+    get_edges = graph.out_edges
+    get_tail = graph.tail
+
+    while stack:
+        last_good, node = stack.pop()
+        data = get_data(node)
+        if data is not None:
+            for filtfunc in filters:
+                if not filtfunc(data):
+                    removes.add(node)
+                    break
+            else:
+                last_good = node
+        for edge in get_edges(node):
+            tail = get_tail(edge)
+            if last_good is not node:
+                orphans.add((last_good, tail))
+            if tail not in visited:
+                visited.add(tail)
+                stack.append((last_good, tail))
+
+    orphans = [(lg, tl) for (lg, tl) in orphans if tl not in removes]
+
+    return visited, removes, orphans
diff --git a/lib/spack/external/_vendoring/altgraph/LICENSE b/lib/spack/external/_vendoring/altgraph/LICENSE
new file mode 100644
index 0000000000..6013a212b8
--- /dev/null
+++ b/lib/spack/external/_vendoring/altgraph/LICENSE
@@ -0,0 +1,18 @@
+Copyright (c) 2004 Istvan Albert unless otherwise noted.
+Copyright (c) 2006-2010 Bob Ippolito
+Copyright (2) 2010-2020 Ronald Oussoren, et. al.
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to
+deal in the Software without restriction, including without limitation the
+rights to use, copy, modify, merge, publish, distribute, sublicense,
+and/or sell copies of the Software, and to permit persons to whom the
+Software is furnished to do so.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+IN THE SOFTWARE.
diff --git a/lib/spack/external/_vendoring/altgraph/ObjectGraph.py b/lib/spack/external/_vendoring/altgraph/ObjectGraph.py
new file mode 100644
index 0000000000..379b05b129
--- /dev/null
+++ b/lib/spack/external/_vendoring/altgraph/ObjectGraph.py
@@ -0,0 +1,212 @@
+"""
+altgraph.ObjectGraph - Graph of objects with an identifier
+==========================================================
+
+A graph of objects that have a "graphident" attribute.
+graphident is the key for the object in the graph
+"""
+
+from altgraph import GraphError
+from altgraph.Graph import Graph
+from altgraph.GraphUtil import filter_stack
+
+
+class ObjectGraph(object):
+    """
+    A graph of objects that have a "graphident" attribute.
+    graphident is the key for the object in the graph
+    """
+
+    def __init__(self, graph=None, debug=0):
+        if graph is None:
+            graph = Graph()
+        self.graphident = self
+        self.graph = graph
+        self.debug = debug
+        self.indent = 0
+        graph.add_node(self, None)
+
+    def __repr__(self):
+        return "<%s>" % (type(self).__name__,)
+
+    def flatten(self, condition=None, start=None):
+        """
+        Iterate over the subgraph that is entirely reachable by condition
+        starting from the given start node or the ObjectGraph root
+        """
+        if start is None:
+            start = self
+        start = self.getRawIdent(start)
+        return self.graph.iterdata(start=start, condition=condition)
+
+    def nodes(self):
+        for ident in self.graph:
+            node = self.graph.node_data(ident)
+            if node is not None:
+                yield self.graph.node_data(ident)
+
+    def get_edges(self, node):
+        if node is None:
+            node = self
+        start = self.getRawIdent(node)
+        _, _, outraw, incraw = self.graph.describe_node(start)
+
+        def iter_edges(lst, n):
+            seen = set()
+            for tpl in (self.graph.describe_edge(e) for e in lst):
+                ident = tpl[n]
+                if ident not in seen:
+                    yield self.findNode(ident)
+                    seen.add(ident)
+
+        return iter_edges(outraw, 3), iter_edges(incraw, 2)
+
+    def edgeData(self, fromNode, toNode):
+        if fromNode is None:
+            fromNode = self
+        start = self.getRawIdent(fromNode)
+        stop = self.getRawIdent(toNode)
+        edge = self.graph.edge_by_node(start, stop)
+        return self.graph.edge_data(edge)
+
+    def updateEdgeData(self, fromNode, toNode, edgeData):
+        if fromNode is None:
+            fromNode = self
+        start = self.getRawIdent(fromNode)
+        stop = self.getRawIdent(toNode)
+        edge = self.graph.edge_by_node(start, stop)
+        self.graph.update_edge_data(edge, edgeData)
+
+    def filterStack(self, filters):
+        """
+        Filter the ObjectGraph in-place by removing all edges to nodes that
+        do not match every filter in the given filter list
+
+        Returns a tuple containing the number of:
+            (nodes_visited, nodes_removed, nodes_orphaned)
+        """
+        visited, removes, orphans = filter_stack(self.graph, self, filters)
+
+        for last_good, tail in orphans:
+            self.graph.add_edge(last_good, tail, edge_data="orphan")
+
+        for node in removes:
+            self.graph.hide_node(node)
+
+        return len(visited) - 1, len(removes), len(orphans)
+
+    def removeNode(self, node):
+        """
+        Remove the given node from the graph if it exists
+        """
+        ident = self.getIdent(node)
+        if ident is not None:
+            self.graph.hide_node(ident)
+
+    def removeReference(self, fromnode, tonode):
+        """
+        Remove all edges from fromnode to tonode
+        """
+        if fromnode is None:
+            fromnode = self
+        fromident = self.getIdent(fromnode)
+        toident = self.getIdent(tonode)
+        if fromident is not None and toident is not None:
+            while True:
+                edge = self.graph.edge_by_node(fromident, toident)
+                if edge is None:
+                    break
+                self.graph.hide_edge(edge)
+
+    def getIdent(self, node):
+        """
+        Get the graph identifier for a node
+        """
+        ident = self.getRawIdent(node)
+        if ident is not None:
+            return ident
+        node = self.findNode(node)
+        if node is None:
+            return None
+        return node.graphident
+
+    def getRawIdent(self, node):
+        """
+        Get the identifier for a node object
+        """
+        if node is self:
+            return node
+        ident = getattr(node, "graphident", None)
+        return ident
+
+    def __contains__(self, node):
+        return self.findNode(node) is not None
+
+    def findNode(self, node):
+        """
+        Find the node on the graph
+        """
+        ident = self.getRawIdent(node)
+        if ident is None:
+            ident = node
+        try:
+            return self.graph.node_data(ident)
+        except KeyError:
+            return None
+
+    def addNode(self, node):
+        """
+        Add a node to the graph referenced by the root
+        """
+        self.msg(4, "addNode", node)
+
+        try:
+            self.graph.restore_node(node.graphident)
+        except GraphError:
+            self.graph.add_node(node.graphident, node)
+
+    def createReference(self, fromnode, tonode, edge_data=None):
+        """
+        Create a reference from fromnode to tonode
+        """
+        if fromnode is None:
+            fromnode = self
+        fromident, toident = self.getIdent(fromnode), self.getIdent(tonode)
+        if fromident is None or toident is None:
+            return
+        self.msg(4, "createReference", fromnode, tonode, edge_data)
+        self.graph.add_edge(fromident, toident, edge_data=edge_data)
+
+    def createNode(self, cls, name, *args, **kw):
+        """
+        Add a node of type cls to the graph if it does not already exist
+        by the given name
+        """
+        m = self.findNode(name)
+        if m is None:
+            m = cls(name, *args, **kw)
+            self.addNode(m)
+        return m
+
+    def msg(self, level, s, *args):
+        """
+        Print a debug message with the given level
+        """
+        if s and level <= self.debug:
+            print("%s%s %s" % ("  " * self.indent, s, " ".join(map(repr, args))))
+
+    def msgin(self, level, s, *args):
+        """
+        Print a debug message and indent
+        """
+        if level <= self.debug:
+            self.msg(level, s, *args)
+            self.indent = self.indent + 1
+
+    def msgout(self, level, s, *args):
+        """
+        Dedent and print a debug message
+        """
+        if level <= self.debug:
+            self.indent = self.indent - 1
+            self.msg(level, s, *args)
diff --git a/lib/spack/external/_vendoring/altgraph/__init__.py b/lib/spack/external/_vendoring/altgraph/__init__.py
new file mode 100644
index 0000000000..a56342438b
--- /dev/null
+++ b/lib/spack/external/_vendoring/altgraph/__init__.py
@@ -0,0 +1,148 @@
+"""
+altgraph - a python graph library
+=================================
+
+altgraph is a fork of `graphlib <http://pygraphlib.sourceforge.net>`_ tailored
+to use newer Python 2.3+ features, including additional support used by the
+py2app suite (modulegraph and macholib, specifically).
+
+altgraph is a python based graph (network) representation and manipulation
+package.  It has started out as an extension to the
+`graph_lib module
+<http://www.ece.arizona.edu/~denny/python_nest/graph_lib_1.0.1.html>`_
+written by Nathan Denny it has been significantly optimized and expanded.
+
+The :class:`altgraph.Graph.Graph` class is loosely modeled after the
+`LEDA <http://www.algorithmic-solutions.com/enleda.htm>`_
+(Library of Efficient Datatypes) representation. The library
+includes methods for constructing graphs, BFS and DFS traversals,
+topological sort, finding connected components, shortest paths as well as a
+number graph statistics functions. The library can also visualize graphs
+via `graphviz <http://www.research.att.com/sw/tools/graphviz/>`_.
+
+The package contains the following modules:
+
+    -  the :py:mod:`altgraph.Graph` module contains the
+       :class:`~altgraph.Graph.Graph` class that stores the graph data
+
+    -  the :py:mod:`altgraph.GraphAlgo` module implements graph algorithms
+       operating on graphs (:py:class:`~altgraph.Graph.Graph`} instances)
+
+    -  the :py:mod:`altgraph.GraphStat` module contains functions for
+       computing statistical measures on graphs
+
+    -  the :py:mod:`altgraph.GraphUtil` module contains functions for
+       generating, reading and saving graphs
+
+    -  the :py:mod:`altgraph.Dot` module  contains functions for displaying
+       graphs via `graphviz <http://www.research.att.com/sw/tools/graphviz/>`_
+
+    -  the :py:mod:`altgraph.ObjectGraph` module implements a graph of
+       objects with a unique identifier
+
+Installation
+------------
+
+Download and unpack the archive then type::
+
+    python setup.py install
+
+This will install the library in the default location. For instructions on
+how to customize the install procedure read the output of::
+
+    python setup.py --help install
+
+To verify that the code works run the test suite::
+
+    python setup.py test
+
+Example usage
+-------------
+
+Lets assume that we want to analyze the graph below (links to the full picture)
+GRAPH_IMG.  Our script then might look the following way::
+
+    from altgraph import Graph, GraphAlgo, Dot
+
+    # these are the edges
+    edges = [ (1,2), (2,4), (1,3), (2,4), (3,4), (4,5), (6,5),
+        (6,14), (14,15), (6, 15),  (5,7), (7, 8), (7,13), (12,8),
+        (8,13), (11,12), (11,9), (13,11), (9,13), (13,10) ]
+
+    # creates the graph
+    graph = Graph.Graph()
+    for head, tail in edges:
+        graph.add_edge(head, tail)
+
+    # do a forward bfs from 1 at most to 20
+    print(graph.forw_bfs(1))
+
+This will print the nodes in some breadth first order::
+
+    [1, 2, 3, 4, 5, 7, 8, 13, 11, 10, 12, 9]
+
+If we wanted to get the hop-distance from node 1 to node 8
+we coud write::
+
+    print(graph.get_hops(1, 8))
+
+This will print the following::
+
+    [(1, 0), (2, 1), (3, 1), (4, 2), (5, 3), (7, 4), (8, 5)]
+
+Node 1 is at 0 hops since it is the starting node, nodes 2,3 are 1 hop away ...
+node 8 is 5 hops away. To find the shortest distance between two nodes you
+can use::
+
+    print(GraphAlgo.shortest_path(graph, 1, 12))
+
+It will print the nodes on one (if there are more) the shortest paths::
+
+    [1, 2, 4, 5, 7, 13, 11, 12]
+
+To display the graph we can use the GraphViz backend::
+
+    dot = Dot.Dot(graph)
+
+    # display the graph on the monitor
+    dot.display()
+
+    # save it in an image file
+    dot.save_img(file_name='graph', file_type='gif')
+
+
+
+..
+  @author: U{Istvan Albert<http://www.personal.psu.edu/staff/i/u/iua1/>}
+
+  @license:  MIT License
+
+  Copyright (c) 2004 Istvan Albert unless otherwise noted.
+
+  Permission is hereby granted, free of charge, to any person obtaining a copy
+  of this software and associated documentation files (the "Software"), to
+  deal in the Software without restriction, including without limitation the
+  rights to use, copy, modify, merge, publish, distribute, sublicense,
+  and/or sell copies of the Software, and to permit persons to whom the
+  Software is furnished to do so.
+
+  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+  FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+  IN THE SOFTWARE.
+  @requires: Python 2.3 or higher
+
+  @newfield contributor: Contributors:
+  @contributor: U{Reka Albert <http://www.phys.psu.edu/~ralbert/>}
+
+"""
+import pkg_resources
+
+__version__ = pkg_resources.require("altgraph")[0].version
+
+
+class GraphError(ValueError):
+    pass
diff --git a/lib/spack/external/_vendoring/attr/__init__.py b/lib/spack/external/_vendoring/attr/__init__.py
new file mode 100644
index 0000000000..386305d628
--- /dev/null
+++ b/lib/spack/external/_vendoring/attr/__init__.py
@@ -0,0 +1,79 @@
+# SPDX-License-Identifier: MIT
+
+
+import sys
+
+from functools import partial
+
+from . import converters, exceptions, filters, setters, validators
+from ._cmp import cmp_using
+from ._config import get_run_validators, set_run_validators
+from ._funcs import asdict, assoc, astuple, evolve, has, resolve_types
+from ._make import (
+    NOTHING,
+    Attribute,
+    Factory,
+    attrib,
+    attrs,
+    fields,
+    fields_dict,
+    make_class,
+    validate,
+)
+from ._version_info import VersionInfo
+
+
+__version__ = "22.1.0"
+__version_info__ = VersionInfo._from_version_string(__version__)
+
+__title__ = "attrs"
+__description__ = "Classes Without Boilerplate"
+__url__ = "https://www.attrs.org/"
+__uri__ = __url__
+__doc__ = __description__ + " <" + __uri__ + ">"
+
+__author__ = "Hynek Schlawack"
+__email__ = "hs@ox.cx"
+
+__license__ = "MIT"
+__copyright__ = "Copyright (c) 2015 Hynek Schlawack"
+
+
+s = attributes = attrs
+ib = attr = attrib
+dataclass = partial(attrs, auto_attribs=True)  # happy Easter ;)
+
+__all__ = [
+    "Attribute",
+    "Factory",
+    "NOTHING",
+    "asdict",
+    "assoc",
+    "astuple",
+    "attr",
+    "attrib",
+    "attributes",
+    "attrs",
+    "cmp_using",
+    "converters",
+    "evolve",
+    "exceptions",
+    "fields",
+    "fields_dict",
+    "filters",
+    "get_run_validators",
+    "has",
+    "ib",
+    "make_class",
+    "resolve_types",
+    "s",
+    "set_run_validators",
+    "setters",
+    "validate",
+    "validators",
+]
+
+if sys.version_info[:2] >= (3, 6):
+    from ._next_gen import define, field, frozen, mutable  # noqa: F401
+
+    __all__.extend(("define", "field", "frozen", "mutable"))
diff --git a/lib/spack/external/_vendoring/attr/__init__.pyi b/lib/spack/external/_vendoring/attr/__init__.pyi
new file mode 100644
index 0000000000..03cc4c82d2
--- /dev/null
+++ b/lib/spack/external/_vendoring/attr/__init__.pyi
@@ -0,0 +1,486 @@
+import sys
+
+from typing import (
+    Any,
+    Callable,
+    ClassVar,
+    Dict,
+    Generic,
+    List,
+    Mapping,
+    Optional,
+    Protocol,
+    Sequence,
+    Tuple,
+    Type,
+    TypeVar,
+    Union,
+    overload,
+)
+
+# `import X as X` is required to make these public
+from . import converters as converters
+from . import exceptions as exceptions
+from . import filters as filters
+from . import setters as setters
+from . import validators as validators
+from ._cmp import cmp_using as cmp_using
+from ._version_info import VersionInfo
+
+__version__: str
+__version_info__: VersionInfo
+__title__: str
+__description__: str
+__url__: str
+__uri__: str
+__author__: str
+__email__: str
+__license__: str
+__copyright__: str
+
+_T = TypeVar("_T")
+_C = TypeVar("_C", bound=type)
+
+_EqOrderType = Union[bool, Callable[[Any], Any]]
+_ValidatorType = Callable[[Any, Attribute[_T], _T], Any]
+_ConverterType = Callable[[Any], Any]
+_FilterType = Callable[[Attribute[_T], _T], bool]
+_ReprType = Callable[[Any], str]
+_ReprArgType = Union[bool, _ReprType]
+_OnSetAttrType = Callable[[Any, Attribute[Any], Any], Any]
+_OnSetAttrArgType = Union[
+    _OnSetAttrType, List[_OnSetAttrType], setters._NoOpType
+]
+_FieldTransformer = Callable[
+    [type, List[Attribute[Any]]], List[Attribute[Any]]
+]
+# FIXME: in reality, if multiple validators are passed they must be in a list
+# or tuple, but those are invariant and so would prevent subtypes of
+# _ValidatorType from working when passed in a list or tuple.
+_ValidatorArgType = Union[_ValidatorType[_T], Sequence[_ValidatorType[_T]]]
+
+# A protocol to be able to statically accept an attrs class.
+class AttrsInstance(Protocol):
+    __attrs_attrs__: ClassVar[Any]
+
+# _make --
+
+NOTHING: object
+
+# NOTE: Factory lies about its return type to make this possible:
+# `x: List[int] # = Factory(list)`
+# Work around mypy issue #4554 in the common case by using an overload.
+if sys.version_info >= (3, 8):
+    from typing import Literal
+    @overload
+    def Factory(factory: Callable[[], _T]) -> _T: ...
+    @overload
+    def Factory(
+        factory: Callable[[Any], _T],
+        takes_self: Literal[True],
+    ) -> _T: ...
+    @overload
+    def Factory(
+        factory: Callable[[], _T],
+        takes_self: Literal[False],
+    ) -> _T: ...
+
+else:
+    @overload
+    def Factory(factory: Callable[[], _T]) -> _T: ...
+    @overload
+    def Factory(
+        factory: Union[Callable[[Any], _T], Callable[[], _T]],
+        takes_self: bool = ...,
+    ) -> _T: ...
+
+# Static type inference support via __dataclass_transform__ implemented as per:
+# https://github.com/microsoft/pyright/blob/1.1.135/specs/dataclass_transforms.md
+# This annotation must be applied to all overloads of "define" and "attrs"
+#
+# NOTE: This is a typing construct and does not exist at runtime.  Extensions
+# wrapping attrs decorators should declare a separate __dataclass_transform__
+# signature in the extension module using the specification linked above to
+# provide pyright support.
+def __dataclass_transform__(
+    *,
+    eq_default: bool = True,
+    order_default: bool = False,
+    kw_only_default: bool = False,
+    field_descriptors: Tuple[Union[type, Callable[..., Any]], ...] = (()),
+) -> Callable[[_T], _T]: ...
+
+class Attribute(Generic[_T]):
+    name: str
+    default: Optional[_T]
+    validator: Optional[_ValidatorType[_T]]
+    repr: _ReprArgType
+    cmp: _EqOrderType
+    eq: _EqOrderType
+    order: _EqOrderType
+    hash: Optional[bool]
+    init: bool
+    converter: Optional[_ConverterType]
+    metadata: Dict[Any, Any]
+    type: Optional[Type[_T]]
+    kw_only: bool
+    on_setattr: _OnSetAttrType
+    def evolve(self, **changes: Any) -> "Attribute[Any]": ...
+
+# NOTE: We had several choices for the annotation to use for type arg:
+# 1) Type[_T]
+#   - Pros: Handles simple cases correctly
+#   - Cons: Might produce less informative errors in the case of conflicting
+#     TypeVars e.g. `attr.ib(default='bad', type=int)`
+# 2) Callable[..., _T]
+#   - Pros: Better error messages than #1 for conflicting TypeVars
+#   - Cons: Terrible error messages for validator checks.
+#   e.g. attr.ib(type=int, validator=validate_str)
+#        -> error: Cannot infer function type argument
+# 3) type (and do all of the work in the mypy plugin)
+#   - Pros: Simple here, and we could customize the plugin with our own errors.
+#   - Cons: Would need to write mypy plugin code to handle all the cases.
+# We chose option #1.
+
+# `attr` lies about its return type to make the following possible:
+#     attr()    -> Any
+#     attr(8)   -> int
+#     attr(validator=<some callable>)  -> Whatever the callable expects.
+# This makes this type of assignments possible:
+#     x: int = attr(8)
+#
+# This form catches explicit None or no default but with no other arguments
+# returns Any.
+@overload
+def attrib(
+    default: None = ...,
+    validator: None = ...,
+    repr: _ReprArgType = ...,
+    cmp: Optional[_EqOrderType] = ...,
+    hash: Optional[bool] = ...,
+    init: bool = ...,
+    metadata: Optional[Mapping[Any, Any]] = ...,
+    type: None = ...,
+    converter: None = ...,
+    factory: None = ...,
+    kw_only: bool = ...,
+    eq: Optional[_EqOrderType] = ...,
+    order: Optional[_EqOrderType] = ...,
+    on_setattr: Optional[_OnSetAttrArgType] = ...,
+) -> Any: ...
+
+# This form catches an explicit None or no default and infers the type from the
+# other arguments.
+@overload
+def attrib(
+    default: None = ...,
+    validator: Optional[_ValidatorArgType[_T]] = ...,
+    repr: _ReprArgType = ...,
+    cmp: Optional[_EqOrderType] = ...,
+    hash: Optional[bool] = ...,
+    init: bool = ...,
+    metadata: Optional[Mapping[Any, Any]] = ...,
+    type: Optional[Type[_T]] = ...,
+    converter: Optional[_ConverterType] = ...,
+    factory: Optional[Callable[[], _T]] = ...,
+    kw_only: bool = ...,
+    eq: Optional[_EqOrderType] = ...,
+    order: Optional[_EqOrderType] = ...,
+    on_setattr: Optional[_OnSetAttrArgType] = ...,
+) -> _T: ...
+
+# This form catches an explicit default argument.
+@overload
+def attrib(
+    default: _T,
+    validator: Optional[_ValidatorArgType[_T]] = ...,
+    repr: _ReprArgType = ...,
+    cmp: Optional[_EqOrderType] = ...,
+    hash: Optional[bool] = ...,
+    init: bool = ...,
+    metadata: Optional[Mapping[Any, Any]] = ...,
+    type: Optional[Type[_T]] = ...,
+    converter: Optional[_ConverterType] = ...,
+    factory: Optional[Callable[[], _T]] = ...,
+    kw_only: bool = ...,
+    eq: Optional[_EqOrderType] = ...,
+    order: Optional[_EqOrderType] = ...,
+    on_setattr: Optional[_OnSetAttrArgType] = ...,
+) -> _T: ...
+
+# This form covers type=non-Type: e.g. forward references (str), Any
+@overload
+def attrib(
+    default: Optional[_T] = ...,
+    validator: Optional[_ValidatorArgType[_T]] = ...,
+    repr: _ReprArgType = ...,
+    cmp: Optional[_EqOrderType] = ...,
+    hash: Optional[bool] = ...,
+    init: bool = ...,
+    metadata: Optional[Mapping[Any, Any]] = ...,
+    type: object = ...,
+    converter: Optional[_ConverterType] = ...,
+    factory: Optional[Callable[[], _T]] = ...,
+    kw_only: bool = ...,
+    eq: Optional[_EqOrderType] = ...,
+    order: Optional[_EqOrderType] = ...,
+    on_setattr: Optional[_OnSetAttrArgType] = ...,
+) -> Any: ...
+@overload
+def field(
+    *,
+    default: None = ...,
+    validator: None = ...,
+    repr: _ReprArgType = ...,
+    hash: Optional[bool] = ...,
+    init: bool = ...,
+    metadata: Optional[Mapping[Any, Any]] = ...,
+    converter: None = ...,
+    factory: None = ...,
+    kw_only: bool = ...,
+    eq: Optional[bool] = ...,
+    order: Optional[bool] = ...,
+    on_setattr: Optional[_OnSetAttrArgType] = ...,
+) -> Any: ...
+
+# This form catches an explicit None or no default and infers the type from the
+# other arguments.
+@overload
+def field(
+    *,
+    default: None = ...,
+    validator: Optional[_ValidatorArgType[_T]] = ...,
+    repr: _ReprArgType = ...,
+    hash: Optional[bool] = ...,
+    init: bool = ...,
+    metadata: Optional[Mapping[Any, Any]] = ...,
+    converter: Optional[_ConverterType] = ...,
+    factory: Optional[Callable[[], _T]] = ...,
+    kw_only: bool = ...,
+    eq: Optional[_EqOrderType] = ...,
+    order: Optional[_EqOrderType] = ...,
+    on_setattr: Optional[_OnSetAttrArgType] = ...,
+) -> _T: ...
+
+# This form catches an explicit default argument.
+@overload
+def field(
+    *,
+    default: _T,
+    validator: Optional[_ValidatorArgType[_T]] = ...,
+    repr: _ReprArgType = ...,
+    hash: Optional[bool] = ...,
+    init: bool = ...,
+    metadata: Optional[Mapping[Any, Any]] = ...,
+    converter: Optional[_ConverterType] = ...,
+    factory: Optional[Callable[[], _T]] = ...,
+    kw_only: bool = ...,
+    eq: Optional[_EqOrderType] = ...,
+    order: Optional[_EqOrderType] = ...,
+    on_setattr: Optional[_OnSetAttrArgType] = ...,
+) -> _T: ...
+
+# This form covers type=non-Type: e.g. forward references (str), Any
+@overload
+def field(
+    *,
+    default: Optional[_T] = ...,
+    validator: Optional[_ValidatorArgType[_T]] = ...,
+    repr: _ReprArgType = ...,
+    hash: Optional[bool] = ...,
+    init: bool = ...,
+    metadata: Optional[Mapping[Any, Any]] = ...,
+    converter: Optional[_ConverterType] = ...,
+    factory: Optional[Callable[[], _T]] = ...,
+    kw_only: bool = ...,
+    eq: Optional[_EqOrderType] = ...,
+    order: Optional[_EqOrderType] = ...,
+    on_setattr: Optional[_OnSetAttrArgType] = ...,
+) -> Any: ...
+@overload
+@__dataclass_transform__(order_default=True, field_descriptors=(attrib, field))
+def attrs(
+    maybe_cls: _C,
+    these: Optional[Dict[str, Any]] = ...,
+    repr_ns: Optional[str] = ...,
+    repr: bool = ...,
+    cmp: Optional[_EqOrderType] = ...,
+    hash: Optional[bool] = ...,
+    init: bool = ...,
+    slots: bool = ...,
+    frozen: bool = ...,
+    weakref_slot: bool = ...,
+    str: bool = ...,
+    auto_attribs: bool = ...,
+    kw_only: bool = ...,
+    cache_hash: bool = ...,
+    auto_exc: bool = ...,
+    eq: Optional[_EqOrderType] = ...,
+    order: Optional[_EqOrderType] = ...,
+    auto_detect: bool = ...,
+    collect_by_mro: bool = ...,
+    getstate_setstate: Optional[bool] = ...,
+    on_setattr: Optional[_OnSetAttrArgType] = ...,
+    field_transformer: Optional[_FieldTransformer] = ...,
+    match_args: bool = ...,
+) -> _C: ...
+@overload
+@__dataclass_transform__(order_default=True, field_descriptors=(attrib, field))
+def attrs(
+    maybe_cls: None = ...,
+    these: Optional[Dict[str, Any]] = ...,
+    repr_ns: Optional[str] = ...,
+    repr: bool = ...,
+    cmp: Optional[_EqOrderType] = ...,
+    hash: Optional[bool] = ...,
+    init: bool = ...,
+    slots: bool = ...,
+    frozen: bool = ...,
+    weakref_slot: bool = ...,
+    str: bool = ...,
+    auto_attribs: bool = ...,
+    kw_only: bool = ...,
+    cache_hash: bool = ...,
+    auto_exc: bool = ...,
+    eq: Optional[_EqOrderType] = ...,
+    order: Optional[_EqOrderType] = ...,
+    auto_detect: bool = ...,
+    collect_by_mro: bool = ...,
+    getstate_setstate: Optional[bool] = ...,
+    on_setattr: Optional[_OnSetAttrArgType] = ...,
+    field_transformer: Optional[_FieldTransformer] = ...,
+    match_args: bool = ...,
+) -> Callable[[_C], _C]: ...
+@overload
+@__dataclass_transform__(field_descriptors=(attrib, field))
+def define(
+    maybe_cls: _C,
+    *,
+    these: Optional[Dict[str, Any]] = ...,
+    repr: bool = ...,
+    hash: Optional[bool] = ...,
+    init: bool = ...,
+    slots: bool = ...,
+    frozen: bool = ...,
+    weakref_slot: bool = ...,
+    str: bool = ...,
+    auto_attribs: bool = ...,
+    kw_only: bool = ...,
+    cache_hash: bool = ...,
+    auto_exc: bool = ...,
+    eq: Optional[bool] = ...,
+    order: Optional[bool] = ...,
+    auto_detect: bool = ...,
+    getstate_setstate: Optional[bool] = ...,
+    on_setattr: Optional[_OnSetAttrArgType] = ...,
+    field_transformer: Optional[_FieldTransformer] = ...,
+    match_args: bool = ...,
+) -> _C: ...
+@overload
+@__dataclass_transform__(field_descriptors=(attrib, field))
+def define(
+    maybe_cls: None = ...,
+    *,
+    these: Optional[Dict[str, Any]] = ...,
+    repr: bool = ...,
+    hash: Optional[bool] = ...,
+    init: bool = ...,
+    slots: bool = ...,
+    frozen: bool = ...,
+    weakref_slot: bool = ...,
+    str: bool = ...,
+    auto_attribs: bool = ...,
+    kw_only: bool = ...,
+    cache_hash: bool = ...,
+    auto_exc: bool = ...,
+    eq: Optional[bool] = ...,
+    order: Optional[bool] = ...,
+    auto_detect: bool = ...,
+    getstate_setstate: Optional[bool] = ...,
+    on_setattr: Optional[_OnSetAttrArgType] = ...,
+    field_transformer: Optional[_FieldTransformer] = ...,
+    match_args: bool = ...,
+) -> Callable[[_C], _C]: ...
+
+mutable = define
+frozen = define  # they differ only in their defaults
+
+def fields(cls: Type[AttrsInstance]) -> Any: ...
+def fields_dict(cls: Type[AttrsInstance]) -> Dict[str, Attribute[Any]]: ...
+def validate(inst: AttrsInstance) -> None: ...
+def resolve_types(
+    cls: _C,
+    globalns: Optional[Dict[str, Any]] = ...,
+    localns: Optional[Dict[str, Any]] = ...,
+    attribs: Optional[List[Attribute[Any]]] = ...,
+) -> _C: ...
+
+# TODO: add support for returning a proper attrs class from the mypy plugin
+# we use Any instead of _CountingAttr so that e.g. `make_class('Foo',
+# [attr.ib()])` is valid
+def make_class(
+    name: str,
+    attrs: Union[List[str], Tuple[str, ...], Dict[str, Any]],
+    bases: Tuple[type, ...] = ...,
+    repr_ns: Optional[str] = ...,
+    repr: bool = ...,
+    cmp: Optional[_EqOrderType] = ...,
+    hash: Optional[bool] = ...,
+    init: bool = ...,
+    slots: bool = ...,
+    frozen: bool = ...,
+    weakref_slot: bool = ...,
+    str: bool = ...,
+    auto_attribs: bool = ...,
+    kw_only: bool = ...,
+    cache_hash: bool = ...,
+    auto_exc: bool = ...,
+    eq: Optional[_EqOrderType] = ...,
+    order: Optional[_EqOrderType] = ...,
+    collect_by_mro: bool = ...,
+    on_setattr: Optional[_OnSetAttrArgType] = ...,
+    field_transformer: Optional[_FieldTransformer] = ...,
+) -> type: ...
+
+# _funcs --
+
+# TODO: add support for returning TypedDict from the mypy plugin
+# FIXME: asdict/astuple do not honor their factory args. Waiting on one of
+# these:
+# https://github.com/python/mypy/issues/4236
+# https://github.com/python/typing/issues/253
+# XXX: remember to fix attrs.asdict/astuple too!
+def asdict(
+    inst: AttrsInstance,
+    recurse: bool = ...,
+    filter: Optional[_FilterType[Any]] = ...,
+    dict_factory: Type[Mapping[Any, Any]] = ...,
+    retain_collection_types: bool = ...,
+    value_serializer: Optional[
+        Callable[[type, Attribute[Any], Any], Any]
+    ] = ...,
+    tuple_keys: Optional[bool] = ...,
+) -> Dict[str, Any]: ...
+
+# TODO: add support for returning NamedTuple from the mypy plugin
+def astuple(
+    inst: AttrsInstance,
+    recurse: bool = ...,
+    filter: Optional[_FilterType[Any]] = ...,
+    tuple_factory: Type[Sequence[Any]] = ...,
+    retain_collection_types: bool = ...,
+) -> Tuple[Any, ...]: ...
+def has(cls: type) -> bool: ...
+def assoc(inst: _T, **changes: Any) -> _T: ...
+def evolve(inst: _T, **changes: Any) -> _T: ...
+
+# _config --
+
+def set_run_validators(run: bool) -> None: ...
+def get_run_validators() -> bool: ...
+
+# aliases --
+
+s = attributes = attrs
+ib = attr = attrib
+dataclass = attrs  # Technically, partial(attrs, auto_attribs=True) ;)
diff --git a/lib/spack/external/_vendoring/attr/_cmp.py b/lib/spack/external/_vendoring/attr/_cmp.py
new file mode 100644
index 0000000000..81b99e4c33
--- /dev/null
+++ b/lib/spack/external/_vendoring/attr/_cmp.py
@@ -0,0 +1,155 @@
+# SPDX-License-Identifier: MIT
+
+
+import functools
+import types
+
+from ._make import _make_ne
+
+
+_operation_names = {"eq": "==", "lt": "<", "le": "<=", "gt": ">", "ge": ">="}
+
+
+def cmp_using(
+    eq=None,
+    lt=None,
+    le=None,
+    gt=None,
+    ge=None,
+    require_same_type=True,
+    class_name="Comparable",
+):
+    """
+    Create a class that can be passed into `attr.ib`'s ``eq``, ``order``, and
+    ``cmp`` arguments to customize field comparison.
+
+    The resulting class will have a full set of ordering methods if
+    at least one of ``{lt, le, gt, ge}`` and ``eq``  are provided.
+
+    :param Optional[callable] eq: `callable` used to evaluate equality
+        of two objects.
+    :param Optional[callable] lt: `callable` used to evaluate whether
+        one object is less than another object.
+    :param Optional[callable] le: `callable` used to evaluate whether
+        one object is less than or equal to another object.
+    :param Optional[callable] gt: `callable` used to evaluate whether
+        one object is greater than another object.
+    :param Optional[callable] ge: `callable` used to evaluate whether
+        one object is greater than or equal to another object.
+
+    :param bool require_same_type: When `True`, equality and ordering methods
+        will return `NotImplemented` if objects are not of the same type.
+
+    :param Optional[str] class_name: Name of class. Defaults to 'Comparable'.
+
+    See `comparison` for more details.
+
+    .. versionadded:: 21.1.0
+    """
+
+    body = {
+        "__slots__": ["value"],
+        "__init__": _make_init(),
+        "_requirements": [],
+        "_is_comparable_to": _is_comparable_to,
+    }
+
+    # Add operations.
+    num_order_functions = 0
+    has_eq_function = False
+
+    if eq is not None:
+        has_eq_function = True
+        body["__eq__"] = _make_operator("eq", eq)
+        body["__ne__"] = _make_ne()
+
+    if lt is not None:
+        num_order_functions += 1
+        body["__lt__"] = _make_operator("lt", lt)
+
+    if le is not None:
+        num_order_functions += 1
+        body["__le__"] = _make_operator("le", le)
+
+    if gt is not None:
+        num_order_functions += 1
+        body["__gt__"] = _make_operator("gt", gt)
+
+    if ge is not None:
+        num_order_functions += 1
+        body["__ge__"] = _make_operator("ge", ge)
+
+    type_ = types.new_class(
+        class_name, (object,), {}, lambda ns: ns.update(body)
+    )
+
+    # Add same type requirement.
+    if require_same_type:
+        type_._requirements.append(_check_same_type)
+
+    # Add total ordering if at least one operation was defined.
+    if 0 < num_order_functions < 4:
+        if not has_eq_function:
+            # functools.total_ordering requires __eq__ to be defined,
+            # so raise early error here to keep a nice stack.
+            raise ValueError(
+                "eq must be define is order to complete ordering from "
+                "lt, le, gt, ge."
+            )
+        type_ = functools.total_ordering(type_)
+
+    return type_
+
+
+def _make_init():
+    """
+    Create __init__ method.
+    """
+
+    def __init__(self, value):
+        """
+        Initialize object with *value*.
+        """
+        self.value = value
+
+    return __init__
+
+
+def _make_operator(name, func):
+    """
+    Create operator method.
+    """
+
+    def method(self, other):
+        if not self._is_comparable_to(other):
+            return NotImplemented
+
+        result = func(self.value, other.value)
+        if result is NotImplemented:
+            return NotImplemented
+
+        return result
+
+    method.__name__ = "__%s__" % (name,)
+    method.__doc__ = "Return a %s b.  Computed by attrs." % (
+        _operation_names[name],
+    )
+
+    return method
+
+
+def _is_comparable_to(self, other):
+    """
+    Check whether `other` is comparable to `self`.
+    """
+    for func in self._requirements:
+        if not func(self, other):
+            return False
+    return True
+
+
+def _check_same_type(self, other):
+    """
+    Return True if *self* and *other* are of the same type, False otherwise.
+    """
+    return other.value.__class__ is self.value.__class__
diff --git a/lib/spack/external/_vendoring/attr/_cmp.pyi b/lib/spack/external/_vendoring/attr/_cmp.pyi
new file mode 100644
index 0000000000..35437eff62
--- /dev/null
+++ b/lib/spack/external/_vendoring/attr/_cmp.pyi
@@ -0,0 +1,13 @@
+from typing import Any, Callable, Optional, Type
+
+_CompareWithType = Callable[[Any, Any], bool]
+
+def cmp_using(
+    eq: Optional[_CompareWithType],
+    lt: Optional[_CompareWithType],
+    le: Optional[_CompareWithType],
+    gt: Optional[_CompareWithType],
+    ge: Optional[_CompareWithType],
+    require_same_type: bool,
+    class_name: str,
+) -> Type: ...
diff --git a/lib/spack/external/_vendoring/attr/_compat.py b/lib/spack/external/_vendoring/attr/_compat.py
new file mode 100644
index 0000000000..5826493257
--- /dev/null
+++ b/lib/spack/external/_vendoring/attr/_compat.py
@@ -0,0 +1,185 @@
+# SPDX-License-Identifier: MIT
+
+
+import inspect
+import platform
+import sys
+import threading
+import types
+import warnings
+
+from collections.abc import Mapping, Sequence  # noqa
+
+
+PYPY = platform.python_implementation() == "PyPy"
+PY36 = sys.version_info[:2] >= (3, 6)
+HAS_F_STRINGS = PY36
+PY310 = sys.version_info[:2] >= (3, 10)
+
+
+if PYPY or PY36:
+    ordered_dict = dict
+else:
+    from collections import OrderedDict
+
+    ordered_dict = OrderedDict
+
+
+def just_warn(*args, **kw):
+    warnings.warn(
+        "Running interpreter doesn't sufficiently support code object "
+        "introspection.  Some features like bare super() or accessing "
+        "__class__ will not work with slotted classes.",
+        RuntimeWarning,
+        stacklevel=2,
+    )
+
+
+class _AnnotationExtractor:
+    """
+    Extract type annotations from a callable, returning None whenever there
+    is none.
+    """
+
+    __slots__ = ["sig"]
+
+    def __init__(self, callable):
+        try:
+            self.sig = inspect.signature(callable)
+        except (ValueError, TypeError):  # inspect failed
+            self.sig = None
+
+    def get_first_param_type(self):
+        """
+        Return the type annotation of the first argument if it's not empty.
+        """
+        if not self.sig:
+            return None
+
+        params = list(self.sig.parameters.values())
+        if params and params[0].annotation is not inspect.Parameter.empty:
+            return params[0].annotation
+
+        return None
+
+    def get_return_type(self):
+        """
+        Return the return type if it's not empty.
+        """
+        if (
+            self.sig
+            and self.sig.return_annotation is not inspect.Signature.empty
+        ):
+            return self.sig.return_annotation
+
+        return None
+
+
+def make_set_closure_cell():
+    """Return a function of two arguments (cell, value) which sets
+    the value stored in the closure cell `cell` to `value`.
+    """
+    # pypy makes this easy. (It also supports the logic below, but
+    # why not do the easy/fast thing?)
+    if PYPY:
+
+        def set_closure_cell(cell, value):
+            cell.__setstate__((value,))
+
+        return set_closure_cell
+
+    # Otherwise gotta do it the hard way.
+
+    # Create a function that will set its first cellvar to `value`.
+    def set_first_cellvar_to(value):
+        x = value
+        return
+
+        # This function will be eliminated as dead code, but
+        # not before its reference to `x` forces `x` to be
+        # represented as a closure cell rather than a local.
+        def force_x_to_be_a_cell():  # pragma: no cover
+            return x
+
+    try:
+        # Extract the code object and make sure our assumptions about
+        # the closure behavior are correct.
+        co = set_first_cellvar_to.__code__
+        if co.co_cellvars != ("x",) or co.co_freevars != ():
+            raise AssertionError  # pragma: no cover
+
+        # Convert this code object to a code object that sets the
+        # function's first _freevar_ (not cellvar) to the argument.
+        if sys.version_info >= (3, 8):
+
+            def set_closure_cell(cell, value):
+                cell.cell_contents = value
+
+        else:
+            args = [co.co_argcount]
+            args.append(co.co_kwonlyargcount)
+            args.extend(
+                [
+                    co.co_nlocals,
+                    co.co_stacksize,
+                    co.co_flags,
+                    co.co_code,
+                    co.co_consts,
+                    co.co_names,
+                    co.co_varnames,
+                    co.co_filename,
+                    co.co_name,
+                    co.co_firstlineno,
+                    co.co_lnotab,
+                    # These two arguments are reversed:
+                    co.co_cellvars,
+                    co.co_freevars,
+                ]
+            )
+            set_first_freevar_code = types.CodeType(*args)
+
+            def set_closure_cell(cell, value):
+                # Create a function using the set_first_freevar_code,
+                # whose first closure cell is `cell`. Calling it will
+                # change the value of that cell.
+                setter = types.FunctionType(
+                    set_first_freevar_code, {}, "setter", (), (cell,)
+                )
+                # And call it to set the cell.
+                setter(value)
+
+        # Make sure it works on this interpreter:
+        def make_func_with_cell():
+            x = None
+
+            def func():
+                return x  # pragma: no cover
+
+            return func
+
+        cell = make_func_with_cell().__closure__[0]
+        set_closure_cell(cell, 100)
+        if cell.cell_contents != 100:
+            raise AssertionError  # pragma: no cover
+
+    except Exception:
+        return just_warn
+    else:
+        return set_closure_cell
+
+
+set_closure_cell = make_set_closure_cell()
+
+# Thread-local global to track attrs instances which are already being repr'd.
+# This is needed because there is no other (thread-safe) way to pass info
+# about the instances that are already being repr'd through the call stack
+# in order to ensure we don't perform infinite recursion.
+#
+# For instance, if an instance contains a dict which contains that instance,
+# we need to know that we're already repr'ing the outside instance from within
+# the dict's repr() call.
+#
+# This lives here rather than in _make.py so that the functions in _make.py
+# don't have a direct reference to the thread-local in their globals dict.
+# If they have such a reference, it breaks cloudpickle.
+repr_context = threading.local()
diff --git a/lib/spack/external/_vendoring/attr/_config.py b/lib/spack/external/_vendoring/attr/_config.py
new file mode 100644
index 0000000000..96d4200773
--- /dev/null
+++ b/lib/spack/external/_vendoring/attr/_config.py
@@ -0,0 +1,31 @@
+# SPDX-License-Identifier: MIT
+
+
+__all__ = ["set_run_validators", "get_run_validators"]
+
+_run_validators = True
+
+
+def set_run_validators(run):
+    """
+    Set whether or not validators are run.  By default, they are run.
+
+    .. deprecated:: 21.3.0 It will not be removed, but it also will not be
+        moved to new ``attrs`` namespace. Use `attrs.validators.set_disabled()`
+        instead.
+    """
+    if not isinstance(run, bool):
+        raise TypeError("'run' must be bool.")
+    global _run_validators
+    _run_validators = run
+
+
+def get_run_validators():
+    """
+    Return whether or not validators are run.
+
+    .. deprecated:: 21.3.0 It will not be removed, but it also will not be
+        moved to new ``attrs`` namespace. Use `attrs.validators.get_disabled()`
+        instead.
+    """
+    return _run_validators
diff --git a/lib/spack/external/_vendoring/attr/_funcs.py b/lib/spack/external/_vendoring/attr/_funcs.py
new file mode 100644
index 0000000000..a982d7cb56
--- /dev/null
+++ b/lib/spack/external/_vendoring/attr/_funcs.py
@@ -0,0 +1,420 @@
+# SPDX-License-Identifier: MIT
+
+
+import copy
+
+from ._make import NOTHING, _obj_setattr, fields
+from .exceptions import AttrsAttributeNotFoundError
+
+
+def asdict(
+    inst,
+    recurse=True,
+    filter=None,
+    dict_factory=dict,
+    retain_collection_types=False,
+    value_serializer=None,
+):
+    """
+    Return the ``attrs`` attribute values of *inst* as a dict.
+
+    Optionally recurse into other ``attrs``-decorated classes.
+
+    :param inst: Instance of an ``attrs``-decorated class.
+    :param bool recurse: Recurse into classes that are also
+        ``attrs``-decorated.
+    :param callable filter: A callable whose return code determines whether an
+        attribute or element is included (``True``) or dropped (``False``).  Is
+        called with the `attrs.Attribute` as the first argument and the
+        value as the second argument.
+    :param callable dict_factory: A callable to produce dictionaries from.  For
+        example, to produce ordered dictionaries instead of normal Python
+        dictionaries, pass in ``collections.OrderedDict``.
+    :param bool retain_collection_types: Do not convert to ``list`` when
+        encountering an attribute whose type is ``tuple`` or ``set``.  Only
+        meaningful if ``recurse`` is ``True``.
+    :param Optional[callable] value_serializer: A hook that is called for every
+        attribute or dict key/value.  It receives the current instance, field
+        and value and must return the (updated) value.  The hook is run *after*
+        the optional *filter* has been applied.
+
+    :rtype: return type of *dict_factory*
+
+    :raise attr.exceptions.NotAnAttrsClassError: If *cls* is not an ``attrs``
+        class.
+
+    ..  versionadded:: 16.0.0 *dict_factory*
+    ..  versionadded:: 16.1.0 *retain_collection_types*
+    ..  versionadded:: 20.3.0 *value_serializer*
+    ..  versionadded:: 21.3.0 If a dict has a collection for a key, it is
+        serialized as a tuple.
+    """
+    attrs = fields(inst.__class__)
+    rv = dict_factory()
+    for a in attrs:
+        v = getattr(inst, a.name)
+        if filter is not None and not filter(a, v):
+            continue
+
+        if value_serializer is not None:
+            v = value_serializer(inst, a, v)
+
+        if recurse is True:
+            if has(v.__class__):
+                rv[a.name] = asdict(
+                    v,
+                    recurse=True,
+                    filter=filter,
+                    dict_factory=dict_factory,
+                    retain_collection_types=retain_collection_types,
+                    value_serializer=value_serializer,
+                )
+            elif isinstance(v, (tuple, list, set, frozenset)):
+                cf = v.__class__ if retain_collection_types is True else list
+                rv[a.name] = cf(
+                    [
+                        _asdict_anything(
+                            i,
+                            is_key=False,
+                            filter=filter,
+                            dict_factory=dict_factory,
+                            retain_collection_types=retain_collection_types,
+                            value_serializer=value_serializer,
+                        )
+                        for i in v
+                    ]
+                )
+            elif isinstance(v, dict):
+                df = dict_factory
+                rv[a.name] = df(
+                    (
+                        _asdict_anything(
+                            kk,
+                            is_key=True,
+                            filter=filter,
+                            dict_factory=df,
+                            retain_collection_types=retain_collection_types,
+                            value_serializer=value_serializer,
+                        ),
+                        _asdict_anything(
+                            vv,
+                            is_key=False,
+                            filter=filter,
+                            dict_factory=df,
+                            retain_collection_types=retain_collection_types,
+                            value_serializer=value_serializer,
+                        ),
+                    )
+                    for kk, vv in v.items()
+                )
+            else:
+                rv[a.name] = v
+        else:
+            rv[a.name] = v
+    return rv
+
+
+def _asdict_anything(
+    val,
+    is_key,
+    filter,
+    dict_factory,
+    retain_collection_types,
+    value_serializer,
+):
+    """
+    ``asdict`` only works on attrs instances, this works on anything.
+    """
+    if getattr(val.__class__, "__attrs_attrs__", None) is not None:
+        # Attrs class.
+        rv = asdict(
+            val,
+            recurse=True,
+            filter=filter,
+            dict_factory=dict_factory,
+            retain_collection_types=retain_collection_types,
+            value_serializer=value_serializer,
+        )
+    elif isinstance(val, (tuple, list, set, frozenset)):
+        if retain_collection_types is True:
+            cf = val.__class__
+        elif is_key:
+            cf = tuple
+        else:
+            cf = list
+
+        rv = cf(
+            [
+                _asdict_anything(
+                    i,
+                    is_key=False,
+                    filter=filter,
+                    dict_factory=dict_factory,
+                    retain_collection_types=retain_collection_types,
+                    value_serializer=value_serializer,
+                )
+                for i in val
+            ]
+        )
+    elif isinstance(val, dict):
+        df = dict_factory
+        rv = df(
+            (
+                _asdict_anything(
+                    kk,
+                    is_key=True,
+                    filter=filter,
+                    dict_factory=df,
+                    retain_collection_types=retain_collection_types,
+                    value_serializer=value_serializer,
+                ),
+                _asdict_anything(
+                    vv,
+                    is_key=False,
+                    filter=filter,
+                    dict_factory=df,
+                    retain_collection_types=retain_collection_types,
+                    value_serializer=value_serializer,
+                ),
+            )
+            for kk, vv in val.items()
+        )
+    else:
+        rv = val
+        if value_serializer is not None:
+            rv = value_serializer(None, None, rv)
+
+    return rv
+
+
+def astuple(
+    inst,
+    recurse=True,
+    filter=None,
+    tuple_factory=tuple,
+    retain_collection_types=False,
+):
+    """
+    Return the ``attrs`` attribute values of *inst* as a tuple.
+
+    Optionally recurse into other ``attrs``-decorated classes.
+
+    :param inst: Instance of an ``attrs``-decorated class.
+    :param bool recurse: Recurse into classes that are also
+        ``attrs``-decorated.
+    :param callable filter: A callable whose return code determines whether an
+        attribute or element is included (``True``) or dropped (``False``).  Is
+        called with the `attrs.Attribute` as the first argument and the
+        value as the second argument.
+    :param callable tuple_factory: A callable to produce tuples from.  For
+        example, to produce lists instead of tuples.
+    :param bool retain_collection_types: Do not convert to ``list``
+        or ``dict`` when encountering an attribute which type is
+        ``tuple``, ``dict`` or ``set``.  Only meaningful if ``recurse`` is
+        ``True``.
+
+    :rtype: return type of *tuple_factory*
+
+    :raise attr.exceptions.NotAnAttrsClassError: If *cls* is not an ``attrs``
+        class.
+
+    ..  versionadded:: 16.2.0
+    """
+    attrs = fields(inst.__class__)
+    rv = []
+    retain = retain_collection_types  # Very long. :/
+    for a in attrs:
+        v = getattr(inst, a.name)
+        if filter is not None and not filter(a, v):
+            continue
+        if recurse is True:
+            if has(v.__class__):
+                rv.append(
+                    astuple(
+                        v,
+                        recurse=True,
+                        filter=filter,
+                        tuple_factory=tuple_factory,
+                        retain_collection_types=retain,
+                    )
+                )
+            elif isinstance(v, (tuple, list, set, frozenset)):
+                cf = v.__class__ if retain is True else list
+                rv.append(
+                    cf(
+                        [
+                            astuple(
+                                j,
+                                recurse=True,
+                                filter=filter,
+                                tuple_factory=tuple_factory,
+                                retain_collection_types=retain,
+                            )
+                            if has(j.__class__)
+                            else j
+                            for j in v
+                        ]
+                    )
+                )
+            elif isinstance(v, dict):
+                df = v.__class__ if retain is True else dict
+                rv.append(
+                    df(
+                        (
+                            astuple(
+                                kk,
+                                tuple_factory=tuple_factory,
+                                retain_collection_types=retain,
+                            )
+                            if has(kk.__class__)
+                            else kk,
+                            astuple(
+                                vv,
+                                tuple_factory=tuple_factory,
+                                retain_collection_types=retain,
+                            )
+                            if has(vv.__class__)
+                            else vv,
+                        )
+                        for kk, vv in v.items()
+                    )
+                )
+            else:
+                rv.append(v)
+        else:
+            rv.append(v)
+
+    return rv if tuple_factory is list else tuple_factory(rv)
+
+
+def has(cls):
+    """
+    Check whether *cls* is a class with ``attrs`` attributes.
+
+    :param type cls: Class to introspect.
+    :raise TypeError: If *cls* is not a class.
+
+    :rtype: bool
+    """
+    return getattr(cls, "__attrs_attrs__", None) is not None
+
+
+def assoc(inst, **changes):
+    """
+    Copy *inst* and apply *changes*.
+
+    :param inst: Instance of a class with ``attrs`` attributes.
+    :param changes: Keyword changes in the new copy.
+
+    :return: A copy of inst with *changes* incorporated.
+
+    :raise attr.exceptions.AttrsAttributeNotFoundError: If *attr_name* couldn't
+        be found on *cls*.
+    :raise attr.exceptions.NotAnAttrsClassError: If *cls* is not an ``attrs``
+        class.
+
+    ..  deprecated:: 17.1.0
+        Use `attrs.evolve` instead if you can.
+        This function will not be removed du to the slightly different approach
+        compared to `attrs.evolve`.
+    """
+    import warnings
+
+    warnings.warn(
+        "assoc is deprecated and will be removed after 2018/01.",
+        DeprecationWarning,
+        stacklevel=2,
+    )
+    new = copy.copy(inst)
+    attrs = fields(inst.__class__)
+    for k, v in changes.items():
+        a = getattr(attrs, k, NOTHING)
+        if a is NOTHING:
+            raise AttrsAttributeNotFoundError(
+                "{k} is not an attrs attribute on {cl}.".format(
+                    k=k, cl=new.__class__
+                )
+            )
+        _obj_setattr(new, k, v)
+    return new
+
+
+def evolve(inst, **changes):
+    """
+    Create a new instance, based on *inst* with *changes* applied.
+
+    :param inst: Instance of a class with ``attrs`` attributes.
+    :param changes: Keyword changes in the new copy.
+
+    :return: A copy of inst with *changes* incorporated.
+
+    :raise TypeError: If *attr_name* couldn't be found in the class
+        ``__init__``.
+    :raise attr.exceptions.NotAnAttrsClassError: If *cls* is not an ``attrs``
+        class.
+
+    ..  versionadded:: 17.1.0
+    """
+    cls = inst.__class__
+    attrs = fields(cls)
+    for a in attrs:
+        if not a.init:
+            continue
+        attr_name = a.name  # To deal with private attributes.
+        init_name = attr_name if attr_name[0] != "_" else attr_name[1:]
+        if init_name not in changes:
+            changes[init_name] = getattr(inst, attr_name)
+
+    return cls(**changes)
+
+
+def resolve_types(cls, globalns=None, localns=None, attribs=None):
+    """
+    Resolve any strings and forward annotations in type annotations.
+
+    This is only required if you need concrete types in `Attribute`'s *type*
+    field. In other words, you don't need to resolve your types if you only
+    use them for static type checking.
+
+    With no arguments, names will be looked up in the module in which the class
+    was created. If this is not what you want, e.g. if the name only exists
+    inside a method, you may pass *globalns* or *localns* to specify other
+    dictionaries in which to look up these names. See the docs of
+    `typing.get_type_hints` for more details.
+
+    :param type cls: Class to resolve.
+    :param Optional[dict] globalns: Dictionary containing global variables.
+    :param Optional[dict] localns: Dictionary containing local variables.
+    :param Optional[list] attribs: List of attribs for the given class.
+        This is necessary when calling from inside a ``field_transformer``
+        since *cls* is not an ``attrs`` class yet.
+
+    :raise TypeError: If *cls* is not a class.
+    :raise attr.exceptions.NotAnAttrsClassError: If *cls* is not an ``attrs``
+        class and you didn't pass any attribs.
+    :raise NameError: If types cannot be resolved because of missing variables.
+
+    :returns: *cls* so you can use this function also as a class decorator.
+        Please note that you have to apply it **after** `attrs.define`. That
+        means the decorator has to come in the line **before** `attrs.define`.
+
+    ..  versionadded:: 20.1.0
+    ..  versionadded:: 21.1.0 *attribs*
+
+    """
+    # Since calling get_type_hints is expensive we cache whether we've
+    # done it already.
+    if getattr(cls, "__attrs_types_resolved__", None) != cls:
+        import typing
+
+        hints = typing.get_type_hints(cls, globalns=globalns, localns=localns)
+        for field in fields(cls) if attribs is None else attribs:
+            if field.name in hints:
+                # Since fields have been frozen we must work around it.
+                _obj_setattr(field, "type", hints[field.name])
+        # We store the class we resolved so that subclasses know they haven't
+        # been resolved.
+        cls.__attrs_types_resolved__ = cls
+
+    # Return the class so you can use it as a decorator too.
+    return cls
diff --git a/lib/spack/external/_vendoring/attr/_make.py b/lib/spack/external/_vendoring/attr/_make.py
new file mode 100644
index 0000000000..4d1afe3fc8
--- /dev/null
+++ b/lib/spack/external/_vendoring/attr/_make.py
@@ -0,0 +1,3006 @@
+# SPDX-License-Identifier: MIT
+
+import copy
+import linecache
+import sys
+import types
+import typing
+
+from operator import itemgetter
+
+# We need to import _compat itself in addition to the _compat members to avoid
+# having the thread-local in the globals here.
+from . import _compat, _config, setters
+from ._compat import (
+    HAS_F_STRINGS,
+    PY310,
+    PYPY,
+    _AnnotationExtractor,
+    ordered_dict,
+    set_closure_cell,
+)
+from .exceptions import (
+    DefaultAlreadySetError,
+    FrozenInstanceError,
+    NotAnAttrsClassError,
+    UnannotatedAttributeError,
+)
+
+
+# This is used at least twice, so cache it here.
+_obj_setattr = object.__setattr__
+_init_converter_pat = "__attr_converter_%s"
+_init_factory_pat = "__attr_factory_{}"
+_tuple_property_pat = (
+    "    {attr_name} = _attrs_property(_attrs_itemgetter({index}))"
+)
+_classvar_prefixes = (
+    "typing.ClassVar",
+    "t.ClassVar",
+    "ClassVar",
+    "typing_extensions.ClassVar",
+)
+# we don't use a double-underscore prefix because that triggers
+# name mangling when trying to create a slot for the field
+# (when slots=True)
+_hash_cache_field = "_attrs_cached_hash"
+
+_empty_metadata_singleton = types.MappingProxyType({})
+
+# Unique object for unequivocal getattr() defaults.
+_sentinel = object()
+
+_ng_default_on_setattr = setters.pipe(setters.convert, setters.validate)
+
+
+class _Nothing:
+    """
+    Sentinel class to indicate the lack of a value when ``None`` is ambiguous.
+
+    ``_Nothing`` is a singleton. There is only ever one of it.
+
+    .. versionchanged:: 21.1.0 ``bool(NOTHING)`` is now False.
+    """
+
+    _singleton = None
+
+    def __new__(cls):
+        if _Nothing._singleton is None:
+            _Nothing._singleton = super().__new__(cls)
+        return _Nothing._singleton
+
+    def __repr__(self):
+        return "NOTHING"
+
+    def __bool__(self):
+        return False
+
+
+NOTHING = _Nothing()
+"""
+Sentinel to indicate the lack of a value when ``None`` is ambiguous.
+"""
+
+
+class _CacheHashWrapper(int):
+    """
+    An integer subclass that pickles / copies as None
+
+    This is used for non-slots classes with ``cache_hash=True``, to avoid
+    serializing a potentially (even likely) invalid hash value. Since ``None``
+    is the default value for uncalculated hashes, whenever this is copied,
+    the copy's value for the hash should automatically reset.
+
+    See GH #613 for more details.
+    """
+
+    def __reduce__(self, _none_constructor=type(None), _args=()):
+        return _none_constructor, _args
+
+
+def attrib(
+    default=NOTHING,
+    validator=None,
+    repr=True,
+    cmp=None,
+    hash=None,
+    init=True,
+    metadata=None,
+    type=None,
+    converter=None,
+    factory=None,
+    kw_only=False,
+    eq=None,
+    order=None,
+    on_setattr=None,
+):
+    """
+    Create a new attribute on a class.
+
+    ..  warning::
+
+        Does *not* do anything unless the class is also decorated with
+        `attr.s`!
+
+    :param default: A value that is used if an ``attrs``-generated ``__init__``
+        is used and no value is passed while instantiating or the attribute is
+        excluded using ``init=False``.
+
+        If the value is an instance of `attrs.Factory`, its callable will be
+        used to construct a new value (useful for mutable data types like lists
+        or dicts).
+
+        If a default is not set (or set manually to `attrs.NOTHING`), a value
+        *must* be supplied when instantiating; otherwise a `TypeError`
+        will be raised.
+
+        The default can also be set using decorator notation as shown below.
+
+    :type default: Any value
+
+    :param callable factory: Syntactic sugar for
+        ``default=attr.Factory(factory)``.
+
+    :param validator: `callable` that is called by ``attrs``-generated
+        ``__init__`` methods after the instance has been initialized.  They
+        receive the initialized instance, the :func:`~attrs.Attribute`, and the
+        passed value.
+
+        The return value is *not* inspected so the validator has to throw an
+        exception itself.
+
+        If a `list` is passed, its items are treated as validators and must
+        all pass.
+
+        Validators can be globally disabled and re-enabled using
+        `get_run_validators`.
+
+        The validator can also be set using decorator notation as shown below.
+
+    :type validator: `callable` or a `list` of `callable`\\ s.
+
+    :param repr: Include this attribute in the generated ``__repr__``
+        method. If ``True``, include the attribute; if ``False``, omit it. By
+        default, the built-in ``repr()`` function is used. To override how the
+        attribute value is formatted, pass a ``callable`` that takes a single
+        value and returns a string. Note that the resulting string is used
+        as-is, i.e. it will be used directly *instead* of calling ``repr()``
+        (the default).
+    :type repr: a `bool` or a `callable` to use a custom function.
+
+    :param eq: If ``True`` (default), include this attribute in the
+        generated ``__eq__`` and ``__ne__`` methods that check two instances
+        for equality. To override how the attribute value is compared,
+        pass a ``callable`` that takes a single value and returns the value
+        to be compared.
+    :type eq: a `bool` or a `callable`.
+
+    :param order: If ``True`` (default), include this attributes in the
+        generated ``__lt__``, ``__le__``, ``__gt__`` and ``__ge__`` methods.
+        To override how the attribute value is ordered,
+        pass a ``callable`` that takes a single value and returns the value
+        to be ordered.
+    :type order: a `bool` or a `callable`.
+
+    :param cmp: Setting *cmp* is equivalent to setting *eq* and *order* to the
+        same value. Must not be mixed with *eq* or *order*.
+    :type cmp: a `bool` or a `callable`.
+
+    :param Optional[bool] hash: Include this attribute in the generated
+        ``__hash__`` method.  If ``None`` (default), mirror *eq*'s value.  This
+        is the correct behavior according the Python spec.  Setting this value
+        to anything else than ``None`` is *discouraged*.
+    :param bool init: Include this attribute in the generated ``__init__``
+        method.  It is possible to set this to ``False`` and set a default
+        value.  In that case this attributed is unconditionally initialized
+        with the specified default value or factory.
+    :param callable converter: `callable` that is called by
+        ``attrs``-generated ``__init__`` methods to convert attribute's value
+        to the desired format.  It is given the passed-in value, and the
+        returned value will be used as the new value of the attribute.  The
+        value is converted before being passed to the validator, if any.
+    :param metadata: An arbitrary mapping, to be used by third-party
+        components.  See `extending_metadata`.
+    :param type: The type of the attribute.  In Python 3.6 or greater, the
+        preferred method to specify the type is using a variable annotation
+        (see :pep:`526`).
+        This argument is provided for backward compatibility.
+        Regardless of the approach used, the type will be stored on
+        ``Attribute.type``.
+
+        Please note that ``attrs`` doesn't do anything with this metadata by
+        itself. You can use it as part of your own code or for
+        `static type checking <types>`.
+    :param kw_only: Make this attribute keyword-only (Python 3+)
+        in the generated ``__init__`` (if ``init`` is ``False``, this
+        parameter is ignored).
+    :param on_setattr: Allows to overwrite the *on_setattr* setting from
+        `attr.s`. If left `None`, the *on_setattr* value from `attr.s` is used.
+        Set to `attrs.setters.NO_OP` to run **no** `setattr` hooks for this
+        attribute -- regardless of the setting in `attr.s`.
+    :type on_setattr: `callable`, or a list of callables, or `None`, or
+        `attrs.setters.NO_OP`
+
+    .. versionadded:: 15.2.0 *convert*
+    .. versionadded:: 16.3.0 *metadata*
+    .. versionchanged:: 17.1.0 *validator* can be a ``list`` now.
+    .. versionchanged:: 17.1.0
+       *hash* is ``None`` and therefore mirrors *eq* by default.
+    .. versionadded:: 17.3.0 *type*
+    .. deprecated:: 17.4.0 *convert*
+    .. versionadded:: 17.4.0 *converter* as a replacement for the deprecated
+       *convert* to achieve consistency with other noun-based arguments.
+    .. versionadded:: 18.1.0
+       ``factory=f`` is syntactic sugar for ``default=attr.Factory(f)``.
+    .. versionadded:: 18.2.0 *kw_only*
+    .. versionchanged:: 19.2.0 *convert* keyword argument removed.
+    .. versionchanged:: 19.2.0 *repr* also accepts a custom callable.
+    .. deprecated:: 19.2.0 *cmp* Removal on or after 2021-06-01.
+    .. versionadded:: 19.2.0 *eq* and *order*
+    .. versionadded:: 20.1.0 *on_setattr*
+    .. versionchanged:: 20.3.0 *kw_only* backported to Python 2
+    .. versionchanged:: 21.1.0
+       *eq*, *order*, and *cmp* also accept a custom callable
+    .. versionchanged:: 21.1.0 *cmp* undeprecated
+    """
+    eq, eq_key, order, order_key = _determine_attrib_eq_order(
+        cmp, eq, order, True
+    )
+
+    if hash is not None and hash is not True and hash is not False:
+        raise TypeError(
+            "Invalid value for hash.  Must be True, False, or None."
+        )
+
+    if factory is not None:
+        if default is not NOTHING:
+            raise ValueError(
+                "The `default` and `factory` arguments are mutually "
+                "exclusive."
+            )
+        if not callable(factory):
+            raise ValueError("The `factory` argument must be a callable.")
+        default = Factory(factory)
+
+    if metadata is None:
+        metadata = {}
+
+    # Apply syntactic sugar by auto-wrapping.
+    if isinstance(on_setattr, (list, tuple)):
+        on_setattr = setters.pipe(*on_setattr)
+
+    if validator and isinstance(validator, (list, tuple)):
+        validator = and_(*validator)
+
+    if converter and isinstance(converter, (list, tuple)):
+        converter = pipe(*converter)
+
+    return _CountingAttr(
+        default=default,
+        validator=validator,
+        repr=repr,
+        cmp=None,
+        hash=hash,
+        init=init,
+        converter=converter,
+        metadata=metadata,
+        type=type,
+        kw_only=kw_only,
+        eq=eq,
+        eq_key=eq_key,
+        order=order,
+        order_key=order_key,
+        on_setattr=on_setattr,
+    )
+
+
+def _compile_and_eval(script, globs, locs=None, filename=""):
+    """
+    "Exec" the script with the given global (globs) and local (locs) variables.
+    """
+    bytecode = compile(script, filename, "exec")
+    eval(bytecode, globs, locs)
+
+
+def _make_method(name, script, filename, globs):
+    """
+    Create the method with the script given and return the method object.
+    """
+    locs = {}
+
+    # In order of debuggers like PDB being able to step through the code,
+    # we add a fake linecache entry.
+    count = 1
+    base_filename = filename
+    while True:
+        linecache_tuple = (
+            len(script),
+            None,
+            script.splitlines(True),
+            filename,
+        )
+        old_val = linecache.cache.setdefault(filename, linecache_tuple)
+        if old_val == linecache_tuple:
+            break
+        else:
+            filename = "{}-{}>".format(base_filename[:-1], count)
+            count += 1
+
+    _compile_and_eval(script, globs, locs, filename)
+
+    return locs[name]
+
+
+def _make_attr_tuple_class(cls_name, attr_names):
+    """
+    Create a tuple subclass to hold `Attribute`s for an `attrs` class.
+
+    The subclass is a bare tuple with properties for names.
+
+    class MyClassAttributes(tuple):
+        __slots__ = ()
+        x = property(itemgetter(0))
+    """
+    attr_class_name = "{}Attributes".format(cls_name)
+    attr_class_template = [
+        "class {}(tuple):".format(attr_class_name),
+        "    __slots__ = ()",
+    ]
+    if attr_names:
+        for i, attr_name in enumerate(attr_names):
+            attr_class_template.append(
+                _tuple_property_pat.format(index=i, attr_name=attr_name)
+            )
+    else:
+        attr_class_template.append("    pass")
+    globs = {"_attrs_itemgetter": itemgetter, "_attrs_property": property}
+    _compile_and_eval("\n".join(attr_class_template), globs)
+    return globs[attr_class_name]
+
+
+# Tuple class for extracted attributes from a class definition.
+# `base_attrs` is a subset of `attrs`.
+_Attributes = _make_attr_tuple_class(
+    "_Attributes",
+    [
+        # all attributes to build dunder methods for
+        "attrs",
+        # attributes that have been inherited
+        "base_attrs",
+        # map inherited attributes to their originating classes
+        "base_attrs_map",
+    ],
+)
+
+
+def _is_class_var(annot):
+    """
+    Check whether *annot* is a typing.ClassVar.
+
+    The string comparison hack is used to avoid evaluating all string
+    annotations which would put attrs-based classes at a performance
+    disadvantage compared to plain old classes.
+    """
+    annot = str(annot)
+
+    # Annotation can be quoted.
+    if annot.startswith(("'", '"')) and annot.endswith(("'", '"')):
+        annot = annot[1:-1]
+
+    return annot.startswith(_classvar_prefixes)
+
+
+def _has_own_attribute(cls, attrib_name):
+    """
+    Check whether *cls* defines *attrib_name* (and doesn't just inherit it).
+
+    Requires Python 3.
+    """
+    attr = getattr(cls, attrib_name, _sentinel)
+    if attr is _sentinel:
+        return False
+
+    for base_cls in cls.__mro__[1:]:
+        a = getattr(base_cls, attrib_name, None)
+        if attr is a:
+            return False
+
+    return True
+
+
+def _get_annotations(cls):
+    """
+    Get annotations for *cls*.
+    """
+    if _has_own_attribute(cls, "__annotations__"):
+        return cls.__annotations__
+
+    return {}
+
+
+def _counter_getter(e):
+    """
+    Key function for sorting to avoid re-creating a lambda for every class.
+    """
+    return e[1].counter
+
+
+def _collect_base_attrs(cls, taken_attr_names):
+    """
+    Collect attr.ibs from base classes of *cls*, except *taken_attr_names*.
+    """
+    base_attrs = []
+    base_attr_map = {}  # A dictionary of base attrs to their classes.
+
+    # Traverse the MRO and collect attributes.
+    for base_cls in reversed(cls.__mro__[1:-1]):
+        for a in getattr(base_cls, "__attrs_attrs__", []):
+            if a.inherited or a.name in taken_attr_names:
+                continue
+
+            a = a.evolve(inherited=True)
+            base_attrs.append(a)
+            base_attr_map[a.name] = base_cls
+
+    # For each name, only keep the freshest definition i.e. the furthest at the
+    # back.  base_attr_map is fine because it gets overwritten with every new
+    # instance.
+    filtered = []
+    seen = set()
+    for a in reversed(base_attrs):
+        if a.name in seen:
+            continue
+        filtered.insert(0, a)
+        seen.add(a.name)
+
+    return filtered, base_attr_map
+
+
+def _collect_base_attrs_broken(cls, taken_attr_names):
+    """
+    Collect attr.ibs from base classes of *cls*, except *taken_attr_names*.
+
+    N.B. *taken_attr_names* will be mutated.
+
+    Adhere to the old incorrect behavior.
+
+    Notably it collects from the front and considers inherited attributes which
+    leads to the buggy behavior reported in #428.
+    """
+    base_attrs = []
+    base_attr_map = {}  # A dictionary of base attrs to their classes.
+
+    # Traverse the MRO and collect attributes.
+    for base_cls in cls.__mro__[1:-1]:
+        for a in getattr(base_cls, "__attrs_attrs__", []):
+            if a.name in taken_attr_names:
+                continue
+
+            a = a.evolve(inherited=True)
+            taken_attr_names.add(a.name)
+            base_attrs.append(a)
+            base_attr_map[a.name] = base_cls
+
+    return base_attrs, base_attr_map
+
+
+def _transform_attrs(
+    cls, these, auto_attribs, kw_only, collect_by_mro, field_transformer
+):
+    """
+    Transform all `_CountingAttr`s on a class into `Attribute`s.
+
+    If *these* is passed, use that and don't look for them on the class.
+
+    *collect_by_mro* is True, collect them in the correct MRO order, otherwise
+    use the old -- incorrect -- order.  See #428.
+
+    Return an `_Attributes`.
+    """
+    cd = cls.__dict__
+    anns = _get_annotations(cls)
+
+    if these is not None:
+        ca_list = [(name, ca) for name, ca in these.items()]
+
+        if not isinstance(these, ordered_dict):
+            ca_list.sort(key=_counter_getter)
+    elif auto_attribs is True:
+        ca_names = {
+            name
+            for name, attr in cd.items()
+            if isinstance(attr, _CountingAttr)
+        }
+        ca_list = []
+        annot_names = set()
+        for attr_name, type in anns.items():
+            if _is_class_var(type):
+                continue
+            annot_names.add(attr_name)
+            a = cd.get(attr_name, NOTHING)
+
+            if not isinstance(a, _CountingAttr):
+                if a is NOTHING:
+                    a = attrib()
+                else:
+                    a = attrib(default=a)
+            ca_list.append((attr_name, a))
+
+        unannotated = ca_names - annot_names
+        if len(unannotated) > 0:
+            raise UnannotatedAttributeError(
+                "The following `attr.ib`s lack a type annotation: "
+                + ", ".join(
+                    sorted(unannotated, key=lambda n: cd.get(n).counter)
+                )
+                + "."
+            )
+    else:
+        ca_list = sorted(
+            (
+                (name, attr)
+                for name, attr in cd.items()
+                if isinstance(attr, _CountingAttr)
+            ),
+            key=lambda e: e[1].counter,
+        )
+
+    own_attrs = [
+        Attribute.from_counting_attr(
+            name=attr_name, ca=ca, type=anns.get(attr_name)
+        )
+        for attr_name, ca in ca_list
+    ]
+
+    if collect_by_mro:
+        base_attrs, base_attr_map = _collect_base_attrs(
+            cls, {a.name for a in own_attrs}
+        )
+    else:
+        base_attrs, base_attr_map = _collect_base_attrs_broken(
+            cls, {a.name for a in own_attrs}
+        )
+
+    if kw_only:
+        own_attrs = [a.evolve(kw_only=True) for a in own_attrs]
+        base_attrs = [a.evolve(kw_only=True) for a in base_attrs]
+
+    attrs = base_attrs + own_attrs
+
+    # Mandatory vs non-mandatory attr order only matters when they are part of
+    # the __init__ signature and when they aren't kw_only (which are moved to
+    # the end and can be mandatory or non-mandatory in any order, as they will
+    # be specified as keyword args anyway). Check the order of those attrs:
+    had_default = False
+    for a in (a for a in attrs if a.init is not False and a.kw_only is False):
+        if had_default is True and a.default is NOTHING:
+            raise ValueError(
+                "No mandatory attributes allowed after an attribute with a "
+                "default value or factory.  Attribute in question: %r" % (a,)
+            )
+
+        if had_default is False and a.default is not NOTHING:
+            had_default = True
+
+    if field_transformer is not None:
+        attrs = field_transformer(cls, attrs)
+
+    # Create AttrsClass *after* applying the field_transformer since it may
+    # add or remove attributes!
+    attr_names = [a.name for a in attrs]
+    AttrsClass = _make_attr_tuple_class(cls.__name__, attr_names)
+
+    return _Attributes((AttrsClass(attrs), base_attrs, base_attr_map))
+
+
+if PYPY:
+
+    def _frozen_setattrs(self, name, value):
+        """
+        Attached to frozen classes as __setattr__.
+        """
+        if isinstance(self, BaseException) and name in (
+            "__cause__",
+            "__context__",
+        ):
+            BaseException.__setattr__(self, name, value)
+            return
+
+        raise FrozenInstanceError()
+
+else:
+
+    def _frozen_setattrs(self, name, value):
+        """
+        Attached to frozen classes as __setattr__.
+        """
+        raise FrozenInstanceError()
+
+
+def _frozen_delattrs(self, name):
+    """
+    Attached to frozen classes as __delattr__.
+    """
+    raise FrozenInstanceError()
+
+
+class _ClassBuilder:
+    """
+    Iteratively build *one* class.
+    """
+
+    __slots__ = (
+        "_attr_names",
+        "_attrs",
+        "_base_attr_map",
+        "_base_names",
+        "_cache_hash",
+        "_cls",
+        "_cls_dict",
+        "_delete_attribs",
+        "_frozen",
+        "_has_pre_init",
+        "_has_post_init",
+        "_is_exc",
+        "_on_setattr",
+        "_slots",
+        "_weakref_slot",
+        "_wrote_own_setattr",
+        "_has_custom_setattr",
+    )
+
+    def __init__(
+        self,
+        cls,
+        these,
+        slots,
+        frozen,
+        weakref_slot,
+        getstate_setstate,
+        auto_attribs,
+        kw_only,
+        cache_hash,
+        is_exc,
+        collect_by_mro,
+        on_setattr,
+        has_custom_setattr,
+        field_transformer,
+    ):
+        attrs, base_attrs, base_map = _transform_attrs(
+            cls,
+            these,
+            auto_attribs,
+            kw_only,
+            collect_by_mro,
+            field_transformer,
+        )
+
+        self._cls = cls
+        self._cls_dict = dict(cls.__dict__) if slots else {}
+        self._attrs = attrs
+        self._base_names = {a.name for a in base_attrs}
+        self._base_attr_map = base_map
+        self._attr_names = tuple(a.name for a in attrs)
+        self._slots = slots
+        self._frozen = frozen
+        self._weakref_slot = weakref_slot
+        self._cache_hash = cache_hash
+        self._has_pre_init = bool(getattr(cls, "__attrs_pre_init__", False))
+        self._has_post_init = bool(getattr(cls, "__attrs_post_init__", False))
+        self._delete_attribs = not bool(these)
+        self._is_exc = is_exc
+        self._on_setattr = on_setattr
+
+        self._has_custom_setattr = has_custom_setattr
+        self._wrote_own_setattr = False
+
+        self._cls_dict["__attrs_attrs__"] = self._attrs
+
+        if frozen:
+            self._cls_dict["__setattr__"] = _frozen_setattrs
+            self._cls_dict["__delattr__"] = _frozen_delattrs
+
+            self._wrote_own_setattr = True
+        elif on_setattr in (
+            _ng_default_on_setattr,
+            setters.validate,
+            setters.convert,
+        ):
+            has_validator = has_converter = False
+            for a in attrs:
+                if a.validator is not None:
+                    has_validator = True
+                if a.converter is not None:
+                    has_converter = True
+
+                if has_validator and has_converter:
+                    break
+            if (
+                (
+                    on_setattr == _ng_default_on_setattr
+                    and not (has_validator or has_converter)
+                )
+                or (on_setattr == setters.validate and not has_validator)
+                or (on_setattr == setters.convert and not has_converter)
+            ):
+                # If class-level on_setattr is set to convert + validate, but
+                # there's no field to convert or validate, pretend like there's
+                # no on_setattr.
+                self._on_setattr = None
+
+        if getstate_setstate:
+            (
+                self._cls_dict["__getstate__"],
+                self._cls_dict["__setstate__"],
+            ) = self._make_getstate_setstate()
+
+    def __repr__(self):
+        return "<_ClassBuilder(cls={cls})>".format(cls=self._cls.__name__)
+
+    def build_class(self):
+        """
+        Finalize class based on the accumulated configuration.
+
+        Builder cannot be used after calling this method.
+        """
+        if self._slots is True:
+            return self._create_slots_class()
+        else:
+            return self._patch_original_class()
+
+    def _patch_original_class(self):
+        """
+        Apply accumulated methods and return the class.
+        """
+        cls = self._cls
+        base_names = self._base_names
+
+        # Clean class of attribute definitions (`attr.ib()`s).
+        if self._delete_attribs:
+            for name in self._attr_names:
+                if (
+                    name not in base_names
+                    and getattr(cls, name, _sentinel) is not _sentinel
+                ):
+                    try:
+                        delattr(cls, name)
+                    except AttributeError:
+                        # This can happen if a base class defines a class
+                        # variable and we want to set an attribute with the
+                        # same name by using only a type annotation.
+                        pass
+
+        # Attach our dunder methods.
+        for name, value in self._cls_dict.items():
+            setattr(cls, name, value)
+
+        # If we've inherited an attrs __setattr__ and don't write our own,
+        # reset it to object's.
+        if not self._wrote_own_setattr and getattr(
+            cls, "__attrs_own_setattr__", False
+        ):
+            cls.__attrs_own_setattr__ = False
+
+            if not self._has_custom_setattr:
+                cls.__setattr__ = _obj_setattr
+
+        return cls
+
+    def _create_slots_class(self):
+        """
+        Build and return a new class with a `__slots__` attribute.
+        """
+        cd = {
+            k: v
+            for k, v in self._cls_dict.items()
+            if k not in tuple(self._attr_names) + ("__dict__", "__weakref__")
+        }
+
+        # If our class doesn't have its own implementation of __setattr__
+        # (either from the user or by us), check the bases, if one of them has
+        # an attrs-made __setattr__, that needs to be reset. We don't walk the
+        # MRO because we only care about our immediate base classes.
+        # XXX: This can be confused by subclassing a slotted attrs class with
+        # XXX: a non-attrs class and subclass the resulting class with an attrs
+        # XXX: class.  See `test_slotted_confused` for details.  For now that's
+        # XXX: OK with us.
+        if not self._wrote_own_setattr:
+            cd["__attrs_own_setattr__"] = False
+
+            if not self._has_custom_setattr:
+                for base_cls in self._cls.__bases__:
+                    if base_cls.__dict__.get("__attrs_own_setattr__", False):
+                        cd["__setattr__"] = _obj_setattr
+                        break
+
+        # Traverse the MRO to collect existing slots
+        # and check for an existing __weakref__.
+        existing_slots = dict()
+        weakref_inherited = False
+        for base_cls in self._cls.__mro__[1:-1]:
+            if base_cls.__dict__.get("__weakref__", None) is not None:
+                weakref_inherited = True
+            existing_slots.update(
+                {
+                    name: getattr(base_cls, name)
+                    for name in getattr(base_cls, "__slots__", [])
+                }
+            )
+
+        base_names = set(self._base_names)
+
+        names = self._attr_names
+        if (
+            self._weakref_slot
+            and "__weakref__" not in getattr(self._cls, "__slots__", ())
+            and "__weakref__" not in names
+            and not weakref_inherited
+        ):
+            names += ("__weakref__",)
+
+        # We only add the names of attributes that aren't inherited.
+        # Setting __slots__ to inherited attributes wastes memory.
+        slot_names = [name for name in names if name not in base_names]
+        # There are slots for attributes from current class
+        # that are defined in parent classes.
+        # As their descriptors may be overridden by a child class,
+        # we collect them here and update the class dict
+        reused_slots = {
+            slot: slot_descriptor
+            for slot, slot_descriptor in existing_slots.items()
+            if slot in slot_names
+        }
+        slot_names = [name for name in slot_names if name not in reused_slots]
+        cd.update(reused_slots)
+        if self._cache_hash:
+            slot_names.append(_hash_cache_field)
+        cd["__slots__"] = tuple(slot_names)
+
+        cd["__qualname__"] = self._cls.__qualname__
+
+        # Create new class based on old class and our methods.
+        cls = type(self._cls)(self._cls.__name__, self._cls.__bases__, cd)
+
+        # The following is a fix for
+        # <https://github.com/python-attrs/attrs/issues/102>.  On Python 3,
+        # if a method mentions `__class__` or uses the no-arg super(), the
+        # compiler will bake a reference to the class in the method itself
+        # as `method.__closure__`.  Since we replace the class with a
+        # clone, we rewrite these references so it keeps working.
+        for item in cls.__dict__.values():
+            if isinstance(item, (classmethod, staticmethod)):
+                # Class- and staticmethods hide their functions inside.
+                # These might need to be rewritten as well.
+                closure_cells = getattr(item.__func__, "__closure__", None)
+            elif isinstance(item, property):
+                # Workaround for property `super()` shortcut (PY3-only).
+                # There is no universal way for other descriptors.
+                closure_cells = getattr(item.fget, "__closure__", None)
+            else:
+                closure_cells = getattr(item, "__closure__", None)
+
+            if not closure_cells:  # Catch None or the empty list.
+                continue
+            for cell in closure_cells:
+                try:
+                    match = cell.cell_contents is self._cls
+                except ValueError:  # ValueError: Cell is empty
+                    pass
+                else:
+                    if match:
+                        set_closure_cell(cell, cls)
+
+        return cls
+
+    def add_repr(self, ns):
+        self._cls_dict["__repr__"] = self._add_method_dunders(
+            _make_repr(self._attrs, ns, self._cls)
+        )
+        return self
+
+    def add_str(self):
+        repr = self._cls_dict.get("__repr__")
+        if repr is None:
+            raise ValueError(
+                "__str__ can only be generated if a __repr__ exists."
+            )
+
+        def __str__(self):
+            return self.__repr__()
+
+        self._cls_dict["__str__"] = self._add_method_dunders(__str__)
+        return self
+
+    def _make_getstate_setstate(self):
+        """
+        Create custom __setstate__ and __getstate__ methods.
+        """
+        # __weakref__ is not writable.
+        state_attr_names = tuple(
+            an for an in self._attr_names if an != "__weakref__"
+        )
+
+        def slots_getstate(self):
+            """
+            Automatically created by attrs.
+            """
+            return tuple(getattr(self, name) for name in state_attr_names)
+
+        hash_caching_enabled = self._cache_hash
+
+        def slots_setstate(self, state):
+            """
+            Automatically created by attrs.
+            """
+            __bound_setattr = _obj_setattr.__get__(self, Attribute)
+            for name, value in zip(state_attr_names, state):
+                __bound_setattr(name, value)
+
+            # The hash code cache is not included when the object is
+            # serialized, but it still needs to be initialized to None to
+            # indicate that the first call to __hash__ should be a cache
+            # miss.
+            if hash_caching_enabled:
+                __bound_setattr(_hash_cache_field, None)
+
+        return slots_getstate, slots_setstate
+
+    def make_unhashable(self):
+        self._cls_dict["__hash__"] = None
+        return self
+
+    def add_hash(self):
+        self._cls_dict["__hash__"] = self._add_method_dunders(
+            _make_hash(
+                self._cls,
+                self._attrs,
+                frozen=self._frozen,
+                cache_hash=self._cache_hash,
+            )
+        )
+
+        return self
+
+    def add_init(self):
+        self._cls_dict["__init__"] = self._add_method_dunders(
+            _make_init(
+                self._cls,
+                self._attrs,
+                self._has_pre_init,
+                self._has_post_init,
+                self._frozen,
+                self._slots,
+                self._cache_hash,
+                self._base_attr_map,
+                self._is_exc,
+                self._on_setattr,
+                attrs_init=False,
+            )
+        )
+
+        return self
+
+    def add_match_args(self):
+        self._cls_dict["__match_args__"] = tuple(
+            field.name
+            for field in self._attrs
+            if field.init and not field.kw_only
+        )
+
+    def add_attrs_init(self):
+        self._cls_dict["__attrs_init__"] = self._add_method_dunders(
+            _make_init(
+                self._cls,
+                self._attrs,
+                self._has_pre_init,
+                self._has_post_init,
+                self._frozen,
+                self._slots,
+                self._cache_hash,
+                self._base_attr_map,
+                self._is_exc,
+                self._on_setattr,
+                attrs_init=True,
+            )
+        )
+
+        return self
+
+    def add_eq(self):
+        cd = self._cls_dict
+
+        cd["__eq__"] = self._add_method_dunders(
+            _make_eq(self._cls, self._attrs)
+        )
+        cd["__ne__"] = self._add_method_dunders(_make_ne())
+
+        return self
+
+    def add_order(self):
+        cd = self._cls_dict
+
+        cd["__lt__"], cd["__le__"], cd["__gt__"], cd["__ge__"] = (
+            self._add_method_dunders(meth)
+            for meth in _make_order(self._cls, self._attrs)
+        )
+
+        return self
+
+    def add_setattr(self):
+        if self._frozen:
+            return self
+
+        sa_attrs = {}
+        for a in self._attrs:
+            on_setattr = a.on_setattr or self._on_setattr
+            if on_setattr and on_setattr is not setters.NO_OP:
+                sa_attrs[a.name] = a, on_setattr
+
+        if not sa_attrs:
+            return self
+
+        if self._has_custom_setattr:
+            # We need to write a __setattr__ but there already is one!
+            raise ValueError(
+                "Can't combine custom __setattr__ with on_setattr hooks."
+            )
+
+        # docstring comes from _add_method_dunders
+        def __setattr__(self, name, val):
+            try:
+                a, hook = sa_attrs[name]
+            except KeyError:
+                nval = val
+            else:
+                nval = hook(self, a, val)
+
+            _obj_setattr(self, name, nval)
+
+        self._cls_dict["__attrs_own_setattr__"] = True
+        self._cls_dict["__setattr__"] = self._add_method_dunders(__setattr__)
+        self._wrote_own_setattr = True
+
+        return self
+
+    def _add_method_dunders(self, method):
+        """
+        Add __module__ and __qualname__ to a *method* if possible.
+        """
+        try:
+            method.__module__ = self._cls.__module__
+        except AttributeError:
+            pass
+
+        try:
+            method.__qualname__ = ".".join(
+                (self._cls.__qualname__, method.__name__)
+            )
+        except AttributeError:
+            pass
+
+        try:
+            method.__doc__ = "Method generated by attrs for class %s." % (
+                self._cls.__qualname__,
+            )
+        except AttributeError:
+            pass
+
+        return method
+
+
+def _determine_attrs_eq_order(cmp, eq, order, default_eq):
+    """
+    Validate the combination of *cmp*, *eq*, and *order*. Derive the effective
+    values of eq and order.  If *eq* is None, set it to *default_eq*.
+    """
+    if cmp is not None and any((eq is not None, order is not None)):
+        raise ValueError("Don't mix `cmp` with `eq' and `order`.")
+
+    # cmp takes precedence due to bw-compatibility.
+    if cmp is not None:
+        return cmp, cmp
+
+    # If left None, equality is set to the specified default and ordering
+    # mirrors equality.
+    if eq is None:
+        eq = default_eq
+
+    if order is None:
+        order = eq
+
+    if eq is False and order is True:
+        raise ValueError("`order` can only be True if `eq` is True too.")
+
+    return eq, order
+
+
+def _determine_attrib_eq_order(cmp, eq, order, default_eq):
+    """
+    Validate the combination of *cmp*, *eq*, and *order*. Derive the effective
+    values of eq and order.  If *eq* is None, set it to *default_eq*.
+    """
+    if cmp is not None and any((eq is not None, order is not None)):
+        raise ValueError("Don't mix `cmp` with `eq' and `order`.")
+
+    def decide_callable_or_boolean(value):
+        """
+        Decide whether a key function is used.
+        """
+        if callable(value):
+            value, key = True, value
+        else:
+            key = None
+        return value, key
+
+    # cmp takes precedence due to bw-compatibility.
+    if cmp is not None:
+        cmp, cmp_key = decide_callable_or_boolean(cmp)
+        return cmp, cmp_key, cmp, cmp_key
+
+    # If left None, equality is set to the specified default and ordering
+    # mirrors equality.
+    if eq is None:
+        eq, eq_key = default_eq, None
+    else:
+        eq, eq_key = decide_callable_or_boolean(eq)
+
+    if order is None:
+        order, order_key = eq, eq_key
+    else:
+        order, order_key = decide_callable_or_boolean(order)
+
+    if eq is False and order is True:
+        raise ValueError("`order` can only be True if `eq` is True too.")
+
+    return eq, eq_key, order, order_key
+
+
+def _determine_whether_to_implement(
+    cls, flag, auto_detect, dunders, default=True
+):
+    """
+    Check whether we should implement a set of methods for *cls*.
+
+    *flag* is the argument passed into @attr.s like 'init', *auto_detect* the
+    same as passed into @attr.s and *dunders* is a tuple of attribute names
+    whose presence signal that the user has implemented it themselves.
+
+    Return *default* if no reason for either for or against is found.
+    """
+    if flag is True or flag is False:
+        return flag
+
+    if flag is None and auto_detect is False:
+        return default
+
+    # Logically, flag is None and auto_detect is True here.
+    for dunder in dunders:
+        if _has_own_attribute(cls, dunder):
+            return False
+
+    return default
+
+
+def attrs(
+    maybe_cls=None,
+    these=None,
+    repr_ns=None,
+    repr=None,
+    cmp=None,
+    hash=None,
+    init=None,
+    slots=False,
+    frozen=False,
+    weakref_slot=True,
+    str=False,
+    auto_attribs=False,
+    kw_only=False,
+    cache_hash=False,
+    auto_exc=False,
+    eq=None,
+    order=None,
+    auto_detect=False,
+    collect_by_mro=False,
+    getstate_setstate=None,
+    on_setattr=None,
+    field_transformer=None,
+    match_args=True,
+):
+    r"""
+    A class decorator that adds `dunder
+    <https://wiki.python.org/moin/DunderAlias>`_\ -methods according to the
+    specified attributes using `attr.ib` or the *these* argument.
+
+    :param these: A dictionary of name to `attr.ib` mappings.  This is
+        useful to avoid the definition of your attributes within the class body
+        because you can't (e.g. if you want to add ``__repr__`` methods to
+        Django models) or don't want to.
+
+        If *these* is not ``None``, ``attrs`` will *not* search the class body
+        for attributes and will *not* remove any attributes from it.
+
+        If *these* is an ordered dict (`dict` on Python 3.6+,
+        `collections.OrderedDict` otherwise), the order is deduced from
+        the order of the attributes inside *these*.  Otherwise the order
+        of the definition of the attributes is used.
+
+    :type these: `dict` of `str` to `attr.ib`
+
+    :param str repr_ns: When using nested classes, there's no way in Python 2
+        to automatically detect that.  Therefore it's possible to set the
+        namespace explicitly for a more meaningful ``repr`` output.
+    :param bool auto_detect: Instead of setting the *init*, *repr*, *eq*,
+        *order*, and *hash* arguments explicitly, assume they are set to
+        ``True`` **unless any** of the involved methods for one of the
+        arguments is implemented in the *current* class (i.e. it is *not*
+        inherited from some base class).
+
+        So for example by implementing ``__eq__`` on a class yourself,
+        ``attrs`` will deduce ``eq=False`` and will create *neither*
+        ``__eq__`` *nor* ``__ne__`` (but Python classes come with a sensible
+        ``__ne__`` by default, so it *should* be enough to only implement
+        ``__eq__`` in most cases).
+
+        .. warning::
+
+           If you prevent ``attrs`` from creating the ordering methods for you
+           (``order=False``, e.g. by implementing ``__le__``), it becomes
+           *your* responsibility to make sure its ordering is sound. The best
+           way is to use the `functools.total_ordering` decorator.
+
+
+        Passing ``True`` or ``False`` to *init*, *repr*, *eq*, *order*,
+        *cmp*, or *hash* overrides whatever *auto_detect* would determine.
+
+        *auto_detect* requires Python 3. Setting it ``True`` on Python 2 raises
+        an `attrs.exceptions.PythonTooOldError`.
+
+    :param bool repr: Create a ``__repr__`` method with a human readable
+        representation of ``attrs`` attributes..
+    :param bool str: Create a ``__str__`` method that is identical to
+        ``__repr__``.  This is usually not necessary except for
+        `Exception`\ s.
+    :param Optional[bool] eq: If ``True`` or ``None`` (default), add ``__eq__``
+        and ``__ne__`` methods that check two instances for equality.
+
+        They compare the instances as if they were tuples of their ``attrs``
+        attributes if and only if the types of both classes are *identical*!
+    :param Optional[bool] order: If ``True``, add ``__lt__``, ``__le__``,
+        ``__gt__``, and ``__ge__`` methods that behave like *eq* above and
+        allow instances to be ordered. If ``None`` (default) mirror value of
+        *eq*.
+    :param Optional[bool] cmp: Setting *cmp* is equivalent to setting *eq*
+        and *order* to the same value. Must not be mixed with *eq* or *order*.
+    :param Optional[bool] hash: If ``None`` (default), the ``__hash__`` method
+        is generated according how *eq* and *frozen* are set.
+
+        1. If *both* are True, ``attrs`` will generate a ``__hash__`` for you.
+        2. If *eq* is True and *frozen* is False, ``__hash__`` will be set to
+           None, marking it unhashable (which it is).
+        3. If *eq* is False, ``__hash__`` will be left untouched meaning the
+           ``__hash__`` method of the base class will be used (if base class is
+           ``object``, this means it will fall back to id-based hashing.).
+
+        Although not recommended, you can decide for yourself and force
+        ``attrs`` to create one (e.g. if the class is immutable even though you
+        didn't freeze it programmatically) by passing ``True`` or not.  Both of
+        these cases are rather special and should be used carefully.
+
+        See our documentation on `hashing`, Python's documentation on
+        `object.__hash__`, and the `GitHub issue that led to the default \
+        behavior <https://github.com/python-attrs/attrs/issues/136>`_ for more
+        details.
+    :param bool init: Create a ``__init__`` method that initializes the
+        ``attrs`` attributes. Leading underscores are stripped for the argument
+        name. If a ``__attrs_pre_init__`` method exists on the class, it will
+        be called before the class is initialized. If a ``__attrs_post_init__``
+        method exists on the class, it will be called after the class is fully
+        initialized.
+
+        If ``init`` is ``False``, an ``__attrs_init__`` method will be
+        injected instead. This allows you to define a custom ``__init__``
+        method that can do pre-init work such as ``super().__init__()``,
+        and then call ``__attrs_init__()`` and ``__attrs_post_init__()``.
+    :param bool slots: Create a `slotted class <slotted classes>` that's more
+        memory-efficient. Slotted classes are generally superior to the default
+        dict classes, but have some gotchas you should know about, so we
+        encourage you to read the `glossary entry <slotted classes>`.
+    :param bool frozen: Make instances immutable after initialization.  If
+        someone attempts to modify a frozen instance,
+        `attr.exceptions.FrozenInstanceError` is raised.
+
+        .. note::
+
+            1. This is achieved by installing a custom ``__setattr__`` method
+               on your class, so you can't implement your own.
+
+            2. True immutability is impossible in Python.
+
+            3. This *does* have a minor a runtime performance `impact
+               <how-frozen>` when initializing new instances.  In other words:
+               ``__init__`` is slightly slower with ``frozen=True``.
+
+            4. If a class is frozen, you cannot modify ``self`` in
+               ``__attrs_post_init__`` or a self-written ``__init__``. You can
+               circumvent that limitation by using
+               ``object.__setattr__(self, "attribute_name", value)``.
+
+            5. Subclasses of a frozen class are frozen too.
+
+    :param bool weakref_slot: Make instances weak-referenceable.  This has no
+        effect unless ``slots`` is also enabled.
+    :param bool auto_attribs: If ``True``, collect :pep:`526`-annotated
+        attributes (Python 3.6 and later only) from the class body.
+
+        In this case, you **must** annotate every field.  If ``attrs``
+        encounters a field that is set to an `attr.ib` but lacks a type
+        annotation, an `attr.exceptions.UnannotatedAttributeError` is
+        raised.  Use ``field_name: typing.Any = attr.ib(...)`` if you don't
+        want to set a type.
+
+        If you assign a value to those attributes (e.g. ``x: int = 42``), that
+        value becomes the default value like if it were passed using
+        ``attr.ib(default=42)``.  Passing an instance of `attrs.Factory` also
+        works as expected in most cases (see warning below).
+
+        Attributes annotated as `typing.ClassVar`, and attributes that are
+        neither annotated nor set to an `attr.ib` are **ignored**.
+
+        .. warning::
+           For features that use the attribute name to create decorators (e.g.
+           `validators <validators>`), you still *must* assign `attr.ib` to
+           them. Otherwise Python will either not find the name or try to use
+           the default value to call e.g. ``validator`` on it.
+
+           These errors can be quite confusing and probably the most common bug
+           report on our bug tracker.
+
+    :param bool kw_only: Make all attributes keyword-only (Python 3+)
+        in the generated ``__init__`` (if ``init`` is ``False``, this
+        parameter is ignored).
+    :param bool cache_hash: Ensure that the object's hash code is computed
+        only once and stored on the object.  If this is set to ``True``,
+        hashing must be either explicitly or implicitly enabled for this
+        class.  If the hash code is cached, avoid any reassignments of
+        fields involved in hash code computation or mutations of the objects
+        those fields point to after object creation.  If such changes occur,
+        the behavior of the object's hash code is undefined.
+    :param bool auto_exc: If the class subclasses `BaseException`
+        (which implicitly includes any subclass of any exception), the
+        following happens to behave like a well-behaved Python exceptions
+        class:
+
+        - the values for *eq*, *order*, and *hash* are ignored and the
+          instances compare and hash by the instance's ids (N.B. ``attrs`` will
+          *not* remove existing implementations of ``__hash__`` or the equality
+          methods. It just won't add own ones.),
+        - all attributes that are either passed into ``__init__`` or have a
+          default value are additionally available as a tuple in the ``args``
+          attribute,
+        - the value of *str* is ignored leaving ``__str__`` to base classes.
+    :param bool collect_by_mro: Setting this to `True` fixes the way ``attrs``
+       collects attributes from base classes.  The default behavior is
+       incorrect in certain cases of multiple inheritance.  It should be on by
+       default but is kept off for backward-compatibility.
+
+       See issue `#428 <https://github.com/python-attrs/attrs/issues/428>`_ for
+       more details.
+
+    :param Optional[bool] getstate_setstate:
+       .. note::
+          This is usually only interesting for slotted classes and you should
+          probably just set *auto_detect* to `True`.
+
+       If `True`, ``__getstate__`` and
+       ``__setstate__`` are generated and attached to the class. This is
+       necessary for slotted classes to be pickleable. If left `None`, it's
+       `True` by default for slotted classes and ``False`` for dict classes.
+
+       If *auto_detect* is `True`, and *getstate_setstate* is left `None`,
+       and **either** ``__getstate__`` or ``__setstate__`` is detected directly
+       on the class (i.e. not inherited), it is set to `False` (this is usually
+       what you want).
+
+    :param on_setattr: A callable that is run whenever the user attempts to set
+        an attribute (either by assignment like ``i.x = 42`` or by using
+        `setattr` like ``setattr(i, "x", 42)``). It receives the same arguments
+        as validators: the instance, the attribute that is being modified, and
+        the new value.
+
+        If no exception is raised, the attribute is set to the return value of
+        the callable.
+
+        If a list of callables is passed, they're automatically wrapped in an
+        `attrs.setters.pipe`.
+    :type on_setattr: `callable`, or a list of callables, or `None`, or
+        `attrs.setters.NO_OP`
+
+    :param Optional[callable] field_transformer:
+        A function that is called with the original class object and all
+        fields right before ``attrs`` finalizes the class.  You can use
+        this, e.g., to automatically add converters or validators to
+        fields based on their types.  See `transform-fields` for more details.
+
+    :param bool match_args:
+        If `True` (default), set ``__match_args__`` on the class to support
+        :pep:`634` (Structural Pattern Matching). It is a tuple of all
+        non-keyword-only ``__init__`` parameter names on Python 3.10 and later.
+        Ignored on older Python versions.
+
+    .. versionadded:: 16.0.0 *slots*
+    .. versionadded:: 16.1.0 *frozen*
+    .. versionadded:: 16.3.0 *str*
+    .. versionadded:: 16.3.0 Support for ``__attrs_post_init__``.
+    .. versionchanged:: 17.1.0
+       *hash* supports ``None`` as value which is also the default now.
+    .. versionadded:: 17.3.0 *auto_attribs*
+    .. versionchanged:: 18.1.0
+       If *these* is passed, no attributes are deleted from the class body.
+    .. versionchanged:: 18.1.0 If *these* is ordered, the order is retained.
+    .. versionadded:: 18.2.0 *weakref_slot*
+    .. deprecated:: 18.2.0
+       ``__lt__``, ``__le__``, ``__gt__``, and ``__ge__`` now raise a
+       `DeprecationWarning` if the classes compared are subclasses of
+       each other. ``__eq`` and ``__ne__`` never tried to compared subclasses
+       to each other.
+    .. versionchanged:: 19.2.0
+       ``__lt__``, ``__le__``, ``__gt__``, and ``__ge__`` now do not consider
+       subclasses comparable anymore.
+    .. versionadded:: 18.2.0 *kw_only*
+    .. versionadded:: 18.2.0 *cache_hash*
+    .. versionadded:: 19.1.0 *auto_exc*
+    .. deprecated:: 19.2.0 *cmp* Removal on or after 2021-06-01.
+    .. versionadded:: 19.2.0 *eq* and *order*
+    .. versionadded:: 20.1.0 *auto_detect*
+    .. versionadded:: 20.1.0 *collect_by_mro*
+    .. versionadded:: 20.1.0 *getstate_setstate*
+    .. versionadded:: 20.1.0 *on_setattr*
+    .. versionadded:: 20.3.0 *field_transformer*
+    .. versionchanged:: 21.1.0
+       ``init=False`` injects ``__attrs_init__``
+    .. versionchanged:: 21.1.0 Support for ``__attrs_pre_init__``
+    .. versionchanged:: 21.1.0 *cmp* undeprecated
+    .. versionadded:: 21.3.0 *match_args*
+    """
+    eq_, order_ = _determine_attrs_eq_order(cmp, eq, order, None)
+    hash_ = hash  # work around the lack of nonlocal
+
+    if isinstance(on_setattr, (list, tuple)):
+        on_setattr = setters.pipe(*on_setattr)
+
+    def wrap(cls):
+        is_frozen = frozen or _has_frozen_base_class(cls)
+        is_exc = auto_exc is True and issubclass(cls, BaseException)
+        has_own_setattr = auto_detect and _has_own_attribute(
+            cls, "__setattr__"
+        )
+
+        if has_own_setattr and is_frozen:
+            raise ValueError("Can't freeze a class with a custom __setattr__.")
+
+        builder = _ClassBuilder(
+            cls,
+            these,
+            slots,
+            is_frozen,
+            weakref_slot,
+            _determine_whether_to_implement(
+                cls,
+                getstate_setstate,
+                auto_detect,
+                ("__getstate__", "__setstate__"),
+                default=slots,
+            ),
+            auto_attribs,
+            kw_only,
+            cache_hash,
+            is_exc,
+            collect_by_mro,
+            on_setattr,
+            has_own_setattr,
+            field_transformer,
+        )
+        if _determine_whether_to_implement(
+            cls, repr, auto_detect, ("__repr__",)
+        ):
+            builder.add_repr(repr_ns)
+        if str is True:
+            builder.add_str()
+
+        eq = _determine_whether_to_implement(
+            cls, eq_, auto_detect, ("__eq__", "__ne__")
+        )
+        if not is_exc and eq is True:
+            builder.add_eq()
+        if not is_exc and _determine_whether_to_implement(
+            cls, order_, auto_detect, ("__lt__", "__le__", "__gt__", "__ge__")
+        ):
+            builder.add_order()
+
+        builder.add_setattr()
+
+        if (
+            hash_ is None
+            and auto_detect is True
+            and _has_own_attribute(cls, "__hash__")
+        ):
+            hash = False
+        else:
+            hash = hash_
+        if hash is not True and hash is not False and hash is not None:
+            # Can't use `hash in` because 1 == True for example.
+            raise TypeError(
+                "Invalid value for hash.  Must be True, False, or None."
+            )
+        elif hash is False or (hash is None and eq is False) or is_exc:
+            # Don't do anything. Should fall back to __object__'s __hash__
+            # which is by id.
+            if cache_hash:
+                raise TypeError(
+                    "Invalid value for cache_hash.  To use hash caching,"
+                    " hashing must be either explicitly or implicitly "
+                    "enabled."
+                )
+        elif hash is True or (
+            hash is None and eq is True and is_frozen is True
+        ):
+            # Build a __hash__ if told so, or if it's safe.
+            builder.add_hash()
+        else:
+            # Raise TypeError on attempts to hash.
+            if cache_hash:
+                raise TypeError(
+                    "Invalid value for cache_hash.  To use hash caching,"
+                    " hashing must be either explicitly or implicitly "
+                    "enabled."
+                )
+            builder.make_unhashable()
+
+        if _determine_whether_to_implement(
+            cls, init, auto_detect, ("__init__",)
+        ):
+            builder.add_init()
+        else:
+            builder.add_attrs_init()
+            if cache_hash:
+                raise TypeError(
+                    "Invalid value for cache_hash.  To use hash caching,"
+                    " init must be True."
+                )
+
+        if (
+            PY310
+            and match_args
+            and not _has_own_attribute(cls, "__match_args__")
+        ):
+            builder.add_match_args()
+
+        return builder.build_class()
+
+    # maybe_cls's type depends on the usage of the decorator.  It's a class
+    # if it's used as `@attrs` but ``None`` if used as `@attrs()`.
+    if maybe_cls is None:
+        return wrap
+    else:
+        return wrap(maybe_cls)
+
+
+_attrs = attrs
+"""
+Internal alias so we can use it in functions that take an argument called
+*attrs*.
+"""
+
+
+def _has_frozen_base_class(cls):
+    """
+    Check whether *cls* has a frozen ancestor by looking at its
+    __setattr__.
+    """
+    return cls.__setattr__ is _frozen_setattrs
+
+
+def _generate_unique_filename(cls, func_name):
+    """
+    Create a "filename" suitable for a function being generated.
+    """
+    unique_filename = "<attrs generated {} {}.{}>".format(
+        func_name,
+        cls.__module__,
+        getattr(cls, "__qualname__", cls.__name__),
+    )
+    return unique_filename
+
+
+def _make_hash(cls, attrs, frozen, cache_hash):
+    attrs = tuple(
+        a for a in attrs if a.hash is True or (a.hash is None and a.eq is True)
+    )
+
+    tab = "        "
+
+    unique_filename = _generate_unique_filename(cls, "hash")
+    type_hash = hash(unique_filename)
+    # If eq is custom generated, we need to include the functions in globs
+    globs = {}
+
+    hash_def = "def __hash__(self"
+    hash_func = "hash(("
+    closing_braces = "))"
+    if not cache_hash:
+        hash_def += "):"
+    else:
+        hash_def += ", *"
+
+        hash_def += (
+            ", _cache_wrapper="
+            + "__import__('attr._make')._make._CacheHashWrapper):"
+        )
+        hash_func = "_cache_wrapper(" + hash_func
+        closing_braces += ")"
+
+    method_lines = [hash_def]
+
+    def append_hash_computation_lines(prefix, indent):
+        """
+        Generate the code for actually computing the hash code.
+        Below this will either be returned directly or used to compute
+        a value which is then cached, depending on the value of cache_hash
+        """
+
+        method_lines.extend(
+            [
+                indent + prefix + hash_func,
+                indent + "        %d," % (type_hash,),
+            ]
+        )
+
+        for a in attrs:
+            if a.eq_key:
+                cmp_name = "_%s_key" % (a.name,)
+                globs[cmp_name] = a.eq_key
+                method_lines.append(
+                    indent + "        %s(self.%s)," % (cmp_name, a.name)
+                )
+            else:
+                method_lines.append(indent + "        self.%s," % a.name)
+
+        method_lines.append(indent + "    " + closing_braces)
+
+    if cache_hash:
+        method_lines.append(tab + "if self.%s is None:" % _hash_cache_field)
+        if frozen:
+            append_hash_computation_lines(
+                "object.__setattr__(self, '%s', " % _hash_cache_field, tab * 2
+            )
+            method_lines.append(tab * 2 + ")")  # close __setattr__
+        else:
+            append_hash_computation_lines(
+                "self.%s = " % _hash_cache_field, tab * 2
+            )
+        method_lines.append(tab + "return self.%s" % _hash_cache_field)
+    else:
+        append_hash_computation_lines("return ", tab)
+
+    script = "\n".join(method_lines)
+    return _make_method("__hash__", script, unique_filename, globs)
+
+
+def _add_hash(cls, attrs):
+    """
+    Add a hash method to *cls*.
+    """
+    cls.__hash__ = _make_hash(cls, attrs, frozen=False, cache_hash=False)
+    return cls
+
+
+def _make_ne():
+    """
+    Create __ne__ method.
+    """
+
+    def __ne__(self, other):
+        """
+        Check equality and either forward a NotImplemented or
+        return the result negated.
+        """
+        result = self.__eq__(other)
+        if result is NotImplemented:
+            return NotImplemented
+
+        return not result
+
+    return __ne__
+
+
+def _make_eq(cls, attrs):
+    """
+    Create __eq__ method for *cls* with *attrs*.
+    """
+    attrs = [a for a in attrs if a.eq]
+
+    unique_filename = _generate_unique_filename(cls, "eq")
+    lines = [
+        "def __eq__(self, other):",
+        "    if other.__class__ is not self.__class__:",
+        "        return NotImplemented",
+    ]
+
+    # We can't just do a big self.x = other.x and... clause due to
+    # irregularities like nan == nan is false but (nan,) == (nan,) is true.
+    globs = {}
+    if attrs:
+        lines.append("    return  (")
+        others = ["    ) == ("]
+        for a in attrs:
+            if a.eq_key:
+                cmp_name = "_%s_key" % (a.name,)
+                # Add the key function to the global namespace
+                # of the evaluated function.
+                globs[cmp_name] = a.eq_key
+                lines.append(
+                    "        %s(self.%s),"
+                    % (
+                        cmp_name,
+                        a.name,
+                    )
+                )
+                others.append(
+                    "        %s(other.%s),"
+                    % (
+                        cmp_name,
+                        a.name,
+                    )
+                )
+            else:
+                lines.append("        self.%s," % (a.name,))
+                others.append("        other.%s," % (a.name,))
+
+        lines += others + ["    )"]
+    else:
+        lines.append("    return True")
+
+    script = "\n".join(lines)
+
+    return _make_method("__eq__", script, unique_filename, globs)
+
+
+def _make_order(cls, attrs):
+    """
+    Create ordering methods for *cls* with *attrs*.
+    """
+    attrs = [a for a in attrs if a.order]
+
+    def attrs_to_tuple(obj):
+        """
+        Save us some typing.
+        """
+        return tuple(
+            key(value) if key else value
+            for value, key in (
+                (getattr(obj, a.name), a.order_key) for a in attrs
+            )
+        )
+
+    def __lt__(self, other):
+        """
+        Automatically created by attrs.
+        """
+        if other.__class__ is self.__class__:
+            return attrs_to_tuple(self) < attrs_to_tuple(other)
+
+        return NotImplemented
+
+    def __le__(self, other):
+        """
+        Automatically created by attrs.
+        """
+        if other.__class__ is self.__class__:
+            return attrs_to_tuple(self) <= attrs_to_tuple(other)
+
+        return NotImplemented
+
+    def __gt__(self, other):
+        """
+        Automatically created by attrs.
+        """
+        if other.__class__ is self.__class__:
+            return attrs_to_tuple(self) > attrs_to_tuple(other)
+
+        return NotImplemented
+
+    def __ge__(self, other):
+        """
+        Automatically created by attrs.
+        """
+        if other.__class__ is self.__class__:
+            return attrs_to_tuple(self) >= attrs_to_tuple(other)
+
+        return NotImplemented
+
+    return __lt__, __le__, __gt__, __ge__
+
+
+def _add_eq(cls, attrs=None):
+    """
+    Add equality methods to *cls* with *attrs*.
+    """
+    if attrs is None:
+        attrs = cls.__attrs_attrs__
+
+    cls.__eq__ = _make_eq(cls, attrs)
+    cls.__ne__ = _make_ne()
+
+    return cls
+
+
+if HAS_F_STRINGS:
+
+    def _make_repr(attrs, ns, cls):
+        unique_filename = _generate_unique_filename(cls, "repr")
+        # Figure out which attributes to include, and which function to use to
+        # format them. The a.repr value can be either bool or a custom
+        # callable.
+        attr_names_with_reprs = tuple(
+            (a.name, (repr if a.repr is True else a.repr), a.init)
+            for a in attrs
+            if a.repr is not False
+        )
+        globs = {
+            name + "_repr": r
+            for name, r, _ in attr_names_with_reprs
+            if r != repr
+        }
+        globs["_compat"] = _compat
+        globs["AttributeError"] = AttributeError
+        globs["NOTHING"] = NOTHING
+        attribute_fragments = []
+        for name, r, i in attr_names_with_reprs:
+            accessor = (
+                "self." + name
+                if i
+                else 'getattr(self, "' + name + '", NOTHING)'
+            )
+            fragment = (
+                "%s={%s!r}" % (name, accessor)
+                if r == repr
+                else "%s={%s_repr(%s)}" % (name, name, accessor)
+            )
+            attribute_fragments.append(fragment)
+        repr_fragment = ", ".join(attribute_fragments)
+
+        if ns is None:
+            cls_name_fragment = (
+                '{self.__class__.__qualname__.rsplit(">.", 1)[-1]}'
+            )
+        else:
+            cls_name_fragment = ns + ".{self.__class__.__name__}"
+
+        lines = [
+            "def __repr__(self):",
+            "  try:",
+            "    already_repring = _compat.repr_context.already_repring",
+            "  except AttributeError:",
+            "    already_repring = {id(self),}",
+            "    _compat.repr_context.already_repring = already_repring",
+            "  else:",
+            "    if id(self) in already_repring:",
+            "      return '...'",
+            "    else:",
+            "      already_repring.add(id(self))",
+            "  try:",
+            "    return f'%s(%s)'" % (cls_name_fragment, repr_fragment),
+            "  finally:",
+            "    already_repring.remove(id(self))",
+        ]
+
+        return _make_method(
+            "__repr__", "\n".join(lines), unique_filename, globs=globs
+        )
+
+else:
+
+    def _make_repr(attrs, ns, _):
+        """
+        Make a repr method that includes relevant *attrs*, adding *ns* to the
+        full name.
+        """
+
+        # Figure out which attributes to include, and which function to use to
+        # format them. The a.repr value can be either bool or a custom
+        # callable.
+        attr_names_with_reprs = tuple(
+            (a.name, repr if a.repr is True else a.repr)
+            for a in attrs
+            if a.repr is not False
+        )
+
+        def __repr__(self):
+            """
+            Automatically created by attrs.
+            """
+            try:
+                already_repring = _compat.repr_context.already_repring
+            except AttributeError:
+                already_repring = set()
+                _compat.repr_context.already_repring = already_repring
+
+            if id(self) in already_repring:
+                return "..."
+            real_cls = self.__class__
+            if ns is None:
+                class_name = real_cls.__qualname__.rsplit(">.", 1)[-1]
+            else:
+                class_name = ns + "." + real_cls.__name__
+
+            # Since 'self' remains on the stack (i.e.: strongly referenced)
+            # for the duration of this call, it's safe to depend on id(...)
+            # stability, and not need to track the instance and therefore
+            # worry about properties like weakref- or hash-ability.
+            already_repring.add(id(self))
+            try:
+                result = [class_name, "("]
+                first = True
+                for name, attr_repr in attr_names_with_reprs:
+                    if first:
+                        first = False
+                    else:
+                        result.append(", ")
+                    result.extend(
+                        (name, "=", attr_repr(getattr(self, name, NOTHING)))
+                    )
+                return "".join(result) + ")"
+            finally:
+                already_repring.remove(id(self))
+
+        return __repr__
+
+
+def _add_repr(cls, ns=None, attrs=None):
+    """
+    Add a repr method to *cls*.
+    """
+    if attrs is None:
+        attrs = cls.__attrs_attrs__
+
+    cls.__repr__ = _make_repr(attrs, ns, cls)
+    return cls
+
+
+def fields(cls):
+    """
+    Return the tuple of ``attrs`` attributes for a class.
+
+    The tuple also allows accessing the fields by their names (see below for
+    examples).
+
+    :param type cls: Class to introspect.
+
+    :raise TypeError: If *cls* is not a class.
+    :raise attr.exceptions.NotAnAttrsClassError: If *cls* is not an ``attrs``
+        class.
+
+    :rtype: tuple (with name accessors) of `attrs.Attribute`
+
+    ..  versionchanged:: 16.2.0 Returned tuple allows accessing the fields
+        by name.
+    """
+    if not isinstance(cls, type):
+        raise TypeError("Passed object must be a class.")
+    attrs = getattr(cls, "__attrs_attrs__", None)
+    if attrs is None:
+        raise NotAnAttrsClassError(
+            "{cls!r} is not an attrs-decorated class.".format(cls=cls)
+        )
+    return attrs
+
+
+def fields_dict(cls):
+    """
+    Return an ordered dictionary of ``attrs`` attributes for a class, whose
+    keys are the attribute names.
+
+    :param type cls: Class to introspect.
+
+    :raise TypeError: If *cls* is not a class.
+    :raise attr.exceptions.NotAnAttrsClassError: If *cls* is not an ``attrs``
+        class.
+
+    :rtype: an ordered dict where keys are attribute names and values are
+        `attrs.Attribute`\\ s. This will be a `dict` if it's
+        naturally ordered like on Python 3.6+ or an
+        :class:`~collections.OrderedDict` otherwise.
+
+    .. versionadded:: 18.1.0
+    """
+    if not isinstance(cls, type):
+        raise TypeError("Passed object must be a class.")
+    attrs = getattr(cls, "__attrs_attrs__", None)
+    if attrs is None:
+        raise NotAnAttrsClassError(
+            "{cls!r} is not an attrs-decorated class.".format(cls=cls)
+        )
+    return ordered_dict((a.name, a) for a in attrs)
+
+
+def validate(inst):
+    """
+    Validate all attributes on *inst* that have a validator.
+
+    Leaves all exceptions through.
+
+    :param inst: Instance of a class with ``attrs`` attributes.
+    """
+    if _config._run_validators is False:
+        return
+
+    for a in fields(inst.__class__):
+        v = a.validator
+        if v is not None:
+            v(inst, a, getattr(inst, a.name))
+
+
+def _is_slot_cls(cls):
+    return "__slots__" in cls.__dict__
+
+
+def _is_slot_attr(a_name, base_attr_map):
+    """
+    Check if the attribute name comes from a slot class.
+    """
+    return a_name in base_attr_map and _is_slot_cls(base_attr_map[a_name])
+
+
+def _make_init(
+    cls,
+    attrs,
+    pre_init,
+    post_init,
+    frozen,
+    slots,
+    cache_hash,
+    base_attr_map,
+    is_exc,
+    cls_on_setattr,
+    attrs_init,
+):
+    has_cls_on_setattr = (
+        cls_on_setattr is not None and cls_on_setattr is not setters.NO_OP
+    )
+
+    if frozen and has_cls_on_setattr:
+        raise ValueError("Frozen classes can't use on_setattr.")
+
+    needs_cached_setattr = cache_hash or frozen
+    filtered_attrs = []
+    attr_dict = {}
+    for a in attrs:
+        if not a.init and a.default is NOTHING:
+            continue
+
+        filtered_attrs.append(a)
+        attr_dict[a.name] = a
+
+        if a.on_setattr is not None:
+            if frozen is True:
+                raise ValueError("Frozen classes can't use on_setattr.")
+
+            needs_cached_setattr = True
+        elif has_cls_on_setattr and a.on_setattr is not setters.NO_OP:
+            needs_cached_setattr = True
+
+    unique_filename = _generate_unique_filename(cls, "init")
+
+    script, globs, annotations = _attrs_to_init_script(
+        filtered_attrs,
+        frozen,
+        slots,
+        pre_init,
+        post_init,
+        cache_hash,
+        base_attr_map,
+        is_exc,
+        has_cls_on_setattr,
+        attrs_init,
+    )
+    if cls.__module__ in sys.modules:
+        # This makes typing.get_type_hints(CLS.__init__) resolve string types.
+        globs.update(sys.modules[cls.__module__].__dict__)
+
+    globs.update({"NOTHING": NOTHING, "attr_dict": attr_dict})
+
+    if needs_cached_setattr:
+        # Save the lookup overhead in __init__ if we need to circumvent
+        # setattr hooks.
+        globs["_setattr"] = _obj_setattr
+
+    init = _make_method(
+        "__attrs_init__" if attrs_init else "__init__",
+        script,
+        unique_filename,
+        globs,
+    )
+    init.__annotations__ = annotations
+
+    return init
+
+
+def _setattr(attr_name, value_var, has_on_setattr):
+    """
+    Use the cached object.setattr to set *attr_name* to *value_var*.
+    """
+    return "_setattr(self, '%s', %s)" % (attr_name, value_var)
+
+
+def _setattr_with_converter(attr_name, value_var, has_on_setattr):
+    """
+    Use the cached object.setattr to set *attr_name* to *value_var*, but run
+    its converter first.
+    """
+    return "_setattr(self, '%s', %s(%s))" % (
+        attr_name,
+        _init_converter_pat % (attr_name,),
+        value_var,
+    )
+
+
+def _assign(attr_name, value, has_on_setattr):
+    """
+    Unless *attr_name* has an on_setattr hook, use normal assignment. Otherwise
+    relegate to _setattr.
+    """
+    if has_on_setattr:
+        return _setattr(attr_name, value, True)
+
+    return "self.%s = %s" % (attr_name, value)
+
+
+def _assign_with_converter(attr_name, value_var, has_on_setattr):
+    """
+    Unless *attr_name* has an on_setattr hook, use normal assignment after
+    conversion. Otherwise relegate to _setattr_with_converter.
+    """
+    if has_on_setattr:
+        return _setattr_with_converter(attr_name, value_var, True)
+
+    return "self.%s = %s(%s)" % (
+        attr_name,
+        _init_converter_pat % (attr_name,),
+        value_var,
+    )
+
+
+def _attrs_to_init_script(
+    attrs,
+    frozen,
+    slots,
+    pre_init,
+    post_init,
+    cache_hash,
+    base_attr_map,
+    is_exc,
+    has_cls_on_setattr,
+    attrs_init,
+):
+    """
+    Return a script of an initializer for *attrs* and a dict of globals.
+
+    The globals are expected by the generated script.
+
+    If *frozen* is True, we cannot set the attributes directly so we use
+    a cached ``object.__setattr__``.
+    """
+    lines = []
+    if pre_init:
+        lines.append("self.__attrs_pre_init__()")
+
+    if frozen is True:
+        if slots is True:
+            fmt_setter = _setattr
+            fmt_setter_with_converter = _setattr_with_converter
+        else:
+            # Dict frozen classes assign directly to __dict__.
+            # But only if the attribute doesn't come from an ancestor slot
+            # class.
+            # Note _inst_dict will be used again below if cache_hash is True
+            lines.append("_inst_dict = self.__dict__")
+
+            def fmt_setter(attr_name, value_var, has_on_setattr):
+                if _is_slot_attr(attr_name, base_attr_map):
+                    return _setattr(attr_name, value_var, has_on_setattr)
+
+                return "_inst_dict['%s'] = %s" % (attr_name, value_var)
+
+            def fmt_setter_with_converter(
+                attr_name, value_var, has_on_setattr
+            ):
+                if has_on_setattr or _is_slot_attr(attr_name, base_attr_map):
+                    return _setattr_with_converter(
+                        attr_name, value_var, has_on_setattr
+                    )
+
+                return "_inst_dict['%s'] = %s(%s)" % (
+                    attr_name,
+                    _init_converter_pat % (attr_name,),
+                    value_var,
+                )
+
+    else:
+        # Not frozen.
+        fmt_setter = _assign
+        fmt_setter_with_converter = _assign_with_converter
+
+    args = []
+    kw_only_args = []
+    attrs_to_validate = []
+
+    # This is a dictionary of names to validator and converter callables.
+    # Injecting this into __init__ globals lets us avoid lookups.
+    names_for_globals = {}
+    annotations = {"return": None}
+
+    for a in attrs:
+        if a.validator:
+            attrs_to_validate.append(a)
+
+        attr_name = a.name
+        has_on_setattr = a.on_setattr is not None or (
+            a.on_setattr is not setters.NO_OP and has_cls_on_setattr
+        )
+        arg_name = a.name.lstrip("_")
+
+        has_factory = isinstance(a.default, Factory)
+        if has_factory and a.default.takes_self:
+            maybe_self = "self"
+        else:
+            maybe_self = ""
+
+        if a.init is False:
+            if has_factory:
+                init_factory_name = _init_factory_pat.format(a.name)
+                if a.converter is not None:
+                    lines.append(
+                        fmt_setter_with_converter(
+                            attr_name,
+                            init_factory_name + "(%s)" % (maybe_self,),
+                            has_on_setattr,
+                        )
+                    )
+                    conv_name = _init_converter_pat % (a.name,)
+                    names_for_globals[conv_name] = a.converter
+                else:
+                    lines.append(
+                        fmt_setter(
+                            attr_name,
+                            init_factory_name + "(%s)" % (maybe_self,),
+                            has_on_setattr,
+                        )
+                    )
+                names_for_globals[init_factory_name] = a.default.factory
+            else:
+                if a.converter is not None:
+                    lines.append(
+                        fmt_setter_with_converter(
+                            attr_name,
+                            "attr_dict['%s'].default" % (attr_name,),
+                            has_on_setattr,
+                        )
+                    )
+                    conv_name = _init_converter_pat % (a.name,)
+                    names_for_globals[conv_name] = a.converter
+                else:
+                    lines.append(
+                        fmt_setter(
+                            attr_name,
+                            "attr_dict['%s'].default" % (attr_name,),
+                            has_on_setattr,
+                        )
+                    )
+        elif a.default is not NOTHING and not has_factory:
+            arg = "%s=attr_dict['%s'].default" % (arg_name, attr_name)
+            if a.kw_only:
+                kw_only_args.append(arg)
+            else:
+                args.append(arg)
+
+            if a.converter is not None:
+                lines.append(
+                    fmt_setter_with_converter(
+                        attr_name, arg_name, has_on_setattr
+                    )
+                )
+                names_for_globals[
+                    _init_converter_pat % (a.name,)
+                ] = a.converter
+            else:
+                lines.append(fmt_setter(attr_name, arg_name, has_on_setattr))
+
+        elif has_factory:
+            arg = "%s=NOTHING" % (arg_name,)
+            if a.kw_only:
+                kw_only_args.append(arg)
+            else:
+                args.append(arg)
+            lines.append("if %s is not NOTHING:" % (arg_name,))
+
+            init_factory_name = _init_factory_pat.format(a.name)
+            if a.converter is not None:
+                lines.append(
+                    "    "
+                    + fmt_setter_with_converter(
+                        attr_name, arg_name, has_on_setattr
+                    )
+                )
+                lines.append("else:")
+                lines.append(
+                    "    "
+                    + fmt_setter_with_converter(
+                        attr_name,
+                        init_factory_name + "(" + maybe_self + ")",
+                        has_on_setattr,
+                    )
+                )
+                names_for_globals[
+                    _init_converter_pat % (a.name,)
+                ] = a.converter
+            else:
+                lines.append(
+                    "    " + fmt_setter(attr_name, arg_name, has_on_setattr)
+                )
+                lines.append("else:")
+                lines.append(
+                    "    "
+                    + fmt_setter(
+                        attr_name,
+                        init_factory_name + "(" + maybe_self + ")",
+                        has_on_setattr,
+                    )
+                )
+            names_for_globals[init_factory_name] = a.default.factory
+        else:
+            if a.kw_only:
+                kw_only_args.append(arg_name)
+            else:
+                args.append(arg_name)
+
+            if a.converter is not None:
+                lines.append(
+                    fmt_setter_with_converter(
+                        attr_name, arg_name, has_on_setattr
+                    )
+                )
+                names_for_globals[
+                    _init_converter_pat % (a.name,)
+                ] = a.converter
+            else:
+                lines.append(fmt_setter(attr_name, arg_name, has_on_setattr))
+
+        if a.init is True:
+            if a.type is not None and a.converter is None:
+                annotations[arg_name] = a.type
+            elif a.converter is not None:
+                # Try to get the type from the converter.
+                t = _AnnotationExtractor(a.converter).get_first_param_type()
+                if t:
+                    annotations[arg_name] = t
+
+    if attrs_to_validate:  # we can skip this if there are no validators.
+        names_for_globals["_config"] = _config
+        lines.append("if _config._run_validators is True:")
+        for a in attrs_to_validate:
+            val_name = "__attr_validator_" + a.name
+            attr_name = "__attr_" + a.name
+            lines.append(
+                "    %s(self, %s, self.%s)" % (val_name, attr_name, a.name)
+            )
+            names_for_globals[val_name] = a.validator
+            names_for_globals[attr_name] = a
+
+    if post_init:
+        lines.append("self.__attrs_post_init__()")
+
+    # because this is set only after __attrs_post_init__ is called, a crash
+    # will result if post-init tries to access the hash code.  This seemed
+    # preferable to setting this beforehand, in which case alteration to
+    # field values during post-init combined with post-init accessing the
+    # hash code would result in silent bugs.
+    if cache_hash:
+        if frozen:
+            if slots:
+                # if frozen and slots, then _setattr defined above
+                init_hash_cache = "_setattr(self, '%s', %s)"
+            else:
+                # if frozen and not slots, then _inst_dict defined above
+                init_hash_cache = "_inst_dict['%s'] = %s"
+        else:
+            init_hash_cache = "self.%s = %s"
+        lines.append(init_hash_cache % (_hash_cache_field, "None"))
+
+    # For exceptions we rely on BaseException.__init__ for proper
+    # initialization.
+    if is_exc:
+        vals = ",".join("self." + a.name for a in attrs if a.init)
+
+        lines.append("BaseException.__init__(self, %s)" % (vals,))
+
+    args = ", ".join(args)
+    if kw_only_args:
+        args += "%s*, %s" % (
+            ", " if args else "",  # leading comma
+            ", ".join(kw_only_args),  # kw_only args
+        )
+    return (
+        """\
+def {init_name}(self, {args}):
+    {lines}
+""".format(
+            init_name=("__attrs_init__" if attrs_init else "__init__"),
+            args=args,
+            lines="\n    ".join(lines) if lines else "pass",
+        ),
+        names_for_globals,
+        annotations,
+    )
+
+
+class Attribute:
+    """
+    *Read-only* representation of an attribute.
+
+    The class has *all* arguments of `attr.ib` (except for ``factory``
+    which is only syntactic sugar for ``default=Factory(...)`` plus the
+    following:
+
+    - ``name`` (`str`): The name of the attribute.
+    - ``inherited`` (`bool`): Whether or not that attribute has been inherited
+      from a base class.
+    - ``eq_key`` and ``order_key`` (`typing.Callable` or `None`): The callables
+      that are used for comparing and ordering objects by this attribute,
+      respectively. These are set by passing a callable to `attr.ib`'s ``eq``,
+      ``order``, or ``cmp`` arguments. See also :ref:`comparison customization
+      <custom-comparison>`.
+
+    Instances of this class are frequently used for introspection purposes
+    like:
+
+    - `fields` returns a tuple of them.
+    - Validators get them passed as the first argument.
+    - The :ref:`field transformer <transform-fields>` hook receives a list of
+      them.
+
+    .. versionadded:: 20.1.0 *inherited*
+    .. versionadded:: 20.1.0 *on_setattr*
+    .. versionchanged:: 20.2.0 *inherited* is not taken into account for
+        equality checks and hashing anymore.
+    .. versionadded:: 21.1.0 *eq_key* and *order_key*
+
+    For the full version history of the fields, see `attr.ib`.
+    """
+
+    __slots__ = (
+        "name",
+        "default",
+        "validator",
+        "repr",
+        "eq",
+        "eq_key",
+        "order",
+        "order_key",
+        "hash",
+        "init",
+        "metadata",
+        "type",
+        "converter",
+        "kw_only",
+        "inherited",
+        "on_setattr",
+    )
+
+    def __init__(
+        self,
+        name,
+        default,
+        validator,
+        repr,
+        cmp,  # XXX: unused, remove along with other cmp code.
+        hash,
+        init,
+        inherited,
+        metadata=None,
+        type=None,
+        converter=None,
+        kw_only=False,
+        eq=None,
+        eq_key=None,
+        order=None,
+        order_key=None,
+        on_setattr=None,
+    ):
+        eq, eq_key, order, order_key = _determine_attrib_eq_order(
+            cmp, eq_key or eq, order_key or order, True
+        )
+
+        # Cache this descriptor here to speed things up later.
+        bound_setattr = _obj_setattr.__get__(self, Attribute)
+
+        # Despite the big red warning, people *do* instantiate `Attribute`
+        # themselves.
+        bound_setattr("name", name)
+        bound_setattr("default", default)
+        bound_setattr("validator", validator)
+        bound_setattr("repr", repr)
+        bound_setattr("eq", eq)
+        bound_setattr("eq_key", eq_key)
+        bound_setattr("order", order)
+        bound_setattr("order_key", order_key)
+        bound_setattr("hash", hash)
+        bound_setattr("init", init)
+        bound_setattr("converter", converter)
+        bound_setattr(
+            "metadata",
+            (
+                types.MappingProxyType(dict(metadata))  # Shallow copy
+                if metadata
+                else _empty_metadata_singleton
+            ),
+        )
+        bound_setattr("type", type)
+        bound_setattr("kw_only", kw_only)
+        bound_setattr("inherited", inherited)
+        bound_setattr("on_setattr", on_setattr)
+
+    def __setattr__(self, name, value):
+        raise FrozenInstanceError()
+
+    @classmethod
+    def from_counting_attr(cls, name, ca, type=None):
+        # type holds the annotated value. deal with conflicts:
+        if type is None:
+            type = ca.type
+        elif ca.type is not None:
+            raise ValueError(
+                "Type annotation and type argument cannot both be present"
+            )
+        inst_dict = {
+            k: getattr(ca, k)
+            for k in Attribute.__slots__
+            if k
+            not in (
+                "name",
+                "validator",
+                "default",
+                "type",
+                "inherited",
+            )  # exclude methods and deprecated alias
+        }
+        return cls(
+            name=name,
+            validator=ca._validator,
+            default=ca._default,
+            type=type,
+            cmp=None,
+            inherited=False,
+            **inst_dict
+        )
+
+    # Don't use attr.evolve since fields(Attribute) doesn't work
+    def evolve(self, **changes):
+        """
+        Copy *self* and apply *changes*.
+
+        This works similarly to `attr.evolve` but that function does not work
+        with ``Attribute``.
+
+        It is mainly meant to be used for `transform-fields`.
+
+        .. versionadded:: 20.3.0
+        """
+        new = copy.copy(self)
+
+        new._setattrs(changes.items())
+
+        return new
+
+    # Don't use _add_pickle since fields(Attribute) doesn't work
+    def __getstate__(self):
+        """
+        Play nice with pickle.
+        """
+        return tuple(
+            getattr(self, name) if name != "metadata" else dict(self.metadata)
+            for name in self.__slots__
+        )
+
+    def __setstate__(self, state):
+        """
+        Play nice with pickle.
+        """
+        self._setattrs(zip(self.__slots__, state))
+
+    def _setattrs(self, name_values_pairs):
+        bound_setattr = _obj_setattr.__get__(self, Attribute)
+        for name, value in name_values_pairs:
+            if name != "metadata":
+                bound_setattr(name, value)
+            else:
+                bound_setattr(
+                    name,
+                    types.MappingProxyType(dict(value))
+                    if value
+                    else _empty_metadata_singleton,
+                )
+
+
+_a = [
+    Attribute(
+        name=name,
+        default=NOTHING,
+        validator=None,
+        repr=True,
+        cmp=None,
+        eq=True,
+        order=False,
+        hash=(name != "metadata"),
+        init=True,
+        inherited=False,
+    )
+    for name in Attribute.__slots__
+]
+
+Attribute = _add_hash(
+    _add_eq(
+        _add_repr(Attribute, attrs=_a),
+        attrs=[a for a in _a if a.name != "inherited"],
+    ),
+    attrs=[a for a in _a if a.hash and a.name != "inherited"],
+)
+
+
+class _CountingAttr:
+    """
+    Intermediate representation of attributes that uses a counter to preserve
+    the order in which the attributes have been defined.
+
+    *Internal* data structure of the attrs library.  Running into is most
+    likely the result of a bug like a forgotten `@attr.s` decorator.
+    """
+
+    __slots__ = (
+        "counter",
+        "_default",
+        "repr",
+        "eq",
+        "eq_key",
+        "order",
+        "order_key",
+        "hash",
+        "init",
+        "metadata",
+        "_validator",
+        "converter",
+        "type",
+        "kw_only",
+        "on_setattr",
+    )
+    __attrs_attrs__ = tuple(
+        Attribute(
+            name=name,
+            default=NOTHING,
+            validator=None,
+            repr=True,
+            cmp=None,
+            hash=True,
+            init=True,
+            kw_only=False,
+            eq=True,
+            eq_key=None,
+            order=False,
+            order_key=None,
+            inherited=False,
+            on_setattr=None,
+        )
+        for name in (
+            "counter",
+            "_default",
+            "repr",
+            "eq",
+            "order",
+            "hash",
+            "init",
+            "on_setattr",
+        )
+    ) + (
+        Attribute(
+            name="metadata",
+            default=None,
+            validator=None,
+            repr=True,
+            cmp=None,
+            hash=False,
+            init=True,
+            kw_only=False,
+            eq=True,
+            eq_key=None,
+            order=False,
+            order_key=None,
+            inherited=False,
+            on_setattr=None,
+        ),
+    )
+    cls_counter = 0
+
+    def __init__(
+        self,
+        default,
+        validator,
+        repr,
+        cmp,
+        hash,
+        init,
+        converter,
+        metadata,
+        type,
+        kw_only,
+        eq,
+        eq_key,
+        order,
+        order_key,
+        on_setattr,
+    ):
+        _CountingAttr.cls_counter += 1
+        self.counter = _CountingAttr.cls_counter
+        self._default = default
+        self._validator = validator
+        self.converter = converter
+        self.repr = repr
+        self.eq = eq
+        self.eq_key = eq_key
+        self.order = order
+        self.order_key = order_key
+        self.hash = hash
+        self.init = init
+        self.metadata = metadata
+        self.type = type
+        self.kw_only = kw_only
+        self.on_setattr = on_setattr
+
+    def validator(self, meth):
+        """
+        Decorator that adds *meth* to the list of validators.
+
+        Returns *meth* unchanged.
+
+        .. versionadded:: 17.1.0
+        """
+        if self._validator is None:
+            self._validator = meth
+        else:
+            self._validator = and_(self._validator, meth)
+        return meth
+
+    def default(self, meth):
+        """
+        Decorator that allows to set the default for an attribute.
+
+        Returns *meth* unchanged.
+
+        :raises DefaultAlreadySetError: If default has been set before.
+
+        .. versionadded:: 17.1.0
+        """
+        if self._default is not NOTHING:
+            raise DefaultAlreadySetError()
+
+        self._default = Factory(meth, takes_self=True)
+
+        return meth
+
+
+_CountingAttr = _add_eq(_add_repr(_CountingAttr))
+
+
+class Factory:
+    """
+    Stores a factory callable.
+
+    If passed as the default value to `attrs.field`, the factory is used to
+    generate a new value.
+
+    :param callable factory: A callable that takes either none or exactly one
+        mandatory positional argument depending on *takes_self*.
+    :param bool takes_self: Pass the partially initialized instance that is
+        being initialized as a positional argument.
+
+    .. versionadded:: 17.1.0  *takes_self*
+    """
+
+    __slots__ = ("factory", "takes_self")
+
+    def __init__(self, factory, takes_self=False):
+        """
+        `Factory` is part of the default machinery so if we want a default
+        value here, we have to implement it ourselves.
+        """
+        self.factory = factory
+        self.takes_self = takes_self
+
+    def __getstate__(self):
+        """
+        Play nice with pickle.
+        """
+        return tuple(getattr(self, name) for name in self.__slots__)
+
+    def __setstate__(self, state):
+        """
+        Play nice with pickle.
+        """
+        for name, value in zip(self.__slots__, state):
+            setattr(self, name, value)
+
+
+_f = [
+    Attribute(
+        name=name,
+        default=NOTHING,
+        validator=None,
+        repr=True,
+        cmp=None,
+        eq=True,
+        order=False,
+        hash=True,
+        init=True,
+        inherited=False,
+    )
+    for name in Factory.__slots__
+]
+
+Factory = _add_hash(_add_eq(_add_repr(Factory, attrs=_f), attrs=_f), attrs=_f)
+
+
+def make_class(name, attrs, bases=(object,), **attributes_arguments):
+    """
+    A quick way to create a new class called *name* with *attrs*.
+
+    :param str name: The name for the new class.
+
+    :param attrs: A list of names or a dictionary of mappings of names to
+        attributes.
+
+        If *attrs* is a list or an ordered dict (`dict` on Python 3.6+,
+        `collections.OrderedDict` otherwise), the order is deduced from
+        the order of the names or attributes inside *attrs*.  Otherwise the
+        order of the definition of the attributes is used.
+    :type attrs: `list` or `dict`
+
+    :param tuple bases: Classes that the new class will subclass.
+
+    :param attributes_arguments: Passed unmodified to `attr.s`.
+
+    :return: A new class with *attrs*.
+    :rtype: type
+
+    .. versionadded:: 17.1.0 *bases*
+    .. versionchanged:: 18.1.0 If *attrs* is ordered, the order is retained.
+    """
+    if isinstance(attrs, dict):
+        cls_dict = attrs
+    elif isinstance(attrs, (list, tuple)):
+        cls_dict = {a: attrib() for a in attrs}
+    else:
+        raise TypeError("attrs argument must be a dict or a list.")
+
+    pre_init = cls_dict.pop("__attrs_pre_init__", None)
+    post_init = cls_dict.pop("__attrs_post_init__", None)
+    user_init = cls_dict.pop("__init__", None)
+
+    body = {}
+    if pre_init is not None:
+        body["__attrs_pre_init__"] = pre_init
+    if post_init is not None:
+        body["__attrs_post_init__"] = post_init
+    if user_init is not None:
+        body["__init__"] = user_init
+
+    type_ = types.new_class(name, bases, {}, lambda ns: ns.update(body))
+
+    # For pickling to work, the __module__ variable needs to be set to the
+    # frame where the class is created.  Bypass this step in environments where
+    # sys._getframe is not defined (Jython for example) or sys._getframe is not
+    # defined for arguments greater than 0 (IronPython).
+    try:
+        type_.__module__ = sys._getframe(1).f_globals.get(
+            "__name__", "__main__"
+        )
+    except (AttributeError, ValueError):
+        pass
+
+    # We do it here for proper warnings with meaningful stacklevel.
+    cmp = attributes_arguments.pop("cmp", None)
+    (
+        attributes_arguments["eq"],
+        attributes_arguments["order"],
+    ) = _determine_attrs_eq_order(
+        cmp,
+        attributes_arguments.get("eq"),
+        attributes_arguments.get("order"),
+        True,
+    )
+
+    return _attrs(these=cls_dict, **attributes_arguments)(type_)
+
+
+# These are required by within this module so we define them here and merely
+# import into .validators / .converters.
+
+
+@attrs(slots=True, hash=True)
+class _AndValidator:
+    """
+    Compose many validators to a single one.
+    """
+
+    _validators = attrib()
+
+    def __call__(self, inst, attr, value):
+        for v in self._validators:
+            v(inst, attr, value)
+
+
+def and_(*validators):
+    """
+    A validator that composes multiple validators into one.
+
+    When called on a value, it runs all wrapped validators.
+
+    :param callables validators: Arbitrary number of validators.
+
+    .. versionadded:: 17.1.0
+    """
+    vals = []
+    for validator in validators:
+        vals.extend(
+            validator._validators
+            if isinstance(validator, _AndValidator)
+            else [validator]
+        )
+
+    return _AndValidator(tuple(vals))
+
+
+def pipe(*converters):
+    """
+    A converter that composes multiple converters into one.
+
+    When called on a value, it runs all wrapped converters, returning the
+    *last* value.
+
+    Type annotations will be inferred from the wrapped converters', if
+    they have any.
+
+    :param callables converters: Arbitrary number of converters.
+
+    .. versionadded:: 20.1.0
+    """
+
+    def pipe_converter(val):
+        for converter in converters:
+            val = converter(val)
+
+        return val
+
+    if not converters:
+        # If the converter list is empty, pipe_converter is the identity.
+        A = typing.TypeVar("A")
+        pipe_converter.__annotations__ = {"val": A, "return": A}
+    else:
+        # Get parameter type from first converter.
+        t = _AnnotationExtractor(converters[0]).get_first_param_type()
+        if t:
+            pipe_converter.__annotations__["val"] = t
+
+        # Get return type from last converter.
+        rt = _AnnotationExtractor(converters[-1]).get_return_type()
+        if rt:
+            pipe_converter.__annotations__["return"] = rt
+
+    return pipe_converter
diff --git a/lib/spack/external/_vendoring/attr/_next_gen.py b/lib/spack/external/_vendoring/attr/_next_gen.py
new file mode 100644
index 0000000000..5a06a74385
--- /dev/null
+++ b/lib/spack/external/_vendoring/attr/_next_gen.py
@@ -0,0 +1,220 @@
+# SPDX-License-Identifier: MIT
+
+"""
+These are Python 3.6+-only and keyword-only APIs that call `attr.s` and
+`attr.ib` with different default values.
+"""
+
+
+from functools import partial
+
+from . import setters
+from ._funcs import asdict as _asdict
+from ._funcs import astuple as _astuple
+from ._make import (
+    NOTHING,
+    _frozen_setattrs,
+    _ng_default_on_setattr,
+    attrib,
+    attrs,
+)
+from .exceptions import UnannotatedAttributeError
+
+
+def define(
+    maybe_cls=None,
+    *,
+    these=None,
+    repr=None,
+    hash=None,
+    init=None,
+    slots=True,
+    frozen=False,
+    weakref_slot=True,
+    str=False,
+    auto_attribs=None,
+    kw_only=False,
+    cache_hash=False,
+    auto_exc=True,
+    eq=None,
+    order=False,
+    auto_detect=True,
+    getstate_setstate=None,
+    on_setattr=None,
+    field_transformer=None,
+    match_args=True,
+):
+    r"""
+    Define an ``attrs`` class.
+
+    Differences to the classic `attr.s` that it uses underneath:
+
+    - Automatically detect whether or not *auto_attribs* should be `True` (c.f.
+      *auto_attribs* parameter).
+    - If *frozen* is `False`, run converters and validators when setting an
+      attribute by default.
+    - *slots=True*
+
+      .. caution::
+
+         Usually this has only upsides and few visible effects in everyday
+         programming. But it *can* lead to some suprising behaviors, so please
+         make sure to read :term:`slotted classes`.
+    - *auto_exc=True*
+    - *auto_detect=True*
+    - *order=False*
+    - Some options that were only relevant on Python 2 or were kept around for
+      backwards-compatibility have been removed.
+
+    Please note that these are all defaults and you can change them as you
+    wish.
+
+    :param Optional[bool] auto_attribs: If set to `True` or `False`, it behaves
+       exactly like `attr.s`. If left `None`, `attr.s` will try to guess:
+
+       1. If any attributes are annotated and no unannotated `attrs.fields`\ s
+          are found, it assumes *auto_attribs=True*.
+       2. Otherwise it assumes *auto_attribs=False* and tries to collect
+          `attrs.fields`\ s.
+
+    For now, please refer to `attr.s` for the rest of the parameters.
+
+    .. versionadded:: 20.1.0
+    .. versionchanged:: 21.3.0 Converters are also run ``on_setattr``.
+    """
+
+    def do_it(cls, auto_attribs):
+        return attrs(
+            maybe_cls=cls,
+            these=these,
+            repr=repr,
+            hash=hash,
+            init=init,
+            slots=slots,
+            frozen=frozen,
+            weakref_slot=weakref_slot,
+            str=str,
+            auto_attribs=auto_attribs,
+            kw_only=kw_only,
+            cache_hash=cache_hash,
+            auto_exc=auto_exc,
+            eq=eq,
+            order=order,
+            auto_detect=auto_detect,
+            collect_by_mro=True,
+            getstate_setstate=getstate_setstate,
+            on_setattr=on_setattr,
+            field_transformer=field_transformer,
+            match_args=match_args,
+        )
+
+    def wrap(cls):
+        """
+        Making this a wrapper ensures this code runs during class creation.
+
+        We also ensure that frozen-ness of classes is inherited.
+        """
+        nonlocal frozen, on_setattr
+
+        had_on_setattr = on_setattr not in (None, setters.NO_OP)
+
+        # By default, mutable classes convert & validate on setattr.
+        if frozen is False and on_setattr is None:
+            on_setattr = _ng_default_on_setattr
+
+        # However, if we subclass a frozen class, we inherit the immutability
+        # and disable on_setattr.
+        for base_cls in cls.__bases__:
+            if base_cls.__setattr__ is _frozen_setattrs:
+                if had_on_setattr:
+                    raise ValueError(
+                        "Frozen classes can't use on_setattr "
+                        "(frozen-ness was inherited)."
+                    )
+
+                on_setattr = setters.NO_OP
+                break
+
+        if auto_attribs is not None:
+            return do_it(cls, auto_attribs)
+
+        try:
+            return do_it(cls, True)
+        except UnannotatedAttributeError:
+            return do_it(cls, False)
+
+    # maybe_cls's type depends on the usage of the decorator.  It's a class
+    # if it's used as `@attrs` but ``None`` if used as `@attrs()`.
+    if maybe_cls is None:
+        return wrap
+    else:
+        return wrap(maybe_cls)
+
+
+mutable = define
+frozen = partial(define, frozen=True, on_setattr=None)
+
+
+def field(
+    *,
+    default=NOTHING,
+    validator=None,
+    repr=True,
+    hash=None,
+    init=True,
+    metadata=None,
+    converter=None,
+    factory=None,
+    kw_only=False,
+    eq=None,
+    order=None,
+    on_setattr=None,
+):
+    """
+    Identical to `attr.ib`, except keyword-only and with some arguments
+    removed.
+
+    .. versionadded:: 20.1.0
+    """
+    return attrib(
+        default=default,
+        validator=validator,
+        repr=repr,
+        hash=hash,
+        init=init,
+        metadata=metadata,
+        converter=converter,
+        factory=factory,
+        kw_only=kw_only,
+        eq=eq,
+        order=order,
+        on_setattr=on_setattr,
+    )
+
+
+def asdict(inst, *, recurse=True, filter=None, value_serializer=None):
+    """
+    Same as `attr.asdict`, except that collections types are always retained
+    and dict is always used as *dict_factory*.
+
+    .. versionadded:: 21.3.0
+    """
+    return _asdict(
+        inst=inst,
+        recurse=recurse,
+        filter=filter,
+        value_serializer=value_serializer,
+        retain_collection_types=True,
+    )
+
+
+def astuple(inst, *, recurse=True, filter=None):
+    """
+    Same as `attr.astuple`, except that collections types are always retained
+    and `tuple` is always used as the *tuple_factory*.
+
+    .. versionadded:: 21.3.0
+    """
+    return _astuple(
+        inst=inst, recurse=recurse, filter=filter, retain_collection_types=True
+    )
diff --git a/lib/spack/external/_vendoring/attr/_version_info.py b/lib/spack/external/_vendoring/attr/_version_info.py
new file mode 100644
index 0000000000..51a1312f97
--- /dev/null
+++ b/lib/spack/external/_vendoring/attr/_version_info.py
@@ -0,0 +1,86 @@
+# SPDX-License-Identifier: MIT
+
+
+from functools import total_ordering
+
+from ._funcs import astuple
+from ._make import attrib, attrs
+
+
+@total_ordering
+@attrs(eq=False, order=False, slots=True, frozen=True)
+class VersionInfo:
+    """
+    A version object that can be compared to tuple of length 1--4:
+
+    >>> attr.VersionInfo(19, 1, 0, "final")  <= (19, 2)
+    True
+    >>> attr.VersionInfo(19, 1, 0, "final") < (19, 1, 1)
+    True
+    >>> vi = attr.VersionInfo(19, 2, 0, "final")
+    >>> vi < (19, 1, 1)
+    False
+    >>> vi < (19,)
+    False
+    >>> vi == (19, 2,)
+    True
+    >>> vi == (19, 2, 1)
+    False
+
+    .. versionadded:: 19.2
+    """
+
+    year = attrib(type=int)
+    minor = attrib(type=int)
+    micro = attrib(type=int)
+    releaselevel = attrib(type=str)
+
+    @classmethod
+    def _from_version_string(cls, s):
+        """
+        Parse *s* and return a _VersionInfo.
+        """
+        v = s.split(".")
+        if len(v) == 3:
+            v.append("final")
+
+        return cls(
+            year=int(v[0]), minor=int(v[1]), micro=int(v[2]), releaselevel=v[3]
+        )
+
+    def _ensure_tuple(self, other):
+        """
+        Ensure *other* is a tuple of a valid length.
+
+        Returns a possibly transformed *other* and ourselves as a tuple of
+        the same length as *other*.
+        """
+
+        if self.__class__ is other.__class__:
+            other = astuple(other)
+
+        if not isinstance(other, tuple):
+            raise NotImplementedError
+
+        if not (1 <= len(other) <= 4):
+            raise NotImplementedError
+
+        return astuple(self)[: len(other)], other
+
+    def __eq__(self, other):
+        try:
+            us, them = self._ensure_tuple(other)
+        except NotImplementedError:
+            return NotImplemented
+
+        return us == them
+
+    def __lt__(self, other):
+        try:
+            us, them = self._ensure_tuple(other)
+        except NotImplementedError:
+            return NotImplemented
+
+        # Since alphabetically "dev0" < "final" < "post1" < "post2", we don't
+        # have to do anything special with releaselevel for now.
+        return us < them
diff --git a/lib/spack/external/_vendoring/attr/_version_info.pyi b/lib/spack/external/_vendoring/attr/_version_info.pyi
new file mode 100644
index 0000000000..45ced08633
--- /dev/null
+++ b/lib/spack/external/_vendoring/attr/_version_info.pyi
@@ -0,0 +1,9 @@
+class VersionInfo:
+    @property
+    def year(self) -> int: ...
+    @property
+    def minor(self) -> int: ...
+    @property
+    def micro(self) -> int: ...
+    @property
+    def releaselevel(self) -> str: ...
diff --git a/lib/spack/external/_vendoring/attr/converters.py b/lib/spack/external/_vendoring/attr/converters.py
new file mode 100644
index 0000000000..a73626c26d
--- /dev/null
+++ b/lib/spack/external/_vendoring/attr/converters.py
@@ -0,0 +1,144 @@
+# SPDX-License-Identifier: MIT
+
+"""
+Commonly useful converters.
+"""
+
+
+import typing
+
+from ._compat import _AnnotationExtractor
+from ._make import NOTHING, Factory, pipe
+
+
+__all__ = [
+    "default_if_none",
+    "optional",
+    "pipe",
+    "to_bool",
+]
+
+
+def optional(converter):
+    """
+    A converter that allows an attribute to be optional. An optional attribute
+    is one which can be set to ``None``.
+
+    Type annotations will be inferred from the wrapped converter's, if it
+    has any.
+
+    :param callable converter: the converter that is used for non-``None``
+        values.
+
+    .. versionadded:: 17.1.0
+    """
+
+    def optional_converter(val):
+        if val is None:
+            return None
+        return converter(val)
+
+    xtr = _AnnotationExtractor(converter)
+
+    t = xtr.get_first_param_type()
+    if t:
+        optional_converter.__annotations__["val"] = typing.Optional[t]
+
+    rt = xtr.get_return_type()
+    if rt:
+        optional_converter.__annotations__["return"] = typing.Optional[rt]
+
+    return optional_converter
+
+
+def default_if_none(default=NOTHING, factory=None):
+    """
+    A converter that allows to replace ``None`` values by *default* or the
+    result of *factory*.
+
+    :param default: Value to be used if ``None`` is passed. Passing an instance
+       of `attrs.Factory` is supported, however the ``takes_self`` option
+       is *not*.
+    :param callable factory: A callable that takes no parameters whose result
+       is used if ``None`` is passed.
+
+    :raises TypeError: If **neither** *default* or *factory* is passed.
+    :raises TypeError: If **both** *default* and *factory* are passed.
+    :raises ValueError: If an instance of `attrs.Factory` is passed with
+       ``takes_self=True``.
+
+    .. versionadded:: 18.2.0
+    """
+    if default is NOTHING and factory is None:
+        raise TypeError("Must pass either `default` or `factory`.")
+
+    if default is not NOTHING and factory is not None:
+        raise TypeError(
+            "Must pass either `default` or `factory` but not both."
+        )
+
+    if factory is not None:
+        default = Factory(factory)
+
+    if isinstance(default, Factory):
+        if default.takes_self:
+            raise ValueError(
+                "`takes_self` is not supported by default_if_none."
+            )
+
+        def default_if_none_converter(val):
+            if val is not None:
+                return val
+
+            return default.factory()
+
+    else:
+
+        def default_if_none_converter(val):
+            if val is not None:
+                return val
+
+            return default
+
+    return default_if_none_converter
+
+
+def to_bool(val):
+    """
+    Convert "boolean" strings (e.g., from env. vars.) to real booleans.
+
+    Values mapping to :code:`True`:
+
+    - :code:`True`
+    - :code:`"true"` / :code:`"t"`
+    - :code:`"yes"` / :code:`"y"`
+    - :code:`"on"`
+    - :code:`"1"`
+    - :code:`1`
+
+    Values mapping to :code:`False`:
+
+    - :code:`False`
+    - :code:`"false"` / :code:`"f"`
+    - :code:`"no"` / :code:`"n"`
+    - :code:`"off"`
+    - :code:`"0"`
+    - :code:`0`
+
+    :raises ValueError: for any other value.
+
+    .. versionadded:: 21.3.0
+    """
+    if isinstance(val, str):
+        val = val.lower()
+    truthy = {True, "true", "t", "yes", "y", "on", "1", 1}
+    falsy = {False, "false", "f", "no", "n", "off", "0", 0}
+    try:
+        if val in truthy:
+            return True
+        if val in falsy:
+            return False
+    except TypeError:
+        # Raised when "val" is not hashable (e.g., lists)
+        pass
+    raise ValueError("Cannot convert value to bool: {}".format(val))
diff --git a/lib/spack/external/_vendoring/attr/converters.pyi b/lib/spack/external/_vendoring/attr/converters.pyi
new file mode 100644
index 0000000000..0f58088a37
--- /dev/null
+++ b/lib/spack/external/_vendoring/attr/converters.pyi
@@ -0,0 +1,13 @@
+from typing import Callable, Optional, TypeVar, overload
+
+from . import _ConverterType
+
+_T = TypeVar("_T")
+
+def pipe(*validators: _ConverterType) -> _ConverterType: ...
+def optional(converter: _ConverterType) -> _ConverterType: ...
+@overload
+def default_if_none(default: _T) -> _ConverterType: ...
+@overload
+def default_if_none(*, factory: Callable[[], _T]) -> _ConverterType: ...
+def to_bool(val: str) -> bool: ...
diff --git a/lib/spack/external/_vendoring/attr/exceptions.py b/lib/spack/external/_vendoring/attr/exceptions.py
new file mode 100644
index 0000000000..5dc51e0a82
--- /dev/null
+++ b/lib/spack/external/_vendoring/attr/exceptions.py
@@ -0,0 +1,92 @@
+# SPDX-License-Identifier: MIT
+
+
+class FrozenError(AttributeError):
+    """
+    A frozen/immutable instance or attribute have been attempted to be
+    modified.
+
+    It mirrors the behavior of ``namedtuples`` by using the same error message
+    and subclassing `AttributeError`.
+
+    .. versionadded:: 20.1.0
+    """
+
+    msg = "can't set attribute"
+    args = [msg]
+
+
+class FrozenInstanceError(FrozenError):
+    """
+    A frozen instance has been attempted to be modified.
+
+    .. versionadded:: 16.1.0
+    """
+
+
+class FrozenAttributeError(FrozenError):
+    """
+    A frozen attribute has been attempted to be modified.
+
+    .. versionadded:: 20.1.0
+    """
+
+
+class AttrsAttributeNotFoundError(ValueError):
+    """
+    An ``attrs`` function couldn't find an attribute that the user asked for.
+
+    .. versionadded:: 16.2.0
+    """
+
+
+class NotAnAttrsClassError(ValueError):
+    """
+    A non-``attrs`` class has been passed into an ``attrs`` function.
+
+    .. versionadded:: 16.2.0
+    """
+
+
+class DefaultAlreadySetError(RuntimeError):
+    """
+    A default has been set using ``attr.ib()`` and is attempted to be reset
+    using the decorator.
+
+    .. versionadded:: 17.1.0
+    """
+
+
+class UnannotatedAttributeError(RuntimeError):
+    """
+    A class with ``auto_attribs=True`` has an ``attr.ib()`` without a type
+    annotation.
+
+    .. versionadded:: 17.3.0
+    """
+
+
+class PythonTooOldError(RuntimeError):
+    """
+    It was attempted to use an ``attrs`` feature that requires a newer Python
+    version.
+
+    .. versionadded:: 18.2.0
+    """
+
+
+class NotCallableError(TypeError):
+    """
+    A ``attr.ib()`` requiring a callable has been set with a value
+    that is not callable.
+
+    .. versionadded:: 19.2.0
+    """
+
+    def __init__(self, msg, value):
+        super(TypeError, self).__init__(msg, value)
+        self.msg = msg
+        self.value = value
+
+    def __str__(self):
+        return str(self.msg)
diff --git a/lib/spack/external/_vendoring/attr/exceptions.pyi b/lib/spack/external/_vendoring/attr/exceptions.pyi
new file mode 100644
index 0000000000..f2680118b4
--- /dev/null
+++ b/lib/spack/external/_vendoring/attr/exceptions.pyi
@@ -0,0 +1,17 @@
+from typing import Any
+
+class FrozenError(AttributeError):
+    msg: str = ...
+
+class FrozenInstanceError(FrozenError): ...
+class FrozenAttributeError(FrozenError): ...
+class AttrsAttributeNotFoundError(ValueError): ...
+class NotAnAttrsClassError(ValueError): ...
+class DefaultAlreadySetError(RuntimeError): ...
+class UnannotatedAttributeError(RuntimeError): ...
+class PythonTooOldError(RuntimeError): ...
+
+class NotCallableError(TypeError):
+    msg: str = ...
+    value: Any = ...
+    def __init__(self, msg: str, value: Any) -> None: ...
diff --git a/lib/spack/external/_vendoring/attr/filters.py b/lib/spack/external/_vendoring/attr/filters.py
new file mode 100644
index 0000000000..baa25e9465
--- /dev/null
+++ b/lib/spack/external/_vendoring/attr/filters.py
@@ -0,0 +1,51 @@
+# SPDX-License-Identifier: MIT
+
+"""
+Commonly useful filters for `attr.asdict`.
+"""
+
+from ._make import Attribute
+
+
+def _split_what(what):
+    """
+    Returns a tuple of `frozenset`s of classes and attributes.
+    """
+    return (
+        frozenset(cls for cls in what if isinstance(cls, type)),
+        frozenset(cls for cls in what if isinstance(cls, Attribute)),
+    )
+
+
+def include(*what):
+    """
+    Include *what*.
+
+    :param what: What to include.
+    :type what: `list` of `type` or `attrs.Attribute`\\ s
+
+    :rtype: `callable`
+    """
+    cls, attrs = _split_what(what)
+
+    def include_(attribute, value):
+        return value.__class__ in cls or attribute in attrs
+
+    return include_
+
+
+def exclude(*what):
+    """
+    Exclude *what*.
+
+    :param what: What to exclude.
+    :type what: `list` of classes or `attrs.Attribute`\\ s.
+
+    :rtype: `callable`
+    """
+    cls, attrs = _split_what(what)
+
+    def exclude_(attribute, value):
+        return value.__class__ not in cls and attribute not in attrs
+
+    return exclude_
diff --git a/lib/spack/external/_vendoring/attr/filters.pyi b/lib/spack/external/_vendoring/attr/filters.pyi
new file mode 100644
index 0000000000..993866865e
--- /dev/null
+++ b/lib/spack/external/_vendoring/attr/filters.pyi
@@ -0,0 +1,6 @@
+from typing import Any, Union
+
+from . import Attribute, _FilterType
+
+def include(*what: Union[type, Attribute[Any]]) -> _FilterType[Any]: ...
+def exclude(*what: Union[type, Attribute[Any]]) -> _FilterType[Any]: ...
diff --git a/lib/spack/external/_vendoring/attr/py.typed b/lib/spack/external/_vendoring/attr/py.typed
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/lib/spack/external/_vendoring/attr/py.typed
diff --git a/lib/spack/external/_vendoring/attr/setters.py b/lib/spack/external/_vendoring/attr/setters.py
new file mode 100644
index 0000000000..12ed6750df
--- /dev/null
+++ b/lib/spack/external/_vendoring/attr/setters.py
@@ -0,0 +1,73 @@
+# SPDX-License-Identifier: MIT
+
+"""
+Commonly used hooks for on_setattr.
+"""
+
+
+from . import _config
+from .exceptions import FrozenAttributeError
+
+
+def pipe(*setters):
+    """
+    Run all *setters* and return the return value of the last one.
+
+    .. versionadded:: 20.1.0
+    """
+
+    def wrapped_pipe(instance, attrib, new_value):
+        rv = new_value
+
+        for setter in setters:
+            rv = setter(instance, attrib, rv)
+
+        return rv
+
+    return wrapped_pipe
+
+
+def frozen(_, __, ___):
+    """
+    Prevent an attribute to be modified.
+
+    .. versionadded:: 20.1.0
+    """
+    raise FrozenAttributeError()
+
+
+def validate(instance, attrib, new_value):
+    """
+    Run *attrib*'s validator on *new_value* if it has one.
+
+    .. versionadded:: 20.1.0
+    """
+    if _config._run_validators is False:
+        return new_value
+
+    v = attrib.validator
+    if not v:
+        return new_value
+
+    v(instance, attrib, new_value)
+
+    return new_value
+
+
+def convert(instance, attrib, new_value):
+    """
+    Run *attrib*'s converter -- if it has one --  on *new_value* and return the
+    result.
+
+    .. versionadded:: 20.1.0
+    """
+    c = attrib.converter
+    if c:
+        return c(new_value)
+
+    return new_value
+
+
+# Sentinel for disabling class-wide *on_setattr* hooks for certain attributes.
+# autodata stopped working, so the docstring is inlined in the API docs.
+NO_OP = object()
diff --git a/lib/spack/external/_vendoring/attr/setters.pyi b/lib/spack/external/_vendoring/attr/setters.pyi
new file mode 100644
index 0000000000..3f5603c2b0
--- /dev/null
+++ b/lib/spack/external/_vendoring/attr/setters.pyi
@@ -0,0 +1,19 @@
+from typing import Any, NewType, NoReturn, TypeVar, cast
+
+from . import Attribute, _OnSetAttrType
+
+_T = TypeVar("_T")
+
+def frozen(
+    instance: Any, attribute: Attribute[Any], new_value: Any
+) -> NoReturn: ...
+def pipe(*setters: _OnSetAttrType) -> _OnSetAttrType: ...
+def validate(instance: Any, attribute: Attribute[_T], new_value: _T) -> _T: ...
+
+# convert is allowed to return Any, because they can be chained using pipe.
+def convert(
+    instance: Any, attribute: Attribute[Any], new_value: Any
+) -> Any: ...
+
+_NoOpType = NewType("_NoOpType", object)
+NO_OP: _NoOpType
diff --git a/lib/spack/external/_vendoring/attr/validators.py b/lib/spack/external/_vendoring/attr/validators.py
new file mode 100644
index 0000000000..eece517da8
--- /dev/null
+++ b/lib/spack/external/_vendoring/attr/validators.py
@@ -0,0 +1,594 @@
+# SPDX-License-Identifier: MIT
+
+"""
+Commonly useful validators.
+"""
+
+
+import operator
+import re
+
+from contextlib import contextmanager
+
+from ._config import get_run_validators, set_run_validators
+from ._make import _AndValidator, and_, attrib, attrs
+from .exceptions import NotCallableError
+
+
+try:
+    Pattern = re.Pattern
+except AttributeError:  # Python <3.7 lacks a Pattern type.
+    Pattern = type(re.compile(""))
+
+
+__all__ = [
+    "and_",
+    "deep_iterable",
+    "deep_mapping",
+    "disabled",
+    "ge",
+    "get_disabled",
+    "gt",
+    "in_",
+    "instance_of",
+    "is_callable",
+    "le",
+    "lt",
+    "matches_re",
+    "max_len",
+    "min_len",
+    "optional",
+    "provides",
+    "set_disabled",
+]
+
+
+def set_disabled(disabled):
+    """
+    Globally disable or enable running validators.
+
+    By default, they are run.
+
+    :param disabled: If ``True``, disable running all validators.
+    :type disabled: bool
+
+    .. warning::
+
+        This function is not thread-safe!
+
+    .. versionadded:: 21.3.0
+    """
+    set_run_validators(not disabled)
+
+
+def get_disabled():
+    """
+    Return a bool indicating whether validators are currently disabled or not.
+
+    :return: ``True`` if validators are currently disabled.
+    :rtype: bool
+
+    .. versionadded:: 21.3.0
+    """
+    return not get_run_validators()
+
+
+@contextmanager
+def disabled():
+    """
+    Context manager that disables running validators within its context.
+
+    .. warning::
+
+        This context manager is not thread-safe!
+
+    .. versionadded:: 21.3.0
+    """
+    set_run_validators(False)
+    try:
+        yield
+    finally:
+        set_run_validators(True)
+
+
+@attrs(repr=False, slots=True, hash=True)
+class _InstanceOfValidator:
+    type = attrib()
+
+    def __call__(self, inst, attr, value):
+        """
+        We use a callable class to be able to change the ``__repr__``.
+        """
+        if not isinstance(value, self.type):
+            raise TypeError(
+                "'{name}' must be {type!r} (got {value!r} that is a "
+                "{actual!r}).".format(
+                    name=attr.name,
+                    type=self.type,
+                    actual=value.__class__,
+                    value=value,
+                ),
+                attr,
+                self.type,
+                value,
+            )
+
+    def __repr__(self):
+        return "<instance_of validator for type {type!r}>".format(
+            type=self.type
+        )
+
+
+def instance_of(type):
+    """
+    A validator that raises a `TypeError` if the initializer is called
+    with a wrong type for this particular attribute (checks are performed using
+    `isinstance` therefore it's also valid to pass a tuple of types).
+
+    :param type: The type to check for.
+    :type type: type or tuple of types
+
+    :raises TypeError: With a human readable error message, the attribute
+        (of type `attrs.Attribute`), the expected type, and the value it
+        got.
+    """
+    return _InstanceOfValidator(type)
+
+
+@attrs(repr=False, frozen=True, slots=True)
+class _MatchesReValidator:
+    pattern = attrib()
+    match_func = attrib()
+
+    def __call__(self, inst, attr, value):
+        """
+        We use a callable class to be able to change the ``__repr__``.
+        """
+        if not self.match_func(value):
+            raise ValueError(
+                "'{name}' must match regex {pattern!r}"
+                " ({value!r} doesn't)".format(
+                    name=attr.name, pattern=self.pattern.pattern, value=value
+                ),
+                attr,
+                self.pattern,
+                value,
+            )
+
+    def __repr__(self):
+        return "<matches_re validator for pattern {pattern!r}>".format(
+            pattern=self.pattern
+        )
+
+
+def matches_re(regex, flags=0, func=None):
+    r"""
+    A validator that raises `ValueError` if the initializer is called
+    with a string that doesn't match *regex*.
+
+    :param regex: a regex string or precompiled pattern to match against
+    :param int flags: flags that will be passed to the underlying re function
+        (default 0)
+    :param callable func: which underlying `re` function to call. Valid options
+        are `re.fullmatch`, `re.search`, and `re.match`; the default ``None``
+        means `re.fullmatch`. For performance reasons, the pattern is always
+        precompiled using `re.compile`.
+
+    .. versionadded:: 19.2.0
+    .. versionchanged:: 21.3.0 *regex* can be a pre-compiled pattern.
+    """
+    valid_funcs = (re.fullmatch, None, re.search, re.match)
+    if func not in valid_funcs:
+        raise ValueError(
+            "'func' must be one of {}.".format(
+                ", ".join(
+                    sorted(
+                        e and e.__name__ or "None" for e in set(valid_funcs)
+                    )
+                )
+            )
+        )
+
+    if isinstance(regex, Pattern):
+        if flags:
+            raise TypeError(
+                "'flags' can only be used with a string pattern; "
+                "pass flags to re.compile() instead"
+            )
+        pattern = regex
+    else:
+        pattern = re.compile(regex, flags)
+
+    if func is re.match:
+        match_func = pattern.match
+    elif func is re.search:
+        match_func = pattern.search
+    else:
+        match_func = pattern.fullmatch
+
+    return _MatchesReValidator(pattern, match_func)
+
+
+@attrs(repr=False, slots=True, hash=True)
+class _ProvidesValidator:
+    interface = attrib()
+
+    def __call__(self, inst, attr, value):
+        """
+        We use a callable class to be able to change the ``__repr__``.
+        """
+        if not self.interface.providedBy(value):
+            raise TypeError(
+                "'{name}' must provide {interface!r} which {value!r} "
+                "doesn't.".format(
+                    name=attr.name, interface=self.interface, value=value
+                ),
+                attr,
+                self.interface,
+                value,
+            )
+
+    def __repr__(self):
+        return "<provides validator for interface {interface!r}>".format(
+            interface=self.interface
+        )
+
+
+def provides(interface):
+    """
+    A validator that raises a `TypeError` if the initializer is called
+    with an object that does not provide the requested *interface* (checks are
+    performed using ``interface.providedBy(value)`` (see `zope.interface
+    <https://zopeinterface.readthedocs.io/en/latest/>`_).
+
+    :param interface: The interface to check for.
+    :type interface: ``zope.interface.Interface``
+
+    :raises TypeError: With a human readable error message, the attribute
+        (of type `attrs.Attribute`), the expected interface, and the
+        value it got.
+    """
+    return _ProvidesValidator(interface)
+
+
+@attrs(repr=False, slots=True, hash=True)
+class _OptionalValidator:
+    validator = attrib()
+
+    def __call__(self, inst, attr, value):
+        if value is None:
+            return
+
+        self.validator(inst, attr, value)
+
+    def __repr__(self):
+        return "<optional validator for {what} or None>".format(
+            what=repr(self.validator)
+        )
+
+
+def optional(validator):
+    """
+    A validator that makes an attribute optional.  An optional attribute is one
+    which can be set to ``None`` in addition to satisfying the requirements of
+    the sub-validator.
+
+    :param validator: A validator (or a list of validators) that is used for
+        non-``None`` values.
+    :type validator: callable or `list` of callables.
+
+    .. versionadded:: 15.1.0
+    .. versionchanged:: 17.1.0 *validator* can be a list of validators.
+    """
+    if isinstance(validator, list):
+        return _OptionalValidator(_AndValidator(validator))
+    return _OptionalValidator(validator)
+
+
+@attrs(repr=False, slots=True, hash=True)
+class _InValidator:
+    options = attrib()
+
+    def __call__(self, inst, attr, value):
+        try:
+            in_options = value in self.options
+        except TypeError:  # e.g. `1 in "abc"`
+            in_options = False
+
+        if not in_options:
+            raise ValueError(
+                "'{name}' must be in {options!r} (got {value!r})".format(
+                    name=attr.name, options=self.options, value=value
+                ),
+                attr,
+                self.options,
+                value,
+            )
+
+    def __repr__(self):
+        return "<in_ validator with options {options!r}>".format(
+            options=self.options
+        )
+
+
+def in_(options):
+    """
+    A validator that raises a `ValueError` if the initializer is called
+    with a value that does not belong in the options provided.  The check is
+    performed using ``value in options``.
+
+    :param options: Allowed options.
+    :type options: list, tuple, `enum.Enum`, ...
+
+    :raises ValueError: With a human readable error message, the attribute (of
+       type `attrs.Attribute`), the expected options, and the value it
+       got.
+
+    .. versionadded:: 17.1.0
+    .. versionchanged:: 22.1.0
+       The ValueError was incomplete until now and only contained the human
+       readable error message. Now it contains all the information that has
+       been promised since 17.1.0.
+    """
+    return _InValidator(options)
+
+
+@attrs(repr=False, slots=False, hash=True)
+class _IsCallableValidator:
+    def __call__(self, inst, attr, value):
+        """
+        We use a callable class to be able to change the ``__repr__``.
+        """
+        if not callable(value):
+            message = (
+                "'{name}' must be callable "
+                "(got {value!r} that is a {actual!r})."
+            )
+            raise NotCallableError(
+                msg=message.format(
+                    name=attr.name, value=value, actual=value.__class__
+                ),
+                value=value,
+            )
+
+    def __repr__(self):
+        return "<is_callable validator>"
+
+
+def is_callable():
+    """
+    A validator that raises a `attr.exceptions.NotCallableError` if the
+    initializer is called with a value for this particular attribute
+    that is not callable.
+
+    .. versionadded:: 19.1.0
+
+    :raises `attr.exceptions.NotCallableError`: With a human readable error
+        message containing the attribute (`attrs.Attribute`) name,
+        and the value it got.
+    """
+    return _IsCallableValidator()
+
+
+@attrs(repr=False, slots=True, hash=True)
+class _DeepIterable:
+    member_validator = attrib(validator=is_callable())
+    iterable_validator = attrib(
+        default=None, validator=optional(is_callable())
+    )
+
+    def __call__(self, inst, attr, value):
+        """
+        We use a callable class to be able to change the ``__repr__``.
+        """
+        if self.iterable_validator is not None:
+            self.iterable_validator(inst, attr, value)
+
+        for member in value:
+            self.member_validator(inst, attr, member)
+
+    def __repr__(self):
+        iterable_identifier = (
+            ""
+            if self.iterable_validator is None
+            else " {iterable!r}".format(iterable=self.iterable_validator)
+        )
+        return (
+            "<deep_iterable validator for{iterable_identifier}"
+            " iterables of {member!r}>"
+        ).format(
+            iterable_identifier=iterable_identifier,
+            member=self.member_validator,
+        )
+
+
+def deep_iterable(member_validator, iterable_validator=None):
+    """
+    A validator that performs deep validation of an iterable.
+
+    :param member_validator: Validator(s) to apply to iterable members
+    :param iterable_validator: Validator to apply to iterable itself
+        (optional)
+
+    .. versionadded:: 19.1.0
+
+    :raises TypeError: if any sub-validators fail
+    """
+    if isinstance(member_validator, (list, tuple)):
+        member_validator = and_(*member_validator)
+    return _DeepIterable(member_validator, iterable_validator)
+
+
+@attrs(repr=False, slots=True, hash=True)
+class _DeepMapping:
+    key_validator = attrib(validator=is_callable())
+    value_validator = attrib(validator=is_callable())
+    mapping_validator = attrib(default=None, validator=optional(is_callable()))
+
+    def __call__(self, inst, attr, value):
+        """
+        We use a callable class to be able to change the ``__repr__``.
+        """
+        if self.mapping_validator is not None:
+            self.mapping_validator(inst, attr, value)
+
+        for key in value:
+            self.key_validator(inst, attr, key)
+            self.value_validator(inst, attr, value[key])
+
+    def __repr__(self):
+        return (
+            "<deep_mapping validator for objects mapping {key!r} to {value!r}>"
+        ).format(key=self.key_validator, value=self.value_validator)
+
+
+def deep_mapping(key_validator, value_validator, mapping_validator=None):
+    """
+    A validator that performs deep validation of a dictionary.
+
+    :param key_validator: Validator to apply to dictionary keys
+    :param value_validator: Validator to apply to dictionary values
+    :param mapping_validator: Validator to apply to top-level mapping
+        attribute (optional)
+
+    .. versionadded:: 19.1.0
+
+    :raises TypeError: if any sub-validators fail
+    """
+    return _DeepMapping(key_validator, value_validator, mapping_validator)
+
+
+@attrs(repr=False, frozen=True, slots=True)
+class _NumberValidator:
+    bound = attrib()
+    compare_op = attrib()
+    compare_func = attrib()
+
+    def __call__(self, inst, attr, value):
+        """
+        We use a callable class to be able to change the ``__repr__``.
+        """
+        if not self.compare_func(value, self.bound):
+            raise ValueError(
+                "'{name}' must be {op} {bound}: {value}".format(
+                    name=attr.name,
+                    op=self.compare_op,
+                    bound=self.bound,
+                    value=value,
+                )
+            )
+
+    def __repr__(self):
+        return "<Validator for x {op} {bound}>".format(
+            op=self.compare_op, bound=self.bound
+        )
+
+
+def lt(val):
+    """
+    A validator that raises `ValueError` if the initializer is called
+    with a number larger or equal to *val*.
+
+    :param val: Exclusive upper bound for values
+
+    .. versionadded:: 21.3.0
+    """
+    return _NumberValidator(val, "<", operator.lt)
+
+
+def le(val):
+    """
+    A validator that raises `ValueError` if the initializer is called
+    with a number greater than *val*.
+
+    :param val: Inclusive upper bound for values
+
+    .. versionadded:: 21.3.0
+    """
+    return _NumberValidator(val, "<=", operator.le)
+
+
+def ge(val):
+    """
+    A validator that raises `ValueError` if the initializer is called
+    with a number smaller than *val*.
+
+    :param val: Inclusive lower bound for values
+
+    .. versionadded:: 21.3.0
+    """
+    return _NumberValidator(val, ">=", operator.ge)
+
+
+def gt(val):
+    """
+    A validator that raises `ValueError` if the initializer is called
+    with a number smaller or equal to *val*.
+
+    :param val: Exclusive lower bound for values
+
+    .. versionadded:: 21.3.0
+    """
+    return _NumberValidator(val, ">", operator.gt)
+
+
+@attrs(repr=False, frozen=True, slots=True)
+class _MaxLengthValidator:
+    max_length = attrib()
+
+    def __call__(self, inst, attr, value):
+        """
+        We use a callable class to be able to change the ``__repr__``.
+        """
+        if len(value) > self.max_length:
+            raise ValueError(
+                "Length of '{name}' must be <= {max}: {len}".format(
+                    name=attr.name, max=self.max_length, len=len(value)
+                )
+            )
+
+    def __repr__(self):
+        return "<max_len validator for {max}>".format(max=self.max_length)
+
+
+def max_len(length):
+    """
+    A validator that raises `ValueError` if the initializer is called
+    with a string or iterable that is longer than *length*.
+
+    :param int length: Maximum length of the string or iterable
+
+    .. versionadded:: 21.3.0
+    """
+    return _MaxLengthValidator(length)
+
+
+@attrs(repr=False, frozen=True, slots=True)
+class _MinLengthValidator:
+    min_length = attrib()
+
+    def __call__(self, inst, attr, value):
+        """
+        We use a callable class to be able to change the ``__repr__``.
+        """
+        if len(value) < self.min_length:
+            raise ValueError(
+                "Length of '{name}' must be => {min}: {len}".format(
+                    name=attr.name, min=self.min_length, len=len(value)
+                )
+            )
+
+    def __repr__(self):
+        return "<min_len validator for {min}>".format(min=self.min_length)
+
+
+def min_len(length):
+    """
+    A validator that raises `ValueError` if the initializer is called
+    with a string or iterable that is shorter than *length*.
+
+    :param int length: Minimum length of the string or iterable
+
+    .. versionadded:: 22.1.0
+    """
+    return _MinLengthValidator(length)
diff --git a/lib/spack/external/_vendoring/attr/validators.pyi b/lib/spack/external/_vendoring/attr/validators.pyi
new file mode 100644
index 0000000000..54b9dba24e
--- /dev/null
+++ b/lib/spack/external/_vendoring/attr/validators.pyi
@@ -0,0 +1,80 @@
+from typing import (
+    Any,
+    AnyStr,
+    Callable,
+    Container,
+    ContextManager,
+    Iterable,
+    List,
+    Mapping,
+    Match,
+    Optional,
+    Pattern,
+    Tuple,
+    Type,
+    TypeVar,
+    Union,
+    overload,
+)
+
+from . import _ValidatorType
+from . import _ValidatorArgType
+
+_T = TypeVar("_T")
+_T1 = TypeVar("_T1")
+_T2 = TypeVar("_T2")
+_T3 = TypeVar("_T3")
+_I = TypeVar("_I", bound=Iterable)
+_K = TypeVar("_K")
+_V = TypeVar("_V")
+_M = TypeVar("_M", bound=Mapping)
+
+def set_disabled(run: bool) -> None: ...
+def get_disabled() -> bool: ...
+def disabled() -> ContextManager[None]: ...
+
+# To be more precise on instance_of use some overloads.
+# If there are more than 3 items in the tuple then we fall back to Any
+@overload
+def instance_of(type: Type[_T]) -> _ValidatorType[_T]: ...
+@overload
+def instance_of(type: Tuple[Type[_T]]) -> _ValidatorType[_T]: ...
+@overload
+def instance_of(
+    type: Tuple[Type[_T1], Type[_T2]]
+) -> _ValidatorType[Union[_T1, _T2]]: ...
+@overload
+def instance_of(
+    type: Tuple[Type[_T1], Type[_T2], Type[_T3]]
+) -> _ValidatorType[Union[_T1, _T2, _T3]]: ...
+@overload
+def instance_of(type: Tuple[type, ...]) -> _ValidatorType[Any]: ...
+def provides(interface: Any) -> _ValidatorType[Any]: ...
+def optional(
+    validator: Union[_ValidatorType[_T], List[_ValidatorType[_T]]]
+) -> _ValidatorType[Optional[_T]]: ...
+def in_(options: Container[_T]) -> _ValidatorType[_T]: ...
+def and_(*validators: _ValidatorType[_T]) -> _ValidatorType[_T]: ...
+def matches_re(
+    regex: Union[Pattern[AnyStr], AnyStr],
+    flags: int = ...,
+    func: Optional[
+        Callable[[AnyStr, AnyStr, int], Optional[Match[AnyStr]]]
+    ] = ...,
+) -> _ValidatorType[AnyStr]: ...
+def deep_iterable(
+    member_validator: _ValidatorArgType[_T],
+    iterable_validator: Optional[_ValidatorType[_I]] = ...,
+) -> _ValidatorType[_I]: ...
+def deep_mapping(
+    key_validator: _ValidatorType[_K],
+    value_validator: _ValidatorType[_V],
+    mapping_validator: Optional[_ValidatorType[_M]] = ...,
+) -> _ValidatorType[_M]: ...
+def is_callable() -> _ValidatorType[_T]: ...
+def lt(val: _T) -> _ValidatorType[_T]: ...
+def le(val: _T) -> _ValidatorType[_T]: ...
+def ge(val: _T) -> _ValidatorType[_T]: ...
+def gt(val: _T) -> _ValidatorType[_T]: ...
+def max_len(length: int) -> _ValidatorType[_T]: ...
+def min_len(length: int) -> _ValidatorType[_T]: ...
diff --git a/lib/spack/external/_vendoring/attrs/LICENSE b/lib/spack/external/_vendoring/attrs/LICENSE
new file mode 100644
index 0000000000..2bd6453d25
--- /dev/null
+++ b/lib/spack/external/_vendoring/attrs/LICENSE
@@ -0,0 +1,21 @@
+The MIT License (MIT)
+
+Copyright (c) 2015 Hynek Schlawack and the attrs contributors
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
diff --git a/lib/spack/external/_vendoring/attrs/__init__.py b/lib/spack/external/_vendoring/attrs/__init__.py
new file mode 100644
index 0000000000..a704b8b56b
--- /dev/null
+++ b/lib/spack/external/_vendoring/attrs/__init__.py
@@ -0,0 +1,70 @@
+# SPDX-License-Identifier: MIT
+
+from attr import (
+    NOTHING,
+    Attribute,
+    Factory,
+    __author__,
+    __copyright__,
+    __description__,
+    __doc__,
+    __email__,
+    __license__,
+    __title__,
+    __url__,
+    __version__,
+    __version_info__,
+    assoc,
+    cmp_using,
+    define,
+    evolve,
+    field,
+    fields,
+    fields_dict,
+    frozen,
+    has,
+    make_class,
+    mutable,
+    resolve_types,
+    validate,
+)
+from attr._next_gen import asdict, astuple
+
+from . import converters, exceptions, filters, setters, validators
+
+
+__all__ = [
+    "__author__",
+    "__copyright__",
+    "__description__",
+    "__doc__",
+    "__email__",
+    "__license__",
+    "__title__",
+    "__url__",
+    "__version__",
+    "__version_info__",
+    "asdict",
+    "assoc",
+    "astuple",
+    "Attribute",
+    "cmp_using",
+    "converters",
+    "define",
+    "evolve",
+    "exceptions",
+    "Factory",
+    "field",
+    "fields_dict",
+    "fields",
+    "filters",
+    "frozen",
+    "has",
+    "make_class",
+    "mutable",
+    "NOTHING",
+    "resolve_types",
+    "setters",
+    "validate",
+    "validators",
+]
diff --git a/lib/spack/external/_vendoring/attrs/__init__.pyi b/lib/spack/external/_vendoring/attrs/__init__.pyi
new file mode 100644
index 0000000000..fc44de46a0
--- /dev/null
+++ b/lib/spack/external/_vendoring/attrs/__init__.pyi
@@ -0,0 +1,66 @@
+from typing import (
+    Any,
+    Callable,
+    Dict,
+    Mapping,
+    Optional,
+    Sequence,
+    Tuple,
+    Type,
+)
+
+# Because we need to type our own stuff, we have to make everything from
+# attr explicitly public too.
+from attr import __author__ as __author__
+from attr import __copyright__ as __copyright__
+from attr import __description__ as __description__
+from attr import __email__ as __email__
+from attr import __license__ as __license__
+from attr import __title__ as __title__
+from attr import __url__ as __url__
+from attr import __version__ as __version__
+from attr import __version_info__ as __version_info__
+from attr import _FilterType
+from attr import assoc as assoc
+from attr import Attribute as Attribute
+from attr import cmp_using as cmp_using
+from attr import converters as converters
+from attr import define as define
+from attr import evolve as evolve
+from attr import exceptions as exceptions
+from attr import Factory as Factory
+from attr import field as field
+from attr import fields as fields
+from attr import fields_dict as fields_dict
+from attr import filters as filters
+from attr import frozen as frozen
+from attr import has as has
+from attr import make_class as make_class
+from attr import mutable as mutable
+from attr import NOTHING as NOTHING
+from attr import resolve_types as resolve_types
+from attr import setters as setters
+from attr import validate as validate
+from attr import validators as validators
+
+# TODO: see definition of attr.asdict/astuple
+def asdict(
+    inst: Any,
+    recurse: bool = ...,
+    filter: Optional[_FilterType[Any]] = ...,
+    dict_factory: Type[Mapping[Any, Any]] = ...,
+    retain_collection_types: bool = ...,
+    value_serializer: Optional[
+        Callable[[type, Attribute[Any], Any], Any]
+    ] = ...,
+    tuple_keys: bool = ...,
+) -> Dict[str, Any]: ...
+
+# TODO: add support for returning NamedTuple from the mypy plugin
+def astuple(
+    inst: Any,
+    recurse: bool = ...,
+    filter: Optional[_FilterType[Any]] = ...,
+    tuple_factory: Type[Sequence[Any]] = ...,
+    retain_collection_types: bool = ...,
+) -> Tuple[Any, ...]: ...
diff --git a/lib/spack/external/_vendoring/attrs/converters.py b/lib/spack/external/_vendoring/attrs/converters.py
new file mode 100644
index 0000000000..edfa8d3c16
--- /dev/null
+++ b/lib/spack/external/_vendoring/attrs/converters.py
@@ -0,0 +1,3 @@
+# SPDX-License-Identifier: MIT
+
+from attr.converters import *  # noqa
diff --git a/lib/spack/external/_vendoring/attrs/exceptions.py b/lib/spack/external/_vendoring/attrs/exceptions.py
new file mode 100644
index 0000000000..bd9efed202
--- /dev/null
+++ b/lib/spack/external/_vendoring/attrs/exceptions.py
@@ -0,0 +1,3 @@
+# SPDX-License-Identifier: MIT
+
+from attr.exceptions import *  # noqa
diff --git a/lib/spack/external/_vendoring/attrs/filters.py b/lib/spack/external/_vendoring/attrs/filters.py
new file mode 100644
index 0000000000..52959005b0
--- /dev/null
+++ b/lib/spack/external/_vendoring/attrs/filters.py
@@ -0,0 +1,3 @@
+# SPDX-License-Identifier: MIT
+
+from attr.filters import *  # noqa
diff --git a/lib/spack/external/_vendoring/attrs/py.typed b/lib/spack/external/_vendoring/attrs/py.typed
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/lib/spack/external/_vendoring/attrs/py.typed
diff --git a/lib/spack/external/_vendoring/attrs/setters.py b/lib/spack/external/_vendoring/attrs/setters.py
new file mode 100644
index 0000000000..9b50770804
--- /dev/null
+++ b/lib/spack/external/_vendoring/attrs/setters.py
@@ -0,0 +1,3 @@
+# SPDX-License-Identifier: MIT
+
+from attr.setters import *  # noqa
diff --git a/lib/spack/external/_vendoring/attrs/validators.py b/lib/spack/external/_vendoring/attrs/validators.py
new file mode 100644
index 0000000000..ab2c9b3024
--- /dev/null
+++ b/lib/spack/external/_vendoring/attrs/validators.py
@@ -0,0 +1,3 @@
+# SPDX-License-Identifier: MIT
+
+from attr.validators import *  # noqa
diff --git a/lib/spack/external/_vendoring/distro/LICENSE b/lib/spack/external/_vendoring/distro/LICENSE
new file mode 100644
index 0000000000..e06d208186
--- /dev/null
+++ b/lib/spack/external/_vendoring/distro/LICENSE
@@ -0,0 +1,202 @@
+Apache License
+                           Version 2.0, January 2004
+                        http://www.apache.org/licenses/
+
+   TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION
+
+   1. Definitions.
+
+      "License" shall mean the terms and conditions for use, reproduction,
+      and distribution as defined by Sections 1 through 9 of this document.
+
+      "Licensor" shall mean the copyright owner or entity authorized by
+      the copyright owner that is granting the License.
+
+      "Legal Entity" shall mean the union of the acting entity and all
+      other entities that control, are controlled by, or are under common
+      control with that entity. For the purposes of this definition,
+      "control" means (i) the power, direct or indirect, to cause the
+      direction or management of such entity, whether by contract or
+      otherwise, or (ii) ownership of fifty percent (50%) or more of the
+      outstanding shares, or (iii) beneficial ownership of such entity.
+
+      "You" (or "Your") shall mean an individual or Legal Entity
+      exercising permissions granted by this License.
+
+      "Source" form shall mean the preferred form for making modifications,
+      including but not limited to software source code, documentation
+      source, and configuration files.
+
+      "Object" form shall mean any form resulting from mechanical
+      transformation or translation of a Source form, including but
+      not limited to compiled object code, generated documentation,
+      and conversions to other media types.
+
+      "Work" shall mean the work of authorship, whether in Source or
+      Object form, made available under the License, as indicated by a
+      copyright notice that is included in or attached to the work
+      (an example is provided in the Appendix below).
+
+      "Derivative Works" shall mean any work, whether in Source or Object
+      form, that is based on (or derived from) the Work and for which the
+      editorial revisions, annotations, elaborations, or other modifications
+      represent, as a whole, an original work of authorship. For the purposes
+      of this License, Derivative Works shall not include works that remain
+      separable from, or merely link (or bind by name) to the interfaces of,
+      the Work and Derivative Works thereof.
+
+      "Contribution" shall mean any work of authorship, including
+      the original version of the Work and any modifications or additions
+      to that Work or Derivative Works thereof, that is intentionally
+      submitted to Licensor for inclusion in the Work by the copyright owner
+      or by an individual or Legal Entity authorized to submit on behalf of
+      the copyright owner. For the purposes of this definition, "submitted"
+      means any form of electronic, verbal, or written communication sent
+      to the Licensor or its representatives, including but not limited to
+      communication on electronic mailing lists, source code control systems,
+      and issue tracking systems that are managed by, or on behalf of, the
+      Licensor for the purpose of discussing and improving the Work, but
+      excluding communication that is conspicuously marked or otherwise
+      designated in writing by the copyright owner as "Not a Contribution."
+
+      "Contributor" shall mean Licensor and any individual or Legal Entity
+      on behalf of whom a Contribution has been received by Licensor and
+      subsequently incorporated within the Work.
+
+   2. Grant of Copyright License. Subject to the terms and conditions of
+      this License, each Contributor hereby grants to You a perpetual,
+      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
+      copyright license to reproduce, prepare Derivative Works of,
+      publicly display, publicly perform, sublicense, and distribute the
+      Work and such Derivative Works in Source or Object form.
+
+   3. Grant of Patent License. Subject to the terms and conditions of
+      this License, each Contributor hereby grants to You a perpetual,
+      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
+      (except as stated in this section) patent license to make, have made,
+      use, offer to sell, sell, import, and otherwise transfer the Work,
+      where such license applies only to those patent claims licensable
+      by such Contributor that are necessarily infringed by their
+      Contribution(s) alone or by combination of their Contribution(s)
+      with the Work to which such Contribution(s) was submitted. If You
+      institute patent litigation against any entity (including a
+      cross-claim or counterclaim in a lawsuit) alleging that the Work
+      or a Contribution incorporated within the Work constitutes direct
+      or contributory patent infringement, then any patent licenses
+      granted to You under this License for that Work shall terminate
+      as of the date such litigation is filed.
+
+   4. Redistribution. You may reproduce and distribute copies of the
+      Work or Derivative Works thereof in any medium, with or without
+      modifications, and in Source or Object form, provided that You
+      meet the following conditions:
+
+      (a) You must give any other recipients of the Work or
+          Derivative Works a copy of this License; and
+
+      (b) You must cause any modified files to carry prominent notices
+          stating that You changed the files; and
+
+      (c) You must retain, in the Source form of any Derivative Works
+          that You distribute, all copyright, patent, trademark, and
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+
diff --git a/lib/spack/external/_vendoring/distro/__init__.py b/lib/spack/external/_vendoring/distro/__init__.py
new file mode 100644
index 0000000000..7686fe85a7
--- /dev/null
+++ b/lib/spack/external/_vendoring/distro/__init__.py
@@ -0,0 +1,54 @@
+from .distro import (
+    NORMALIZED_DISTRO_ID,
+    NORMALIZED_LSB_ID,
+    NORMALIZED_OS_ID,
+    LinuxDistribution,
+    __version__,
+    build_number,
+    codename,
+    distro_release_attr,
+    distro_release_info,
+    id,
+    info,
+    like,
+    linux_distribution,
+    lsb_release_attr,
+    lsb_release_info,
+    major_version,
+    minor_version,
+    name,
+    os_release_attr,
+    os_release_info,
+    uname_attr,
+    uname_info,
+    version,
+    version_parts,
+)
+
+__all__ = [
+    "NORMALIZED_DISTRO_ID",
+    "NORMALIZED_LSB_ID",
+    "NORMALIZED_OS_ID",
+    "LinuxDistribution",
+    "build_number",
+    "codename",
+    "distro_release_attr",
+    "distro_release_info",
+    "id",
+    "info",
+    "like",
+    "linux_distribution",
+    "lsb_release_attr",
+    "lsb_release_info",
+    "major_version",
+    "minor_version",
+    "name",
+    "os_release_attr",
+    "os_release_info",
+    "uname_attr",
+    "uname_info",
+    "version",
+    "version_parts",
+]
+
+__version__ = __version__
diff --git a/lib/spack/external/_vendoring/distro/__main__.py b/lib/spack/external/_vendoring/distro/__main__.py
new file mode 100644
index 0000000000..0c01d5b08b
--- /dev/null
+++ b/lib/spack/external/_vendoring/distro/__main__.py
@@ -0,0 +1,4 @@
+from .distro import main
+
+if __name__ == "__main__":
+    main()
diff --git a/lib/spack/external/_vendoring/distro/distro.py b/lib/spack/external/_vendoring/distro/distro.py
new file mode 100644
index 0000000000..89e1868047
--- /dev/null
+++ b/lib/spack/external/_vendoring/distro/distro.py
@@ -0,0 +1,1399 @@
+#!/usr/bin/env python
+# Copyright 2015,2016,2017 Nir Cohen
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""
+The ``distro`` package (``distro`` stands for Linux Distribution) provides
+information about the Linux distribution it runs on, such as a reliable
+machine-readable distro ID, or version information.
+
+It is the recommended replacement for Python's original
+:py:func:`platform.linux_distribution` function, but it provides much more
+functionality. An alternative implementation became necessary because Python
+3.5 deprecated this function, and Python 3.8 removed it altogether. Its
+predecessor function :py:func:`platform.dist` was already deprecated since
+Python 2.6 and removed in Python 3.8. Still, there are many cases in which
+access to OS distribution information is needed. See `Python issue 1322
+<https://bugs.python.org/issue1322>`_ for more information.
+"""
+
+import argparse
+import json
+import logging
+import os
+import re
+import shlex
+import subprocess
+import sys
+import warnings
+from typing import (
+    Any,
+    Callable,
+    Dict,
+    Iterable,
+    Optional,
+    Sequence,
+    TextIO,
+    Tuple,
+    Type,
+)
+
+try:
+    from typing import TypedDict
+except ImportError:
+    # Python 3.7
+    TypedDict = dict
+
+__version__ = "1.8.0"
+
+
+class VersionDict(TypedDict):
+    major: str
+    minor: str
+    build_number: str
+
+
+class InfoDict(TypedDict):
+    id: str
+    version: str
+    version_parts: VersionDict
+    like: str
+    codename: str
+
+
+_UNIXCONFDIR = os.environ.get("UNIXCONFDIR", "/etc")
+_UNIXUSRLIBDIR = os.environ.get("UNIXUSRLIBDIR", "/usr/lib")
+_OS_RELEASE_BASENAME = "os-release"
+
+#: Translation table for normalizing the "ID" attribute defined in os-release
+#: files, for use by the :func:`distro.id` method.
+#:
+#: * Key: Value as defined in the os-release file, translated to lower case,
+#:   with blanks translated to underscores.
+#:
+#: * Value: Normalized value.
+NORMALIZED_OS_ID = {
+    "ol": "oracle",  # Oracle Linux
+    "opensuse-leap": "opensuse",  # Newer versions of OpenSuSE report as opensuse-leap
+}
+
+#: Translation table for normalizing the "Distributor ID" attribute returned by
+#: the lsb_release command, for use by the :func:`distro.id` method.
+#:
+#: * Key: Value as returned by the lsb_release command, translated to lower
+#:   case, with blanks translated to underscores.
+#:
+#: * Value: Normalized value.
+NORMALIZED_LSB_ID = {
+    "enterpriseenterpriseas": "oracle",  # Oracle Enterprise Linux 4
+    "enterpriseenterpriseserver": "oracle",  # Oracle Linux 5
+    "redhatenterpriseworkstation": "rhel",  # RHEL 6, 7 Workstation
+    "redhatenterpriseserver": "rhel",  # RHEL 6, 7 Server
+    "redhatenterprisecomputenode": "rhel",  # RHEL 6 ComputeNode
+}
+
+#: Translation table for normalizing the distro ID derived from the file name
+#: of distro release files, for use by the :func:`distro.id` method.
+#:
+#: * Key: Value as derived from the file name of a distro release file,
+#:   translated to lower case, with blanks translated to underscores.
+#:
+#: * Value: Normalized value.
+NORMALIZED_DISTRO_ID = {
+    "redhat": "rhel",  # RHEL 6.x, 7.x
+}
+
+# Pattern for content of distro release file (reversed)
+_DISTRO_RELEASE_CONTENT_REVERSED_PATTERN = re.compile(
+    r"(?:[^)]*\)(.*)\()? *(?:STL )?([\d.+\-a-z]*\d) *(?:esaeler *)?(.+)"
+)
+
+# Pattern for base file name of distro release file
+_DISTRO_RELEASE_BASENAME_PATTERN = re.compile(r"(\w+)[-_](release|version)$")
+
+# Base file names to be looked up for if _UNIXCONFDIR is not readable.
+_DISTRO_RELEASE_BASENAMES = [
+    "SuSE-release",
+    "arch-release",
+    "base-release",
+    "centos-release",
+    "fedora-release",
+    "gentoo-release",
+    "mageia-release",
+    "mandrake-release",
+    "mandriva-release",
+    "mandrivalinux-release",
+    "manjaro-release",
+    "oracle-release",
+    "redhat-release",
+    "rocky-release",
+    "sl-release",
+    "slackware-version",
+]
+
+# Base file names to be ignored when searching for distro release file
+_DISTRO_RELEASE_IGNORE_BASENAMES = (
+    "debian_version",
+    "lsb-release",
+    "oem-release",
+    _OS_RELEASE_BASENAME,
+    "system-release",
+    "plesk-release",
+    "iredmail-release",
+)
+
+
+def linux_distribution(full_distribution_name: bool = True) -> Tuple[str, str, str]:
+    """
+    .. deprecated:: 1.6.0
+
+        :func:`distro.linux_distribution()` is deprecated. It should only be
+        used as a compatibility shim with Python's
+        :py:func:`platform.linux_distribution()`. Please use :func:`distro.id`,
+        :func:`distro.version` and :func:`distro.name` instead.
+
+    Return information about the current OS distribution as a tuple
+    ``(id_name, version, codename)`` with items as follows:
+
+    * ``id_name``:  If *full_distribution_name* is false, the result of
+      :func:`distro.id`. Otherwise, the result of :func:`distro.name`.
+
+    * ``version``:  The result of :func:`distro.version`.
+
+    * ``codename``:  The extra item (usually in parentheses) after the
+      os-release version number, or the result of :func:`distro.codename`.
+
+    The interface of this function is compatible with the original
+    :py:func:`platform.linux_distribution` function, supporting a subset of
+    its parameters.
+
+    The data it returns may not exactly be the same, because it uses more data
+    sources than the original function, and that may lead to different data if
+    the OS distribution is not consistent across multiple data sources it
+    provides (there are indeed such distributions ...).
+
+    Another reason for differences is the fact that the :func:`distro.id`
+    method normalizes the distro ID string to a reliable machine-readable value
+    for a number of popular OS distributions.
+    """
+    warnings.warn(
+        "distro.linux_distribution() is deprecated. It should only be used as a "
+        "compatibility shim with Python's platform.linux_distribution(). Please use "
+        "distro.id(), distro.version() and distro.name() instead.",
+        DeprecationWarning,
+        stacklevel=2,
+    )
+    return _distro.linux_distribution(full_distribution_name)
+
+
+def id() -> str:
+    """
+    Return the distro ID of the current distribution, as a
+    machine-readable string.
+
+    For a number of OS distributions, the returned distro ID value is
+    *reliable*, in the sense that it is documented and that it does not change
+    across releases of the distribution.
+
+    This package maintains the following reliable distro ID values:
+
+    ==============  =========================================
+    Distro ID       Distribution
+    ==============  =========================================
+    "ubuntu"        Ubuntu
+    "debian"        Debian
+    "rhel"          RedHat Enterprise Linux
+    "centos"        CentOS
+    "fedora"        Fedora
+    "sles"          SUSE Linux Enterprise Server
+    "opensuse"      openSUSE
+    "amzn"          Amazon Linux
+    "arch"          Arch Linux
+    "buildroot"     Buildroot
+    "cloudlinux"    CloudLinux OS
+    "exherbo"       Exherbo Linux
+    "gentoo"        GenToo Linux
+    "ibm_powerkvm"  IBM PowerKVM
+    "kvmibm"        KVM for IBM z Systems
+    "linuxmint"     Linux Mint
+    "mageia"        Mageia
+    "mandriva"      Mandriva Linux
+    "parallels"     Parallels
+    "pidora"        Pidora
+    "raspbian"      Raspbian
+    "oracle"        Oracle Linux (and Oracle Enterprise Linux)
+    "scientific"    Scientific Linux
+    "slackware"     Slackware
+    "xenserver"     XenServer
+    "openbsd"       OpenBSD
+    "netbsd"        NetBSD
+    "freebsd"       FreeBSD
+    "midnightbsd"   MidnightBSD
+    "rocky"         Rocky Linux
+    "aix"           AIX
+    "guix"          Guix System
+    ==============  =========================================
+
+    If you have a need to get distros for reliable IDs added into this set,
+    or if you find that the :func:`distro.id` function returns a different
+    distro ID for one of the listed distros, please create an issue in the
+    `distro issue tracker`_.
+
+    **Lookup hierarchy and transformations:**
+
+    First, the ID is obtained from the following sources, in the specified
+    order. The first available and non-empty value is used:
+
+    * the value of the "ID" attribute of the os-release file,
+
+    * the value of the "Distributor ID" attribute returned by the lsb_release
+      command,
+
+    * the first part of the file name of the distro release file,
+
+    The so determined ID value then passes the following transformations,
+    before it is returned by this method:
+
+    * it is translated to lower case,
+
+    * blanks (which should not be there anyway) are translated to underscores,
+
+    * a normalization of the ID is performed, based upon
+      `normalization tables`_. The purpose of this normalization is to ensure
+      that the ID is as reliable as possible, even across incompatible changes
+      in the OS distributions. A common reason for an incompatible change is
+      the addition of an os-release file, or the addition of the lsb_release
+      command, with ID values that differ from what was previously determined
+      from the distro release file name.
+    """
+    return _distro.id()
+
+
+def name(pretty: bool = False) -> str:
+    """
+    Return the name of the current OS distribution, as a human-readable
+    string.
+
+    If *pretty* is false, the name is returned without version or codename.
+    (e.g. "CentOS Linux")
+
+    If *pretty* is true, the version and codename are appended.
+    (e.g. "CentOS Linux 7.1.1503 (Core)")
+
+    **Lookup hierarchy:**
+
+    The name is obtained from the following sources, in the specified order.
+    The first available and non-empty value is used:
+
+    * If *pretty* is false:
+
+      - the value of the "NAME" attribute of the os-release file,
+
+      - the value of the "Distributor ID" attribute returned by the lsb_release
+        command,
+
+      - the value of the "<name>" field of the distro release file.
+
+    * If *pretty* is true:
+
+      - the value of the "PRETTY_NAME" attribute of the os-release file,
+
+      - the value of the "Description" attribute returned by the lsb_release
+        command,
+
+      - the value of the "<name>" field of the distro release file, appended
+        with the value of the pretty version ("<version_id>" and "<codename>"
+        fields) of the distro release file, if available.
+    """
+    return _distro.name(pretty)
+
+
+def version(pretty: bool = False, best: bool = False) -> str:
+    """
+    Return the version of the current OS distribution, as a human-readable
+    string.
+
+    If *pretty* is false, the version is returned without codename (e.g.
+    "7.0").
+
+    If *pretty* is true, the codename in parenthesis is appended, if the
+    codename is non-empty (e.g. "7.0 (Maipo)").
+
+    Some distributions provide version numbers with different precisions in
+    the different sources of distribution information. Examining the different
+    sources in a fixed priority order does not always yield the most precise
+    version (e.g. for Debian 8.2, or CentOS 7.1).
+
+    Some other distributions may not provide this kind of information. In these
+    cases, an empty string would be returned. This behavior can be observed
+    with rolling releases distributions (e.g. Arch Linux).
+
+    The *best* parameter can be used to control the approach for the returned
+    version:
+
+    If *best* is false, the first non-empty version number in priority order of
+    the examined sources is returned.
+
+    If *best* is true, the most precise version number out of all examined
+    sources is returned.
+
+    **Lookup hierarchy:**
+
+    In all cases, the version number is obtained from the following sources.
+    If *best* is false, this order represents the priority order:
+
+    * the value of the "VERSION_ID" attribute of the os-release file,
+    * the value of the "Release" attribute returned by the lsb_release
+      command,
+    * the version number parsed from the "<version_id>" field of the first line
+      of the distro release file,
+    * the version number parsed from the "PRETTY_NAME" attribute of the
+      os-release file, if it follows the format of the distro release files.
+    * the version number parsed from the "Description" attribute returned by
+      the lsb_release command, if it follows the format of the distro release
+      files.
+    """
+    return _distro.version(pretty, best)
+
+
+def version_parts(best: bool = False) -> Tuple[str, str, str]:
+    """
+    Return the version of the current OS distribution as a tuple
+    ``(major, minor, build_number)`` with items as follows:
+
+    * ``major``:  The result of :func:`distro.major_version`.
+
+    * ``minor``:  The result of :func:`distro.minor_version`.
+
+    * ``build_number``:  The result of :func:`distro.build_number`.
+
+    For a description of the *best* parameter, see the :func:`distro.version`
+    method.
+    """
+    return _distro.version_parts(best)
+
+
+def major_version(best: bool = False) -> str:
+    """
+    Return the major version of the current OS distribution, as a string,
+    if provided.
+    Otherwise, the empty string is returned. The major version is the first
+    part of the dot-separated version string.
+
+    For a description of the *best* parameter, see the :func:`distro.version`
+    method.
+    """
+    return _distro.major_version(best)
+
+
+def minor_version(best: bool = False) -> str:
+    """
+    Return the minor version of the current OS distribution, as a string,
+    if provided.
+    Otherwise, the empty string is returned. The minor version is the second
+    part of the dot-separated version string.
+
+    For a description of the *best* parameter, see the :func:`distro.version`
+    method.
+    """
+    return _distro.minor_version(best)
+
+
+def build_number(best: bool = False) -> str:
+    """
+    Return the build number of the current OS distribution, as a string,
+    if provided.
+    Otherwise, the empty string is returned. The build number is the third part
+    of the dot-separated version string.
+
+    For a description of the *best* parameter, see the :func:`distro.version`
+    method.
+    """
+    return _distro.build_number(best)
+
+
+def like() -> str:
+    """
+    Return a space-separated list of distro IDs of distributions that are
+    closely related to the current OS distribution in regards to packaging
+    and programming interfaces, for example distributions the current
+    distribution is a derivative from.
+
+    **Lookup hierarchy:**
+
+    This information item is only provided by the os-release file.
+    For details, see the description of the "ID_LIKE" attribute in the
+    `os-release man page
+    <http://www.freedesktop.org/software/systemd/man/os-release.html>`_.
+    """
+    return _distro.like()
+
+
+def codename() -> str:
+    """
+    Return the codename for the release of the current OS distribution,
+    as a string.
+
+    If the distribution does not have a codename, an empty string is returned.
+
+    Note that the returned codename is not always really a codename. For
+    example, openSUSE returns "x86_64". This function does not handle such
+    cases in any special way and just returns the string it finds, if any.
+
+    **Lookup hierarchy:**
+
+    * the codename within the "VERSION" attribute of the os-release file, if
+      provided,
+
+    * the value of the "Codename" attribute returned by the lsb_release
+      command,
+
+    * the value of the "<codename>" field of the distro release file.
+    """
+    return _distro.codename()
+
+
+def info(pretty: bool = False, best: bool = False) -> InfoDict:
+    """
+    Return certain machine-readable information items about the current OS
+    distribution in a dictionary, as shown in the following example:
+
+    .. sourcecode:: python
+
+        {
+            'id': 'rhel',
+            'version': '7.0',
+            'version_parts': {
+                'major': '7',
+                'minor': '0',
+                'build_number': ''
+            },
+            'like': 'fedora',
+            'codename': 'Maipo'
+        }
+
+    The dictionary structure and keys are always the same, regardless of which
+    information items are available in the underlying data sources. The values
+    for the various keys are as follows:
+
+    * ``id``:  The result of :func:`distro.id`.
+
+    * ``version``:  The result of :func:`distro.version`.
+
+    * ``version_parts -> major``:  The result of :func:`distro.major_version`.
+
+    * ``version_parts -> minor``:  The result of :func:`distro.minor_version`.
+
+    * ``version_parts -> build_number``:  The result of
+      :func:`distro.build_number`.
+
+    * ``like``:  The result of :func:`distro.like`.
+
+    * ``codename``:  The result of :func:`distro.codename`.
+
+    For a description of the *pretty* and *best* parameters, see the
+    :func:`distro.version` method.
+    """
+    return _distro.info(pretty, best)
+
+
+def os_release_info() -> Dict[str, str]:
+    """
+    Return a dictionary containing key-value pairs for the information items
+    from the os-release file data source of the current OS distribution.
+
+    See `os-release file`_ for details about these information items.
+    """
+    return _distro.os_release_info()
+
+
+def lsb_release_info() -> Dict[str, str]:
+    """
+    Return a dictionary containing key-value pairs for the information items
+    from the lsb_release command data source of the current OS distribution.
+
+    See `lsb_release command output`_ for details about these information
+    items.
+    """
+    return _distro.lsb_release_info()
+
+
+def distro_release_info() -> Dict[str, str]:
+    """
+    Return a dictionary containing key-value pairs for the information items
+    from the distro release file data source of the current OS distribution.
+
+    See `distro release file`_ for details about these information items.
+    """
+    return _distro.distro_release_info()
+
+
+def uname_info() -> Dict[str, str]:
+    """
+    Return a dictionary containing key-value pairs for the information items
+    from the distro release file data source of the current OS distribution.
+    """
+    return _distro.uname_info()
+
+
+def os_release_attr(attribute: str) -> str:
+    """
+    Return a single named information item from the os-release file data source
+    of the current OS distribution.
+
+    Parameters:
+
+    * ``attribute`` (string): Key of the information item.
+
+    Returns:
+
+    * (string): Value of the information item, if the item exists.
+      The empty string, if the item does not exist.
+
+    See `os-release file`_ for details about these information items.
+    """
+    return _distro.os_release_attr(attribute)
+
+
+def lsb_release_attr(attribute: str) -> str:
+    """
+    Return a single named information item from the lsb_release command output
+    data source of the current OS distribution.
+
+    Parameters:
+
+    * ``attribute`` (string): Key of the information item.
+
+    Returns:
+
+    * (string): Value of the information item, if the item exists.
+      The empty string, if the item does not exist.
+
+    See `lsb_release command output`_ for details about these information
+    items.
+    """
+    return _distro.lsb_release_attr(attribute)
+
+
+def distro_release_attr(attribute: str) -> str:
+    """
+    Return a single named information item from the distro release file
+    data source of the current OS distribution.
+
+    Parameters:
+
+    * ``attribute`` (string): Key of the information item.
+
+    Returns:
+
+    * (string): Value of the information item, if the item exists.
+      The empty string, if the item does not exist.
+
+    See `distro release file`_ for details about these information items.
+    """
+    return _distro.distro_release_attr(attribute)
+
+
+def uname_attr(attribute: str) -> str:
+    """
+    Return a single named information item from the distro release file
+    data source of the current OS distribution.
+
+    Parameters:
+
+    * ``attribute`` (string): Key of the information item.
+
+    Returns:
+
+    * (string): Value of the information item, if the item exists.
+                The empty string, if the item does not exist.
+    """
+    return _distro.uname_attr(attribute)
+
+
+try:
+    from functools import cached_property
+except ImportError:
+    # Python < 3.8
+    class cached_property:  # type: ignore
+        """A version of @property which caches the value.  On access, it calls the
+        underlying function and sets the value in `__dict__` so future accesses
+        will not re-call the property.
+        """
+
+        def __init__(self, f: Callable[[Any], Any]) -> None:
+            self._fname = f.__name__
+            self._f = f
+
+        def __get__(self, obj: Any, owner: Type[Any]) -> Any:
+            assert obj is not None, f"call {self._fname} on an instance"
+            ret = obj.__dict__[self._fname] = self._f(obj)
+            return ret
+
+
+class LinuxDistribution:
+    """
+    Provides information about a OS distribution.
+
+    This package creates a private module-global instance of this class with
+    default initialization arguments, that is used by the
+    `consolidated accessor functions`_ and `single source accessor functions`_.
+    By using default initialization arguments, that module-global instance
+    returns data about the current OS distribution (i.e. the distro this
+    package runs on).
+
+    Normally, it is not necessary to create additional instances of this class.
+    However, in situations where control is needed over the exact data sources
+    that are used, instances of this class can be created with a specific
+    distro release file, or a specific os-release file, or without invoking the
+    lsb_release command.
+    """
+
+    def __init__(
+        self,
+        include_lsb: Optional[bool] = None,
+        os_release_file: str = "",
+        distro_release_file: str = "",
+        include_uname: Optional[bool] = None,
+        root_dir: Optional[str] = None,
+        include_oslevel: Optional[bool] = None,
+    ) -> None:
+        """
+        The initialization method of this class gathers information from the
+        available data sources, and stores that in private instance attributes.
+        Subsequent access to the information items uses these private instance
+        attributes, so that the data sources are read only once.
+
+        Parameters:
+
+        * ``include_lsb`` (bool): Controls whether the
+          `lsb_release command output`_ is included as a data source.
+
+          If the lsb_release command is not available in the program execution
+          path, the data source for the lsb_release command will be empty.
+
+        * ``os_release_file`` (string): The path name of the
+          `os-release file`_ that is to be used as a data source.
+
+          An empty string (the default) will cause the default path name to
+          be used (see `os-release file`_ for details).
+
+          If the specified or defaulted os-release file does not exist, the
+          data source for the os-release file will be empty.
+
+        * ``distro_release_file`` (string): The path name of the
+          `distro release file`_ that is to be used as a data source.
+
+          An empty string (the default) will cause a default search algorithm
+          to be used (see `distro release file`_ for details).
+
+          If the specified distro release file does not exist, or if no default
+          distro release file can be found, the data source for the distro
+          release file will be empty.
+
+        * ``include_uname`` (bool): Controls whether uname command output is
+          included as a data source. If the uname command is not available in
+          the program execution path the data source for the uname command will
+          be empty.
+
+        * ``root_dir`` (string): The absolute path to the root directory to use
+          to find distro-related information files. Note that ``include_*``
+          parameters must not be enabled in combination with ``root_dir``.
+
+        * ``include_oslevel`` (bool): Controls whether (AIX) oslevel command
+          output is included as a data source. If the oslevel command is not
+          available in the program execution path the data source will be
+          empty.
+
+        Public instance attributes:
+
+        * ``os_release_file`` (string): The path name of the
+          `os-release file`_ that is actually used as a data source. The
+          empty string if no distro release file is used as a data source.
+
+        * ``distro_release_file`` (string): The path name of the
+          `distro release file`_ that is actually used as a data source. The
+          empty string if no distro release file is used as a data source.
+
+        * ``include_lsb`` (bool): The result of the ``include_lsb`` parameter.
+          This controls whether the lsb information will be loaded.
+
+        * ``include_uname`` (bool): The result of the ``include_uname``
+          parameter. This controls whether the uname information will
+          be loaded.
+
+        * ``include_oslevel`` (bool): The result of the ``include_oslevel``
+          parameter. This controls whether (AIX) oslevel information will be
+          loaded.
+
+        * ``root_dir`` (string): The result of the ``root_dir`` parameter.
+          The absolute path to the root directory to use to find distro-related
+          information files.
+
+        Raises:
+
+        * :py:exc:`ValueError`: Initialization parameters combination is not
+           supported.
+
+        * :py:exc:`OSError`: Some I/O issue with an os-release file or distro
+          release file.
+
+        * :py:exc:`UnicodeError`: A data source has unexpected characters or
+          uses an unexpected encoding.
+        """
+        self.root_dir = root_dir
+        self.etc_dir = os.path.join(root_dir, "etc") if root_dir else _UNIXCONFDIR
+        self.usr_lib_dir = (
+            os.path.join(root_dir, "usr/lib") if root_dir else _UNIXUSRLIBDIR
+        )
+
+        if os_release_file:
+            self.os_release_file = os_release_file
+        else:
+            etc_dir_os_release_file = os.path.join(self.etc_dir, _OS_RELEASE_BASENAME)
+            usr_lib_os_release_file = os.path.join(
+                self.usr_lib_dir, _OS_RELEASE_BASENAME
+            )
+
+            # NOTE: The idea is to respect order **and** have it set
+            #       at all times for API backwards compatibility.
+            if os.path.isfile(etc_dir_os_release_file) or not os.path.isfile(
+                usr_lib_os_release_file
+            ):
+                self.os_release_file = etc_dir_os_release_file
+            else:
+                self.os_release_file = usr_lib_os_release_file
+
+        self.distro_release_file = distro_release_file or ""  # updated later
+
+        is_root_dir_defined = root_dir is not None
+        if is_root_dir_defined and (include_lsb or include_uname or include_oslevel):
+            raise ValueError(
+                "Including subprocess data sources from specific root_dir is disallowed"
+                " to prevent false information"
+            )
+        self.include_lsb = (
+            include_lsb if include_lsb is not None else not is_root_dir_defined
+        )
+        self.include_uname = (
+            include_uname if include_uname is not None else not is_root_dir_defined
+        )
+        self.include_oslevel = (
+            include_oslevel if include_oslevel is not None else not is_root_dir_defined
+        )
+
+    def __repr__(self) -> str:
+        """Return repr of all info"""
+        return (
+            "LinuxDistribution("
+            "os_release_file={self.os_release_file!r}, "
+            "distro_release_file={self.distro_release_file!r}, "
+            "include_lsb={self.include_lsb!r}, "
+            "include_uname={self.include_uname!r}, "
+            "include_oslevel={self.include_oslevel!r}, "
+            "root_dir={self.root_dir!r}, "
+            "_os_release_info={self._os_release_info!r}, "
+            "_lsb_release_info={self._lsb_release_info!r}, "
+            "_distro_release_info={self._distro_release_info!r}, "
+            "_uname_info={self._uname_info!r}, "
+            "_oslevel_info={self._oslevel_info!r})".format(self=self)
+        )
+
+    def linux_distribution(
+        self, full_distribution_name: bool = True
+    ) -> Tuple[str, str, str]:
+        """
+        Return information about the OS distribution that is compatible
+        with Python's :func:`platform.linux_distribution`, supporting a subset
+        of its parameters.
+
+        For details, see :func:`distro.linux_distribution`.
+        """
+        return (
+            self.name() if full_distribution_name else self.id(),
+            self.version(),
+            self._os_release_info.get("release_codename") or self.codename(),
+        )
+
+    def id(self) -> str:
+        """Return the distro ID of the OS distribution, as a string.
+
+        For details, see :func:`distro.id`.
+        """
+
+        def normalize(distro_id: str, table: Dict[str, str]) -> str:
+            distro_id = distro_id.lower().replace(" ", "_")
+            return table.get(distro_id, distro_id)
+
+        distro_id = self.os_release_attr("id")
+        if distro_id:
+            return normalize(distro_id, NORMALIZED_OS_ID)
+
+        distro_id = self.lsb_release_attr("distributor_id")
+        if distro_id:
+            return normalize(distro_id, NORMALIZED_LSB_ID)
+
+        distro_id = self.distro_release_attr("id")
+        if distro_id:
+            return normalize(distro_id, NORMALIZED_DISTRO_ID)
+
+        distro_id = self.uname_attr("id")
+        if distro_id:
+            return normalize(distro_id, NORMALIZED_DISTRO_ID)
+
+        return ""
+
+    def name(self, pretty: bool = False) -> str:
+        """
+        Return the name of the OS distribution, as a string.
+
+        For details, see :func:`distro.name`.
+        """
+        name = (
+            self.os_release_attr("name")
+            or self.lsb_release_attr("distributor_id")
+            or self.distro_release_attr("name")
+            or self.uname_attr("name")
+        )
+        if pretty:
+            name = self.os_release_attr("pretty_name") or self.lsb_release_attr(
+                "description"
+            )
+            if not name:
+                name = self.distro_release_attr("name") or self.uname_attr("name")
+                version = self.version(pretty=True)
+                if version:
+                    name = f"{name} {version}"
+        return name or ""
+
+    def version(self, pretty: bool = False, best: bool = False) -> str:
+        """
+        Return the version of the OS distribution, as a string.
+
+        For details, see :func:`distro.version`.
+        """
+        versions = [
+            self.os_release_attr("version_id"),
+            self.lsb_release_attr("release"),
+            self.distro_release_attr("version_id"),
+            self._parse_distro_release_content(self.os_release_attr("pretty_name")).get(
+                "version_id", ""
+            ),
+            self._parse_distro_release_content(
+                self.lsb_release_attr("description")
+            ).get("version_id", ""),
+            self.uname_attr("release"),
+        ]
+        if self.uname_attr("id").startswith("aix"):
+            # On AIX platforms, prefer oslevel command output.
+            versions.insert(0, self.oslevel_info())
+        elif self.id() == "debian" or "debian" in self.like().split():
+            # On Debian-like, add debian_version file content to candidates list.
+            versions.append(self._debian_version)
+        version = ""
+        if best:
+            # This algorithm uses the last version in priority order that has
+            # the best precision. If the versions are not in conflict, that
+            # does not matter; otherwise, using the last one instead of the
+            # first one might be considered a surprise.
+            for v in versions:
+                if v.count(".") > version.count(".") or version == "":
+                    version = v
+        else:
+            for v in versions:
+                if v != "":
+                    version = v
+                    break
+        if pretty and version and self.codename():
+            version = f"{version} ({self.codename()})"
+        return version
+
+    def version_parts(self, best: bool = False) -> Tuple[str, str, str]:
+        """
+        Return the version of the OS distribution, as a tuple of version
+        numbers.
+
+        For details, see :func:`distro.version_parts`.
+        """
+        version_str = self.version(best=best)
+        if version_str:
+            version_regex = re.compile(r"(\d+)\.?(\d+)?\.?(\d+)?")
+            matches = version_regex.match(version_str)
+            if matches:
+                major, minor, build_number = matches.groups()
+                return major, minor or "", build_number or ""
+        return "", "", ""
+
+    def major_version(self, best: bool = False) -> str:
+        """
+        Return the major version number of the current distribution.
+
+        For details, see :func:`distro.major_version`.
+        """
+        return self.version_parts(best)[0]
+
+    def minor_version(self, best: bool = False) -> str:
+        """
+        Return the minor version number of the current distribution.
+
+        For details, see :func:`distro.minor_version`.
+        """
+        return self.version_parts(best)[1]
+
+    def build_number(self, best: bool = False) -> str:
+        """
+        Return the build number of the current distribution.
+
+        For details, see :func:`distro.build_number`.
+        """
+        return self.version_parts(best)[2]
+
+    def like(self) -> str:
+        """
+        Return the IDs of distributions that are like the OS distribution.
+
+        For details, see :func:`distro.like`.
+        """
+        return self.os_release_attr("id_like") or ""
+
+    def codename(self) -> str:
+        """
+        Return the codename of the OS distribution.
+
+        For details, see :func:`distro.codename`.
+        """
+        try:
+            # Handle os_release specially since distros might purposefully set
+            # this to empty string to have no codename
+            return self._os_release_info["codename"]
+        except KeyError:
+            return (
+                self.lsb_release_attr("codename")
+                or self.distro_release_attr("codename")
+                or ""
+            )
+
+    def info(self, pretty: bool = False, best: bool = False) -> InfoDict:
+        """
+        Return certain machine-readable information about the OS
+        distribution.
+
+        For details, see :func:`distro.info`.
+        """
+        return dict(
+            id=self.id(),
+            version=self.version(pretty, best),
+            version_parts=dict(
+                major=self.major_version(best),
+                minor=self.minor_version(best),
+                build_number=self.build_number(best),
+            ),
+            like=self.like(),
+            codename=self.codename(),
+        )
+
+    def os_release_info(self) -> Dict[str, str]:
+        """
+        Return a dictionary containing key-value pairs for the information
+        items from the os-release file data source of the OS distribution.
+
+        For details, see :func:`distro.os_release_info`.
+        """
+        return self._os_release_info
+
+    def lsb_release_info(self) -> Dict[str, str]:
+        """
+        Return a dictionary containing key-value pairs for the information
+        items from the lsb_release command data source of the OS
+        distribution.
+
+        For details, see :func:`distro.lsb_release_info`.
+        """
+        return self._lsb_release_info
+
+    def distro_release_info(self) -> Dict[str, str]:
+        """
+        Return a dictionary containing key-value pairs for the information
+        items from the distro release file data source of the OS
+        distribution.
+
+        For details, see :func:`distro.distro_release_info`.
+        """
+        return self._distro_release_info
+
+    def uname_info(self) -> Dict[str, str]:
+        """
+        Return a dictionary containing key-value pairs for the information
+        items from the uname command data source of the OS distribution.
+
+        For details, see :func:`distro.uname_info`.
+        """
+        return self._uname_info
+
+    def oslevel_info(self) -> str:
+        """
+        Return AIX' oslevel command output.
+        """
+        return self._oslevel_info
+
+    def os_release_attr(self, attribute: str) -> str:
+        """
+        Return a single named information item from the os-release file data
+        source of the OS distribution.
+
+        For details, see :func:`distro.os_release_attr`.
+        """
+        return self._os_release_info.get(attribute, "")
+
+    def lsb_release_attr(self, attribute: str) -> str:
+        """
+        Return a single named information item from the lsb_release command
+        output data source of the OS distribution.
+
+        For details, see :func:`distro.lsb_release_attr`.
+        """
+        return self._lsb_release_info.get(attribute, "")
+
+    def distro_release_attr(self, attribute: str) -> str:
+        """
+        Return a single named information item from the distro release file
+        data source of the OS distribution.
+
+        For details, see :func:`distro.distro_release_attr`.
+        """
+        return self._distro_release_info.get(attribute, "")
+
+    def uname_attr(self, attribute: str) -> str:
+        """
+        Return a single named information item from the uname command
+        output data source of the OS distribution.
+
+        For details, see :func:`distro.uname_attr`.
+        """
+        return self._uname_info.get(attribute, "")
+
+    @cached_property
+    def _os_release_info(self) -> Dict[str, str]:
+        """
+        Get the information items from the specified os-release file.
+
+        Returns:
+            A dictionary containing all information items.
+        """
+        if os.path.isfile(self.os_release_file):
+            with open(self.os_release_file, encoding="utf-8") as release_file:
+                return self._parse_os_release_content(release_file)
+        return {}
+
+    @staticmethod
+    def _parse_os_release_content(lines: TextIO) -> Dict[str, str]:
+        """
+        Parse the lines of an os-release file.
+
+        Parameters:
+
+        * lines: Iterable through the lines in the os-release file.
+                 Each line must be a unicode string or a UTF-8 encoded byte
+                 string.
+
+        Returns:
+            A dictionary containing all information items.
+        """
+        props = {}
+        lexer = shlex.shlex(lines, posix=True)
+        lexer.whitespace_split = True
+
+        tokens = list(lexer)
+        for token in tokens:
+            # At this point, all shell-like parsing has been done (i.e.
+            # comments processed, quotes and backslash escape sequences
+            # processed, multi-line values assembled, trailing newlines
+            # stripped, etc.), so the tokens are now either:
+            # * variable assignments: var=value
+            # * commands or their arguments (not allowed in os-release)
+            # Ignore any tokens that are not variable assignments
+            if "=" in token:
+                k, v = token.split("=", 1)
+                props[k.lower()] = v
+
+        if "version" in props:
+            # extract release codename (if any) from version attribute
+            match = re.search(r"\((\D+)\)|,\s*(\D+)", props["version"])
+            if match:
+                release_codename = match.group(1) or match.group(2)
+                props["codename"] = props["release_codename"] = release_codename
+
+        if "version_codename" in props:
+            # os-release added a version_codename field.  Use that in
+            # preference to anything else Note that some distros purposefully
+            # do not have code names.  They should be setting
+            # version_codename=""
+            props["codename"] = props["version_codename"]
+        elif "ubuntu_codename" in props:
+            # Same as above but a non-standard field name used on older Ubuntus
+            props["codename"] = props["ubuntu_codename"]
+
+        return props
+
+    @cached_property
+    def _lsb_release_info(self) -> Dict[str, str]:
+        """
+        Get the information items from the lsb_release command output.
+
+        Returns:
+            A dictionary containing all information items.
+        """
+        if not self.include_lsb:
+            return {}
+        try:
+            cmd = ("lsb_release", "-a")
+            stdout = subprocess.check_output(cmd, stderr=subprocess.DEVNULL)
+        # Command not found or lsb_release returned error
+        except (OSError, subprocess.CalledProcessError):
+            return {}
+        content = self._to_str(stdout).splitlines()
+        return self._parse_lsb_release_content(content)
+
+    @staticmethod
+    def _parse_lsb_release_content(lines: Iterable[str]) -> Dict[str, str]:
+        """
+        Parse the output of the lsb_release command.
+
+        Parameters:
+
+        * lines: Iterable through the lines of the lsb_release output.
+                 Each line must be a unicode string or a UTF-8 encoded byte
+                 string.
+
+        Returns:
+            A dictionary containing all information items.
+        """
+        props = {}
+        for line in lines:
+            kv = line.strip("\n").split(":", 1)
+            if len(kv) != 2:
+                # Ignore lines without colon.
+                continue
+            k, v = kv
+            props.update({k.replace(" ", "_").lower(): v.strip()})
+        return props
+
+    @cached_property
+    def _uname_info(self) -> Dict[str, str]:
+        if not self.include_uname:
+            return {}
+        try:
+            cmd = ("uname", "-rs")
+            stdout = subprocess.check_output(cmd, stderr=subprocess.DEVNULL)
+        except OSError:
+            return {}
+        content = self._to_str(stdout).splitlines()
+        return self._parse_uname_content(content)
+
+    @cached_property
+    def _oslevel_info(self) -> str:
+        if not self.include_oslevel:
+            return ""
+        try:
+            stdout = subprocess.check_output("oslevel", stderr=subprocess.DEVNULL)
+        except (OSError, subprocess.CalledProcessError):
+            return ""
+        return self._to_str(stdout).strip()
+
+    @cached_property
+    def _debian_version(self) -> str:
+        try:
+            with open(
+                os.path.join(self.etc_dir, "debian_version"), encoding="ascii"
+            ) as fp:
+                return fp.readline().rstrip()
+        except FileNotFoundError:
+            return ""
+
+    @staticmethod
+    def _parse_uname_content(lines: Sequence[str]) -> Dict[str, str]:
+        if not lines:
+            return {}
+        props = {}
+        match = re.search(r"^([^\s]+)\s+([\d\.]+)", lines[0].strip())
+        if match:
+            name, version = match.groups()
+
+            # This is to prevent the Linux kernel version from
+            # appearing as the 'best' version on otherwise
+            # identifiable distributions.
+            if name == "Linux":
+                return {}
+            props["id"] = name.lower()
+            props["name"] = name
+            props["release"] = version
+        return props
+
+    @staticmethod
+    def _to_str(bytestring: bytes) -> str:
+        encoding = sys.getfilesystemencoding()
+        return bytestring.decode(encoding)
+
+    @cached_property
+    def _distro_release_info(self) -> Dict[str, str]:
+        """
+        Get the information items from the specified distro release file.
+
+        Returns:
+            A dictionary containing all information items.
+        """
+        if self.distro_release_file:
+            # If it was specified, we use it and parse what we can, even if
+            # its file name or content does not match the expected pattern.
+            distro_info = self._parse_distro_release_file(self.distro_release_file)
+            basename = os.path.basename(self.distro_release_file)
+            # The file name pattern for user-specified distro release files
+            # is somewhat more tolerant (compared to when searching for the
+            # file), because we want to use what was specified as best as
+            # possible.
+            match = _DISTRO_RELEASE_BASENAME_PATTERN.match(basename)
+        else:
+            try:
+                basenames = [
+                    basename
+                    for basename in os.listdir(self.etc_dir)
+                    if basename not in _DISTRO_RELEASE_IGNORE_BASENAMES
+                    and os.path.isfile(os.path.join(self.etc_dir, basename))
+                ]
+                # We sort for repeatability in cases where there are multiple
+                # distro specific files; e.g. CentOS, Oracle, Enterprise all
+                # containing `redhat-release` on top of their own.
+                basenames.sort()
+            except OSError:
+                # This may occur when /etc is not readable but we can't be
+                # sure about the *-release files. Check common entries of
+                # /etc for information. If they turn out to not be there the
+                # error is handled in `_parse_distro_release_file()`.
+                basenames = _DISTRO_RELEASE_BASENAMES
+            for basename in basenames:
+                match = _DISTRO_RELEASE_BASENAME_PATTERN.match(basename)
+                if match is None:
+                    continue
+                filepath = os.path.join(self.etc_dir, basename)
+                distro_info = self._parse_distro_release_file(filepath)
+                # The name is always present if the pattern matches.
+                if "name" not in distro_info:
+                    continue
+                self.distro_release_file = filepath
+                break
+            else:  # the loop didn't "break": no candidate.
+                return {}
+
+        if match is not None:
+            distro_info["id"] = match.group(1)
+
+        # CloudLinux < 7: manually enrich info with proper id.
+        if "cloudlinux" in distro_info.get("name", "").lower():
+            distro_info["id"] = "cloudlinux"
+
+        return distro_info
+
+    def _parse_distro_release_file(self, filepath: str) -> Dict[str, str]:
+        """
+        Parse a distro release file.
+
+        Parameters:
+
+        * filepath: Path name of the distro release file.
+
+        Returns:
+            A dictionary containing all information items.
+        """
+        try:
+            with open(filepath, encoding="utf-8") as fp:
+                # Only parse the first line. For instance, on SLES there
+                # are multiple lines. We don't want them...
+                return self._parse_distro_release_content(fp.readline())
+        except OSError:
+            # Ignore not being able to read a specific, seemingly version
+            # related file.
+            # See https://github.com/python-distro/distro/issues/162
+            return {}
+
+    @staticmethod
+    def _parse_distro_release_content(line: str) -> Dict[str, str]:
+        """
+        Parse a line from a distro release file.
+
+        Parameters:
+        * line: Line from the distro release file. Must be a unicode string
+                or a UTF-8 encoded byte string.
+
+        Returns:
+            A dictionary containing all information items.
+        """
+        matches = _DISTRO_RELEASE_CONTENT_REVERSED_PATTERN.match(line.strip()[::-1])
+        distro_info = {}
+        if matches:
+            # regexp ensures non-None
+            distro_info["name"] = matches.group(3)[::-1]
+            if matches.group(2):
+                distro_info["version_id"] = matches.group(2)[::-1]
+            if matches.group(1):
+                distro_info["codename"] = matches.group(1)[::-1]
+        elif line:
+            distro_info["name"] = line.strip()
+        return distro_info
+
+
+_distro = LinuxDistribution()
+
+
+def main() -> None:
+    logger = logging.getLogger(__name__)
+    logger.setLevel(logging.DEBUG)
+    logger.addHandler(logging.StreamHandler(sys.stdout))
+
+    parser = argparse.ArgumentParser(description="OS distro info tool")
+    parser.add_argument(
+        "--json", "-j", help="Output in machine readable format", action="store_true"
+    )
+
+    parser.add_argument(
+        "--root-dir",
+        "-r",
+        type=str,
+        dest="root_dir",
+        help="Path to the root filesystem directory (defaults to /)",
+    )
+
+    args = parser.parse_args()
+
+    if args.root_dir:
+        dist = LinuxDistribution(
+            include_lsb=False,
+            include_uname=False,
+            include_oslevel=False,
+            root_dir=args.root_dir,
+        )
+    else:
+        dist = _distro
+
+    if args.json:
+        logger.info(json.dumps(dist.info(), indent=4, sort_keys=True))
+    else:
+        logger.info("Name: %s", dist.name(pretty=True))
+        distribution_version = dist.version(pretty=True)
+        logger.info("Version: %s", distribution_version)
+        distribution_codename = dist.codename()
+        logger.info("Codename: %s", distribution_codename)
+
+
+if __name__ == "__main__":
+    main()
diff --git a/lib/spack/external/_vendoring/distro/py.typed b/lib/spack/external/_vendoring/distro/py.typed
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/lib/spack/external/_vendoring/distro/py.typed
diff --git a/lib/spack/external/_vendoring/jinja2/LICENSE.rst b/lib/spack/external/_vendoring/jinja2/LICENSE.rst
new file mode 100644
index 0000000000..c37cae49ec
--- /dev/null
+++ b/lib/spack/external/_vendoring/jinja2/LICENSE.rst
@@ -0,0 +1,28 @@
+Copyright 2007 Pallets
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are
+met:
+
+1.  Redistributions of source code must retain the above copyright
+    notice, this list of conditions and the following disclaimer.
+
+2.  Redistributions in binary form must reproduce the above copyright
+    notice, this list of conditions and the following disclaimer in the
+    documentation and/or other materials provided with the distribution.
+
+3.  Neither the name of the copyright holder nor the names of its
+    contributors may be used to endorse or promote products derived from
+    this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
+PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
+TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
diff --git a/lib/spack/external/_vendoring/jinja2/__init__.py b/lib/spack/external/_vendoring/jinja2/__init__.py
new file mode 100644
index 0000000000..9dcd901a51
--- /dev/null
+++ b/lib/spack/external/_vendoring/jinja2/__init__.py
@@ -0,0 +1,45 @@
+"""Jinja is a template engine written in pure Python. It provides a
+non-XML syntax that supports inline expressions and an optional
+sandboxed environment.
+"""
+from .bccache import BytecodeCache as BytecodeCache
+from .bccache import FileSystemBytecodeCache as FileSystemBytecodeCache
+from .bccache import MemcachedBytecodeCache as MemcachedBytecodeCache
+from .environment import Environment as Environment
+from .environment import Template as Template
+from .exceptions import TemplateAssertionError as TemplateAssertionError
+from .exceptions import TemplateError as TemplateError
+from .exceptions import TemplateNotFound as TemplateNotFound
+from .exceptions import TemplateRuntimeError as TemplateRuntimeError
+from .exceptions import TemplatesNotFound as TemplatesNotFound
+from .exceptions import TemplateSyntaxError as TemplateSyntaxError
+from .exceptions import UndefinedError as UndefinedError
+from .filters import contextfilter
+from .filters import environmentfilter
+from .filters import evalcontextfilter
+from .loaders import BaseLoader as BaseLoader
+from .loaders import ChoiceLoader as ChoiceLoader
+from .loaders import DictLoader as DictLoader
+from .loaders import FileSystemLoader as FileSystemLoader
+from .loaders import FunctionLoader as FunctionLoader
+from .loaders import ModuleLoader as ModuleLoader
+from .loaders import PackageLoader as PackageLoader
+from .loaders import PrefixLoader as PrefixLoader
+from .runtime import ChainableUndefined as ChainableUndefined
+from .runtime import DebugUndefined as DebugUndefined
+from .runtime import make_logging_undefined as make_logging_undefined
+from .runtime import StrictUndefined as StrictUndefined
+from .runtime import Undefined as Undefined
+from .utils import clear_caches as clear_caches
+from .utils import contextfunction
+from .utils import environmentfunction
+from .utils import escape
+from .utils import evalcontextfunction
+from .utils import is_undefined as is_undefined
+from .utils import Markup
+from .utils import pass_context as pass_context
+from .utils import pass_environment as pass_environment
+from .utils import pass_eval_context as pass_eval_context
+from .utils import select_autoescape as select_autoescape
+
+__version__ = "3.0.3"
diff --git a/lib/spack/external/_vendoring/jinja2/_identifier.py b/lib/spack/external/_vendoring/jinja2/_identifier.py
new file mode 100644
index 0000000000..224d5449d1
--- /dev/null
+++ b/lib/spack/external/_vendoring/jinja2/_identifier.py
@@ -0,0 +1,6 @@
+import re
+
+# generated by scripts/generate_identifier_pattern.py
+pattern = re.compile(
+    r"[\w·̀-ͯ·҃-֑҇-ׇֽֿׁׂׅׄؐ-ًؚ-ٰٟۖ-ۜ۟-۪ۤۧۨ-ܑۭܰ-݊ަ-ް߫-߳ࠖ-࠙ࠛ-ࠣࠥ-ࠧࠩ-࡙࠭-࡛ࣔ-ࣣ࣡-ःऺ-़ा-ॏ॑-ॗॢॣঁ-ঃ়া-ৄেৈো-্ৗৢৣਁ-ਃ਼ਾ-ੂੇੈੋ-੍ੑੰੱੵઁ-ઃ઼ા-ૅે-ૉો-્ૢૣଁ-ଃ଼ା-ୄେୈୋ-୍ୖୗୢୣஂா-ூெ-ைொ-்ௗఀ-ఃా-ౄె-ైొ-్ౕౖౢౣಁ-ಃ಼ಾ-ೄೆ-ೈೊ-್ೕೖೢೣഁ-ഃാ-ൄെ-ൈൊ-്ൗൢൣංඃ්ා-ුූෘ-ෟෲෳัิ-ฺ็-๎ັິ-ູົຼ່-ໍ༹༘༙༵༷༾༿ཱ-྄྆྇ྍ-ྗྙ-ྼ࿆ါ-ှၖ-ၙၞ-ၠၢ-ၤၧ-ၭၱ-ၴႂ-ႍႏႚ-ႝ፝-፟ᜒ-᜔ᜲ-᜴ᝒᝓᝲᝳ឴-៓៝᠋-᠍ᢅᢆᢩᤠ-ᤫᤰ-᤻ᨗ-ᨛᩕ-ᩞ᩠-᩿᩼᪰-᪽ᬀ-ᬄ᬴-᭄᭫-᭳ᮀ-ᮂᮡ-ᮭ᯦-᯳ᰤ-᰷᳐-᳔᳒-᳨᳭ᳲ-᳴᳸᳹᷀-᷵᷻-᷿‿⁀⁔⃐-⃥⃜⃡-⃰℘℮⳯-⵿⳱ⷠ-〪ⷿ-゙゚〯꙯ꙴ-꙽ꚞꚟ꛰꛱ꠂ꠆ꠋꠣ-ꠧꢀꢁꢴ-ꣅ꣠-꣱ꤦ-꤭ꥇ-꥓ꦀ-ꦃ꦳-꧀ꧥꨩ-ꨶꩃꩌꩍꩻ-ꩽꪰꪲ-ꪴꪷꪸꪾ꪿꫁ꫫ-ꫯꫵ꫶ꯣ-ꯪ꯬꯭ﬞ︀-️︠-︯︳︴﹍-﹏＿𐇽𐋠𐍶-𐍺𐨁-𐨃𐨅𐨆𐨌-𐨏𐨸-𐨿𐨺𐫦𐫥𑀀-𑀂𑀸-𑁆𑁿-𑂂𑂰-𑂺𑄀-𑄂𑄧-𑅳𑄴𑆀-𑆂𑆳-𑇊𑇀-𑇌𑈬-𑈷𑈾𑋟-𑋪𑌀-𑌃𑌼𑌾-𑍄𑍇𑍈𑍋-𑍍𑍗𑍢𑍣𑍦-𑍬𑍰-𑍴𑐵-𑑆𑒰-𑓃𑖯-𑖵𑖸-𑗀𑗜𑗝𑘰-𑙀𑚫-𑚷𑜝-𑜫𑰯-𑰶𑰸-𑰿𑲒-𑲧𑲩-𑲶𖫰-𖫴𖬰-𖬶𖽑-𖽾𖾏-𖾒𛲝𛲞𝅥-𝅩𝅭-𝅲𝅻-𝆂𝆅-𝆋𝆪-𝆭𝉂-𝉄𝨀-𝨶𝨻-𝩬𝩵𝪄𝪛-𝪟𝪡-𝪯𞀀-𞀆𞀈-𞀘𞀛-𞀡𞀣𞀤𞀦-𞣐𞀪-𞣖𞥄-𞥊󠄀-󠇯]+"  # noqa: B950
+)
diff --git a/lib/spack/external/_vendoring/jinja2/async_utils.py b/lib/spack/external/_vendoring/jinja2/async_utils.py
new file mode 100644
index 0000000000..35e6cb1090
--- /dev/null
+++ b/lib/spack/external/_vendoring/jinja2/async_utils.py
@@ -0,0 +1,75 @@
+import inspect
+import typing as t
+from functools import wraps
+
+from .utils import _PassArg
+from .utils import pass_eval_context
+
+V = t.TypeVar("V")
+
+
+def async_variant(normal_func):  # type: ignore
+    def decorator(async_func):  # type: ignore
+        pass_arg = _PassArg.from_obj(normal_func)
+        need_eval_context = pass_arg is None
+
+        if pass_arg is _PassArg.environment:
+
+            def is_async(args: t.Any) -> bool:
+                return t.cast(bool, args[0].is_async)
+
+        else:
+
+            def is_async(args: t.Any) -> bool:
+                return t.cast(bool, args[0].environment.is_async)
+
+        @wraps(normal_func)
+        def wrapper(*args, **kwargs):  # type: ignore
+            b = is_async(args)
+
+            if need_eval_context:
+                args = args[1:]
+
+            if b:
+                return async_func(*args, **kwargs)
+
+            return normal_func(*args, **kwargs)
+
+        if need_eval_context:
+            wrapper = pass_eval_context(wrapper)
+
+        wrapper.jinja_async_variant = True
+        return wrapper
+
+    return decorator
+
+
+_common_primitives = {int, float, bool, str, list, dict, tuple, type(None)}
+
+
+async def auto_await(value: t.Union[t.Awaitable["V"], "V"]) -> "V":
+    # Avoid a costly call to isawaitable
+    if type(value) in _common_primitives:
+        return t.cast("V", value)
+
+    if inspect.isawaitable(value):
+        return await t.cast("t.Awaitable[V]", value)
+
+    return t.cast("V", value)
+
+
+async def auto_aiter(
+    iterable: "t.Union[t.AsyncIterable[V], t.Iterable[V]]",
+) -> "t.AsyncIterator[V]":
+    if hasattr(iterable, "__aiter__"):
+        async for item in t.cast("t.AsyncIterable[V]", iterable):
+            yield item
+    else:
+        for item in t.cast("t.Iterable[V]", iterable):
+            yield item
+
+
+async def auto_to_list(
+    value: "t.Union[t.AsyncIterable[V], t.Iterable[V]]",
+) -> t.List["V"]:
+    return [x async for x in auto_aiter(value)]
diff --git a/lib/spack/external/_vendoring/jinja2/bccache.py b/lib/spack/external/_vendoring/jinja2/bccache.py
new file mode 100644
index 0000000000..3bb61b7c34
--- /dev/null
+++ b/lib/spack/external/_vendoring/jinja2/bccache.py
@@ -0,0 +1,364 @@
+"""The optional bytecode cache system. This is useful if you have very
+complex template situations and the compilation of all those templates
+slows down your application too much.
+
+Situations where this is useful are often forking web applications that
+are initialized on the first request.
+"""
+import errno
+import fnmatch
+import marshal
+import os
+import pickle
+import stat
+import sys
+import tempfile
+import typing as t
+from hashlib import sha1
+from io import BytesIO
+from types import CodeType
+
+if t.TYPE_CHECKING:
+    import typing_extensions as te
+    from .environment import Environment
+
+    class _MemcachedClient(te.Protocol):
+        def get(self, key: str) -> bytes:
+            ...
+
+        def set(self, key: str, value: bytes, timeout: t.Optional[int] = None) -> None:
+            ...
+
+
+bc_version = 5
+# Magic bytes to identify Jinja bytecode cache files. Contains the
+# Python major and minor version to avoid loading incompatible bytecode
+# if a project upgrades its Python version.
+bc_magic = (
+    b"j2"
+    + pickle.dumps(bc_version, 2)
+    + pickle.dumps((sys.version_info[0] << 24) | sys.version_info[1], 2)
+)
+
+
+class Bucket:
+    """Buckets are used to store the bytecode for one template.  It's created
+    and initialized by the bytecode cache and passed to the loading functions.
+
+    The buckets get an internal checksum from the cache assigned and use this
+    to automatically reject outdated cache material.  Individual bytecode
+    cache subclasses don't have to care about cache invalidation.
+    """
+
+    def __init__(self, environment: "Environment", key: str, checksum: str) -> None:
+        self.environment = environment
+        self.key = key
+        self.checksum = checksum
+        self.reset()
+
+    def reset(self) -> None:
+        """Resets the bucket (unloads the bytecode)."""
+        self.code: t.Optional[CodeType] = None
+
+    def load_bytecode(self, f: t.BinaryIO) -> None:
+        """Loads bytecode from a file or file like object."""
+        # make sure the magic header is correct
+        magic = f.read(len(bc_magic))
+        if magic != bc_magic:
+            self.reset()
+            return
+        # the source code of the file changed, we need to reload
+        checksum = pickle.load(f)
+        if self.checksum != checksum:
+            self.reset()
+            return
+        # if marshal_load fails then we need to reload
+        try:
+            self.code = marshal.load(f)
+        except (EOFError, ValueError, TypeError):
+            self.reset()
+            return
+
+    def write_bytecode(self, f: t.BinaryIO) -> None:
+        """Dump the bytecode into the file or file like object passed."""
+        if self.code is None:
+            raise TypeError("can't write empty bucket")
+        f.write(bc_magic)
+        pickle.dump(self.checksum, f, 2)
+        marshal.dump(self.code, f)
+
+    def bytecode_from_string(self, string: bytes) -> None:
+        """Load bytecode from bytes."""
+        self.load_bytecode(BytesIO(string))
+
+    def bytecode_to_string(self) -> bytes:
+        """Return the bytecode as bytes."""
+        out = BytesIO()
+        self.write_bytecode(out)
+        return out.getvalue()
+
+
+class BytecodeCache:
+    """To implement your own bytecode cache you have to subclass this class
+    and override :meth:`load_bytecode` and :meth:`dump_bytecode`.  Both of
+    these methods are passed a :class:`~jinja2.bccache.Bucket`.
+
+    A very basic bytecode cache that saves the bytecode on the file system::
+
+        from os import path
+
+        class MyCache(BytecodeCache):
+
+            def __init__(self, directory):
+                self.directory = directory
+
+            def load_bytecode(self, bucket):
+                filename = path.join(self.directory, bucket.key)
+                if path.exists(filename):
+                    with open(filename, 'rb') as f:
+                        bucket.load_bytecode(f)
+
+            def dump_bytecode(self, bucket):
+                filename = path.join(self.directory, bucket.key)
+                with open(filename, 'wb') as f:
+                    bucket.write_bytecode(f)
+
+    A more advanced version of a filesystem based bytecode cache is part of
+    Jinja.
+    """
+
+    def load_bytecode(self, bucket: Bucket) -> None:
+        """Subclasses have to override this method to load bytecode into a
+        bucket.  If they are not able to find code in the cache for the
+        bucket, it must not do anything.
+        """
+        raise NotImplementedError()
+
+    def dump_bytecode(self, bucket: Bucket) -> None:
+        """Subclasses have to override this method to write the bytecode
+        from a bucket back to the cache.  If it unable to do so it must not
+        fail silently but raise an exception.
+        """
+        raise NotImplementedError()
+
+    def clear(self) -> None:
+        """Clears the cache.  This method is not used by Jinja but should be
+        implemented to allow applications to clear the bytecode cache used
+        by a particular environment.
+        """
+
+    def get_cache_key(
+        self, name: str, filename: t.Optional[t.Union[str]] = None
+    ) -> str:
+        """Returns the unique hash key for this template name."""
+        hash = sha1(name.encode("utf-8"))
+
+        if filename is not None:
+            hash.update(f"|{filename}".encode())
+
+        return hash.hexdigest()
+
+    def get_source_checksum(self, source: str) -> str:
+        """Returns a checksum for the source."""
+        return sha1(source.encode("utf-8")).hexdigest()
+
+    def get_bucket(
+        self,
+        environment: "Environment",
+        name: str,
+        filename: t.Optional[str],
+        source: str,
+    ) -> Bucket:
+        """Return a cache bucket for the given template.  All arguments are
+        mandatory but filename may be `None`.
+        """
+        key = self.get_cache_key(name, filename)
+        checksum = self.get_source_checksum(source)
+        bucket = Bucket(environment, key, checksum)
+        self.load_bytecode(bucket)
+        return bucket
+
+    def set_bucket(self, bucket: Bucket) -> None:
+        """Put the bucket into the cache."""
+        self.dump_bytecode(bucket)
+
+
+class FileSystemBytecodeCache(BytecodeCache):
+    """A bytecode cache that stores bytecode on the filesystem.  It accepts
+    two arguments: The directory where the cache items are stored and a
+    pattern string that is used to build the filename.
+
+    If no directory is specified a default cache directory is selected.  On
+    Windows the user's temp directory is used, on UNIX systems a directory
+    is created for the user in the system temp directory.
+
+    The pattern can be used to have multiple separate caches operate on the
+    same directory.  The default pattern is ``'__jinja2_%s.cache'``.  ``%s``
+    is replaced with the cache key.
+
+    >>> bcc = FileSystemBytecodeCache('/tmp/jinja_cache', '%s.cache')
+
+    This bytecode cache supports clearing of the cache using the clear method.
+    """
+
+    def __init__(
+        self, directory: t.Optional[str] = None, pattern: str = "__jinja2_%s.cache"
+    ) -> None:
+        if directory is None:
+            directory = self._get_default_cache_dir()
+        self.directory = directory
+        self.pattern = pattern
+
+    def _get_default_cache_dir(self) -> str:
+        def _unsafe_dir() -> "te.NoReturn":
+            raise RuntimeError(
+                "Cannot determine safe temp directory.  You "
+                "need to explicitly provide one."
+            )
+
+        tmpdir = tempfile.gettempdir()
+
+        # On windows the temporary directory is used specific unless
+        # explicitly forced otherwise.  We can just use that.
+        if os.name == "nt":
+            return tmpdir
+        if not hasattr(os, "getuid"):
+            _unsafe_dir()
+
+        dirname = f"_jinja2-cache-{os.getuid()}"
+        actual_dir = os.path.join(tmpdir, dirname)
+
+        try:
+            os.mkdir(actual_dir, stat.S_IRWXU)
+        except OSError as e:
+            if e.errno != errno.EEXIST:
+                raise
+        try:
+            os.chmod(actual_dir, stat.S_IRWXU)
+            actual_dir_stat = os.lstat(actual_dir)
+            if (
+                actual_dir_stat.st_uid != os.getuid()
+                or not stat.S_ISDIR(actual_dir_stat.st_mode)
+                or stat.S_IMODE(actual_dir_stat.st_mode) != stat.S_IRWXU
+            ):
+                _unsafe_dir()
+        except OSError as e:
+            if e.errno != errno.EEXIST:
+                raise
+
+        actual_dir_stat = os.lstat(actual_dir)
+        if (
+            actual_dir_stat.st_uid != os.getuid()
+            or not stat.S_ISDIR(actual_dir_stat.st_mode)
+            or stat.S_IMODE(actual_dir_stat.st_mode) != stat.S_IRWXU
+        ):
+            _unsafe_dir()
+
+        return actual_dir
+
+    def _get_cache_filename(self, bucket: Bucket) -> str:
+        return os.path.join(self.directory, self.pattern % (bucket.key,))
+
+    def load_bytecode(self, bucket: Bucket) -> None:
+        filename = self._get_cache_filename(bucket)
+
+        if os.path.exists(filename):
+            with open(filename, "rb") as f:
+                bucket.load_bytecode(f)
+
+    def dump_bytecode(self, bucket: Bucket) -> None:
+        with open(self._get_cache_filename(bucket), "wb") as f:
+            bucket.write_bytecode(f)
+
+    def clear(self) -> None:
+        # imported lazily here because google app-engine doesn't support
+        # write access on the file system and the function does not exist
+        # normally.
+        from os import remove
+
+        files = fnmatch.filter(os.listdir(self.directory), self.pattern % ("*",))
+        for filename in files:
+            try:
+                remove(os.path.join(self.directory, filename))
+            except OSError:
+                pass
+
+
+class MemcachedBytecodeCache(BytecodeCache):
+    """This class implements a bytecode cache that uses a memcache cache for
+    storing the information.  It does not enforce a specific memcache library
+    (tummy's memcache or cmemcache) but will accept any class that provides
+    the minimal interface required.
+
+    Libraries compatible with this class:
+
+    -   `cachelib <https://github.com/pallets/cachelib>`_
+    -   `python-memcached <https://pypi.org/project/python-memcached/>`_
+
+    (Unfortunately the django cache interface is not compatible because it
+    does not support storing binary data, only text. You can however pass
+    the underlying cache client to the bytecode cache which is available
+    as `django.core.cache.cache._client`.)
+
+    The minimal interface for the client passed to the constructor is this:
+
+    .. class:: MinimalClientInterface
+
+        .. method:: set(key, value[, timeout])
+
+            Stores the bytecode in the cache.  `value` is a string and
+            `timeout` the timeout of the key.  If timeout is not provided
+            a default timeout or no timeout should be assumed, if it's
+            provided it's an integer with the number of seconds the cache
+            item should exist.
+
+        .. method:: get(key)
+
+            Returns the value for the cache key.  If the item does not
+            exist in the cache the return value must be `None`.
+
+    The other arguments to the constructor are the prefix for all keys that
+    is added before the actual cache key and the timeout for the bytecode in
+    the cache system.  We recommend a high (or no) timeout.
+
+    This bytecode cache does not support clearing of used items in the cache.
+    The clear method is a no-operation function.
+
+    .. versionadded:: 2.7
+       Added support for ignoring memcache errors through the
+       `ignore_memcache_errors` parameter.
+    """
+
+    def __init__(
+        self,
+        client: "_MemcachedClient",
+        prefix: str = "jinja2/bytecode/",
+        timeout: t.Optional[int] = None,
+        ignore_memcache_errors: bool = True,
+    ):
+        self.client = client
+        self.prefix = prefix
+        self.timeout = timeout
+        self.ignore_memcache_errors = ignore_memcache_errors
+
+    def load_bytecode(self, bucket: Bucket) -> None:
+        try:
+            code = self.client.get(self.prefix + bucket.key)
+        except Exception:
+            if not self.ignore_memcache_errors:
+                raise
+        else:
+            bucket.bytecode_from_string(code)
+
+    def dump_bytecode(self, bucket: Bucket) -> None:
+        key = self.prefix + bucket.key
+        value = bucket.bytecode_to_string()
+
+        try:
+            if self.timeout is not None:
+                self.client.set(key, value, self.timeout)
+            else:
+                self.client.set(key, value)
+        except Exception:
+            if not self.ignore_memcache_errors:
+                raise
diff --git a/lib/spack/external/_vendoring/jinja2/compiler.py b/lib/spack/external/_vendoring/jinja2/compiler.py
new file mode 100644
index 0000000000..52fd5b83e2
--- /dev/null
+++ b/lib/spack/external/_vendoring/jinja2/compiler.py
@@ -0,0 +1,1957 @@
+"""Compiles nodes from the parser into Python code."""
+import typing as t
+from contextlib import contextmanager
+from functools import update_wrapper
+from io import StringIO
+from itertools import chain
+from keyword import iskeyword as is_python_keyword
+
+from markupsafe import escape
+from markupsafe import Markup
+
+from . import nodes
+from .exceptions import TemplateAssertionError
+from .idtracking import Symbols
+from .idtracking import VAR_LOAD_ALIAS
+from .idtracking import VAR_LOAD_PARAMETER
+from .idtracking import VAR_LOAD_RESOLVE
+from .idtracking import VAR_LOAD_UNDEFINED
+from .nodes import EvalContext
+from .optimizer import Optimizer
+from .utils import _PassArg
+from .utils import concat
+from .visitor import NodeVisitor
+
+if t.TYPE_CHECKING:
+    import typing_extensions as te
+    from .environment import Environment
+
+F = t.TypeVar("F", bound=t.Callable[..., t.Any])
+
+operators = {
+    "eq": "==",
+    "ne": "!=",
+    "gt": ">",
+    "gteq": ">=",
+    "lt": "<",
+    "lteq": "<=",
+    "in": "in",
+    "notin": "not in",
+}
+
+
+def optimizeconst(f: F) -> F:
+    def new_func(
+        self: "CodeGenerator", node: nodes.Expr, frame: "Frame", **kwargs: t.Any
+    ) -> t.Any:
+        # Only optimize if the frame is not volatile
+        if self.optimizer is not None and not frame.eval_ctx.volatile:
+            new_node = self.optimizer.visit(node, frame.eval_ctx)
+
+            if new_node != node:
+                return self.visit(new_node, frame)
+
+        return f(self, node, frame, **kwargs)
+
+    return update_wrapper(t.cast(F, new_func), f)
+
+
+def _make_binop(op: str) -> t.Callable[["CodeGenerator", nodes.BinExpr, "Frame"], None]:
+    @optimizeconst
+    def visitor(self: "CodeGenerator", node: nodes.BinExpr, frame: Frame) -> None:
+        if (
+            self.environment.sandboxed
+            and op in self.environment.intercepted_binops  # type: ignore
+        ):
+            self.write(f"environment.call_binop(context, {op!r}, ")
+            self.visit(node.left, frame)
+            self.write(", ")
+            self.visit(node.right, frame)
+        else:
+            self.write("(")
+            self.visit(node.left, frame)
+            self.write(f" {op} ")
+            self.visit(node.right, frame)
+
+        self.write(")")
+
+    return visitor
+
+
+def _make_unop(
+    op: str,
+) -> t.Callable[["CodeGenerator", nodes.UnaryExpr, "Frame"], None]:
+    @optimizeconst
+    def visitor(self: "CodeGenerator", node: nodes.UnaryExpr, frame: Frame) -> None:
+        if (
+            self.environment.sandboxed
+            and op in self.environment.intercepted_unops  # type: ignore
+        ):
+            self.write(f"environment.call_unop(context, {op!r}, ")
+            self.visit(node.node, frame)
+        else:
+            self.write("(" + op)
+            self.visit(node.node, frame)
+
+        self.write(")")
+
+    return visitor
+
+
+def generate(
+    node: nodes.Template,
+    environment: "Environment",
+    name: t.Optional[str],
+    filename: t.Optional[str],
+    stream: t.Optional[t.TextIO] = None,
+    defer_init: bool = False,
+    optimized: bool = True,
+) -> t.Optional[str]:
+    """Generate the python source for a node tree."""
+    if not isinstance(node, nodes.Template):
+        raise TypeError("Can't compile non template nodes")
+
+    generator = environment.code_generator_class(
+        environment, name, filename, stream, defer_init, optimized
+    )
+    generator.visit(node)
+
+    if stream is None:
+        return generator.stream.getvalue()  # type: ignore
+
+    return None
+
+
+def has_safe_repr(value: t.Any) -> bool:
+    """Does the node have a safe representation?"""
+    if value is None or value is NotImplemented or value is Ellipsis:
+        return True
+
+    if type(value) in {bool, int, float, complex, range, str, Markup}:
+        return True
+
+    if type(value) in {tuple, list, set, frozenset}:
+        return all(has_safe_repr(v) for v in value)
+
+    if type(value) is dict:
+        return all(has_safe_repr(k) and has_safe_repr(v) for k, v in value.items())
+
+    return False
+
+
+def find_undeclared(
+    nodes: t.Iterable[nodes.Node], names: t.Iterable[str]
+) -> t.Set[str]:
+    """Check if the names passed are accessed undeclared.  The return value
+    is a set of all the undeclared names from the sequence of names found.
+    """
+    visitor = UndeclaredNameVisitor(names)
+    try:
+        for node in nodes:
+            visitor.visit(node)
+    except VisitorExit:
+        pass
+    return visitor.undeclared
+
+
+class MacroRef:
+    def __init__(self, node: t.Union[nodes.Macro, nodes.CallBlock]) -> None:
+        self.node = node
+        self.accesses_caller = False
+        self.accesses_kwargs = False
+        self.accesses_varargs = False
+
+
+class Frame:
+    """Holds compile time information for us."""
+
+    def __init__(
+        self,
+        eval_ctx: EvalContext,
+        parent: t.Optional["Frame"] = None,
+        level: t.Optional[int] = None,
+    ) -> None:
+        self.eval_ctx = eval_ctx
+
+        # the parent of this frame
+        self.parent = parent
+
+        if parent is None:
+            self.symbols = Symbols(level=level)
+
+            # in some dynamic inheritance situations the compiler needs to add
+            # write tests around output statements.
+            self.require_output_check = False
+
+            # inside some tags we are using a buffer rather than yield statements.
+            # this for example affects {% filter %} or {% macro %}.  If a frame
+            # is buffered this variable points to the name of the list used as
+            # buffer.
+            self.buffer: t.Optional[str] = None
+
+            # the name of the block we're in, otherwise None.
+            self.block: t.Optional[str] = None
+
+        else:
+            self.symbols = Symbols(parent.symbols, level=level)
+            self.require_output_check = parent.require_output_check
+            self.buffer = parent.buffer
+            self.block = parent.block
+
+        # a toplevel frame is the root + soft frames such as if conditions.
+        self.toplevel = False
+
+        # the root frame is basically just the outermost frame, so no if
+        # conditions.  This information is used to optimize inheritance
+        # situations.
+        self.rootlevel = False
+
+        # variables set inside of loops and blocks should not affect outer frames,
+        # but they still needs to be kept track of as part of the active context.
+        self.loop_frame = False
+        self.block_frame = False
+
+        # track whether the frame is being used in an if-statement or conditional
+        # expression as it determines which errors should be raised during runtime
+        # or compile time.
+        self.soft_frame = False
+
+    def copy(self) -> "Frame":
+        """Create a copy of the current one."""
+        rv = t.cast(Frame, object.__new__(self.__class__))
+        rv.__dict__.update(self.__dict__)
+        rv.symbols = self.symbols.copy()
+        return rv
+
+    def inner(self, isolated: bool = False) -> "Frame":
+        """Return an inner frame."""
+        if isolated:
+            return Frame(self.eval_ctx, level=self.symbols.level + 1)
+        return Frame(self.eval_ctx, self)
+
+    def soft(self) -> "Frame":
+        """Return a soft frame.  A soft frame may not be modified as
+        standalone thing as it shares the resources with the frame it
+        was created of, but it's not a rootlevel frame any longer.
+
+        This is only used to implement if-statements and conditional
+        expressions.
+        """
+        rv = self.copy()
+        rv.rootlevel = False
+        rv.soft_frame = True
+        return rv
+
+    __copy__ = copy
+
+
+class VisitorExit(RuntimeError):
+    """Exception used by the `UndeclaredNameVisitor` to signal a stop."""
+
+
+class DependencyFinderVisitor(NodeVisitor):
+    """A visitor that collects filter and test calls."""
+
+    def __init__(self) -> None:
+        self.filters: t.Set[str] = set()
+        self.tests: t.Set[str] = set()
+
+    def visit_Filter(self, node: nodes.Filter) -> None:
+        self.generic_visit(node)
+        self.filters.add(node.name)
+
+    def visit_Test(self, node: nodes.Test) -> None:
+        self.generic_visit(node)
+        self.tests.add(node.name)
+
+    def visit_Block(self, node: nodes.Block) -> None:
+        """Stop visiting at blocks."""
+
+
+class UndeclaredNameVisitor(NodeVisitor):
+    """A visitor that checks if a name is accessed without being
+    declared.  This is different from the frame visitor as it will
+    not stop at closure frames.
+    """
+
+    def __init__(self, names: t.Iterable[str]) -> None:
+        self.names = set(names)
+        self.undeclared: t.Set[str] = set()
+
+    def visit_Name(self, node: nodes.Name) -> None:
+        if node.ctx == "load" and node.name in self.names:
+            self.undeclared.add(node.name)
+            if self.undeclared == self.names:
+                raise VisitorExit()
+        else:
+            self.names.discard(node.name)
+
+    def visit_Block(self, node: nodes.Block) -> None:
+        """Stop visiting a blocks."""
+
+
+class CompilerExit(Exception):
+    """Raised if the compiler encountered a situation where it just
+    doesn't make sense to further process the code.  Any block that
+    raises such an exception is not further processed.
+    """
+
+
+class CodeGenerator(NodeVisitor):
+    def __init__(
+        self,
+        environment: "Environment",
+        name: t.Optional[str],
+        filename: t.Optional[str],
+        stream: t.Optional[t.TextIO] = None,
+        defer_init: bool = False,
+        optimized: bool = True,
+    ) -> None:
+        if stream is None:
+            stream = StringIO()
+        self.environment = environment
+        self.name = name
+        self.filename = filename
+        self.stream = stream
+        self.created_block_context = False
+        self.defer_init = defer_init
+        self.optimizer: t.Optional[Optimizer] = None
+
+        if optimized:
+            self.optimizer = Optimizer(environment)
+
+        # aliases for imports
+        self.import_aliases: t.Dict[str, str] = {}
+
+        # a registry for all blocks.  Because blocks are moved out
+        # into the global python scope they are registered here
+        self.blocks: t.Dict[str, nodes.Block] = {}
+
+        # the number of extends statements so far
+        self.extends_so_far = 0
+
+        # some templates have a rootlevel extends.  In this case we
+        # can safely assume that we're a child template and do some
+        # more optimizations.
+        self.has_known_extends = False
+
+        # the current line number
+        self.code_lineno = 1
+
+        # registry of all filters and tests (global, not block local)
+        self.tests: t.Dict[str, str] = {}
+        self.filters: t.Dict[str, str] = {}
+
+        # the debug information
+        self.debug_info: t.List[t.Tuple[int, int]] = []
+        self._write_debug_info: t.Optional[int] = None
+
+        # the number of new lines before the next write()
+        self._new_lines = 0
+
+        # the line number of the last written statement
+        self._last_line = 0
+
+        # true if nothing was written so far.
+        self._first_write = True
+
+        # used by the `temporary_identifier` method to get new
+        # unique, temporary identifier
+        self._last_identifier = 0
+
+        # the current indentation
+        self._indentation = 0
+
+        # Tracks toplevel assignments
+        self._assign_stack: t.List[t.Set[str]] = []
+
+        # Tracks parameter definition blocks
+        self._param_def_block: t.List[t.Set[str]] = []
+
+        # Tracks the current context.
+        self._context_reference_stack = ["context"]
+
+    @property
+    def optimized(self) -> bool:
+        return self.optimizer is not None
+
+    # -- Various compilation helpers
+
+    def fail(self, msg: str, lineno: int) -> "te.NoReturn":
+        """Fail with a :exc:`TemplateAssertionError`."""
+        raise TemplateAssertionError(msg, lineno, self.name, self.filename)
+
+    def temporary_identifier(self) -> str:
+        """Get a new unique identifier."""
+        self._last_identifier += 1
+        return f"t_{self._last_identifier}"
+
+    def buffer(self, frame: Frame) -> None:
+        """Enable buffering for the frame from that point onwards."""
+        frame.buffer = self.temporary_identifier()
+        self.writeline(f"{frame.buffer} = []")
+
+    def return_buffer_contents(
+        self, frame: Frame, force_unescaped: bool = False
+    ) -> None:
+        """Return the buffer contents of the frame."""
+        if not force_unescaped:
+            if frame.eval_ctx.volatile:
+                self.writeline("if context.eval_ctx.autoescape:")
+                self.indent()
+                self.writeline(f"return Markup(concat({frame.buffer}))")
+                self.outdent()
+                self.writeline("else:")
+                self.indent()
+                self.writeline(f"return concat({frame.buffer})")
+                self.outdent()
+                return
+            elif frame.eval_ctx.autoescape:
+                self.writeline(f"return Markup(concat({frame.buffer}))")
+                return
+        self.writeline(f"return concat({frame.buffer})")
+
+    def indent(self) -> None:
+        """Indent by one."""
+        self._indentation += 1
+
+    def outdent(self, step: int = 1) -> None:
+        """Outdent by step."""
+        self._indentation -= step
+
+    def start_write(self, frame: Frame, node: t.Optional[nodes.Node] = None) -> None:
+        """Yield or write into the frame buffer."""
+        if frame.buffer is None:
+            self.writeline("yield ", node)
+        else:
+            self.writeline(f"{frame.buffer}.append(", node)
+
+    def end_write(self, frame: Frame) -> None:
+        """End the writing process started by `start_write`."""
+        if frame.buffer is not None:
+            self.write(")")
+
+    def simple_write(
+        self, s: str, frame: Frame, node: t.Optional[nodes.Node] = None
+    ) -> None:
+        """Simple shortcut for start_write + write + end_write."""
+        self.start_write(frame, node)
+        self.write(s)
+        self.end_write(frame)
+
+    def blockvisit(self, nodes: t.Iterable[nodes.Node], frame: Frame) -> None:
+        """Visit a list of nodes as block in a frame.  If the current frame
+        is no buffer a dummy ``if 0: yield None`` is written automatically.
+        """
+        try:
+            self.writeline("pass")
+            for node in nodes:
+                self.visit(node, frame)
+        except CompilerExit:
+            pass
+
+    def write(self, x: str) -> None:
+        """Write a string into the output stream."""
+        if self._new_lines:
+            if not self._first_write:
+                self.stream.write("\n" * self._new_lines)
+                self.code_lineno += self._new_lines
+                if self._write_debug_info is not None:
+                    self.debug_info.append((self._write_debug_info, self.code_lineno))
+                    self._write_debug_info = None
+            self._first_write = False
+            self.stream.write("    " * self._indentation)
+            self._new_lines = 0
+        self.stream.write(x)
+
+    def writeline(
+        self, x: str, node: t.Optional[nodes.Node] = None, extra: int = 0
+    ) -> None:
+        """Combination of newline and write."""
+        self.newline(node, extra)
+        self.write(x)
+
+    def newline(self, node: t.Optional[nodes.Node] = None, extra: int = 0) -> None:
+        """Add one or more newlines before the next write."""
+        self._new_lines = max(self._new_lines, 1 + extra)
+        if node is not None and node.lineno != self._last_line:
+            self._write_debug_info = node.lineno
+            self._last_line = node.lineno
+
+    def signature(
+        self,
+        node: t.Union[nodes.Call, nodes.Filter, nodes.Test],
+        frame: Frame,
+        extra_kwargs: t.Optional[t.Mapping[str, t.Any]] = None,
+    ) -> None:
+        """Writes a function call to the stream for the current node.
+        A leading comma is added automatically.  The extra keyword
+        arguments may not include python keywords otherwise a syntax
+        error could occur.  The extra keyword arguments should be given
+        as python dict.
+        """
+        # if any of the given keyword arguments is a python keyword
+        # we have to make sure that no invalid call is created.
+        kwarg_workaround = any(
+            is_python_keyword(t.cast(str, k))
+            for k in chain((x.key for x in node.kwargs), extra_kwargs or ())
+        )
+
+        for arg in node.args:
+            self.write(", ")
+            self.visit(arg, frame)
+
+        if not kwarg_workaround:
+            for kwarg in node.kwargs:
+                self.write(", ")
+                self.visit(kwarg, frame)
+            if extra_kwargs is not None:
+                for key, value in extra_kwargs.items():
+                    self.write(f", {key}={value}")
+        if node.dyn_args:
+            self.write(", *")
+            self.visit(node.dyn_args, frame)
+
+        if kwarg_workaround:
+            if node.dyn_kwargs is not None:
+                self.write(", **dict({")
+            else:
+                self.write(", **{")
+            for kwarg in node.kwargs:
+                self.write(f"{kwarg.key!r}: ")
+                self.visit(kwarg.value, frame)
+                self.write(", ")
+            if extra_kwargs is not None:
+                for key, value in extra_kwargs.items():
+                    self.write(f"{key!r}: {value}, ")
+            if node.dyn_kwargs is not None:
+                self.write("}, **")
+                self.visit(node.dyn_kwargs, frame)
+                self.write(")")
+            else:
+                self.write("}")
+
+        elif node.dyn_kwargs is not None:
+            self.write(", **")
+            self.visit(node.dyn_kwargs, frame)
+
+    def pull_dependencies(self, nodes: t.Iterable[nodes.Node]) -> None:
+        """Find all filter and test names used in the template and
+        assign them to variables in the compiled namespace. Checking
+        that the names are registered with the environment is done when
+        compiling the Filter and Test nodes. If the node is in an If or
+        CondExpr node, the check is done at runtime instead.
+
+        .. versionchanged:: 3.0
+            Filters and tests in If and CondExpr nodes are checked at
+            runtime instead of compile time.
+        """
+        visitor = DependencyFinderVisitor()
+
+        for node in nodes:
+            visitor.visit(node)
+
+        for id_map, names, dependency in (self.filters, visitor.filters, "filters"), (
+            self.tests,
+            visitor.tests,
+            "tests",
+        ):
+            for name in sorted(names):
+                if name not in id_map:
+                    id_map[name] = self.temporary_identifier()
+
+                # add check during runtime that dependencies used inside of executed
+                # blocks are defined, as this step may be skipped during compile time
+                self.writeline("try:")
+                self.indent()
+                self.writeline(f"{id_map[name]} = environment.{dependency}[{name!r}]")
+                self.outdent()
+                self.writeline("except KeyError:")
+                self.indent()
+                self.writeline("@internalcode")
+                self.writeline(f"def {id_map[name]}(*unused):")
+                self.indent()
+                self.writeline(
+                    f'raise TemplateRuntimeError("No {dependency[:-1]}'
+                    f' named {name!r} found.")'
+                )
+                self.outdent()
+                self.outdent()
+
+    def enter_frame(self, frame: Frame) -> None:
+        undefs = []
+        for target, (action, param) in frame.symbols.loads.items():
+            if action == VAR_LOAD_PARAMETER:
+                pass
+            elif action == VAR_LOAD_RESOLVE:
+                self.writeline(f"{target} = {self.get_resolve_func()}({param!r})")
+            elif action == VAR_LOAD_ALIAS:
+                self.writeline(f"{target} = {param}")
+            elif action == VAR_LOAD_UNDEFINED:
+                undefs.append(target)
+            else:
+                raise NotImplementedError("unknown load instruction")
+        if undefs:
+            self.writeline(f"{' = '.join(undefs)} = missing")
+
+    def leave_frame(self, frame: Frame, with_python_scope: bool = False) -> None:
+        if not with_python_scope:
+            undefs = []
+            for target in frame.symbols.loads:
+                undefs.append(target)
+            if undefs:
+                self.writeline(f"{' = '.join(undefs)} = missing")
+
+    def choose_async(self, async_value: str = "async ", sync_value: str = "") -> str:
+        return async_value if self.environment.is_async else sync_value
+
+    def func(self, name: str) -> str:
+        return f"{self.choose_async()}def {name}"
+
+    def macro_body(
+        self, node: t.Union[nodes.Macro, nodes.CallBlock], frame: Frame
+    ) -> t.Tuple[Frame, MacroRef]:
+        """Dump the function def of a macro or call block."""
+        frame = frame.inner()
+        frame.symbols.analyze_node(node)
+        macro_ref = MacroRef(node)
+
+        explicit_caller = None
+        skip_special_params = set()
+        args = []
+
+        for idx, arg in enumerate(node.args):
+            if arg.name == "caller":
+                explicit_caller = idx
+            if arg.name in ("kwargs", "varargs"):
+                skip_special_params.add(arg.name)
+            args.append(frame.symbols.ref(arg.name))
+
+        undeclared = find_undeclared(node.body, ("caller", "kwargs", "varargs"))
+
+        if "caller" in undeclared:
+            # In older Jinja versions there was a bug that allowed caller
+            # to retain the special behavior even if it was mentioned in
+            # the argument list.  However thankfully this was only really
+            # working if it was the last argument.  So we are explicitly
+            # checking this now and error out if it is anywhere else in
+            # the argument list.
+            if explicit_caller is not None:
+                try:
+                    node.defaults[explicit_caller - len(node.args)]
+                except IndexError:
+                    self.fail(
+                        "When defining macros or call blocks the "
+                        'special "caller" argument must be omitted '
+                        "or be given a default.",
+                        node.lineno,
+                    )
+            else:
+                args.append(frame.symbols.declare_parameter("caller"))
+            macro_ref.accesses_caller = True
+        if "kwargs" in undeclared and "kwargs" not in skip_special_params:
+            args.append(frame.symbols.declare_parameter("kwargs"))
+            macro_ref.accesses_kwargs = True
+        if "varargs" in undeclared and "varargs" not in skip_special_params:
+            args.append(frame.symbols.declare_parameter("varargs"))
+            macro_ref.accesses_varargs = True
+
+        # macros are delayed, they never require output checks
+        frame.require_output_check = False
+        frame.symbols.analyze_node(node)
+        self.writeline(f"{self.func('macro')}({', '.join(args)}):", node)
+        self.indent()
+
+        self.buffer(frame)
+        self.enter_frame(frame)
+
+        self.push_parameter_definitions(frame)
+        for idx, arg in enumerate(node.args):
+            ref = frame.symbols.ref(arg.name)
+            self.writeline(f"if {ref} is missing:")
+            self.indent()
+            try:
+                default = node.defaults[idx - len(node.args)]
+            except IndexError:
+                self.writeline(
+                    f'{ref} = undefined("parameter {arg.name!r} was not provided",'
+                    f" name={arg.name!r})"
+                )
+            else:
+                self.writeline(f"{ref} = ")
+                self.visit(default, frame)
+            self.mark_parameter_stored(ref)
+            self.outdent()
+        self.pop_parameter_definitions()
+
+        self.blockvisit(node.body, frame)
+        self.return_buffer_contents(frame, force_unescaped=True)
+        self.leave_frame(frame, with_python_scope=True)
+        self.outdent()
+
+        return frame, macro_ref
+
+    def macro_def(self, macro_ref: MacroRef, frame: Frame) -> None:
+        """Dump the macro definition for the def created by macro_body."""
+        arg_tuple = ", ".join(repr(x.name) for x in macro_ref.node.args)
+        name = getattr(macro_ref.node, "name", None)
+        if len(macro_ref.node.args) == 1:
+            arg_tuple += ","
+        self.write(
+            f"Macro(environment, macro, {name!r}, ({arg_tuple}),"
+            f" {macro_ref.accesses_kwargs!r}, {macro_ref.accesses_varargs!r},"
+            f" {macro_ref.accesses_caller!r}, context.eval_ctx.autoescape)"
+        )
+
+    def position(self, node: nodes.Node) -> str:
+        """Return a human readable position for the node."""
+        rv = f"line {node.lineno}"
+        if self.name is not None:
+            rv = f"{rv} in {self.name!r}"
+        return rv
+
+    def dump_local_context(self, frame: Frame) -> str:
+        items_kv = ", ".join(
+            f"{name!r}: {target}"
+            for name, target in frame.symbols.dump_stores().items()
+        )
+        return f"{{{items_kv}}}"
+
+    def write_commons(self) -> None:
+        """Writes a common preamble that is used by root and block functions.
+        Primarily this sets up common local helpers and enforces a generator
+        through a dead branch.
+        """
+        self.writeline("resolve = context.resolve_or_missing")
+        self.writeline("undefined = environment.undefined")
+        # always use the standard Undefined class for the implicit else of
+        # conditional expressions
+        self.writeline("cond_expr_undefined = Undefined")
+        self.writeline("if 0: yield None")
+
+    def push_parameter_definitions(self, frame: Frame) -> None:
+        """Pushes all parameter targets from the given frame into a local
+        stack that permits tracking of yet to be assigned parameters.  In
+        particular this enables the optimization from `visit_Name` to skip
+        undefined expressions for parameters in macros as macros can reference
+        otherwise unbound parameters.
+        """
+        self._param_def_block.append(frame.symbols.dump_param_targets())
+
+    def pop_parameter_definitions(self) -> None:
+        """Pops the current parameter definitions set."""
+        self._param_def_block.pop()
+
+    def mark_parameter_stored(self, target: str) -> None:
+        """Marks a parameter in the current parameter definitions as stored.
+        This will skip the enforced undefined checks.
+        """
+        if self._param_def_block:
+            self._param_def_block[-1].discard(target)
+
+    def push_context_reference(self, target: str) -> None:
+        self._context_reference_stack.append(target)
+
+    def pop_context_reference(self) -> None:
+        self._context_reference_stack.pop()
+
+    def get_context_ref(self) -> str:
+        return self._context_reference_stack[-1]
+
+    def get_resolve_func(self) -> str:
+        target = self._context_reference_stack[-1]
+        if target == "context":
+            return "resolve"
+        return f"{target}.resolve"
+
+    def derive_context(self, frame: Frame) -> str:
+        return f"{self.get_context_ref()}.derived({self.dump_local_context(frame)})"
+
+    def parameter_is_undeclared(self, target: str) -> bool:
+        """Checks if a given target is an undeclared parameter."""
+        if not self._param_def_block:
+            return False
+        return target in self._param_def_block[-1]
+
+    def push_assign_tracking(self) -> None:
+        """Pushes a new layer for assignment tracking."""
+        self._assign_stack.append(set())
+
+    def pop_assign_tracking(self, frame: Frame) -> None:
+        """Pops the topmost level for assignment tracking and updates the
+        context variables if necessary.
+        """
+        vars = self._assign_stack.pop()
+        if (
+            not frame.block_frame
+            and not frame.loop_frame
+            and not frame.toplevel
+            or not vars
+        ):
+            return
+        public_names = [x for x in vars if x[:1] != "_"]
+        if len(vars) == 1:
+            name = next(iter(vars))
+            ref = frame.symbols.ref(name)
+            if frame.loop_frame:
+                self.writeline(f"_loop_vars[{name!r}] = {ref}")
+                return
+            if frame.block_frame:
+                self.writeline(f"_block_vars[{name!r}] = {ref}")
+                return
+            self.writeline(f"context.vars[{name!r}] = {ref}")
+        else:
+            if frame.loop_frame:
+                self.writeline("_loop_vars.update({")
+            elif frame.block_frame:
+                self.writeline("_block_vars.update({")
+            else:
+                self.writeline("context.vars.update({")
+            for idx, name in enumerate(vars):
+                if idx:
+                    self.write(", ")
+                ref = frame.symbols.ref(name)
+                self.write(f"{name!r}: {ref}")
+            self.write("})")
+        if not frame.block_frame and not frame.loop_frame and public_names:
+            if len(public_names) == 1:
+                self.writeline(f"context.exported_vars.add({public_names[0]!r})")
+            else:
+                names_str = ", ".join(map(repr, public_names))
+                self.writeline(f"context.exported_vars.update(({names_str}))")
+
+    # -- Statement Visitors
+
+    def visit_Template(
+        self, node: nodes.Template, frame: t.Optional[Frame] = None
+    ) -> None:
+        assert frame is None, "no root frame allowed"
+        eval_ctx = EvalContext(self.environment, self.name)
+
+        from .runtime import exported, async_exported
+
+        if self.environment.is_async:
+            exported_names = sorted(exported + async_exported)
+        else:
+            exported_names = sorted(exported)
+
+        self.writeline("from __future__ import generator_stop")  # Python < 3.7
+        self.writeline("from jinja2.runtime import " + ", ".join(exported_names))
+
+        # if we want a deferred initialization we cannot move the
+        # environment into a local name
+        envenv = "" if self.defer_init else ", environment=environment"
+
+        # do we have an extends tag at all?  If not, we can save some
+        # overhead by just not processing any inheritance code.
+        have_extends = node.find(nodes.Extends) is not None
+
+        # find all blocks
+        for block in node.find_all(nodes.Block):
+            if block.name in self.blocks:
+                self.fail(f"block {block.name!r} defined twice", block.lineno)
+            self.blocks[block.name] = block
+
+        # find all imports and import them
+        for import_ in node.find_all(nodes.ImportedName):
+            if import_.importname not in self.import_aliases:
+                imp = import_.importname
+                self.import_aliases[imp] = alias = self.temporary_identifier()
+                if "." in imp:
+                    module, obj = imp.rsplit(".", 1)
+                    self.writeline(f"from {module} import {obj} as {alias}")
+                else:
+                    self.writeline(f"import {imp} as {alias}")
+
+        # add the load name
+        self.writeline(f"name = {self.name!r}")
+
+        # generate the root render function.
+        self.writeline(
+            f"{self.func('root')}(context, missing=missing{envenv}):", extra=1
+        )
+        self.indent()
+        self.write_commons()
+
+        # process the root
+        frame = Frame(eval_ctx)
+        if "self" in find_undeclared(node.body, ("self",)):
+            ref = frame.symbols.declare_parameter("self")
+            self.writeline(f"{ref} = TemplateReference(context)")
+        frame.symbols.analyze_node(node)
+        frame.toplevel = frame.rootlevel = True
+        frame.require_output_check = have_extends and not self.has_known_extends
+        if have_extends:
+            self.writeline("parent_template = None")
+        self.enter_frame(frame)
+        self.pull_dependencies(node.body)
+        self.blockvisit(node.body, frame)
+        self.leave_frame(frame, with_python_scope=True)
+        self.outdent()
+
+        # make sure that the parent root is called.
+        if have_extends:
+            if not self.has_known_extends:
+                self.indent()
+                self.writeline("if parent_template is not None:")
+            self.indent()
+            if not self.environment.is_async:
+                self.writeline("yield from parent_template.root_render_func(context)")
+            else:
+                self.writeline(
+                    "async for event in parent_template.root_render_func(context):"
+                )
+                self.indent()
+                self.writeline("yield event")
+                self.outdent()
+            self.outdent(1 + (not self.has_known_extends))
+
+        # at this point we now have the blocks collected and can visit them too.
+        for name, block in self.blocks.items():
+            self.writeline(
+                f"{self.func('block_' + name)}(context, missing=missing{envenv}):",
+                block,
+                1,
+            )
+            self.indent()
+            self.write_commons()
+            # It's important that we do not make this frame a child of the
+            # toplevel template.  This would cause a variety of
+            # interesting issues with identifier tracking.
+            block_frame = Frame(eval_ctx)
+            block_frame.block_frame = True
+            undeclared = find_undeclared(block.body, ("self", "super"))
+            if "self" in undeclared:
+                ref = block_frame.symbols.declare_parameter("self")
+                self.writeline(f"{ref} = TemplateReference(context)")
+            if "super" in undeclared:
+                ref = block_frame.symbols.declare_parameter("super")
+                self.writeline(f"{ref} = context.super({name!r}, block_{name})")
+            block_frame.symbols.analyze_node(block)
+            block_frame.block = name
+            self.writeline("_block_vars = {}")
+            self.enter_frame(block_frame)
+            self.pull_dependencies(block.body)
+            self.blockvisit(block.body, block_frame)
+            self.leave_frame(block_frame, with_python_scope=True)
+            self.outdent()
+
+        blocks_kv_str = ", ".join(f"{x!r}: block_{x}" for x in self.blocks)
+        self.writeline(f"blocks = {{{blocks_kv_str}}}", extra=1)
+        debug_kv_str = "&".join(f"{k}={v}" for k, v in self.debug_info)
+        self.writeline(f"debug_info = {debug_kv_str!r}")
+
+    def visit_Block(self, node: nodes.Block, frame: Frame) -> None:
+        """Call a block and register it for the template."""
+        level = 0
+        if frame.toplevel:
+            # if we know that we are a child template, there is no need to
+            # check if we are one
+            if self.has_known_extends:
+                return
+            if self.extends_so_far > 0:
+                self.writeline("if parent_template is None:")
+                self.indent()
+                level += 1
+
+        if node.scoped:
+            context = self.derive_context(frame)
+        else:
+            context = self.get_context_ref()
+
+        if node.required:
+            self.writeline(f"if len(context.blocks[{node.name!r}]) <= 1:", node)
+            self.indent()
+            self.writeline(
+                f'raise TemplateRuntimeError("Required block {node.name!r} not found")',
+                node,
+            )
+            self.outdent()
+
+        if not self.environment.is_async and frame.buffer is None:
+            self.writeline(
+                f"yield from context.blocks[{node.name!r}][0]({context})", node
+            )
+        else:
+            self.writeline(
+                f"{self.choose_async()}for event in"
+                f" context.blocks[{node.name!r}][0]({context}):",
+                node,
+            )
+            self.indent()
+            self.simple_write("event", frame)
+            self.outdent()
+
+        self.outdent(level)
+
+    def visit_Extends(self, node: nodes.Extends, frame: Frame) -> None:
+        """Calls the extender."""
+        if not frame.toplevel:
+            self.fail("cannot use extend from a non top-level scope", node.lineno)
+
+        # if the number of extends statements in general is zero so
+        # far, we don't have to add a check if something extended
+        # the template before this one.
+        if self.extends_so_far > 0:
+
+            # if we have a known extends we just add a template runtime
+            # error into the generated code.  We could catch that at compile
+            # time too, but i welcome it not to confuse users by throwing the
+            # same error at different times just "because we can".
+            if not self.has_known_extends:
+                self.writeline("if parent_template is not None:")
+                self.indent()
+            self.writeline('raise TemplateRuntimeError("extended multiple times")')
+
+            # if we have a known extends already we don't need that code here
+            # as we know that the template execution will end here.
+            if self.has_known_extends:
+                raise CompilerExit()
+            else:
+                self.outdent()
+
+        self.writeline("parent_template = environment.get_template(", node)
+        self.visit(node.template, frame)
+        self.write(f", {self.name!r})")
+        self.writeline("for name, parent_block in parent_template.blocks.items():")
+        self.indent()
+        self.writeline("context.blocks.setdefault(name, []).append(parent_block)")
+        self.outdent()
+
+        # if this extends statement was in the root level we can take
+        # advantage of that information and simplify the generated code
+        # in the top level from this point onwards
+        if frame.rootlevel:
+            self.has_known_extends = True
+
+        # and now we have one more
+        self.extends_so_far += 1
+
+    def visit_Include(self, node: nodes.Include, frame: Frame) -> None:
+        """Handles includes."""
+        if node.ignore_missing:
+            self.writeline("try:")
+            self.indent()
+
+        func_name = "get_or_select_template"
+        if isinstance(node.template, nodes.Const):
+            if isinstance(node.template.value, str):
+                func_name = "get_template"
+            elif isinstance(node.template.value, (tuple, list)):
+                func_name = "select_template"
+        elif isinstance(node.template, (nodes.Tuple, nodes.List)):
+            func_name = "select_template"
+
+        self.writeline(f"template = environment.{func_name}(", node)
+        self.visit(node.template, frame)
+        self.write(f", {self.name!r})")
+        if node.ignore_missing:
+            self.outdent()
+            self.writeline("except TemplateNotFound:")
+            self.indent()
+            self.writeline("pass")
+            self.outdent()
+            self.writeline("else:")
+            self.indent()
+
+        skip_event_yield = False
+        if node.with_context:
+            self.writeline(
+                f"{self.choose_async()}for event in template.root_render_func("
+                "template.new_context(context.get_all(), True,"
+                f" {self.dump_local_context(frame)})):"
+            )
+        elif self.environment.is_async:
+            self.writeline(
+                "for event in (await template._get_default_module_async())"
+                "._body_stream:"
+            )
+        else:
+            self.writeline("yield from template._get_default_module()._body_stream")
+            skip_event_yield = True
+
+        if not skip_event_yield:
+            self.indent()
+            self.simple_write("event", frame)
+            self.outdent()
+
+        if node.ignore_missing:
+            self.outdent()
+
+    def _import_common(
+        self, node: t.Union[nodes.Import, nodes.FromImport], frame: Frame
+    ) -> None:
+        self.write(f"{self.choose_async('await ')}environment.get_template(")
+        self.visit(node.template, frame)
+        self.write(f", {self.name!r}).")
+
+        if node.with_context:
+            f_name = f"make_module{self.choose_async('_async')}"
+            self.write(
+                f"{f_name}(context.get_all(), True, {self.dump_local_context(frame)})"
+            )
+        else:
+            self.write(f"_get_default_module{self.choose_async('_async')}(context)")
+
+    def visit_Import(self, node: nodes.Import, frame: Frame) -> None:
+        """Visit regular imports."""
+        self.writeline(f"{frame.symbols.ref(node.target)} = ", node)
+        if frame.toplevel:
+            self.write(f"context.vars[{node.target!r}] = ")
+
+        self._import_common(node, frame)
+
+        if frame.toplevel and not node.target.startswith("_"):
+            self.writeline(f"context.exported_vars.discard({node.target!r})")
+
+    def visit_FromImport(self, node: nodes.FromImport, frame: Frame) -> None:
+        """Visit named imports."""
+        self.newline(node)
+        self.write("included_template = ")
+        self._import_common(node, frame)
+        var_names = []
+        discarded_names = []
+        for name in node.names:
+            if isinstance(name, tuple):
+                name, alias = name
+            else:
+                alias = name
+            self.writeline(
+                f"{frame.symbols.ref(alias)} ="
+                f" getattr(included_template, {name!r}, missing)"
+            )
+            self.writeline(f"if {frame.symbols.ref(alias)} is missing:")
+            self.indent()
+            message = (
+                "the template {included_template.__name__!r}"
+                f" (imported on {self.position(node)})"
+                f" does not export the requested name {name!r}"
+            )
+            self.writeline(
+                f"{frame.symbols.ref(alias)} = undefined(f{message!r}, name={name!r})"
+            )
+            self.outdent()
+            if frame.toplevel:
+                var_names.append(alias)
+                if not alias.startswith("_"):
+                    discarded_names.append(alias)
+
+        if var_names:
+            if len(var_names) == 1:
+                name = var_names[0]
+                self.writeline(f"context.vars[{name!r}] = {frame.symbols.ref(name)}")
+            else:
+                names_kv = ", ".join(
+                    f"{name!r}: {frame.symbols.ref(name)}" for name in var_names
+                )
+                self.writeline(f"context.vars.update({{{names_kv}}})")
+        if discarded_names:
+            if len(discarded_names) == 1:
+                self.writeline(f"context.exported_vars.discard({discarded_names[0]!r})")
+            else:
+                names_str = ", ".join(map(repr, discarded_names))
+                self.writeline(
+                    f"context.exported_vars.difference_update(({names_str}))"
+                )
+
+    def visit_For(self, node: nodes.For, frame: Frame) -> None:
+        loop_frame = frame.inner()
+        loop_frame.loop_frame = True
+        test_frame = frame.inner()
+        else_frame = frame.inner()
+
+        # try to figure out if we have an extended loop.  An extended loop
+        # is necessary if the loop is in recursive mode if the special loop
+        # variable is accessed in the body if the body is a scoped block.
+        extended_loop = (
+            node.recursive
+            or "loop"
+            in find_undeclared(node.iter_child_nodes(only=("body",)), ("loop",))
+            or any(block.scoped for block in node.find_all(nodes.Block))
+        )
+
+        loop_ref = None
+        if extended_loop:
+            loop_ref = loop_frame.symbols.declare_parameter("loop")
+
+        loop_frame.symbols.analyze_node(node, for_branch="body")
+        if node.else_:
+            else_frame.symbols.analyze_node(node, for_branch="else")
+
+        if node.test:
+            loop_filter_func = self.temporary_identifier()
+            test_frame.symbols.analyze_node(node, for_branch="test")
+            self.writeline(f"{self.func(loop_filter_func)}(fiter):", node.test)
+            self.indent()
+            self.enter_frame(test_frame)
+            self.writeline(self.choose_async("async for ", "for "))
+            self.visit(node.target, loop_frame)
+            self.write(" in ")
+            self.write(self.choose_async("auto_aiter(fiter)", "fiter"))
+            self.write(":")
+            self.indent()
+            self.writeline("if ", node.test)
+            self.visit(node.test, test_frame)
+            self.write(":")
+            self.indent()
+            self.writeline("yield ")
+            self.visit(node.target, loop_frame)
+            self.outdent(3)
+            self.leave_frame(test_frame, with_python_scope=True)
+
+        # if we don't have an recursive loop we have to find the shadowed
+        # variables at that point.  Because loops can be nested but the loop
+        # variable is a special one we have to enforce aliasing for it.
+        if node.recursive:
+            self.writeline(
+                f"{self.func('loop')}(reciter, loop_render_func, depth=0):", node
+            )
+            self.indent()
+            self.buffer(loop_frame)
+
+            # Use the same buffer for the else frame
+            else_frame.buffer = loop_frame.buffer
+
+        # make sure the loop variable is a special one and raise a template
+        # assertion error if a loop tries to write to loop
+        if extended_loop:
+            self.writeline(f"{loop_ref} = missing")
+
+        for name in node.find_all(nodes.Name):
+            if name.ctx == "store" and name.name == "loop":
+                self.fail(
+                    "Can't assign to special loop variable in for-loop target",
+                    name.lineno,
+                )
+
+        if node.else_:
+            iteration_indicator = self.temporary_identifier()
+            self.writeline(f"{iteration_indicator} = 1")
+
+        self.writeline(self.choose_async("async for ", "for "), node)
+        self.visit(node.target, loop_frame)
+        if extended_loop:
+            self.write(f", {loop_ref} in {self.choose_async('Async')}LoopContext(")
+        else:
+            self.write(" in ")
+
+        if node.test:
+            self.write(f"{loop_filter_func}(")
+        if node.recursive:
+            self.write("reciter")
+        else:
+            if self.environment.is_async and not extended_loop:
+                self.write("auto_aiter(")
+            self.visit(node.iter, frame)
+            if self.environment.is_async and not extended_loop:
+                self.write(")")
+        if node.test:
+            self.write(")")
+
+        if node.recursive:
+            self.write(", undefined, loop_render_func, depth):")
+        else:
+            self.write(", undefined):" if extended_loop else ":")
+
+        self.indent()
+        self.enter_frame(loop_frame)
+
+        self.writeline("_loop_vars = {}")
+        self.blockvisit(node.body, loop_frame)
+        if node.else_:
+            self.writeline(f"{iteration_indicator} = 0")
+        self.outdent()
+        self.leave_frame(
+            loop_frame, with_python_scope=node.recursive and not node.else_
+        )
+
+        if node.else_:
+            self.writeline(f"if {iteration_indicator}:")
+            self.indent()
+            self.enter_frame(else_frame)
+            self.blockvisit(node.else_, else_frame)
+            self.leave_frame(else_frame)
+            self.outdent()
+
+        # if the node was recursive we have to return the buffer contents
+        # and start the iteration code
+        if node.recursive:
+            self.return_buffer_contents(loop_frame)
+            self.outdent()
+            self.start_write(frame, node)
+            self.write(f"{self.choose_async('await ')}loop(")
+            if self.environment.is_async:
+                self.write("auto_aiter(")
+            self.visit(node.iter, frame)
+            if self.environment.is_async:
+                self.write(")")
+            self.write(", loop)")
+            self.end_write(frame)
+
+        # at the end of the iteration, clear any assignments made in the
+        # loop from the top level
+        if self._assign_stack:
+            self._assign_stack[-1].difference_update(loop_frame.symbols.stores)
+
+    def visit_If(self, node: nodes.If, frame: Frame) -> None:
+        if_frame = frame.soft()
+        self.writeline("if ", node)
+        self.visit(node.test, if_frame)
+        self.write(":")
+        self.indent()
+        self.blockvisit(node.body, if_frame)
+        self.outdent()
+        for elif_ in node.elif_:
+            self.writeline("elif ", elif_)
+            self.visit(elif_.test, if_frame)
+            self.write(":")
+            self.indent()
+            self.blockvisit(elif_.body, if_frame)
+            self.outdent()
+        if node.else_:
+            self.writeline("else:")
+            self.indent()
+            self.blockvisit(node.else_, if_frame)
+            self.outdent()
+
+    def visit_Macro(self, node: nodes.Macro, frame: Frame) -> None:
+        macro_frame, macro_ref = self.macro_body(node, frame)
+        self.newline()
+        if frame.toplevel:
+            if not node.name.startswith("_"):
+                self.write(f"context.exported_vars.add({node.name!r})")
+            self.writeline(f"context.vars[{node.name!r}] = ")
+        self.write(f"{frame.symbols.ref(node.name)} = ")
+        self.macro_def(macro_ref, macro_frame)
+
+    def visit_CallBlock(self, node: nodes.CallBlock, frame: Frame) -> None:
+        call_frame, macro_ref = self.macro_body(node, frame)
+        self.writeline("caller = ")
+        self.macro_def(macro_ref, call_frame)
+        self.start_write(frame, node)
+        self.visit_Call(node.call, frame, forward_caller=True)
+        self.end_write(frame)
+
+    def visit_FilterBlock(self, node: nodes.FilterBlock, frame: Frame) -> None:
+        filter_frame = frame.inner()
+        filter_frame.symbols.analyze_node(node)
+        self.enter_frame(filter_frame)
+        self.buffer(filter_frame)
+        self.blockvisit(node.body, filter_frame)
+        self.start_write(frame, node)
+        self.visit_Filter(node.filter, filter_frame)
+        self.end_write(frame)
+        self.leave_frame(filter_frame)
+
+    def visit_With(self, node: nodes.With, frame: Frame) -> None:
+        with_frame = frame.inner()
+        with_frame.symbols.analyze_node(node)
+        self.enter_frame(with_frame)
+        for target, expr in zip(node.targets, node.values):
+            self.newline()
+            self.visit(target, with_frame)
+            self.write(" = ")
+            self.visit(expr, frame)
+        self.blockvisit(node.body, with_frame)
+        self.leave_frame(with_frame)
+
+    def visit_ExprStmt(self, node: nodes.ExprStmt, frame: Frame) -> None:
+        self.newline(node)
+        self.visit(node.node, frame)
+
+    class _FinalizeInfo(t.NamedTuple):
+        const: t.Optional[t.Callable[..., str]]
+        src: t.Optional[str]
+
+    @staticmethod
+    def _default_finalize(value: t.Any) -> t.Any:
+        """The default finalize function if the environment isn't
+        configured with one. Or, if the environment has one, this is
+        called on that function's output for constants.
+        """
+        return str(value)
+
+    _finalize: t.Optional[_FinalizeInfo] = None
+
+    def _make_finalize(self) -> _FinalizeInfo:
+        """Build the finalize function to be used on constants and at
+        runtime. Cached so it's only created once for all output nodes.
+
+        Returns a ``namedtuple`` with the following attributes:
+
+        ``const``
+            A function to finalize constant data at compile time.
+
+        ``src``
+            Source code to output around nodes to be evaluated at
+            runtime.
+        """
+        if self._finalize is not None:
+            return self._finalize
+
+        finalize: t.Optional[t.Callable[..., t.Any]]
+        finalize = default = self._default_finalize
+        src = None
+
+        if self.environment.finalize:
+            src = "environment.finalize("
+            env_finalize = self.environment.finalize
+            pass_arg = {
+                _PassArg.context: "context",
+                _PassArg.eval_context: "context.eval_ctx",
+                _PassArg.environment: "environment",
+            }.get(
+                _PassArg.from_obj(env_finalize)  # type: ignore
+            )
+            finalize = None
+
+            if pass_arg is None:
+
+                def finalize(value: t.Any) -> t.Any:
+                    return default(env_finalize(value))
+
+            else:
+                src = f"{src}{pass_arg}, "
+
+                if pass_arg == "environment":
+
+                    def finalize(value: t.Any) -> t.Any:
+                        return default(env_finalize(self.environment, value))
+
+        self._finalize = self._FinalizeInfo(finalize, src)
+        return self._finalize
+
+    def _output_const_repr(self, group: t.Iterable[t.Any]) -> str:
+        """Given a group of constant values converted from ``Output``
+        child nodes, produce a string to write to the template module
+        source.
+        """
+        return repr(concat(group))
+
+    def _output_child_to_const(
+        self, node: nodes.Expr, frame: Frame, finalize: _FinalizeInfo
+    ) -> str:
+        """Try to optimize a child of an ``Output`` node by trying to
+        convert it to constant, finalized data at compile time.
+
+        If :exc:`Impossible` is raised, the node is not constant and
+        will be evaluated at runtime. Any other exception will also be
+        evaluated at runtime for easier debugging.
+        """
+        const = node.as_const(frame.eval_ctx)
+
+        if frame.eval_ctx.autoescape:
+            const = escape(const)
+
+        # Template data doesn't go through finalize.
+        if isinstance(node, nodes.TemplateData):
+            return str(const)
+
+        return finalize.const(const)  # type: ignore
+
+    def _output_child_pre(
+        self, node: nodes.Expr, frame: Frame, finalize: _FinalizeInfo
+    ) -> None:
+        """Output extra source code before visiting a child of an
+        ``Output`` node.
+        """
+        if frame.eval_ctx.volatile:
+            self.write("(escape if context.eval_ctx.autoescape else str)(")
+        elif frame.eval_ctx.autoescape:
+            self.write("escape(")
+        else:
+            self.write("str(")
+
+        if finalize.src is not None:
+            self.write(finalize.src)
+
+    def _output_child_post(
+        self, node: nodes.Expr, frame: Frame, finalize: _FinalizeInfo
+    ) -> None:
+        """Output extra source code after visiting a child of an
+        ``Output`` node.
+        """
+        self.write(")")
+
+        if finalize.src is not None:
+            self.write(")")
+
+    def visit_Output(self, node: nodes.Output, frame: Frame) -> None:
+        # If an extends is active, don't render outside a block.
+        if frame.require_output_check:
+            # A top-level extends is known to exist at compile time.
+            if self.has_known_extends:
+                return
+
+            self.writeline("if parent_template is None:")
+            self.indent()
+
+        finalize = self._make_finalize()
+        body: t.List[t.Union[t.List[t.Any], nodes.Expr]] = []
+
+        # Evaluate constants at compile time if possible. Each item in
+        # body will be either a list of static data or a node to be
+        # evaluated at runtime.
+        for child in node.nodes:
+            try:
+                if not (
+                    # If the finalize function requires runtime context,
+                    # constants can't be evaluated at compile time.
+                    finalize.const
+                    # Unless it's basic template data that won't be
+                    # finalized anyway.
+                    or isinstance(child, nodes.TemplateData)
+                ):
+                    raise nodes.Impossible()
+
+                const = self._output_child_to_const(child, frame, finalize)
+            except (nodes.Impossible, Exception):
+                # The node was not constant and needs to be evaluated at
+                # runtime. Or another error was raised, which is easier
+                # to debug at runtime.
+                body.append(child)
+                continue
+
+            if body and isinstance(body[-1], list):
+                body[-1].append(const)
+            else:
+                body.append([const])
+
+        if frame.buffer is not None:
+            if len(body) == 1:
+                self.writeline(f"{frame.buffer}.append(")
+            else:
+                self.writeline(f"{frame.buffer}.extend((")
+
+            self.indent()
+
+        for item in body:
+            if isinstance(item, list):
+                # A group of constant data to join and output.
+                val = self._output_const_repr(item)
+
+                if frame.buffer is None:
+                    self.writeline("yield " + val)
+                else:
+                    self.writeline(val + ",")
+            else:
+                if frame.buffer is None:
+                    self.writeline("yield ", item)
+                else:
+                    self.newline(item)
+
+                # A node to be evaluated at runtime.
+                self._output_child_pre(item, frame, finalize)
+                self.visit(item, frame)
+                self._output_child_post(item, frame, finalize)
+
+                if frame.buffer is not None:
+                    self.write(",")
+
+        if frame.buffer is not None:
+            self.outdent()
+            self.writeline(")" if len(body) == 1 else "))")
+
+        if frame.require_output_check:
+            self.outdent()
+
+    def visit_Assign(self, node: nodes.Assign, frame: Frame) -> None:
+        self.push_assign_tracking()
+        self.newline(node)
+        self.visit(node.target, frame)
+        self.write(" = ")
+        self.visit(node.node, frame)
+        self.pop_assign_tracking(frame)
+
+    def visit_AssignBlock(self, node: nodes.AssignBlock, frame: Frame) -> None:
+        self.push_assign_tracking()
+        block_frame = frame.inner()
+        # This is a special case.  Since a set block always captures we
+        # will disable output checks.  This way one can use set blocks
+        # toplevel even in extended templates.
+        block_frame.require_output_check = False
+        block_frame.symbols.analyze_node(node)
+        self.enter_frame(block_frame)
+        self.buffer(block_frame)
+        self.blockvisit(node.body, block_frame)
+        self.newline(node)
+        self.visit(node.target, frame)
+        self.write(" = (Markup if context.eval_ctx.autoescape else identity)(")
+        if node.filter is not None:
+            self.visit_Filter(node.filter, block_frame)
+        else:
+            self.write(f"concat({block_frame.buffer})")
+        self.write(")")
+        self.pop_assign_tracking(frame)
+        self.leave_frame(block_frame)
+
+    # -- Expression Visitors
+
+    def visit_Name(self, node: nodes.Name, frame: Frame) -> None:
+        if node.ctx == "store" and (
+            frame.toplevel or frame.loop_frame or frame.block_frame
+        ):
+            if self._assign_stack:
+                self._assign_stack[-1].add(node.name)
+        ref = frame.symbols.ref(node.name)
+
+        # If we are looking up a variable we might have to deal with the
+        # case where it's undefined.  We can skip that case if the load
+        # instruction indicates a parameter which are always defined.
+        if node.ctx == "load":
+            load = frame.symbols.find_load(ref)
+            if not (
+                load is not None
+                and load[0] == VAR_LOAD_PARAMETER
+                and not self.parameter_is_undeclared(ref)
+            ):
+                self.write(
+                    f"(undefined(name={node.name!r}) if {ref} is missing else {ref})"
+                )
+                return
+
+        self.write(ref)
+
+    def visit_NSRef(self, node: nodes.NSRef, frame: Frame) -> None:
+        # NSRefs can only be used to store values; since they use the normal
+        # `foo.bar` notation they will be parsed as a normal attribute access
+        # when used anywhere but in a `set` context
+        ref = frame.symbols.ref(node.name)
+        self.writeline(f"if not isinstance({ref}, Namespace):")
+        self.indent()
+        self.writeline(
+            "raise TemplateRuntimeError"
+            '("cannot assign attribute on non-namespace object")'
+        )
+        self.outdent()
+        self.writeline(f"{ref}[{node.attr!r}]")
+
+    def visit_Const(self, node: nodes.Const, frame: Frame) -> None:
+        val = node.as_const(frame.eval_ctx)
+        if isinstance(val, float):
+            self.write(str(val))
+        else:
+            self.write(repr(val))
+
+    def visit_TemplateData(self, node: nodes.TemplateData, frame: Frame) -> None:
+        try:
+            self.write(repr(node.as_const(frame.eval_ctx)))
+        except nodes.Impossible:
+            self.write(
+                f"(Markup if context.eval_ctx.autoescape else identity)({node.data!r})"
+            )
+
+    def visit_Tuple(self, node: nodes.Tuple, frame: Frame) -> None:
+        self.write("(")
+        idx = -1
+        for idx, item in enumerate(node.items):
+            if idx:
+                self.write(", ")
+            self.visit(item, frame)
+        self.write(",)" if idx == 0 else ")")
+
+    def visit_List(self, node: nodes.List, frame: Frame) -> None:
+        self.write("[")
+        for idx, item in enumerate(node.items):
+            if idx:
+                self.write(", ")
+            self.visit(item, frame)
+        self.write("]")
+
+    def visit_Dict(self, node: nodes.Dict, frame: Frame) -> None:
+        self.write("{")
+        for idx, item in enumerate(node.items):
+            if idx:
+                self.write(", ")
+            self.visit(item.key, frame)
+            self.write(": ")
+            self.visit(item.value, frame)
+        self.write("}")
+
+    visit_Add = _make_binop("+")
+    visit_Sub = _make_binop("-")
+    visit_Mul = _make_binop("*")
+    visit_Div = _make_binop("/")
+    visit_FloorDiv = _make_binop("//")
+    visit_Pow = _make_binop("**")
+    visit_Mod = _make_binop("%")
+    visit_And = _make_binop("and")
+    visit_Or = _make_binop("or")
+    visit_Pos = _make_unop("+")
+    visit_Neg = _make_unop("-")
+    visit_Not = _make_unop("not ")
+
+    @optimizeconst
+    def visit_Concat(self, node: nodes.Concat, frame: Frame) -> None:
+        if frame.eval_ctx.volatile:
+            func_name = "(markup_join if context.eval_ctx.volatile else str_join)"
+        elif frame.eval_ctx.autoescape:
+            func_name = "markup_join"
+        else:
+            func_name = "str_join"
+        self.write(f"{func_name}((")
+        for arg in node.nodes:
+            self.visit(arg, frame)
+            self.write(", ")
+        self.write("))")
+
+    @optimizeconst
+    def visit_Compare(self, node: nodes.Compare, frame: Frame) -> None:
+        self.write("(")
+        self.visit(node.expr, frame)
+        for op in node.ops:
+            self.visit(op, frame)
+        self.write(")")
+
+    def visit_Operand(self, node: nodes.Operand, frame: Frame) -> None:
+        self.write(f" {operators[node.op]} ")
+        self.visit(node.expr, frame)
+
+    @optimizeconst
+    def visit_Getattr(self, node: nodes.Getattr, frame: Frame) -> None:
+        if self.environment.is_async:
+            self.write("(await auto_await(")
+
+        self.write("environment.getattr(")
+        self.visit(node.node, frame)
+        self.write(f", {node.attr!r})")
+
+        if self.environment.is_async:
+            self.write("))")
+
+    @optimizeconst
+    def visit_Getitem(self, node: nodes.Getitem, frame: Frame) -> None:
+        # slices bypass the environment getitem method.
+        if isinstance(node.arg, nodes.Slice):
+            self.visit(node.node, frame)
+            self.write("[")
+            self.visit(node.arg, frame)
+            self.write("]")
+        else:
+            if self.environment.is_async:
+                self.write("(await auto_await(")
+
+            self.write("environment.getitem(")
+            self.visit(node.node, frame)
+            self.write(", ")
+            self.visit(node.arg, frame)
+            self.write(")")
+
+            if self.environment.is_async:
+                self.write("))")
+
+    def visit_Slice(self, node: nodes.Slice, frame: Frame) -> None:
+        if node.start is not None:
+            self.visit(node.start, frame)
+        self.write(":")
+        if node.stop is not None:
+            self.visit(node.stop, frame)
+        if node.step is not None:
+            self.write(":")
+            self.visit(node.step, frame)
+
+    @contextmanager
+    def _filter_test_common(
+        self, node: t.Union[nodes.Filter, nodes.Test], frame: Frame, is_filter: bool
+    ) -> t.Iterator[None]:
+        if self.environment.is_async:
+            self.write("await auto_await(")
+
+        if is_filter:
+            self.write(f"{self.filters[node.name]}(")
+            func = self.environment.filters.get(node.name)
+        else:
+            self.write(f"{self.tests[node.name]}(")
+            func = self.environment.tests.get(node.name)
+
+        # When inside an If or CondExpr frame, allow the filter to be
+        # undefined at compile time and only raise an error if it's
+        # actually called at runtime. See pull_dependencies.
+        if func is None and not frame.soft_frame:
+            type_name = "filter" if is_filter else "test"
+            self.fail(f"No {type_name} named {node.name!r}.", node.lineno)
+
+        pass_arg = {
+            _PassArg.context: "context",
+            _PassArg.eval_context: "context.eval_ctx",
+            _PassArg.environment: "environment",
+        }.get(
+            _PassArg.from_obj(func)  # type: ignore
+        )
+
+        if pass_arg is not None:
+            self.write(f"{pass_arg}, ")
+
+        # Back to the visitor function to handle visiting the target of
+        # the filter or test.
+        yield
+
+        self.signature(node, frame)
+        self.write(")")
+
+        if self.environment.is_async:
+            self.write(")")
+
+    @optimizeconst
+    def visit_Filter(self, node: nodes.Filter, frame: Frame) -> None:
+        with self._filter_test_common(node, frame, True):
+            # if the filter node is None we are inside a filter block
+            # and want to write to the current buffer
+            if node.node is not None:
+                self.visit(node.node, frame)
+            elif frame.eval_ctx.volatile:
+                self.write(
+                    f"(Markup(concat({frame.buffer}))"
+                    f" if context.eval_ctx.autoescape else concat({frame.buffer}))"
+                )
+            elif frame.eval_ctx.autoescape:
+                self.write(f"Markup(concat({frame.buffer}))")
+            else:
+                self.write(f"concat({frame.buffer})")
+
+    @optimizeconst
+    def visit_Test(self, node: nodes.Test, frame: Frame) -> None:
+        with self._filter_test_common(node, frame, False):
+            self.visit(node.node, frame)
+
+    @optimizeconst
+    def visit_CondExpr(self, node: nodes.CondExpr, frame: Frame) -> None:
+        frame = frame.soft()
+
+        def write_expr2() -> None:
+            if node.expr2 is not None:
+                self.visit(node.expr2, frame)
+                return
+
+            self.write(
+                f'cond_expr_undefined("the inline if-expression on'
+                f" {self.position(node)} evaluated to false and no else"
+                f' section was defined.")'
+            )
+
+        self.write("(")
+        self.visit(node.expr1, frame)
+        self.write(" if ")
+        self.visit(node.test, frame)
+        self.write(" else ")
+        write_expr2()
+        self.write(")")
+
+    @optimizeconst
+    def visit_Call(
+        self, node: nodes.Call, frame: Frame, forward_caller: bool = False
+    ) -> None:
+        if self.environment.is_async:
+            self.write("await auto_await(")
+        if self.environment.sandboxed:
+            self.write("environment.call(context, ")
+        else:
+            self.write("context.call(")
+        self.visit(node.node, frame)
+        extra_kwargs = {"caller": "caller"} if forward_caller else None
+        loop_kwargs = {"_loop_vars": "_loop_vars"} if frame.loop_frame else {}
+        block_kwargs = {"_block_vars": "_block_vars"} if frame.block_frame else {}
+        if extra_kwargs:
+            extra_kwargs.update(loop_kwargs, **block_kwargs)
+        elif loop_kwargs or block_kwargs:
+            extra_kwargs = dict(loop_kwargs, **block_kwargs)
+        self.signature(node, frame, extra_kwargs)
+        self.write(")")
+        if self.environment.is_async:
+            self.write(")")
+
+    def visit_Keyword(self, node: nodes.Keyword, frame: Frame) -> None:
+        self.write(node.key + "=")
+        self.visit(node.value, frame)
+
+    # -- Unused nodes for extensions
+
+    def visit_MarkSafe(self, node: nodes.MarkSafe, frame: Frame) -> None:
+        self.write("Markup(")
+        self.visit(node.expr, frame)
+        self.write(")")
+
+    def visit_MarkSafeIfAutoescape(
+        self, node: nodes.MarkSafeIfAutoescape, frame: Frame
+    ) -> None:
+        self.write("(Markup if context.eval_ctx.autoescape else identity)(")
+        self.visit(node.expr, frame)
+        self.write(")")
+
+    def visit_EnvironmentAttribute(
+        self, node: nodes.EnvironmentAttribute, frame: Frame
+    ) -> None:
+        self.write("environment." + node.name)
+
+    def visit_ExtensionAttribute(
+        self, node: nodes.ExtensionAttribute, frame: Frame
+    ) -> None:
+        self.write(f"environment.extensions[{node.identifier!r}].{node.name}")
+
+    def visit_ImportedName(self, node: nodes.ImportedName, frame: Frame) -> None:
+        self.write(self.import_aliases[node.importname])
+
+    def visit_InternalName(self, node: nodes.InternalName, frame: Frame) -> None:
+        self.write(node.name)
+
+    def visit_ContextReference(
+        self, node: nodes.ContextReference, frame: Frame
+    ) -> None:
+        self.write("context")
+
+    def visit_DerivedContextReference(
+        self, node: nodes.DerivedContextReference, frame: Frame
+    ) -> None:
+        self.write(self.derive_context(frame))
+
+    def visit_Continue(self, node: nodes.Continue, frame: Frame) -> None:
+        self.writeline("continue", node)
+
+    def visit_Break(self, node: nodes.Break, frame: Frame) -> None:
+        self.writeline("break", node)
+
+    def visit_Scope(self, node: nodes.Scope, frame: Frame) -> None:
+        scope_frame = frame.inner()
+        scope_frame.symbols.analyze_node(node)
+        self.enter_frame(scope_frame)
+        self.blockvisit(node.body, scope_frame)
+        self.leave_frame(scope_frame)
+
+    def visit_OverlayScope(self, node: nodes.OverlayScope, frame: Frame) -> None:
+        ctx = self.temporary_identifier()
+        self.writeline(f"{ctx} = {self.derive_context(frame)}")
+        self.writeline(f"{ctx}.vars = ")
+        self.visit(node.context, frame)
+        self.push_context_reference(ctx)
+
+        scope_frame = frame.inner(isolated=True)
+        scope_frame.symbols.analyze_node(node)
+        self.enter_frame(scope_frame)
+        self.blockvisit(node.body, scope_frame)
+        self.leave_frame(scope_frame)
+        self.pop_context_reference()
+
+    def visit_EvalContextModifier(
+        self, node: nodes.EvalContextModifier, frame: Frame
+    ) -> None:
+        for keyword in node.options:
+            self.writeline(f"context.eval_ctx.{keyword.key} = ")
+            self.visit(keyword.value, frame)
+            try:
+                val = keyword.value.as_const(frame.eval_ctx)
+            except nodes.Impossible:
+                frame.eval_ctx.volatile = True
+            else:
+                setattr(frame.eval_ctx, keyword.key, val)
+
+    def visit_ScopedEvalContextModifier(
+        self, node: nodes.ScopedEvalContextModifier, frame: Frame
+    ) -> None:
+        old_ctx_name = self.temporary_identifier()
+        saved_ctx = frame.eval_ctx.save()
+        self.writeline(f"{old_ctx_name} = context.eval_ctx.save()")
+        self.visit_EvalContextModifier(node, frame)
+        for child in node.body:
+            self.visit(child, frame)
+        frame.eval_ctx.revert(saved_ctx)
+        self.writeline(f"context.eval_ctx.revert({old_ctx_name})")
diff --git a/lib/spack/external/_vendoring/jinja2/constants.py b/lib/spack/external/_vendoring/jinja2/constants.py
new file mode 100644
index 0000000000..41a1c23b0a
--- /dev/null
+++ b/lib/spack/external/_vendoring/jinja2/constants.py
@@ -0,0 +1,20 @@
+#: list of lorem ipsum words used by the lipsum() helper function
+LOREM_IPSUM_WORDS = """\
+a ac accumsan ad adipiscing aenean aliquam aliquet amet ante aptent arcu at
+auctor augue bibendum blandit class commodo condimentum congue consectetuer
+consequat conubia convallis cras cubilia cum curabitur curae cursus dapibus
+diam dictum dictumst dignissim dis dolor donec dui duis egestas eget eleifend
+elementum elit enim erat eros est et etiam eu euismod facilisi facilisis fames
+faucibus felis fermentum feugiat fringilla fusce gravida habitant habitasse hac
+hendrerit hymenaeos iaculis id imperdiet in inceptos integer interdum ipsum
+justo lacinia lacus laoreet lectus leo libero ligula litora lobortis lorem
+luctus maecenas magna magnis malesuada massa mattis mauris metus mi molestie
+mollis montes morbi mus nam nascetur natoque nec neque netus nibh nisi nisl non
+nonummy nostra nulla nullam nunc odio orci ornare parturient pede pellentesque
+penatibus per pharetra phasellus placerat platea porta porttitor posuere
+potenti praesent pretium primis proin pulvinar purus quam quis quisque rhoncus
+ridiculus risus rutrum sagittis sapien scelerisque sed sem semper senectus sit
+sociis sociosqu sodales sollicitudin suscipit suspendisse taciti tellus tempor
+tempus tincidunt torquent tortor tristique turpis ullamcorper ultrices
+ultricies urna ut varius vehicula vel velit venenatis vestibulum vitae vivamus
+viverra volutpat vulputate"""
diff --git a/lib/spack/external/_vendoring/jinja2/debug.py b/lib/spack/external/_vendoring/jinja2/debug.py
new file mode 100644
index 0000000000..805866bd6f
--- /dev/null
+++ b/lib/spack/external/_vendoring/jinja2/debug.py
@@ -0,0 +1,259 @@
+import platform
+import sys
+import typing as t
+from types import CodeType
+from types import TracebackType
+
+from .exceptions import TemplateSyntaxError
+from .utils import internal_code
+from .utils import missing
+
+if t.TYPE_CHECKING:
+    from .runtime import Context
+
+
+def rewrite_traceback_stack(source: t.Optional[str] = None) -> BaseException:
+    """Rewrite the current exception to replace any tracebacks from
+    within compiled template code with tracebacks that look like they
+    came from the template source.
+
+    This must be called within an ``except`` block.
+
+    :param source: For ``TemplateSyntaxError``, the original source if
+        known.
+    :return: The original exception with the rewritten traceback.
+    """
+    _, exc_value, tb = sys.exc_info()
+    exc_value = t.cast(BaseException, exc_value)
+    tb = t.cast(TracebackType, tb)
+
+    if isinstance(exc_value, TemplateSyntaxError) and not exc_value.translated:
+        exc_value.translated = True
+        exc_value.source = source
+        # Remove the old traceback, otherwise the frames from the
+        # compiler still show up.
+        exc_value.with_traceback(None)
+        # Outside of runtime, so the frame isn't executing template
+        # code, but it still needs to point at the template.
+        tb = fake_traceback(
+            exc_value, None, exc_value.filename or "<unknown>", exc_value.lineno
+        )
+    else:
+        # Skip the frame for the render function.
+        tb = tb.tb_next
+
+    stack = []
+
+    # Build the stack of traceback object, replacing any in template
+    # code with the source file and line information.
+    while tb is not None:
+        # Skip frames decorated with @internalcode. These are internal
+        # calls that aren't useful in template debugging output.
+        if tb.tb_frame.f_code in internal_code:
+            tb = tb.tb_next
+            continue
+
+        template = tb.tb_frame.f_globals.get("__jinja_template__")
+
+        if template is not None:
+            lineno = template.get_corresponding_lineno(tb.tb_lineno)
+            fake_tb = fake_traceback(exc_value, tb, template.filename, lineno)
+            stack.append(fake_tb)
+        else:
+            stack.append(tb)
+
+        tb = tb.tb_next
+
+    tb_next = None
+
+    # Assign tb_next in reverse to avoid circular references.
+    for tb in reversed(stack):
+        tb_next = tb_set_next(tb, tb_next)
+
+    return exc_value.with_traceback(tb_next)
+
+
+def fake_traceback(  # type: ignore
+    exc_value: BaseException, tb: t.Optional[TracebackType], filename: str, lineno: int
+) -> TracebackType:
+    """Produce a new traceback object that looks like it came from the
+    template source instead of the compiled code. The filename, line
+    number, and location name will point to the template, and the local
+    variables will be the current template context.
+
+    :param exc_value: The original exception to be re-raised to create
+        the new traceback.
+    :param tb: The original traceback to get the local variables and
+        code info from.
+    :param filename: The template filename.
+    :param lineno: The line number in the template source.
+    """
+    if tb is not None:
+        # Replace the real locals with the context that would be
+        # available at that point in the template.
+        locals = get_template_locals(tb.tb_frame.f_locals)
+        locals.pop("__jinja_exception__", None)
+    else:
+        locals = {}
+
+    globals = {
+        "__name__": filename,
+        "__file__": filename,
+        "__jinja_exception__": exc_value,
+    }
+    # Raise an exception at the correct line number.
+    code: CodeType = compile(
+        "\n" * (lineno - 1) + "raise __jinja_exception__", filename, "exec"
+    )
+
+    # Build a new code object that points to the template file and
+    # replaces the location with a block name.
+    location = "template"
+
+    if tb is not None:
+        function = tb.tb_frame.f_code.co_name
+
+        if function == "root":
+            location = "top-level template code"
+        elif function.startswith("block_"):
+            location = f"block {function[6:]!r}"
+
+    if sys.version_info >= (3, 8):
+        code = code.replace(co_name=location)
+    else:
+        code = CodeType(
+            code.co_argcount,
+            code.co_kwonlyargcount,
+            code.co_nlocals,
+            code.co_stacksize,
+            code.co_flags,
+            code.co_code,
+            code.co_consts,
+            code.co_names,
+            code.co_varnames,
+            code.co_filename,
+            location,
+            code.co_firstlineno,
+            code.co_lnotab,
+            code.co_freevars,
+            code.co_cellvars,
+        )
+
+    # Execute the new code, which is guaranteed to raise, and return
+    # the new traceback without this frame.
+    try:
+        exec(code, globals, locals)
+    except BaseException:
+        return sys.exc_info()[2].tb_next  # type: ignore
+
+
+def get_template_locals(real_locals: t.Mapping[str, t.Any]) -> t.Dict[str, t.Any]:
+    """Based on the runtime locals, get the context that would be
+    available at that point in the template.
+    """
+    # Start with the current template context.
+    ctx: "t.Optional[Context]" = real_locals.get("context")
+
+    if ctx is not None:
+        data: t.Dict[str, t.Any] = ctx.get_all().copy()
+    else:
+        data = {}
+
+    # Might be in a derived context that only sets local variables
+    # rather than pushing a context. Local variables follow the scheme
+    # l_depth_name. Find the highest-depth local that has a value for
+    # each name.
+    local_overrides: t.Dict[str, t.Tuple[int, t.Any]] = {}
+
+    for name, value in real_locals.items():
+        if not name.startswith("l_") or value is missing:
+            # Not a template variable, or no longer relevant.
+            continue
+
+        try:
+            _, depth_str, name = name.split("_", 2)
+            depth = int(depth_str)
+        except ValueError:
+            continue
+
+        cur_depth = local_overrides.get(name, (-1,))[0]
+
+        if cur_depth < depth:
+            local_overrides[name] = (depth, value)
+
+    # Modify the context with any derived context.
+    for name, (_, value) in local_overrides.items():
+        if value is missing:
+            data.pop(name, None)
+        else:
+            data[name] = value
+
+    return data
+
+
+if sys.version_info >= (3, 7):
+    # tb_next is directly assignable as of Python 3.7
+    def tb_set_next(
+        tb: TracebackType, tb_next: t.Optional[TracebackType]
+    ) -> TracebackType:
+        tb.tb_next = tb_next
+        return tb
+
+
+elif platform.python_implementation() == "PyPy":
+    # PyPy might have special support, and won't work with ctypes.
+    try:
+        import tputil  # type: ignore
+    except ImportError:
+        # Without tproxy support, use the original traceback.
+        def tb_set_next(
+            tb: TracebackType, tb_next: t.Optional[TracebackType]
+        ) -> TracebackType:
+            return tb
+
+    else:
+        # With tproxy support, create a proxy around the traceback that
+        # returns the new tb_next.
+        def tb_set_next(
+            tb: TracebackType, tb_next: t.Optional[TracebackType]
+        ) -> TracebackType:
+            def controller(op):  # type: ignore
+                if op.opname == "__getattribute__" and op.args[0] == "tb_next":
+                    return tb_next
+
+                return op.delegate()
+
+            return tputil.make_proxy(controller, obj=tb)  # type: ignore
+
+
+else:
+    # Use ctypes to assign tb_next at the C level since it's read-only
+    # from Python.
+    import ctypes
+
+    class _CTraceback(ctypes.Structure):
+        _fields_ = [
+            # Extra PyObject slots when compiled with Py_TRACE_REFS.
+            ("PyObject_HEAD", ctypes.c_byte * object().__sizeof__()),
+            # Only care about tb_next as an object, not a traceback.
+            ("tb_next", ctypes.py_object),
+        ]
+
+    def tb_set_next(
+        tb: TracebackType, tb_next: t.Optional[TracebackType]
+    ) -> TracebackType:
+        c_tb = _CTraceback.from_address(id(tb))
+
+        # Clear out the old tb_next.
+        if tb.tb_next is not None:
+            c_tb_next = ctypes.py_object(tb.tb_next)
+            c_tb.tb_next = ctypes.py_object()
+            ctypes.pythonapi.Py_DecRef(c_tb_next)
+
+        # Assign the new tb_next.
+        if tb_next is not None:
+            c_tb_next = ctypes.py_object(tb_next)
+            ctypes.pythonapi.Py_IncRef(c_tb_next)
+            c_tb.tb_next = c_tb_next
+
+        return tb
diff --git a/lib/spack/external/_vendoring/jinja2/defaults.py b/lib/spack/external/_vendoring/jinja2/defaults.py
new file mode 100644
index 0000000000..638cad3d2d
--- /dev/null
+++ b/lib/spack/external/_vendoring/jinja2/defaults.py
@@ -0,0 +1,48 @@
+import typing as t
+
+from .filters import FILTERS as DEFAULT_FILTERS  # noqa: F401
+from .tests import TESTS as DEFAULT_TESTS  # noqa: F401
+from .utils import Cycler
+from .utils import generate_lorem_ipsum
+from .utils import Joiner
+from .utils import Namespace
+
+if t.TYPE_CHECKING:
+    import typing_extensions as te
+
+# defaults for the parser / lexer
+BLOCK_START_STRING = "{%"
+BLOCK_END_STRING = "%}"
+VARIABLE_START_STRING = "{{"
+VARIABLE_END_STRING = "}}"
+COMMENT_START_STRING = "{#"
+COMMENT_END_STRING = "#}"
+LINE_STATEMENT_PREFIX: t.Optional[str] = None
+LINE_COMMENT_PREFIX: t.Optional[str] = None
+TRIM_BLOCKS = False
+LSTRIP_BLOCKS = False
+NEWLINE_SEQUENCE: "te.Literal['\\n', '\\r\\n', '\\r']" = "\n"
+KEEP_TRAILING_NEWLINE = False
+
+# default filters, tests and namespace
+
+DEFAULT_NAMESPACE = {
+    "range": range,
+    "dict": dict,
+    "lipsum": generate_lorem_ipsum,
+    "cycler": Cycler,
+    "joiner": Joiner,
+    "namespace": Namespace,
+}
+
+# default policies
+DEFAULT_POLICIES: t.Dict[str, t.Any] = {
+    "compiler.ascii_str": True,
+    "urlize.rel": "noopener",
+    "urlize.target": None,
+    "urlize.extra_schemes": None,
+    "truncate.leeway": 5,
+    "json.dumps_function": None,
+    "json.dumps_kwargs": {"sort_keys": True},
+    "ext.i18n.trimmed": False,
+}
diff --git a/lib/spack/external/_vendoring/jinja2/environment.py b/lib/spack/external/_vendoring/jinja2/environment.py
new file mode 100644
index 0000000000..a231d9cd57
--- /dev/null
+++ b/lib/spack/external/_vendoring/jinja2/environment.py
@@ -0,0 +1,1661 @@
+"""Classes for managing templates and their runtime and compile time
+options.
+"""
+import os
+import sys
+import typing
+import typing as t
+import weakref
+from collections import ChainMap
+from functools import lru_cache
+from functools import partial
+from functools import reduce
+from types import CodeType
+
+from markupsafe import Markup
+
+from . import nodes
+from .compiler import CodeGenerator
+from .compiler import generate
+from .defaults import BLOCK_END_STRING
+from .defaults import BLOCK_START_STRING
+from .defaults import COMMENT_END_STRING
+from .defaults import COMMENT_START_STRING
+from .defaults import DEFAULT_FILTERS
+from .defaults import DEFAULT_NAMESPACE
+from .defaults import DEFAULT_POLICIES
+from .defaults import DEFAULT_TESTS
+from .defaults import KEEP_TRAILING_NEWLINE
+from .defaults import LINE_COMMENT_PREFIX
+from .defaults import LINE_STATEMENT_PREFIX
+from .defaults import LSTRIP_BLOCKS
+from .defaults import NEWLINE_SEQUENCE
+from .defaults import TRIM_BLOCKS
+from .defaults import VARIABLE_END_STRING
+from .defaults import VARIABLE_START_STRING
+from .exceptions import TemplateNotFound
+from .exceptions import TemplateRuntimeError
+from .exceptions import TemplatesNotFound
+from .exceptions import TemplateSyntaxError
+from .exceptions import UndefinedError
+from .lexer import get_lexer
+from .lexer import Lexer
+from .lexer import TokenStream
+from .nodes import EvalContext
+from .parser import Parser
+from .runtime import Context
+from .runtime import new_context
+from .runtime import Undefined
+from .utils import _PassArg
+from .utils import concat
+from .utils import consume
+from .utils import import_string
+from .utils import internalcode
+from .utils import LRUCache
+from .utils import missing
+
+if t.TYPE_CHECKING:
+    import typing_extensions as te
+    from .bccache import BytecodeCache
+    from .ext import Extension
+    from .loaders import BaseLoader
+
+_env_bound = t.TypeVar("_env_bound", bound="Environment")
+
+
+# for direct template usage we have up to ten living environments
+@lru_cache(maxsize=10)
+def get_spontaneous_environment(cls: t.Type[_env_bound], *args: t.Any) -> _env_bound:
+    """Return a new spontaneous environment. A spontaneous environment
+    is used for templates created directly rather than through an
+    existing environment.
+
+    :param cls: Environment class to create.
+    :param args: Positional arguments passed to environment.
+    """
+    env = cls(*args)
+    env.shared = True
+    return env
+
+
+def create_cache(
+    size: int,
+) -> t.Optional[t.MutableMapping[t.Tuple[weakref.ref, str], "Template"]]:
+    """Return the cache class for the given size."""
+    if size == 0:
+        return None
+
+    if size < 0:
+        return {}
+
+    return LRUCache(size)  # type: ignore
+
+
+def copy_cache(
+    cache: t.Optional[t.MutableMapping],
+) -> t.Optional[t.MutableMapping[t.Tuple[weakref.ref, str], "Template"]]:
+    """Create an empty copy of the given cache."""
+    if cache is None:
+        return None
+
+    if type(cache) is dict:
+        return {}
+
+    return LRUCache(cache.capacity)  # type: ignore
+
+
+def load_extensions(
+    environment: "Environment",
+    extensions: t.Sequence[t.Union[str, t.Type["Extension"]]],
+) -> t.Dict[str, "Extension"]:
+    """Load the extensions from the list and bind it to the environment.
+    Returns a dict of instantiated extensions.
+    """
+    result = {}
+
+    for extension in extensions:
+        if isinstance(extension, str):
+            extension = t.cast(t.Type["Extension"], import_string(extension))
+
+        result[extension.identifier] = extension(environment)
+
+    return result
+
+
+def _environment_config_check(environment: "Environment") -> "Environment":
+    """Perform a sanity check on the environment."""
+    assert issubclass(
+        environment.undefined, Undefined
+    ), "'undefined' must be a subclass of 'jinja2.Undefined'."
+    assert (
+        environment.block_start_string
+        != environment.variable_start_string
+        != environment.comment_start_string
+    ), "block, variable and comment start strings must be different."
+    assert environment.newline_sequence in {
+        "\r",
+        "\r\n",
+        "\n",
+    }, "'newline_sequence' must be one of '\\n', '\\r\\n', or '\\r'."
+    return environment
+
+
+class Environment:
+    r"""The core component of Jinja is the `Environment`.  It contains
+    important shared variables like configuration, filters, tests,
+    globals and others.  Instances of this class may be modified if
+    they are not shared and if no template was loaded so far.
+    Modifications on environments after the first template was loaded
+    will lead to surprising effects and undefined behavior.
+
+    Here are the possible initialization parameters:
+
+        `block_start_string`
+            The string marking the beginning of a block.  Defaults to ``'{%'``.
+
+        `block_end_string`
+            The string marking the end of a block.  Defaults to ``'%}'``.
+
+        `variable_start_string`
+            The string marking the beginning of a print statement.
+            Defaults to ``'{{'``.
+
+        `variable_end_string`
+            The string marking the end of a print statement.  Defaults to
+            ``'}}'``.
+
+        `comment_start_string`
+            The string marking the beginning of a comment.  Defaults to ``'{#'``.
+
+        `comment_end_string`
+            The string marking the end of a comment.  Defaults to ``'#}'``.
+
+        `line_statement_prefix`
+            If given and a string, this will be used as prefix for line based
+            statements.  See also :ref:`line-statements`.
+
+        `line_comment_prefix`
+            If given and a string, this will be used as prefix for line based
+            comments.  See also :ref:`line-statements`.
+
+            .. versionadded:: 2.2
+
+        `trim_blocks`
+            If this is set to ``True`` the first newline after a block is
+            removed (block, not variable tag!).  Defaults to `False`.
+
+        `lstrip_blocks`
+            If this is set to ``True`` leading spaces and tabs are stripped
+            from the start of a line to a block.  Defaults to `False`.
+
+        `newline_sequence`
+            The sequence that starts a newline.  Must be one of ``'\r'``,
+            ``'\n'`` or ``'\r\n'``.  The default is ``'\n'`` which is a
+            useful default for Linux and OS X systems as well as web
+            applications.
+
+        `keep_trailing_newline`
+            Preserve the trailing newline when rendering templates.
+            The default is ``False``, which causes a single newline,
+            if present, to be stripped from the end of the template.
+
+            .. versionadded:: 2.7
+
+        `extensions`
+            List of Jinja extensions to use.  This can either be import paths
+            as strings or extension classes.  For more information have a
+            look at :ref:`the extensions documentation <jinja-extensions>`.
+
+        `optimized`
+            should the optimizer be enabled?  Default is ``True``.
+
+        `undefined`
+            :class:`Undefined` or a subclass of it that is used to represent
+            undefined values in the template.
+
+        `finalize`
+            A callable that can be used to process the result of a variable
+            expression before it is output.  For example one can convert
+            ``None`` implicitly into an empty string here.
+
+        `autoescape`
+            If set to ``True`` the XML/HTML autoescaping feature is enabled by
+            default.  For more details about autoescaping see
+            :class:`~markupsafe.Markup`.  As of Jinja 2.4 this can also
+            be a callable that is passed the template name and has to
+            return ``True`` or ``False`` depending on autoescape should be
+            enabled by default.
+
+            .. versionchanged:: 2.4
+               `autoescape` can now be a function
+
+        `loader`
+            The template loader for this environment.
+
+        `cache_size`
+            The size of the cache.  Per default this is ``400`` which means
+            that if more than 400 templates are loaded the loader will clean
+            out the least recently used template.  If the cache size is set to
+            ``0`` templates are recompiled all the time, if the cache size is
+            ``-1`` the cache will not be cleaned.
+
+            .. versionchanged:: 2.8
+               The cache size was increased to 400 from a low 50.
+
+        `auto_reload`
+            Some loaders load templates from locations where the template
+            sources may change (ie: file system or database).  If
+            ``auto_reload`` is set to ``True`` (default) every time a template is
+            requested the loader checks if the source changed and if yes, it
+            will reload the template.  For higher performance it's possible to
+            disable that.
+
+        `bytecode_cache`
+            If set to a bytecode cache object, this object will provide a
+            cache for the internal Jinja bytecode so that templates don't
+            have to be parsed if they were not changed.
+
+            See :ref:`bytecode-cache` for more information.
+
+        `enable_async`
+            If set to true this enables async template execution which
+            allows using async functions and generators.
+    """
+
+    #: if this environment is sandboxed.  Modifying this variable won't make
+    #: the environment sandboxed though.  For a real sandboxed environment
+    #: have a look at jinja2.sandbox.  This flag alone controls the code
+    #: generation by the compiler.
+    sandboxed = False
+
+    #: True if the environment is just an overlay
+    overlayed = False
+
+    #: the environment this environment is linked to if it is an overlay
+    linked_to: t.Optional["Environment"] = None
+
+    #: shared environments have this set to `True`.  A shared environment
+    #: must not be modified
+    shared = False
+
+    #: the class that is used for code generation.  See
+    #: :class:`~jinja2.compiler.CodeGenerator` for more information.
+    code_generator_class: t.Type["CodeGenerator"] = CodeGenerator
+
+    #: the context class that is used for templates.  See
+    #: :class:`~jinja2.runtime.Context` for more information.
+    context_class: t.Type[Context] = Context
+
+    template_class: t.Type["Template"]
+
+    def __init__(
+        self,
+        block_start_string: str = BLOCK_START_STRING,
+        block_end_string: str = BLOCK_END_STRING,
+        variable_start_string: str = VARIABLE_START_STRING,
+        variable_end_string: str = VARIABLE_END_STRING,
+        comment_start_string: str = COMMENT_START_STRING,
+        comment_end_string: str = COMMENT_END_STRING,
+        line_statement_prefix: t.Optional[str] = LINE_STATEMENT_PREFIX,
+        line_comment_prefix: t.Optional[str] = LINE_COMMENT_PREFIX,
+        trim_blocks: bool = TRIM_BLOCKS,
+        lstrip_blocks: bool = LSTRIP_BLOCKS,
+        newline_sequence: "te.Literal['\\n', '\\r\\n', '\\r']" = NEWLINE_SEQUENCE,
+        keep_trailing_newline: bool = KEEP_TRAILING_NEWLINE,
+        extensions: t.Sequence[t.Union[str, t.Type["Extension"]]] = (),
+        optimized: bool = True,
+        undefined: t.Type[Undefined] = Undefined,
+        finalize: t.Optional[t.Callable[..., t.Any]] = None,
+        autoescape: t.Union[bool, t.Callable[[t.Optional[str]], bool]] = False,
+        loader: t.Optional["BaseLoader"] = None,
+        cache_size: int = 400,
+        auto_reload: bool = True,
+        bytecode_cache: t.Optional["BytecodeCache"] = None,
+        enable_async: bool = False,
+    ):
+        # !!Important notice!!
+        #   The constructor accepts quite a few arguments that should be
+        #   passed by keyword rather than position.  However it's important to
+        #   not change the order of arguments because it's used at least
+        #   internally in those cases:
+        #       -   spontaneous environments (i18n extension and Template)
+        #       -   unittests
+        #   If parameter changes are required only add parameters at the end
+        #   and don't change the arguments (or the defaults!) of the arguments
+        #   existing already.
+
+        # lexer / parser information
+        self.block_start_string = block_start_string
+        self.block_end_string = block_end_string
+        self.variable_start_string = variable_start_string
+        self.variable_end_string = variable_end_string
+        self.comment_start_string = comment_start_string
+        self.comment_end_string = comment_end_string
+        self.line_statement_prefix = line_statement_prefix
+        self.line_comment_prefix = line_comment_prefix
+        self.trim_blocks = trim_blocks
+        self.lstrip_blocks = lstrip_blocks
+        self.newline_sequence = newline_sequence
+        self.keep_trailing_newline = keep_trailing_newline
+
+        # runtime information
+        self.undefined: t.Type[Undefined] = undefined
+        self.optimized = optimized
+        self.finalize = finalize
+        self.autoescape = autoescape
+
+        # defaults
+        self.filters = DEFAULT_FILTERS.copy()
+        self.tests = DEFAULT_TESTS.copy()
+        self.globals = DEFAULT_NAMESPACE.copy()
+
+        # set the loader provided
+        self.loader = loader
+        self.cache = create_cache(cache_size)
+        self.bytecode_cache = bytecode_cache
+        self.auto_reload = auto_reload
+
+        # configurable policies
+        self.policies = DEFAULT_POLICIES.copy()
+
+        # load extensions
+        self.extensions = load_extensions(self, extensions)
+
+        self.is_async = enable_async
+        _environment_config_check(self)
+
+    def add_extension(self, extension: t.Union[str, t.Type["Extension"]]) -> None:
+        """Adds an extension after the environment was created.
+
+        .. versionadded:: 2.5
+        """
+        self.extensions.update(load_extensions(self, [extension]))
+
+    def extend(self, **attributes: t.Any) -> None:
+        """Add the items to the instance of the environment if they do not exist
+        yet.  This is used by :ref:`extensions <writing-extensions>` to register
+        callbacks and configuration values without breaking inheritance.
+        """
+        for key, value in attributes.items():
+            if not hasattr(self, key):
+                setattr(self, key, value)
+
+    def overlay(
+        self,
+        block_start_string: str = missing,
+        block_end_string: str = missing,
+        variable_start_string: str = missing,
+        variable_end_string: str = missing,
+        comment_start_string: str = missing,
+        comment_end_string: str = missing,
+        line_statement_prefix: t.Optional[str] = missing,
+        line_comment_prefix: t.Optional[str] = missing,
+        trim_blocks: bool = missing,
+        lstrip_blocks: bool = missing,
+        extensions: t.Sequence[t.Union[str, t.Type["Extension"]]] = missing,
+        optimized: bool = missing,
+        undefined: t.Type[Undefined] = missing,
+        finalize: t.Optional[t.Callable[..., t.Any]] = missing,
+        autoescape: t.Union[bool, t.Callable[[t.Optional[str]], bool]] = missing,
+        loader: t.Optional["BaseLoader"] = missing,
+        cache_size: int = missing,
+        auto_reload: bool = missing,
+        bytecode_cache: t.Optional["BytecodeCache"] = missing,
+    ) -> "Environment":
+        """Create a new overlay environment that shares all the data with the
+        current environment except for cache and the overridden attributes.
+        Extensions cannot be removed for an overlayed environment.  An overlayed
+        environment automatically gets all the extensions of the environment it
+        is linked to plus optional extra extensions.
+
+        Creating overlays should happen after the initial environment was set
+        up completely.  Not all attributes are truly linked, some are just
+        copied over so modifications on the original environment may not shine
+        through.
+        """
+        args = dict(locals())
+        del args["self"], args["cache_size"], args["extensions"]
+
+        rv = object.__new__(self.__class__)
+        rv.__dict__.update(self.__dict__)
+        rv.overlayed = True
+        rv.linked_to = self
+
+        for key, value in args.items():
+            if value is not missing:
+                setattr(rv, key, value)
+
+        if cache_size is not missing:
+            rv.cache = create_cache(cache_size)
+        else:
+            rv.cache = copy_cache(self.cache)
+
+        rv.extensions = {}
+        for key, value in self.extensions.items():
+            rv.extensions[key] = value.bind(rv)
+        if extensions is not missing:
+            rv.extensions.update(load_extensions(rv, extensions))
+
+        return _environment_config_check(rv)
+
+    @property
+    def lexer(self) -> Lexer:
+        """The lexer for this environment."""
+        return get_lexer(self)
+
+    def iter_extensions(self) -> t.Iterator["Extension"]:
+        """Iterates over the extensions by priority."""
+        return iter(sorted(self.extensions.values(), key=lambda x: x.priority))
+
+    def getitem(
+        self, obj: t.Any, argument: t.Union[str, t.Any]
+    ) -> t.Union[t.Any, Undefined]:
+        """Get an item or attribute of an object but prefer the item."""
+        try:
+            return obj[argument]
+        except (AttributeError, TypeError, LookupError):
+            if isinstance(argument, str):
+                try:
+                    attr = str(argument)
+                except Exception:
+                    pass
+                else:
+                    try:
+                        return getattr(obj, attr)
+                    except AttributeError:
+                        pass
+            return self.undefined(obj=obj, name=argument)
+
+    def getattr(self, obj: t.Any, attribute: str) -> t.Any:
+        """Get an item or attribute of an object but prefer the attribute.
+        Unlike :meth:`getitem` the attribute *must* be a string.
+        """
+        try:
+            return getattr(obj, attribute)
+        except AttributeError:
+            pass
+        try:
+            return obj[attribute]
+        except (TypeError, LookupError, AttributeError):
+            return self.undefined(obj=obj, name=attribute)
+
+    def _filter_test_common(
+        self,
+        name: t.Union[str, Undefined],
+        value: t.Any,
+        args: t.Optional[t.Sequence[t.Any]],
+        kwargs: t.Optional[t.Mapping[str, t.Any]],
+        context: t.Optional[Context],
+        eval_ctx: t.Optional[EvalContext],
+        is_filter: bool,
+    ) -> t.Any:
+        if is_filter:
+            env_map = self.filters
+            type_name = "filter"
+        else:
+            env_map = self.tests
+            type_name = "test"
+
+        func = env_map.get(name)  # type: ignore
+
+        if func is None:
+            msg = f"No {type_name} named {name!r}."
+
+            if isinstance(name, Undefined):
+                try:
+                    name._fail_with_undefined_error()
+                except Exception as e:
+                    msg = f"{msg} ({e}; did you forget to quote the callable name?)"
+
+            raise TemplateRuntimeError(msg)
+
+        args = [value, *(args if args is not None else ())]
+        kwargs = kwargs if kwargs is not None else {}
+        pass_arg = _PassArg.from_obj(func)
+
+        if pass_arg is _PassArg.context:
+            if context is None:
+                raise TemplateRuntimeError(
+                    f"Attempted to invoke a context {type_name} without context."
+                )
+
+            args.insert(0, context)
+        elif pass_arg is _PassArg.eval_context:
+            if eval_ctx is None:
+                if context is not None:
+                    eval_ctx = context.eval_ctx
+                else:
+                    eval_ctx = EvalContext(self)
+
+            args.insert(0, eval_ctx)
+        elif pass_arg is _PassArg.environment:
+            args.insert(0, self)
+
+        return func(*args, **kwargs)
+
+    def call_filter(
+        self,
+        name: str,
+        value: t.Any,
+        args: t.Optional[t.Sequence[t.Any]] = None,
+        kwargs: t.Optional[t.Mapping[str, t.Any]] = None,
+        context: t.Optional[Context] = None,
+        eval_ctx: t.Optional[EvalContext] = None,
+    ) -> t.Any:
+        """Invoke a filter on a value the same way the compiler does.
+
+        This might return a coroutine if the filter is running from an
+        environment in async mode and the filter supports async
+        execution. It's your responsibility to await this if needed.
+
+        .. versionadded:: 2.7
+        """
+        return self._filter_test_common(
+            name, value, args, kwargs, context, eval_ctx, True
+        )
+
+    def call_test(
+        self,
+        name: str,
+        value: t.Any,
+        args: t.Optional[t.Sequence[t.Any]] = None,
+        kwargs: t.Optional[t.Mapping[str, t.Any]] = None,
+        context: t.Optional[Context] = None,
+        eval_ctx: t.Optional[EvalContext] = None,
+    ) -> t.Any:
+        """Invoke a test on a value the same way the compiler does.
+
+        This might return a coroutine if the test is running from an
+        environment in async mode and the test supports async execution.
+        It's your responsibility to await this if needed.
+
+        .. versionchanged:: 3.0
+            Tests support ``@pass_context``, etc. decorators. Added
+            the ``context`` and ``eval_ctx`` parameters.
+
+        .. versionadded:: 2.7
+        """
+        return self._filter_test_common(
+            name, value, args, kwargs, context, eval_ctx, False
+        )
+
+    @internalcode
+    def parse(
+        self,
+        source: str,
+        name: t.Optional[str] = None,
+        filename: t.Optional[str] = None,
+    ) -> nodes.Template:
+        """Parse the sourcecode and return the abstract syntax tree.  This
+        tree of nodes is used by the compiler to convert the template into
+        executable source- or bytecode.  This is useful for debugging or to
+        extract information from templates.
+
+        If you are :ref:`developing Jinja extensions <writing-extensions>`
+        this gives you a good overview of the node tree generated.
+        """
+        try:
+            return self._parse(source, name, filename)
+        except TemplateSyntaxError:
+            self.handle_exception(source=source)
+
+    def _parse(
+        self, source: str, name: t.Optional[str], filename: t.Optional[str]
+    ) -> nodes.Template:
+        """Internal parsing function used by `parse` and `compile`."""
+        return Parser(self, source, name, filename).parse()
+
+    def lex(
+        self,
+        source: str,
+        name: t.Optional[str] = None,
+        filename: t.Optional[str] = None,
+    ) -> t.Iterator[t.Tuple[int, str, str]]:
+        """Lex the given sourcecode and return a generator that yields
+        tokens as tuples in the form ``(lineno, token_type, value)``.
+        This can be useful for :ref:`extension development <writing-extensions>`
+        and debugging templates.
+
+        This does not perform preprocessing.  If you want the preprocessing
+        of the extensions to be applied you have to filter source through
+        the :meth:`preprocess` method.
+        """
+        source = str(source)
+        try:
+            return self.lexer.tokeniter(source, name, filename)
+        except TemplateSyntaxError:
+            self.handle_exception(source=source)
+
+    def preprocess(
+        self,
+        source: str,
+        name: t.Optional[str] = None,
+        filename: t.Optional[str] = None,
+    ) -> str:
+        """Preprocesses the source with all extensions.  This is automatically
+        called for all parsing and compiling methods but *not* for :meth:`lex`
+        because there you usually only want the actual source tokenized.
+        """
+        return reduce(
+            lambda s, e: e.preprocess(s, name, filename),
+            self.iter_extensions(),
+            str(source),
+        )
+
+    def _tokenize(
+        self,
+        source: str,
+        name: t.Optional[str],
+        filename: t.Optional[str] = None,
+        state: t.Optional[str] = None,
+    ) -> TokenStream:
+        """Called by the parser to do the preprocessing and filtering
+        for all the extensions.  Returns a :class:`~jinja2.lexer.TokenStream`.
+        """
+        source = self.preprocess(source, name, filename)
+        stream = self.lexer.tokenize(source, name, filename, state)
+
+        for ext in self.iter_extensions():
+            stream = ext.filter_stream(stream)  # type: ignore
+
+            if not isinstance(stream, TokenStream):
+                stream = TokenStream(stream, name, filename)  # type: ignore
+
+        return stream
+
+    def _generate(
+        self,
+        source: nodes.Template,
+        name: t.Optional[str],
+        filename: t.Optional[str],
+        defer_init: bool = False,
+    ) -> str:
+        """Internal hook that can be overridden to hook a different generate
+        method in.
+
+        .. versionadded:: 2.5
+        """
+        return generate(  # type: ignore
+            source,
+            self,
+            name,
+            filename,
+            defer_init=defer_init,
+            optimized=self.optimized,
+        )
+
+    def _compile(self, source: str, filename: str) -> CodeType:
+        """Internal hook that can be overridden to hook a different compile
+        method in.
+
+        .. versionadded:: 2.5
+        """
+        return compile(source, filename, "exec")  # type: ignore
+
+    @typing.overload
+    def compile(  # type: ignore
+        self,
+        source: t.Union[str, nodes.Template],
+        name: t.Optional[str] = None,
+        filename: t.Optional[str] = None,
+        raw: "te.Literal[False]" = False,
+        defer_init: bool = False,
+    ) -> CodeType:
+        ...
+
+    @typing.overload
+    def compile(
+        self,
+        source: t.Union[str, nodes.Template],
+        name: t.Optional[str] = None,
+        filename: t.Optional[str] = None,
+        raw: "te.Literal[True]" = ...,
+        defer_init: bool = False,
+    ) -> str:
+        ...
+
+    @internalcode
+    def compile(
+        self,
+        source: t.Union[str, nodes.Template],
+        name: t.Optional[str] = None,
+        filename: t.Optional[str] = None,
+        raw: bool = False,
+        defer_init: bool = False,
+    ) -> t.Union[str, CodeType]:
+        """Compile a node or template source code.  The `name` parameter is
+        the load name of the template after it was joined using
+        :meth:`join_path` if necessary, not the filename on the file system.
+        the `filename` parameter is the estimated filename of the template on
+        the file system.  If the template came from a database or memory this
+        can be omitted.
+
+        The return value of this method is a python code object.  If the `raw`
+        parameter is `True` the return value will be a string with python
+        code equivalent to the bytecode returned otherwise.  This method is
+        mainly used internally.
+
+        `defer_init` is use internally to aid the module code generator.  This
+        causes the generated code to be able to import without the global
+        environment variable to be set.
+
+        .. versionadded:: 2.4
+           `defer_init` parameter added.
+        """
+        source_hint = None
+        try:
+            if isinstance(source, str):
+                source_hint = source
+                source = self._parse(source, name, filename)
+            source = self._generate(source, name, filename, defer_init=defer_init)
+            if raw:
+                return source
+            if filename is None:
+                filename = "<template>"
+            return self._compile(source, filename)
+        except TemplateSyntaxError:
+            self.handle_exception(source=source_hint)
+
+    def compile_expression(
+        self, source: str, undefined_to_none: bool = True
+    ) -> "TemplateExpression":
+        """A handy helper method that returns a callable that accepts keyword
+        arguments that appear as variables in the expression.  If called it
+        returns the result of the expression.
+
+        This is useful if applications want to use the same rules as Jinja
+        in template "configuration files" or similar situations.
+
+        Example usage:
+
+        >>> env = Environment()
+        >>> expr = env.compile_expression('foo == 42')
+        >>> expr(foo=23)
+        False
+        >>> expr(foo=42)
+        True
+
+        Per default the return value is converted to `None` if the
+        expression returns an undefined value.  This can be changed
+        by setting `undefined_to_none` to `False`.
+
+        >>> env.compile_expression('var')() is None
+        True
+        >>> env.compile_expression('var', undefined_to_none=False)()
+        Undefined
+
+        .. versionadded:: 2.1
+        """
+        parser = Parser(self, source, state="variable")
+        try:
+            expr = parser.parse_expression()
+            if not parser.stream.eos:
+                raise TemplateSyntaxError(
+                    "chunk after expression", parser.stream.current.lineno, None, None
+                )
+            expr.set_environment(self)
+        except TemplateSyntaxError:
+            self.handle_exception(source=source)
+
+        body = [nodes.Assign(nodes.Name("result", "store"), expr, lineno=1)]
+        template = self.from_string(nodes.Template(body, lineno=1))
+        return TemplateExpression(template, undefined_to_none)
+
+    def compile_templates(
+        self,
+        target: t.Union[str, os.PathLike],
+        extensions: t.Optional[t.Collection[str]] = None,
+        filter_func: t.Optional[t.Callable[[str], bool]] = None,
+        zip: t.Optional[str] = "deflated",
+        log_function: t.Optional[t.Callable[[str], None]] = None,
+        ignore_errors: bool = True,
+    ) -> None:
+        """Finds all the templates the loader can find, compiles them
+        and stores them in `target`.  If `zip` is `None`, instead of in a
+        zipfile, the templates will be stored in a directory.
+        By default a deflate zip algorithm is used. To switch to
+        the stored algorithm, `zip` can be set to ``'stored'``.
+
+        `extensions` and `filter_func` are passed to :meth:`list_templates`.
+        Each template returned will be compiled to the target folder or
+        zipfile.
+
+        By default template compilation errors are ignored.  In case a
+        log function is provided, errors are logged.  If you want template
+        syntax errors to abort the compilation you can set `ignore_errors`
+        to `False` and you will get an exception on syntax errors.
+
+        .. versionadded:: 2.4
+        """
+        from .loaders import ModuleLoader
+
+        if log_function is None:
+
+            def log_function(x: str) -> None:
+                pass
+
+        assert log_function is not None
+        assert self.loader is not None, "No loader configured."
+
+        def write_file(filename: str, data: str) -> None:
+            if zip:
+                info = ZipInfo(filename)
+                info.external_attr = 0o755 << 16
+                zip_file.writestr(info, data)
+            else:
+                with open(os.path.join(target, filename), "wb") as f:
+                    f.write(data.encode("utf8"))
+
+        if zip is not None:
+            from zipfile import ZipFile, ZipInfo, ZIP_DEFLATED, ZIP_STORED
+
+            zip_file = ZipFile(
+                target, "w", dict(deflated=ZIP_DEFLATED, stored=ZIP_STORED)[zip]
+            )
+            log_function(f"Compiling into Zip archive {target!r}")
+        else:
+            if not os.path.isdir(target):
+                os.makedirs(target)
+            log_function(f"Compiling into folder {target!r}")
+
+        try:
+            for name in self.list_templates(extensions, filter_func):
+                source, filename, _ = self.loader.get_source(self, name)
+                try:
+                    code = self.compile(source, name, filename, True, True)
+                except TemplateSyntaxError as e:
+                    if not ignore_errors:
+                        raise
+                    log_function(f'Could not compile "{name}": {e}')
+                    continue
+
+                filename = ModuleLoader.get_module_filename(name)
+
+                write_file(filename, code)
+                log_function(f'Compiled "{name}" as {filename}')
+        finally:
+            if zip:
+                zip_file.close()
+
+        log_function("Finished compiling templates")
+
+    def list_templates(
+        self,
+        extensions: t.Optional[t.Collection[str]] = None,
+        filter_func: t.Optional[t.Callable[[str], bool]] = None,
+    ) -> t.List[str]:
+        """Returns a list of templates for this environment.  This requires
+        that the loader supports the loader's
+        :meth:`~BaseLoader.list_templates` method.
+
+        If there are other files in the template folder besides the
+        actual templates, the returned list can be filtered.  There are two
+        ways: either `extensions` is set to a list of file extensions for
+        templates, or a `filter_func` can be provided which is a callable that
+        is passed a template name and should return `True` if it should end up
+        in the result list.
+
+        If the loader does not support that, a :exc:`TypeError` is raised.
+
+        .. versionadded:: 2.4
+        """
+        assert self.loader is not None, "No loader configured."
+        names = self.loader.list_templates()
+
+        if extensions is not None:
+            if filter_func is not None:
+                raise TypeError(
+                    "either extensions or filter_func can be passed, but not both"
+                )
+
+            def filter_func(x: str) -> bool:
+                return "." in x and x.rsplit(".", 1)[1] in extensions  # type: ignore
+
+        if filter_func is not None:
+            names = [name for name in names if filter_func(name)]
+
+        return names
+
+    def handle_exception(self, source: t.Optional[str] = None) -> "te.NoReturn":
+        """Exception handling helper.  This is used internally to either raise
+        rewritten exceptions or return a rendered traceback for the template.
+        """
+        from .debug import rewrite_traceback_stack
+
+        raise rewrite_traceback_stack(source=source)
+
+    def join_path(self, template: str, parent: str) -> str:
+        """Join a template with the parent.  By default all the lookups are
+        relative to the loader root so this method returns the `template`
+        parameter unchanged, but if the paths should be relative to the
+        parent template, this function can be used to calculate the real
+        template name.
+
+        Subclasses may override this method and implement template path
+        joining here.
+        """
+        return template
+
+    @internalcode
+    def _load_template(
+        self, name: str, globals: t.Optional[t.Mapping[str, t.Any]]
+    ) -> "Template":
+        if self.loader is None:
+            raise TypeError("no loader for this environment specified")
+        cache_key = (weakref.ref(self.loader), name)
+        if self.cache is not None:
+            template = self.cache.get(cache_key)
+            if template is not None and (
+                not self.auto_reload or template.is_up_to_date
+            ):
+                # template.globals is a ChainMap, modifying it will only
+                # affect the template, not the environment globals.
+                if globals:
+                    template.globals.update(globals)
+
+                return template
+
+        template = self.loader.load(self, name, self.make_globals(globals))
+
+        if self.cache is not None:
+            self.cache[cache_key] = template
+        return template
+
+    @internalcode
+    def get_template(
+        self,
+        name: t.Union[str, "Template"],
+        parent: t.Optional[str] = None,
+        globals: t.Optional[t.Mapping[str, t.Any]] = None,
+    ) -> "Template":
+        """Load a template by name with :attr:`loader` and return a
+        :class:`Template`. If the template does not exist a
+        :exc:`TemplateNotFound` exception is raised.
+
+        :param name: Name of the template to load.
+        :param parent: The name of the parent template importing this
+            template. :meth:`join_path` can be used to implement name
+            transformations with this.
+        :param globals: Extend the environment :attr:`globals` with
+            these extra variables available for all renders of this
+            template. If the template has already been loaded and
+            cached, its globals are updated with any new items.
+
+        .. versionchanged:: 3.0
+            If a template is loaded from cache, ``globals`` will update
+            the template's globals instead of ignoring the new values.
+
+        .. versionchanged:: 2.4
+            If ``name`` is a :class:`Template` object it is returned
+            unchanged.
+        """
+        if isinstance(name, Template):
+            return name
+        if parent is not None:
+            name = self.join_path(name, parent)
+
+        return self._load_template(name, globals)
+
+    @internalcode
+    def select_template(
+        self,
+        names: t.Iterable[t.Union[str, "Template"]],
+        parent: t.Optional[str] = None,
+        globals: t.Optional[t.Mapping[str, t.Any]] = None,
+    ) -> "Template":
+        """Like :meth:`get_template`, but tries loading multiple names.
+        If none of the names can be loaded a :exc:`TemplatesNotFound`
+        exception is raised.
+
+        :param names: List of template names to try loading in order.
+        :param parent: The name of the parent template importing this
+            template. :meth:`join_path` can be used to implement name
+            transformations with this.
+        :param globals: Extend the environment :attr:`globals` with
+            these extra variables available for all renders of this
+            template. If the template has already been loaded and
+            cached, its globals are updated with any new items.
+
+        .. versionchanged:: 3.0
+            If a template is loaded from cache, ``globals`` will update
+            the template's globals instead of ignoring the new values.
+
+        .. versionchanged:: 2.11
+            If ``names`` is :class:`Undefined`, an :exc:`UndefinedError`
+            is raised instead. If no templates were found and ``names``
+            contains :class:`Undefined`, the message is more helpful.
+
+        .. versionchanged:: 2.4
+            If ``names`` contains a :class:`Template` object it is
+            returned unchanged.
+
+        .. versionadded:: 2.3
+        """
+        if isinstance(names, Undefined):
+            names._fail_with_undefined_error()
+
+        if not names:
+            raise TemplatesNotFound(
+                message="Tried to select from an empty list of templates."
+            )
+
+        for name in names:
+            if isinstance(name, Template):
+                return name
+            if parent is not None:
+                name = self.join_path(name, parent)
+            try:
+                return self._load_template(name, globals)
+            except (TemplateNotFound, UndefinedError):
+                pass
+        raise TemplatesNotFound(names)  # type: ignore
+
+    @internalcode
+    def get_or_select_template(
+        self,
+        template_name_or_list: t.Union[
+            str, "Template", t.List[t.Union[str, "Template"]]
+        ],
+        parent: t.Optional[str] = None,
+        globals: t.Optional[t.Mapping[str, t.Any]] = None,
+    ) -> "Template":
+        """Use :meth:`select_template` if an iterable of template names
+        is given, or :meth:`get_template` if one name is given.
+
+        .. versionadded:: 2.3
+        """
+        if isinstance(template_name_or_list, (str, Undefined)):
+            return self.get_template(template_name_or_list, parent, globals)
+        elif isinstance(template_name_or_list, Template):
+            return template_name_or_list
+        return self.select_template(template_name_or_list, parent, globals)
+
+    def from_string(
+        self,
+        source: t.Union[str, nodes.Template],
+        globals: t.Optional[t.Mapping[str, t.Any]] = None,
+        template_class: t.Optional[t.Type["Template"]] = None,
+    ) -> "Template":
+        """Load a template from a source string without using
+        :attr:`loader`.
+
+        :param source: Jinja source to compile into a template.
+        :param globals: Extend the environment :attr:`globals` with
+            these extra variables available for all renders of this
+            template. If the template has already been loaded and
+            cached, its globals are updated with any new items.
+        :param template_class: Return an instance of this
+            :class:`Template` class.
+        """
+        gs = self.make_globals(globals)
+        cls = template_class or self.template_class
+        return cls.from_code(self, self.compile(source), gs, None)
+
+    def make_globals(
+        self, d: t.Optional[t.Mapping[str, t.Any]]
+    ) -> t.MutableMapping[str, t.Any]:
+        """Make the globals map for a template. Any given template
+        globals overlay the environment :attr:`globals`.
+
+        Returns a :class:`collections.ChainMap`. This allows any changes
+        to a template's globals to only affect that template, while
+        changes to the environment's globals are still reflected.
+        However, avoid modifying any globals after a template is loaded.
+
+        :param d: Dict of template-specific globals.
+
+        .. versionchanged:: 3.0
+            Use :class:`collections.ChainMap` to always prevent mutating
+            environment globals.
+        """
+        if d is None:
+            d = {}
+
+        return ChainMap(d, self.globals)
+
+
+class Template:
+    """A compiled template that can be rendered.
+
+    Use the methods on :class:`Environment` to create or load templates.
+    The environment is used to configure how templates are compiled and
+    behave.
+
+    It is also possible to create a template object directly. This is
+    not usually recommended. The constructor takes most of the same
+    arguments as :class:`Environment`. All templates created with the
+    same environment arguments share the same ephemeral ``Environment``
+    instance behind the scenes.
+
+    A template object should be considered immutable. Modifications on
+    the object are not supported.
+    """
+
+    #: Type of environment to create when creating a template directly
+    #: rather than through an existing environment.
+    environment_class: t.Type[Environment] = Environment
+
+    environment: Environment
+    globals: t.MutableMapping[str, t.Any]
+    name: t.Optional[str]
+    filename: t.Optional[str]
+    blocks: t.Dict[str, t.Callable[[Context], t.Iterator[str]]]
+    root_render_func: t.Callable[[Context], t.Iterator[str]]
+    _module: t.Optional["TemplateModule"]
+    _debug_info: str
+    _uptodate: t.Optional[t.Callable[[], bool]]
+
+    def __new__(
+        cls,
+        source: t.Union[str, nodes.Template],
+        block_start_string: str = BLOCK_START_STRING,
+        block_end_string: str = BLOCK_END_STRING,
+        variable_start_string: str = VARIABLE_START_STRING,
+        variable_end_string: str = VARIABLE_END_STRING,
+        comment_start_string: str = COMMENT_START_STRING,
+        comment_end_string: str = COMMENT_END_STRING,
+        line_statement_prefix: t.Optional[str] = LINE_STATEMENT_PREFIX,
+        line_comment_prefix: t.Optional[str] = LINE_COMMENT_PREFIX,
+        trim_blocks: bool = TRIM_BLOCKS,
+        lstrip_blocks: bool = LSTRIP_BLOCKS,
+        newline_sequence: "te.Literal['\\n', '\\r\\n', '\\r']" = NEWLINE_SEQUENCE,
+        keep_trailing_newline: bool = KEEP_TRAILING_NEWLINE,
+        extensions: t.Sequence[t.Union[str, t.Type["Extension"]]] = (),
+        optimized: bool = True,
+        undefined: t.Type[Undefined] = Undefined,
+        finalize: t.Optional[t.Callable[..., t.Any]] = None,
+        autoescape: t.Union[bool, t.Callable[[t.Optional[str]], bool]] = False,
+        enable_async: bool = False,
+    ) -> t.Any:  # it returns a `Template`, but this breaks the sphinx build...
+        env = get_spontaneous_environment(
+            cls.environment_class,  # type: ignore
+            block_start_string,
+            block_end_string,
+            variable_start_string,
+            variable_end_string,
+            comment_start_string,
+            comment_end_string,
+            line_statement_prefix,
+            line_comment_prefix,
+            trim_blocks,
+            lstrip_blocks,
+            newline_sequence,
+            keep_trailing_newline,
+            frozenset(extensions),
+            optimized,
+            undefined,  # type: ignore
+            finalize,
+            autoescape,
+            None,
+            0,
+            False,
+            None,
+            enable_async,
+        )
+        return env.from_string(source, template_class=cls)
+
+    @classmethod
+    def from_code(
+        cls,
+        environment: Environment,
+        code: CodeType,
+        globals: t.MutableMapping[str, t.Any],
+        uptodate: t.Optional[t.Callable[[], bool]] = None,
+    ) -> "Template":
+        """Creates a template object from compiled code and the globals.  This
+        is used by the loaders and environment to create a template object.
+        """
+        namespace = {"environment": environment, "__file__": code.co_filename}
+        exec(code, namespace)
+        rv = cls._from_namespace(environment, namespace, globals)
+        rv._uptodate = uptodate
+        return rv
+
+    @classmethod
+    def from_module_dict(
+        cls,
+        environment: Environment,
+        module_dict: t.MutableMapping[str, t.Any],
+        globals: t.MutableMapping[str, t.Any],
+    ) -> "Template":
+        """Creates a template object from a module.  This is used by the
+        module loader to create a template object.
+
+        .. versionadded:: 2.4
+        """
+        return cls._from_namespace(environment, module_dict, globals)
+
+    @classmethod
+    def _from_namespace(
+        cls,
+        environment: Environment,
+        namespace: t.MutableMapping[str, t.Any],
+        globals: t.MutableMapping[str, t.Any],
+    ) -> "Template":
+        t: "Template" = object.__new__(cls)
+        t.environment = environment
+        t.globals = globals
+        t.name = namespace["name"]
+        t.filename = namespace["__file__"]
+        t.blocks = namespace["blocks"]
+
+        # render function and module
+        t.root_render_func = namespace["root"]  # type: ignore
+        t._module = None
+
+        # debug and loader helpers
+        t._debug_info = namespace["debug_info"]
+        t._uptodate = None
+
+        # store the reference
+        namespace["environment"] = environment
+        namespace["__jinja_template__"] = t
+
+        return t
+
+    def render(self, *args: t.Any, **kwargs: t.Any) -> str:
+        """This method accepts the same arguments as the `dict` constructor:
+        A dict, a dict subclass or some keyword arguments.  If no arguments
+        are given the context will be empty.  These two calls do the same::
+
+            template.render(knights='that say nih')
+            template.render({'knights': 'that say nih'})
+
+        This will return the rendered template as a string.
+        """
+        if self.environment.is_async:
+            import asyncio
+
+            close = False
+
+            if sys.version_info < (3, 7):
+                loop = asyncio.get_event_loop()
+            else:
+                try:
+                    loop = asyncio.get_running_loop()
+                except RuntimeError:
+                    loop = asyncio.new_event_loop()
+                    close = True
+
+            try:
+                return loop.run_until_complete(self.render_async(*args, **kwargs))
+            finally:
+                if close:
+                    loop.close()
+
+        ctx = self.new_context(dict(*args, **kwargs))
+
+        try:
+            return concat(self.root_render_func(ctx))  # type: ignore
+        except Exception:
+            self.environment.handle_exception()
+
+    async def render_async(self, *args: t.Any, **kwargs: t.Any) -> str:
+        """This works similar to :meth:`render` but returns a coroutine
+        that when awaited returns the entire rendered template string.  This
+        requires the async feature to be enabled.
+
+        Example usage::
+
+            await template.render_async(knights='that say nih; asynchronously')
+        """
+        if not self.environment.is_async:
+            raise RuntimeError(
+                "The environment was not created with async mode enabled."
+            )
+
+        ctx = self.new_context(dict(*args, **kwargs))
+
+        try:
+            return concat([n async for n in self.root_render_func(ctx)])  # type: ignore
+        except Exception:
+            return self.environment.handle_exception()
+
+    def stream(self, *args: t.Any, **kwargs: t.Any) -> "TemplateStream":
+        """Works exactly like :meth:`generate` but returns a
+        :class:`TemplateStream`.
+        """
+        return TemplateStream(self.generate(*args, **kwargs))
+
+    def generate(self, *args: t.Any, **kwargs: t.Any) -> t.Iterator[str]:
+        """For very large templates it can be useful to not render the whole
+        template at once but evaluate each statement after another and yield
+        piece for piece.  This method basically does exactly that and returns
+        a generator that yields one item after another as strings.
+
+        It accepts the same arguments as :meth:`render`.
+        """
+        if self.environment.is_async:
+            import asyncio
+
+            async def to_list() -> t.List[str]:
+                return [x async for x in self.generate_async(*args, **kwargs)]
+
+            if sys.version_info < (3, 7):
+                loop = asyncio.get_event_loop()
+                out = loop.run_until_complete(to_list())
+            else:
+                out = asyncio.run(to_list())
+
+            yield from out
+            return
+
+        ctx = self.new_context(dict(*args, **kwargs))
+
+        try:
+            yield from self.root_render_func(ctx)  # type: ignore
+        except Exception:
+            yield self.environment.handle_exception()
+
+    async def generate_async(
+        self, *args: t.Any, **kwargs: t.Any
+    ) -> t.AsyncIterator[str]:
+        """An async version of :meth:`generate`.  Works very similarly but
+        returns an async iterator instead.
+        """
+        if not self.environment.is_async:
+            raise RuntimeError(
+                "The environment was not created with async mode enabled."
+            )
+
+        ctx = self.new_context(dict(*args, **kwargs))
+
+        try:
+            async for event in self.root_render_func(ctx):  # type: ignore
+                yield event
+        except Exception:
+            yield self.environment.handle_exception()
+
+    def new_context(
+        self,
+        vars: t.Optional[t.Dict[str, t.Any]] = None,
+        shared: bool = False,
+        locals: t.Optional[t.Mapping[str, t.Any]] = None,
+    ) -> Context:
+        """Create a new :class:`Context` for this template.  The vars
+        provided will be passed to the template.  Per default the globals
+        are added to the context.  If shared is set to `True` the data
+        is passed as is to the context without adding the globals.
+
+        `locals` can be a dict of local variables for internal usage.
+        """
+        return new_context(
+            self.environment, self.name, self.blocks, vars, shared, self.globals, locals
+        )
+
+    def make_module(
+        self,
+        vars: t.Optional[t.Dict[str, t.Any]] = None,
+        shared: bool = False,
+        locals: t.Optional[t.Mapping[str, t.Any]] = None,
+    ) -> "TemplateModule":
+        """This method works like the :attr:`module` attribute when called
+        without arguments but it will evaluate the template on every call
+        rather than caching it.  It's also possible to provide
+        a dict which is then used as context.  The arguments are the same
+        as for the :meth:`new_context` method.
+        """
+        ctx = self.new_context(vars, shared, locals)
+        return TemplateModule(self, ctx)
+
+    async def make_module_async(
+        self,
+        vars: t.Optional[t.Dict[str, t.Any]] = None,
+        shared: bool = False,
+        locals: t.Optional[t.Mapping[str, t.Any]] = None,
+    ) -> "TemplateModule":
+        """As template module creation can invoke template code for
+        asynchronous executions this method must be used instead of the
+        normal :meth:`make_module` one.  Likewise the module attribute
+        becomes unavailable in async mode.
+        """
+        ctx = self.new_context(vars, shared, locals)
+        return TemplateModule(
+            self, ctx, [x async for x in self.root_render_func(ctx)]  # type: ignore
+        )
+
+    @internalcode
+    def _get_default_module(self, ctx: t.Optional[Context] = None) -> "TemplateModule":
+        """If a context is passed in, this means that the template was
+        imported. Imported templates have access to the current
+        template's globals by default, but they can only be accessed via
+        the context during runtime.
+
+        If there are new globals, we need to create a new module because
+        the cached module is already rendered and will not have access
+        to globals from the current context. This new module is not
+        cached because the template can be imported elsewhere, and it
+        should have access to only the current template's globals.
+        """
+        if self.environment.is_async:
+            raise RuntimeError("Module is not available in async mode.")
+
+        if ctx is not None:
+            keys = ctx.globals_keys - self.globals.keys()
+
+            if keys:
+                return self.make_module({k: ctx.parent[k] for k in keys})
+
+        if self._module is None:
+            self._module = self.make_module()
+
+        return self._module
+
+    async def _get_default_module_async(
+        self, ctx: t.Optional[Context] = None
+    ) -> "TemplateModule":
+        if ctx is not None:
+            keys = ctx.globals_keys - self.globals.keys()
+
+            if keys:
+                return await self.make_module_async({k: ctx.parent[k] for k in keys})
+
+        if self._module is None:
+            self._module = await self.make_module_async()
+
+        return self._module
+
+    @property
+    def module(self) -> "TemplateModule":
+        """The template as module.  This is used for imports in the
+        template runtime but is also useful if one wants to access
+        exported template variables from the Python layer:
+
+        >>> t = Template('{% macro foo() %}42{% endmacro %}23')
+        >>> str(t.module)
+        '23'
+        >>> t.module.foo() == u'42'
+        True
+
+        This attribute is not available if async mode is enabled.
+        """
+        return self._get_default_module()
+
+    def get_corresponding_lineno(self, lineno: int) -> int:
+        """Return the source line number of a line number in the
+        generated bytecode as they are not in sync.
+        """
+        for template_line, code_line in reversed(self.debug_info):
+            if code_line <= lineno:
+                return template_line
+        return 1
+
+    @property
+    def is_up_to_date(self) -> bool:
+        """If this variable is `False` there is a newer version available."""
+        if self._uptodate is None:
+            return True
+        return self._uptodate()
+
+    @property
+    def debug_info(self) -> t.List[t.Tuple[int, int]]:
+        """The debug info mapping."""
+        if self._debug_info:
+            return [
+                tuple(map(int, x.split("=")))  # type: ignore
+                for x in self._debug_info.split("&")
+            ]
+
+        return []
+
+    def __repr__(self) -> str:
+        if self.name is None:
+            name = f"memory:{id(self):x}"
+        else:
+            name = repr(self.name)
+        return f"<{type(self).__name__} {name}>"
+
+
+class TemplateModule:
+    """Represents an imported template.  All the exported names of the
+    template are available as attributes on this object.  Additionally
+    converting it into a string renders the contents.
+    """
+
+    def __init__(
+        self,
+        template: Template,
+        context: Context,
+        body_stream: t.Optional[t.Iterable[str]] = None,
+    ) -> None:
+        if body_stream is None:
+            if context.environment.is_async:
+                raise RuntimeError(
+                    "Async mode requires a body stream to be passed to"
+                    " a template module. Use the async methods of the"
+                    " API you are using."
+                )
+
+            body_stream = list(template.root_render_func(context))  # type: ignore
+
+        self._body_stream = body_stream
+        self.__dict__.update(context.get_exported())
+        self.__name__ = template.name
+
+    def __html__(self) -> Markup:
+        return Markup(concat(self._body_stream))
+
+    def __str__(self) -> str:
+        return concat(self._body_stream)
+
+    def __repr__(self) -> str:
+        if self.__name__ is None:
+            name = f"memory:{id(self):x}"
+        else:
+            name = repr(self.__name__)
+        return f"<{type(self).__name__} {name}>"
+
+
+class TemplateExpression:
+    """The :meth:`jinja2.Environment.compile_expression` method returns an
+    instance of this object.  It encapsulates the expression-like access
+    to the template with an expression it wraps.
+    """
+
+    def __init__(self, template: Template, undefined_to_none: bool) -> None:
+        self._template = template
+        self._undefined_to_none = undefined_to_none
+
+    def __call__(self, *args: t.Any, **kwargs: t.Any) -> t.Optional[t.Any]:
+        context = self._template.new_context(dict(*args, **kwargs))
+        consume(self._template.root_render_func(context))  # type: ignore
+        rv = context.vars["result"]
+        if self._undefined_to_none and isinstance(rv, Undefined):
+            rv = None
+        return rv
+
+
+class TemplateStream:
+    """A template stream works pretty much like an ordinary python generator
+    but it can buffer multiple items to reduce the number of total iterations.
+    Per default the output is unbuffered which means that for every unbuffered
+    instruction in the template one string is yielded.
+
+    If buffering is enabled with a buffer size of 5, five items are combined
+    into a new string.  This is mainly useful if you are streaming
+    big templates to a client via WSGI which flushes after each iteration.
+    """
+
+    def __init__(self, gen: t.Iterator[str]) -> None:
+        self._gen = gen
+        self.disable_buffering()
+
+    def dump(
+        self,
+        fp: t.Union[str, t.IO],
+        encoding: t.Optional[str] = None,
+        errors: t.Optional[str] = "strict",
+    ) -> None:
+        """Dump the complete stream into a file or file-like object.
+        Per default strings are written, if you want to encode
+        before writing specify an `encoding`.
+
+        Example usage::
+
+            Template('Hello {{ name }}!').stream(name='foo').dump('hello.html')
+        """
+        close = False
+
+        if isinstance(fp, str):
+            if encoding is None:
+                encoding = "utf-8"
+
+            fp = open(fp, "wb")
+            close = True
+        try:
+            if encoding is not None:
+                iterable = (x.encode(encoding, errors) for x in self)  # type: ignore
+            else:
+                iterable = self  # type: ignore
+
+            if hasattr(fp, "writelines"):
+                fp.writelines(iterable)
+            else:
+                for item in iterable:
+                    fp.write(item)
+        finally:
+            if close:
+                fp.close()
+
+    def disable_buffering(self) -> None:
+        """Disable the output buffering."""
+        self._next = partial(next, self._gen)
+        self.buffered = False
+
+    def _buffered_generator(self, size: int) -> t.Iterator[str]:
+        buf: t.List[str] = []
+        c_size = 0
+        push = buf.append
+
+        while True:
+            try:
+                while c_size < size:
+                    c = next(self._gen)
+                    push(c)
+                    if c:
+                        c_size += 1
+            except StopIteration:
+                if not c_size:
+                    return
+            yield concat(buf)
+            del buf[:]
+            c_size = 0
+
+    def enable_buffering(self, size: int = 5) -> None:
+        """Enable buffering.  Buffer `size` items before yielding them."""
+        if size <= 1:
+            raise ValueError("buffer size too small")
+
+        self.buffered = True
+        self._next = partial(next, self._buffered_generator(size))
+
+    def __iter__(self) -> "TemplateStream":
+        return self
+
+    def __next__(self) -> str:
+        return self._next()  # type: ignore
+
+
+# hook in default template class.  if anyone reads this comment: ignore that
+# it's possible to use custom templates ;-)
+Environment.template_class = Template
diff --git a/lib/spack/external/_vendoring/jinja2/exceptions.py b/lib/spack/external/_vendoring/jinja2/exceptions.py
new file mode 100644
index 0000000000..082ebe8f22
--- /dev/null
+++ b/lib/spack/external/_vendoring/jinja2/exceptions.py
@@ -0,0 +1,166 @@
+import typing as t
+
+if t.TYPE_CHECKING:
+    from .runtime import Undefined
+
+
+class TemplateError(Exception):
+    """Baseclass for all template errors."""
+
+    def __init__(self, message: t.Optional[str] = None) -> None:
+        super().__init__(message)
+
+    @property
+    def message(self) -> t.Optional[str]:
+        return self.args[0] if self.args else None
+
+
+class TemplateNotFound(IOError, LookupError, TemplateError):
+    """Raised if a template does not exist.
+
+    .. versionchanged:: 2.11
+        If the given name is :class:`Undefined` and no message was
+        provided, an :exc:`UndefinedError` is raised.
+    """
+
+    # Silence the Python warning about message being deprecated since
+    # it's not valid here.
+    message: t.Optional[str] = None
+
+    def __init__(
+        self,
+        name: t.Optional[t.Union[str, "Undefined"]],
+        message: t.Optional[str] = None,
+    ) -> None:
+        IOError.__init__(self, name)
+
+        if message is None:
+            from .runtime import Undefined
+
+            if isinstance(name, Undefined):
+                name._fail_with_undefined_error()
+
+            message = name
+
+        self.message = message
+        self.name = name
+        self.templates = [name]
+
+    def __str__(self) -> str:
+        return str(self.message)
+
+
+class TemplatesNotFound(TemplateNotFound):
+    """Like :class:`TemplateNotFound` but raised if multiple templates
+    are selected.  This is a subclass of :class:`TemplateNotFound`
+    exception, so just catching the base exception will catch both.
+
+    .. versionchanged:: 2.11
+        If a name in the list of names is :class:`Undefined`, a message
+        about it being undefined is shown rather than the empty string.
+
+    .. versionadded:: 2.2
+    """
+
+    def __init__(
+        self,
+        names: t.Sequence[t.Union[str, "Undefined"]] = (),
+        message: t.Optional[str] = None,
+    ) -> None:
+        if message is None:
+            from .runtime import Undefined
+
+            parts = []
+
+            for name in names:
+                if isinstance(name, Undefined):
+                    parts.append(name._undefined_message)
+                else:
+                    parts.append(name)
+
+            parts_str = ", ".join(map(str, parts))
+            message = f"none of the templates given were found: {parts_str}"
+
+        super().__init__(names[-1] if names else None, message)
+        self.templates = list(names)
+
+
+class TemplateSyntaxError(TemplateError):
+    """Raised to tell the user that there is a problem with the template."""
+
+    def __init__(
+        self,
+        message: str,
+        lineno: int,
+        name: t.Optional[str] = None,
+        filename: t.Optional[str] = None,
+    ) -> None:
+        super().__init__(message)
+        self.lineno = lineno
+        self.name = name
+        self.filename = filename
+        self.source: t.Optional[str] = None
+
+        # this is set to True if the debug.translate_syntax_error
+        # function translated the syntax error into a new traceback
+        self.translated = False
+
+    def __str__(self) -> str:
+        # for translated errors we only return the message
+        if self.translated:
+            return t.cast(str, self.message)
+
+        # otherwise attach some stuff
+        location = f"line {self.lineno}"
+        name = self.filename or self.name
+        if name:
+            location = f'File "{name}", {location}'
+        lines = [t.cast(str, self.message), "  " + location]
+
+        # if the source is set, add the line to the output
+        if self.source is not None:
+            try:
+                line = self.source.splitlines()[self.lineno - 1]
+            except IndexError:
+                pass
+            else:
+                lines.append("    " + line.strip())
+
+        return "\n".join(lines)
+
+    def __reduce__(self):  # type: ignore
+        # https://bugs.python.org/issue1692335 Exceptions that take
+        # multiple required arguments have problems with pickling.
+        # Without this, raises TypeError: __init__() missing 1 required
+        # positional argument: 'lineno'
+        return self.__class__, (self.message, self.lineno, self.name, self.filename)
+
+
+class TemplateAssertionError(TemplateSyntaxError):
+    """Like a template syntax error, but covers cases where something in the
+    template caused an error at compile time that wasn't necessarily caused
+    by a syntax error.  However it's a direct subclass of
+    :exc:`TemplateSyntaxError` and has the same attributes.
+    """
+
+
+class TemplateRuntimeError(TemplateError):
+    """A generic runtime error in the template engine.  Under some situations
+    Jinja may raise this exception.
+    """
+
+
+class UndefinedError(TemplateRuntimeError):
+    """Raised if a template tries to operate on :class:`Undefined`."""
+
+
+class SecurityError(TemplateRuntimeError):
+    """Raised if a template tries to do something insecure if the
+    sandbox is enabled.
+    """
+
+
+class FilterArgumentError(TemplateRuntimeError):
+    """This error is raised if a filter was called with inappropriate
+    arguments
+    """
diff --git a/lib/spack/external/_vendoring/jinja2/ext.py b/lib/spack/external/_vendoring/jinja2/ext.py
new file mode 100644
index 0000000000..3e982930c4
--- /dev/null
+++ b/lib/spack/external/_vendoring/jinja2/ext.py
@@ -0,0 +1,879 @@
+"""Extension API for adding custom tags and behavior."""
+import pprint
+import re
+import typing as t
+import warnings
+
+from markupsafe import Markup
+
+from . import defaults
+from . import nodes
+from .environment import Environment
+from .exceptions import TemplateAssertionError
+from .exceptions import TemplateSyntaxError
+from .runtime import concat  # type: ignore
+from .runtime import Context
+from .runtime import Undefined
+from .utils import import_string
+from .utils import pass_context
+
+if t.TYPE_CHECKING:
+    import typing_extensions as te
+    from .lexer import Token
+    from .lexer import TokenStream
+    from .parser import Parser
+
+    class _TranslationsBasic(te.Protocol):
+        def gettext(self, message: str) -> str:
+            ...
+
+        def ngettext(self, singular: str, plural: str, n: int) -> str:
+            pass
+
+    class _TranslationsContext(_TranslationsBasic):
+        def pgettext(self, context: str, message: str) -> str:
+            ...
+
+        def npgettext(self, context: str, singular: str, plural: str, n: int) -> str:
+            ...
+
+    _SupportedTranslations = t.Union[_TranslationsBasic, _TranslationsContext]
+
+
+# I18N functions available in Jinja templates. If the I18N library
+# provides ugettext, it will be assigned to gettext.
+GETTEXT_FUNCTIONS: t.Tuple[str, ...] = (
+    "_",
+    "gettext",
+    "ngettext",
+    "pgettext",
+    "npgettext",
+)
+_ws_re = re.compile(r"\s*\n\s*")
+
+
+class Extension:
+    """Extensions can be used to add extra functionality to the Jinja template
+    system at the parser level.  Custom extensions are bound to an environment
+    but may not store environment specific data on `self`.  The reason for
+    this is that an extension can be bound to another environment (for
+    overlays) by creating a copy and reassigning the `environment` attribute.
+
+    As extensions are created by the environment they cannot accept any
+    arguments for configuration.  One may want to work around that by using
+    a factory function, but that is not possible as extensions are identified
+    by their import name.  The correct way to configure the extension is
+    storing the configuration values on the environment.  Because this way the
+    environment ends up acting as central configuration storage the
+    attributes may clash which is why extensions have to ensure that the names
+    they choose for configuration are not too generic.  ``prefix`` for example
+    is a terrible name, ``fragment_cache_prefix`` on the other hand is a good
+    name as includes the name of the extension (fragment cache).
+    """
+
+    identifier: t.ClassVar[str]
+
+    def __init_subclass__(cls) -> None:
+        cls.identifier = f"{cls.__module__}.{cls.__name__}"
+
+    #: if this extension parses this is the list of tags it's listening to.
+    tags: t.Set[str] = set()
+
+    #: the priority of that extension.  This is especially useful for
+    #: extensions that preprocess values.  A lower value means higher
+    #: priority.
+    #:
+    #: .. versionadded:: 2.4
+    priority = 100
+
+    def __init__(self, environment: Environment) -> None:
+        self.environment = environment
+
+    def bind(self, environment: Environment) -> "Extension":
+        """Create a copy of this extension bound to another environment."""
+        rv = t.cast(Extension, object.__new__(self.__class__))
+        rv.__dict__.update(self.__dict__)
+        rv.environment = environment
+        return rv
+
+    def preprocess(
+        self, source: str, name: t.Optional[str], filename: t.Optional[str] = None
+    ) -> str:
+        """This method is called before the actual lexing and can be used to
+        preprocess the source.  The `filename` is optional.  The return value
+        must be the preprocessed source.
+        """
+        return source
+
+    def filter_stream(
+        self, stream: "TokenStream"
+    ) -> t.Union["TokenStream", t.Iterable["Token"]]:
+        """It's passed a :class:`~jinja2.lexer.TokenStream` that can be used
+        to filter tokens returned.  This method has to return an iterable of
+        :class:`~jinja2.lexer.Token`\\s, but it doesn't have to return a
+        :class:`~jinja2.lexer.TokenStream`.
+        """
+        return stream
+
+    def parse(self, parser: "Parser") -> t.Union[nodes.Node, t.List[nodes.Node]]:
+        """If any of the :attr:`tags` matched this method is called with the
+        parser as first argument.  The token the parser stream is pointing at
+        is the name token that matched.  This method has to return one or a
+        list of multiple nodes.
+        """
+        raise NotImplementedError()
+
+    def attr(
+        self, name: str, lineno: t.Optional[int] = None
+    ) -> nodes.ExtensionAttribute:
+        """Return an attribute node for the current extension.  This is useful
+        to pass constants on extensions to generated template code.
+
+        ::
+
+            self.attr('_my_attribute', lineno=lineno)
+        """
+        return nodes.ExtensionAttribute(self.identifier, name, lineno=lineno)
+
+    def call_method(
+        self,
+        name: str,
+        args: t.Optional[t.List[nodes.Expr]] = None,
+        kwargs: t.Optional[t.List[nodes.Keyword]] = None,
+        dyn_args: t.Optional[nodes.Expr] = None,
+        dyn_kwargs: t.Optional[nodes.Expr] = None,
+        lineno: t.Optional[int] = None,
+    ) -> nodes.Call:
+        """Call a method of the extension.  This is a shortcut for
+        :meth:`attr` + :class:`jinja2.nodes.Call`.
+        """
+        if args is None:
+            args = []
+        if kwargs is None:
+            kwargs = []
+        return nodes.Call(
+            self.attr(name, lineno=lineno),
+            args,
+            kwargs,
+            dyn_args,
+            dyn_kwargs,
+            lineno=lineno,
+        )
+
+
+@pass_context
+def _gettext_alias(
+    __context: Context, *args: t.Any, **kwargs: t.Any
+) -> t.Union[t.Any, Undefined]:
+    return __context.call(__context.resolve("gettext"), *args, **kwargs)
+
+
+def _make_new_gettext(func: t.Callable[[str], str]) -> t.Callable[..., str]:
+    @pass_context
+    def gettext(__context: Context, __string: str, **variables: t.Any) -> str:
+        rv = __context.call(func, __string)
+        if __context.eval_ctx.autoescape:
+            rv = Markup(rv)
+        # Always treat as a format string, even if there are no
+        # variables. This makes translation strings more consistent
+        # and predictable. This requires escaping
+        return rv % variables  # type: ignore
+
+    return gettext
+
+
+def _make_new_ngettext(func: t.Callable[[str, str, int], str]) -> t.Callable[..., str]:
+    @pass_context
+    def ngettext(
+        __context: Context,
+        __singular: str,
+        __plural: str,
+        __num: int,
+        **variables: t.Any,
+    ) -> str:
+        variables.setdefault("num", __num)
+        rv = __context.call(func, __singular, __plural, __num)
+        if __context.eval_ctx.autoescape:
+            rv = Markup(rv)
+        # Always treat as a format string, see gettext comment above.
+        return rv % variables  # type: ignore
+
+    return ngettext
+
+
+def _make_new_pgettext(func: t.Callable[[str, str], str]) -> t.Callable[..., str]:
+    @pass_context
+    def pgettext(
+        __context: Context, __string_ctx: str, __string: str, **variables: t.Any
+    ) -> str:
+        variables.setdefault("context", __string_ctx)
+        rv = __context.call(func, __string_ctx, __string)
+
+        if __context.eval_ctx.autoescape:
+            rv = Markup(rv)
+
+        # Always treat as a format string, see gettext comment above.
+        return rv % variables  # type: ignore
+
+    return pgettext
+
+
+def _make_new_npgettext(
+    func: t.Callable[[str, str, str, int], str]
+) -> t.Callable[..., str]:
+    @pass_context
+    def npgettext(
+        __context: Context,
+        __string_ctx: str,
+        __singular: str,
+        __plural: str,
+        __num: int,
+        **variables: t.Any,
+    ) -> str:
+        variables.setdefault("context", __string_ctx)
+        variables.setdefault("num", __num)
+        rv = __context.call(func, __string_ctx, __singular, __plural, __num)
+
+        if __context.eval_ctx.autoescape:
+            rv = Markup(rv)
+
+        # Always treat as a format string, see gettext comment above.
+        return rv % variables  # type: ignore
+
+    return npgettext
+
+
+class InternationalizationExtension(Extension):
+    """This extension adds gettext support to Jinja."""
+
+    tags = {"trans"}
+
+    # TODO: the i18n extension is currently reevaluating values in a few
+    # situations.  Take this example:
+    #   {% trans count=something() %}{{ count }} foo{% pluralize
+    #     %}{{ count }} fooss{% endtrans %}
+    # something is called twice here.  One time for the gettext value and
+    # the other time for the n-parameter of the ngettext function.
+
+    def __init__(self, environment: Environment) -> None:
+        super().__init__(environment)
+        environment.globals["_"] = _gettext_alias
+        environment.extend(
+            install_gettext_translations=self._install,
+            install_null_translations=self._install_null,
+            install_gettext_callables=self._install_callables,
+            uninstall_gettext_translations=self._uninstall,
+            extract_translations=self._extract,
+            newstyle_gettext=False,
+        )
+
+    def _install(
+        self, translations: "_SupportedTranslations", newstyle: t.Optional[bool] = None
+    ) -> None:
+        # ugettext and ungettext are preferred in case the I18N library
+        # is providing compatibility with older Python versions.
+        gettext = getattr(translations, "ugettext", None)
+        if gettext is None:
+            gettext = translations.gettext
+        ngettext = getattr(translations, "ungettext", None)
+        if ngettext is None:
+            ngettext = translations.ngettext
+
+        pgettext = getattr(translations, "pgettext", None)
+        npgettext = getattr(translations, "npgettext", None)
+        self._install_callables(
+            gettext, ngettext, newstyle=newstyle, pgettext=pgettext, npgettext=npgettext
+        )
+
+    def _install_null(self, newstyle: t.Optional[bool] = None) -> None:
+        import gettext
+
+        translations = gettext.NullTranslations()
+
+        if hasattr(translations, "pgettext"):
+            # Python < 3.8
+            pgettext = translations.pgettext  # type: ignore
+        else:
+
+            def pgettext(c: str, s: str) -> str:
+                return s
+
+        if hasattr(translations, "npgettext"):
+            npgettext = translations.npgettext  # type: ignore
+        else:
+
+            def npgettext(c: str, s: str, p: str, n: int) -> str:
+                return s if n == 1 else p
+
+        self._install_callables(
+            gettext=translations.gettext,
+            ngettext=translations.ngettext,
+            newstyle=newstyle,
+            pgettext=pgettext,
+            npgettext=npgettext,
+        )
+
+    def _install_callables(
+        self,
+        gettext: t.Callable[[str], str],
+        ngettext: t.Callable[[str, str, int], str],
+        newstyle: t.Optional[bool] = None,
+        pgettext: t.Optional[t.Callable[[str, str], str]] = None,
+        npgettext: t.Optional[t.Callable[[str, str, str, int], str]] = None,
+    ) -> None:
+        if newstyle is not None:
+            self.environment.newstyle_gettext = newstyle  # type: ignore
+        if self.environment.newstyle_gettext:  # type: ignore
+            gettext = _make_new_gettext(gettext)
+            ngettext = _make_new_ngettext(ngettext)
+
+            if pgettext is not None:
+                pgettext = _make_new_pgettext(pgettext)
+
+            if npgettext is not None:
+                npgettext = _make_new_npgettext(npgettext)
+
+        self.environment.globals.update(
+            gettext=gettext, ngettext=ngettext, pgettext=pgettext, npgettext=npgettext
+        )
+
+    def _uninstall(self, translations: "_SupportedTranslations") -> None:
+        for key in ("gettext", "ngettext", "pgettext", "npgettext"):
+            self.environment.globals.pop(key, None)
+
+    def _extract(
+        self,
+        source: t.Union[str, nodes.Template],
+        gettext_functions: t.Sequence[str] = GETTEXT_FUNCTIONS,
+    ) -> t.Iterator[
+        t.Tuple[int, str, t.Union[t.Optional[str], t.Tuple[t.Optional[str], ...]]]
+    ]:
+        if isinstance(source, str):
+            source = self.environment.parse(source)
+        return extract_from_ast(source, gettext_functions)
+
+    def parse(self, parser: "Parser") -> t.Union[nodes.Node, t.List[nodes.Node]]:
+        """Parse a translatable tag."""
+        lineno = next(parser.stream).lineno
+        num_called_num = False
+
+        # find all the variables referenced.  Additionally a variable can be
+        # defined in the body of the trans block too, but this is checked at
+        # a later state.
+        plural_expr: t.Optional[nodes.Expr] = None
+        plural_expr_assignment: t.Optional[nodes.Assign] = None
+        variables: t.Dict[str, nodes.Expr] = {}
+        trimmed = None
+        while parser.stream.current.type != "block_end":
+            if variables:
+                parser.stream.expect("comma")
+
+            # skip colon for python compatibility
+            if parser.stream.skip_if("colon"):
+                break
+
+            token = parser.stream.expect("name")
+            if token.value in variables:
+                parser.fail(
+                    f"translatable variable {token.value!r} defined twice.",
+                    token.lineno,
+                    exc=TemplateAssertionError,
+                )
+
+            # expressions
+            if parser.stream.current.type == "assign":
+                next(parser.stream)
+                variables[token.value] = var = parser.parse_expression()
+            elif trimmed is None and token.value in ("trimmed", "notrimmed"):
+                trimmed = token.value == "trimmed"
+                continue
+            else:
+                variables[token.value] = var = nodes.Name(token.value, "load")
+
+            if plural_expr is None:
+                if isinstance(var, nodes.Call):
+                    plural_expr = nodes.Name("_trans", "load")
+                    variables[token.value] = plural_expr
+                    plural_expr_assignment = nodes.Assign(
+                        nodes.Name("_trans", "store"), var
+                    )
+                else:
+                    plural_expr = var
+                num_called_num = token.value == "num"
+
+        parser.stream.expect("block_end")
+
+        plural = None
+        have_plural = False
+        referenced = set()
+
+        # now parse until endtrans or pluralize
+        singular_names, singular = self._parse_block(parser, True)
+        if singular_names:
+            referenced.update(singular_names)
+            if plural_expr is None:
+                plural_expr = nodes.Name(singular_names[0], "load")
+                num_called_num = singular_names[0] == "num"
+
+        # if we have a pluralize block, we parse that too
+        if parser.stream.current.test("name:pluralize"):
+            have_plural = True
+            next(parser.stream)
+            if parser.stream.current.type != "block_end":
+                token = parser.stream.expect("name")
+                if token.value not in variables:
+                    parser.fail(
+                        f"unknown variable {token.value!r} for pluralization",
+                        token.lineno,
+                        exc=TemplateAssertionError,
+                    )
+                plural_expr = variables[token.value]
+                num_called_num = token.value == "num"
+            parser.stream.expect("block_end")
+            plural_names, plural = self._parse_block(parser, False)
+            next(parser.stream)
+            referenced.update(plural_names)
+        else:
+            next(parser.stream)
+
+        # register free names as simple name expressions
+        for name in referenced:
+            if name not in variables:
+                variables[name] = nodes.Name(name, "load")
+
+        if not have_plural:
+            plural_expr = None
+        elif plural_expr is None:
+            parser.fail("pluralize without variables", lineno)
+
+        if trimmed is None:
+            trimmed = self.environment.policies["ext.i18n.trimmed"]
+        if trimmed:
+            singular = self._trim_whitespace(singular)
+            if plural:
+                plural = self._trim_whitespace(plural)
+
+        node = self._make_node(
+            singular,
+            plural,
+            variables,
+            plural_expr,
+            bool(referenced),
+            num_called_num and have_plural,
+        )
+        node.set_lineno(lineno)
+        if plural_expr_assignment is not None:
+            return [plural_expr_assignment, node]
+        else:
+            return node
+
+    def _trim_whitespace(self, string: str, _ws_re: t.Pattern[str] = _ws_re) -> str:
+        return _ws_re.sub(" ", string.strip())
+
+    def _parse_block(
+        self, parser: "Parser", allow_pluralize: bool
+    ) -> t.Tuple[t.List[str], str]:
+        """Parse until the next block tag with a given name."""
+        referenced = []
+        buf = []
+
+        while True:
+            if parser.stream.current.type == "data":
+                buf.append(parser.stream.current.value.replace("%", "%%"))
+                next(parser.stream)
+            elif parser.stream.current.type == "variable_begin":
+                next(parser.stream)
+                name = parser.stream.expect("name").value
+                referenced.append(name)
+                buf.append(f"%({name})s")
+                parser.stream.expect("variable_end")
+            elif parser.stream.current.type == "block_begin":
+                next(parser.stream)
+                if parser.stream.current.test("name:endtrans"):
+                    break
+                elif parser.stream.current.test("name:pluralize"):
+                    if allow_pluralize:
+                        break
+                    parser.fail(
+                        "a translatable section can have only one pluralize section"
+                    )
+                parser.fail(
+                    "control structures in translatable sections are not allowed"
+                )
+            elif parser.stream.eos:
+                parser.fail("unclosed translation block")
+            else:
+                raise RuntimeError("internal parser error")
+
+        return referenced, concat(buf)
+
+    def _make_node(
+        self,
+        singular: str,
+        plural: t.Optional[str],
+        variables: t.Dict[str, nodes.Expr],
+        plural_expr: t.Optional[nodes.Expr],
+        vars_referenced: bool,
+        num_called_num: bool,
+    ) -> nodes.Output:
+        """Generates a useful node from the data provided."""
+        newstyle = self.environment.newstyle_gettext  # type: ignore
+        node: nodes.Expr
+
+        # no variables referenced?  no need to escape for old style
+        # gettext invocations only if there are vars.
+        if not vars_referenced and not newstyle:
+            singular = singular.replace("%%", "%")
+            if plural:
+                plural = plural.replace("%%", "%")
+
+        # singular only:
+        if plural_expr is None:
+            gettext = nodes.Name("gettext", "load")
+            node = nodes.Call(gettext, [nodes.Const(singular)], [], None, None)
+
+        # singular and plural
+        else:
+            ngettext = nodes.Name("ngettext", "load")
+            node = nodes.Call(
+                ngettext,
+                [nodes.Const(singular), nodes.Const(plural), plural_expr],
+                [],
+                None,
+                None,
+            )
+
+        # in case newstyle gettext is used, the method is powerful
+        # enough to handle the variable expansion and autoescape
+        # handling itself
+        if newstyle:
+            for key, value in variables.items():
+                # the function adds that later anyways in case num was
+                # called num, so just skip it.
+                if num_called_num and key == "num":
+                    continue
+                node.kwargs.append(nodes.Keyword(key, value))
+
+        # otherwise do that here
+        else:
+            # mark the return value as safe if we are in an
+            # environment with autoescaping turned on
+            node = nodes.MarkSafeIfAutoescape(node)
+            if variables:
+                node = nodes.Mod(
+                    node,
+                    nodes.Dict(
+                        [
+                            nodes.Pair(nodes.Const(key), value)
+                            for key, value in variables.items()
+                        ]
+                    ),
+                )
+        return nodes.Output([node])
+
+
+class ExprStmtExtension(Extension):
+    """Adds a `do` tag to Jinja that works like the print statement just
+    that it doesn't print the return value.
+    """
+
+    tags = {"do"}
+
+    def parse(self, parser: "Parser") -> nodes.ExprStmt:
+        node = nodes.ExprStmt(lineno=next(parser.stream).lineno)
+        node.node = parser.parse_tuple()
+        return node
+
+
+class LoopControlExtension(Extension):
+    """Adds break and continue to the template engine."""
+
+    tags = {"break", "continue"}
+
+    def parse(self, parser: "Parser") -> t.Union[nodes.Break, nodes.Continue]:
+        token = next(parser.stream)
+        if token.value == "break":
+            return nodes.Break(lineno=token.lineno)
+        return nodes.Continue(lineno=token.lineno)
+
+
+class WithExtension(Extension):
+    def __init__(self, environment: Environment) -> None:
+        super().__init__(environment)
+        warnings.warn(
+            "The 'with' extension is deprecated and will be removed in"
+            " Jinja 3.1. This is built in now.",
+            DeprecationWarning,
+            stacklevel=3,
+        )
+
+
+class AutoEscapeExtension(Extension):
+    def __init__(self, environment: Environment) -> None:
+        super().__init__(environment)
+        warnings.warn(
+            "The 'autoescape' extension is deprecated and will be"
+            " removed in Jinja 3.1. This is built in now.",
+            DeprecationWarning,
+            stacklevel=3,
+        )
+
+
+class DebugExtension(Extension):
+    """A ``{% debug %}`` tag that dumps the available variables,
+    filters, and tests.
+
+    .. code-block:: html+jinja
+
+        <pre>{% debug %}</pre>
+
+    .. code-block:: text
+
+        {'context': {'cycler': <class 'jinja2.utils.Cycler'>,
+                     ...,
+                     'namespace': <class 'jinja2.utils.Namespace'>},
+         'filters': ['abs', 'attr', 'batch', 'capitalize', 'center', 'count', 'd',
+                     ..., 'urlencode', 'urlize', 'wordcount', 'wordwrap', 'xmlattr'],
+         'tests': ['!=', '<', '<=', '==', '>', '>=', 'callable', 'defined',
+                   ..., 'odd', 'sameas', 'sequence', 'string', 'undefined', 'upper']}
+
+    .. versionadded:: 2.11.0
+    """
+
+    tags = {"debug"}
+
+    def parse(self, parser: "Parser") -> nodes.Output:
+        lineno = parser.stream.expect("name:debug").lineno
+        context = nodes.ContextReference()
+        result = self.call_method("_render", [context], lineno=lineno)
+        return nodes.Output([result], lineno=lineno)
+
+    def _render(self, context: Context) -> str:
+        result = {
+            "context": context.get_all(),
+            "filters": sorted(self.environment.filters.keys()),
+            "tests": sorted(self.environment.tests.keys()),
+        }
+
+        # Set the depth since the intent is to show the top few names.
+        return pprint.pformat(result, depth=3, compact=True)
+
+
+def extract_from_ast(
+    ast: nodes.Template,
+    gettext_functions: t.Sequence[str] = GETTEXT_FUNCTIONS,
+    babel_style: bool = True,
+) -> t.Iterator[
+    t.Tuple[int, str, t.Union[t.Optional[str], t.Tuple[t.Optional[str], ...]]]
+]:
+    """Extract localizable strings from the given template node.  Per
+    default this function returns matches in babel style that means non string
+    parameters as well as keyword arguments are returned as `None`.  This
+    allows Babel to figure out what you really meant if you are using
+    gettext functions that allow keyword arguments for placeholder expansion.
+    If you don't want that behavior set the `babel_style` parameter to `False`
+    which causes only strings to be returned and parameters are always stored
+    in tuples.  As a consequence invalid gettext calls (calls without a single
+    string parameter or string parameters after non-string parameters) are
+    skipped.
+
+    This example explains the behavior:
+
+    >>> from jinja2 import Environment
+    >>> env = Environment()
+    >>> node = env.parse('{{ (_("foo"), _(), ngettext("foo", "bar", 42)) }}')
+    >>> list(extract_from_ast(node))
+    [(1, '_', 'foo'), (1, '_', ()), (1, 'ngettext', ('foo', 'bar', None))]
+    >>> list(extract_from_ast(node, babel_style=False))
+    [(1, '_', ('foo',)), (1, 'ngettext', ('foo', 'bar'))]
+
+    For every string found this function yields a ``(lineno, function,
+    message)`` tuple, where:
+
+    * ``lineno`` is the number of the line on which the string was found,
+    * ``function`` is the name of the ``gettext`` function used (if the
+      string was extracted from embedded Python code), and
+    *   ``message`` is the string, or a tuple of strings for functions
+         with multiple string arguments.
+
+    This extraction function operates on the AST and is because of that unable
+    to extract any comments.  For comment support you have to use the babel
+    extraction interface or extract comments yourself.
+    """
+    out: t.Union[t.Optional[str], t.Tuple[t.Optional[str], ...]]
+
+    for node in ast.find_all(nodes.Call):
+        if (
+            not isinstance(node.node, nodes.Name)
+            or node.node.name not in gettext_functions
+        ):
+            continue
+
+        strings: t.List[t.Optional[str]] = []
+
+        for arg in node.args:
+            if isinstance(arg, nodes.Const) and isinstance(arg.value, str):
+                strings.append(arg.value)
+            else:
+                strings.append(None)
+
+        for _ in node.kwargs:
+            strings.append(None)
+        if node.dyn_args is not None:
+            strings.append(None)
+        if node.dyn_kwargs is not None:
+            strings.append(None)
+
+        if not babel_style:
+            out = tuple(x for x in strings if x is not None)
+
+            if not out:
+                continue
+        else:
+            if len(strings) == 1:
+                out = strings[0]
+            else:
+                out = tuple(strings)
+
+        yield node.lineno, node.node.name, out
+
+
+class _CommentFinder:
+    """Helper class to find comments in a token stream.  Can only
+    find comments for gettext calls forwards.  Once the comment
+    from line 4 is found, a comment for line 1 will not return a
+    usable value.
+    """
+
+    def __init__(
+        self, tokens: t.Sequence[t.Tuple[int, str, str]], comment_tags: t.Sequence[str]
+    ) -> None:
+        self.tokens = tokens
+        self.comment_tags = comment_tags
+        self.offset = 0
+        self.last_lineno = 0
+
+    def find_backwards(self, offset: int) -> t.List[str]:
+        try:
+            for _, token_type, token_value in reversed(
+                self.tokens[self.offset : offset]
+            ):
+                if token_type in ("comment", "linecomment"):
+                    try:
+                        prefix, comment = token_value.split(None, 1)
+                    except ValueError:
+                        continue
+                    if prefix in self.comment_tags:
+                        return [comment.rstrip()]
+            return []
+        finally:
+            self.offset = offset
+
+    def find_comments(self, lineno: int) -> t.List[str]:
+        if not self.comment_tags or self.last_lineno > lineno:
+            return []
+        for idx, (token_lineno, _, _) in enumerate(self.tokens[self.offset :]):
+            if token_lineno > lineno:
+                return self.find_backwards(self.offset + idx)
+        return self.find_backwards(len(self.tokens))
+
+
+def babel_extract(
+    fileobj: t.BinaryIO,
+    keywords: t.Sequence[str],
+    comment_tags: t.Sequence[str],
+    options: t.Dict[str, t.Any],
+) -> t.Iterator[
+    t.Tuple[
+        int, str, t.Union[t.Optional[str], t.Tuple[t.Optional[str], ...]], t.List[str]
+    ]
+]:
+    """Babel extraction method for Jinja templates.
+
+    .. versionchanged:: 2.3
+       Basic support for translation comments was added.  If `comment_tags`
+       is now set to a list of keywords for extraction, the extractor will
+       try to find the best preceding comment that begins with one of the
+       keywords.  For best results, make sure to not have more than one
+       gettext call in one line of code and the matching comment in the
+       same line or the line before.
+
+    .. versionchanged:: 2.5.1
+       The `newstyle_gettext` flag can be set to `True` to enable newstyle
+       gettext calls.
+
+    .. versionchanged:: 2.7
+       A `silent` option can now be provided.  If set to `False` template
+       syntax errors are propagated instead of being ignored.
+
+    :param fileobj: the file-like object the messages should be extracted from
+    :param keywords: a list of keywords (i.e. function names) that should be
+                     recognized as translation functions
+    :param comment_tags: a list of translator tags to search for and include
+                         in the results.
+    :param options: a dictionary of additional options (optional)
+    :return: an iterator over ``(lineno, funcname, message, comments)`` tuples.
+             (comments will be empty currently)
+    """
+    extensions: t.Dict[t.Type[Extension], None] = {}
+
+    for extension_name in options.get("extensions", "").split(","):
+        extension_name = extension_name.strip()
+
+        if not extension_name:
+            continue
+
+        extensions[import_string(extension_name)] = None
+
+    if InternationalizationExtension not in extensions:
+        extensions[InternationalizationExtension] = None
+
+    def getbool(options: t.Mapping[str, str], key: str, default: bool = False) -> bool:
+        return options.get(key, str(default)).lower() in {"1", "on", "yes", "true"}
+
+    silent = getbool(options, "silent", True)
+    environment = Environment(
+        options.get("block_start_string", defaults.BLOCK_START_STRING),
+        options.get("block_end_string", defaults.BLOCK_END_STRING),
+        options.get("variable_start_string", defaults.VARIABLE_START_STRING),
+        options.get("variable_end_string", defaults.VARIABLE_END_STRING),
+        options.get("comment_start_string", defaults.COMMENT_START_STRING),
+        options.get("comment_end_string", defaults.COMMENT_END_STRING),
+        options.get("line_statement_prefix") or defaults.LINE_STATEMENT_PREFIX,
+        options.get("line_comment_prefix") or defaults.LINE_COMMENT_PREFIX,
+        getbool(options, "trim_blocks", defaults.TRIM_BLOCKS),
+        getbool(options, "lstrip_blocks", defaults.LSTRIP_BLOCKS),
+        defaults.NEWLINE_SEQUENCE,
+        getbool(options, "keep_trailing_newline", defaults.KEEP_TRAILING_NEWLINE),
+        tuple(extensions),
+        cache_size=0,
+        auto_reload=False,
+    )
+
+    if getbool(options, "trimmed"):
+        environment.policies["ext.i18n.trimmed"] = True
+    if getbool(options, "newstyle_gettext"):
+        environment.newstyle_gettext = True  # type: ignore
+
+    source = fileobj.read().decode(options.get("encoding", "utf-8"))
+    try:
+        node = environment.parse(source)
+        tokens = list(environment.lex(environment.preprocess(source)))
+    except TemplateSyntaxError:
+        if not silent:
+            raise
+        # skip templates with syntax errors
+        return
+
+    finder = _CommentFinder(tokens, comment_tags)
+    for lineno, func, message in extract_from_ast(node, keywords):
+        yield lineno, func, message, finder.find_comments(lineno)
+
+
+#: nicer import names
+i18n = InternationalizationExtension
+do = ExprStmtExtension
+loopcontrols = LoopControlExtension
+with_ = WithExtension
+autoescape = AutoEscapeExtension
+debug = DebugExtension
diff --git a/lib/spack/external/_vendoring/jinja2/filters.py b/lib/spack/external/_vendoring/jinja2/filters.py
new file mode 100644
index 0000000000..ffb98bf4e3
--- /dev/null
+++ b/lib/spack/external/_vendoring/jinja2/filters.py
@@ -0,0 +1,1824 @@
+"""Built-in template filters used with the ``|`` operator."""
+import math
+import random
+import re
+import typing
+import typing as t
+import warnings
+from collections import abc
+from itertools import chain
+from itertools import groupby
+
+from markupsafe import escape
+from markupsafe import Markup
+from markupsafe import soft_str
+
+from .async_utils import async_variant
+from .async_utils import auto_aiter
+from .async_utils import auto_await
+from .async_utils import auto_to_list
+from .exceptions import FilterArgumentError
+from .runtime import Undefined
+from .utils import htmlsafe_json_dumps
+from .utils import pass_context
+from .utils import pass_environment
+from .utils import pass_eval_context
+from .utils import pformat
+from .utils import url_quote
+from .utils import urlize
+
+if t.TYPE_CHECKING:
+    import typing_extensions as te
+    from .environment import Environment
+    from .nodes import EvalContext
+    from .runtime import Context
+    from .sandbox import SandboxedEnvironment  # noqa: F401
+
+    class HasHTML(te.Protocol):
+        def __html__(self) -> str:
+            pass
+
+
+F = t.TypeVar("F", bound=t.Callable[..., t.Any])
+K = t.TypeVar("K")
+V = t.TypeVar("V")
+
+
+def contextfilter(f: F) -> F:
+    """Pass the context as the first argument to the decorated function.
+
+    .. deprecated:: 3.0
+        Will be removed in Jinja 3.1. Use :func:`~jinja2.pass_context`
+        instead.
+    """
+    warnings.warn(
+        "'contextfilter' is renamed to 'pass_context', the old name"
+        " will be removed in Jinja 3.1.",
+        DeprecationWarning,
+        stacklevel=2,
+    )
+    return pass_context(f)
+
+
+def evalcontextfilter(f: F) -> F:
+    """Pass the eval context as the first argument to the decorated
+    function.
+
+    .. deprecated:: 3.0
+        Will be removed in Jinja 3.1. Use
+        :func:`~jinja2.pass_eval_context` instead.
+
+    .. versionadded:: 2.4
+    """
+    warnings.warn(
+        "'evalcontextfilter' is renamed to 'pass_eval_context', the old"
+        " name will be removed in Jinja 3.1.",
+        DeprecationWarning,
+        stacklevel=2,
+    )
+    return pass_eval_context(f)
+
+
+def environmentfilter(f: F) -> F:
+    """Pass the environment as the first argument to the decorated
+    function.
+
+    .. deprecated:: 3.0
+        Will be removed in Jinja 3.1. Use
+        :func:`~jinja2.pass_environment` instead.
+    """
+    warnings.warn(
+        "'environmentfilter' is renamed to 'pass_environment', the old"
+        " name will be removed in Jinja 3.1.",
+        DeprecationWarning,
+        stacklevel=2,
+    )
+    return pass_environment(f)
+
+
+def ignore_case(value: V) -> V:
+    """For use as a postprocessor for :func:`make_attrgetter`. Converts strings
+    to lowercase and returns other types as-is."""
+    if isinstance(value, str):
+        return t.cast(V, value.lower())
+
+    return value
+
+
+def make_attrgetter(
+    environment: "Environment",
+    attribute: t.Optional[t.Union[str, int]],
+    postprocess: t.Optional[t.Callable[[t.Any], t.Any]] = None,
+    default: t.Optional[t.Any] = None,
+) -> t.Callable[[t.Any], t.Any]:
+    """Returns a callable that looks up the given attribute from a
+    passed object with the rules of the environment.  Dots are allowed
+    to access attributes of attributes.  Integer parts in paths are
+    looked up as integers.
+    """
+    parts = _prepare_attribute_parts(attribute)
+
+    def attrgetter(item: t.Any) -> t.Any:
+        for part in parts:
+            item = environment.getitem(item, part)
+
+            if default is not None and isinstance(item, Undefined):
+                item = default
+
+        if postprocess is not None:
+            item = postprocess(item)
+
+        return item
+
+    return attrgetter
+
+
+def make_multi_attrgetter(
+    environment: "Environment",
+    attribute: t.Optional[t.Union[str, int]],
+    postprocess: t.Optional[t.Callable[[t.Any], t.Any]] = None,
+) -> t.Callable[[t.Any], t.List[t.Any]]:
+    """Returns a callable that looks up the given comma separated
+    attributes from a passed object with the rules of the environment.
+    Dots are allowed to access attributes of each attribute.  Integer
+    parts in paths are looked up as integers.
+
+    The value returned by the returned callable is a list of extracted
+    attribute values.
+
+    Examples of attribute: "attr1,attr2", "attr1.inner1.0,attr2.inner2.0", etc.
+    """
+    if isinstance(attribute, str):
+        split: t.Sequence[t.Union[str, int, None]] = attribute.split(",")
+    else:
+        split = [attribute]
+
+    parts = [_prepare_attribute_parts(item) for item in split]
+
+    def attrgetter(item: t.Any) -> t.List[t.Any]:
+        items = [None] * len(parts)
+
+        for i, attribute_part in enumerate(parts):
+            item_i = item
+
+            for part in attribute_part:
+                item_i = environment.getitem(item_i, part)
+
+            if postprocess is not None:
+                item_i = postprocess(item_i)
+
+            items[i] = item_i
+
+        return items
+
+    return attrgetter
+
+
+def _prepare_attribute_parts(
+    attr: t.Optional[t.Union[str, int]]
+) -> t.List[t.Union[str, int]]:
+    if attr is None:
+        return []
+
+    if isinstance(attr, str):
+        return [int(x) if x.isdigit() else x for x in attr.split(".")]
+
+    return [attr]
+
+
+def do_forceescape(value: "t.Union[str, HasHTML]") -> Markup:
+    """Enforce HTML escaping.  This will probably double escape variables."""
+    if hasattr(value, "__html__"):
+        value = t.cast("HasHTML", value).__html__()
+
+    return escape(str(value))
+
+
+def do_urlencode(
+    value: t.Union[str, t.Mapping[str, t.Any], t.Iterable[t.Tuple[str, t.Any]]]
+) -> str:
+    """Quote data for use in a URL path or query using UTF-8.
+
+    Basic wrapper around :func:`urllib.parse.quote` when given a
+    string, or :func:`urllib.parse.urlencode` for a dict or iterable.
+
+    :param value: Data to quote. A string will be quoted directly. A
+        dict or iterable of ``(key, value)`` pairs will be joined as a
+        query string.
+
+    When given a string, "/" is not quoted. HTTP servers treat "/" and
+    "%2F" equivalently in paths. If you need quoted slashes, use the
+    ``|replace("/", "%2F")`` filter.
+
+    .. versionadded:: 2.7
+    """
+    if isinstance(value, str) or not isinstance(value, abc.Iterable):
+        return url_quote(value)
+
+    if isinstance(value, dict):
+        items: t.Iterable[t.Tuple[str, t.Any]] = value.items()
+    else:
+        items = value  # type: ignore
+
+    return "&".join(
+        f"{url_quote(k, for_qs=True)}={url_quote(v, for_qs=True)}" for k, v in items
+    )
+
+
+@pass_eval_context
+def do_replace(
+    eval_ctx: "EvalContext", s: str, old: str, new: str, count: t.Optional[int] = None
+) -> str:
+    """Return a copy of the value with all occurrences of a substring
+    replaced with a new one. The first argument is the substring
+    that should be replaced, the second is the replacement string.
+    If the optional third argument ``count`` is given, only the first
+    ``count`` occurrences are replaced:
+
+    .. sourcecode:: jinja
+
+        {{ "Hello World"|replace("Hello", "Goodbye") }}
+            -> Goodbye World
+
+        {{ "aaaaargh"|replace("a", "d'oh, ", 2) }}
+            -> d'oh, d'oh, aaargh
+    """
+    if count is None:
+        count = -1
+
+    if not eval_ctx.autoescape:
+        return str(s).replace(str(old), str(new), count)
+
+    if (
+        hasattr(old, "__html__")
+        or hasattr(new, "__html__")
+        and not hasattr(s, "__html__")
+    ):
+        s = escape(s)
+    else:
+        s = soft_str(s)
+
+    return s.replace(soft_str(old), soft_str(new), count)
+
+
+def do_upper(s: str) -> str:
+    """Convert a value to uppercase."""
+    return soft_str(s).upper()
+
+
+def do_lower(s: str) -> str:
+    """Convert a value to lowercase."""
+    return soft_str(s).lower()
+
+
+@pass_eval_context
+def do_xmlattr(
+    eval_ctx: "EvalContext", d: t.Mapping[str, t.Any], autospace: bool = True
+) -> str:
+    """Create an SGML/XML attribute string based on the items in a dict.
+    All values that are neither `none` nor `undefined` are automatically
+    escaped:
+
+    .. sourcecode:: html+jinja
+
+        <ul{{ {'class': 'my_list', 'missing': none,
+                'id': 'list-%d'|format(variable)}|xmlattr }}>
+        ...
+        </ul>
+
+    Results in something like this:
+
+    .. sourcecode:: html
+
+        <ul class="my_list" id="list-42">
+        ...
+        </ul>
+
+    As you can see it automatically prepends a space in front of the item
+    if the filter returned something unless the second parameter is false.
+    """
+    rv = " ".join(
+        f'{escape(key)}="{escape(value)}"'
+        for key, value in d.items()
+        if value is not None and not isinstance(value, Undefined)
+    )
+
+    if autospace and rv:
+        rv = " " + rv
+
+    if eval_ctx.autoescape:
+        rv = Markup(rv)
+
+    return rv
+
+
+def do_capitalize(s: str) -> str:
+    """Capitalize a value. The first character will be uppercase, all others
+    lowercase.
+    """
+    return soft_str(s).capitalize()
+
+
+_word_beginning_split_re = re.compile(r"([-\s({\[<]+)")
+
+
+def do_title(s: str) -> str:
+    """Return a titlecased version of the value. I.e. words will start with
+    uppercase letters, all remaining characters are lowercase.
+    """
+    return "".join(
+        [
+            item[0].upper() + item[1:].lower()
+            for item in _word_beginning_split_re.split(soft_str(s))
+            if item
+        ]
+    )
+
+
+def do_dictsort(
+    value: t.Mapping[K, V],
+    case_sensitive: bool = False,
+    by: 'te.Literal["key", "value"]' = "key",
+    reverse: bool = False,
+) -> t.List[t.Tuple[K, V]]:
+    """Sort a dict and yield (key, value) pairs. Python dicts may not
+    be in the order you want to display them in, so sort them first.
+
+    .. sourcecode:: jinja
+
+        {% for key, value in mydict|dictsort %}
+            sort the dict by key, case insensitive
+
+        {% for key, value in mydict|dictsort(reverse=true) %}
+            sort the dict by key, case insensitive, reverse order
+
+        {% for key, value in mydict|dictsort(true) %}
+            sort the dict by key, case sensitive
+
+        {% for key, value in mydict|dictsort(false, 'value') %}
+            sort the dict by value, case insensitive
+    """
+    if by == "key":
+        pos = 0
+    elif by == "value":
+        pos = 1
+    else:
+        raise FilterArgumentError('You can only sort by either "key" or "value"')
+
+    def sort_func(item: t.Tuple[t.Any, t.Any]) -> t.Any:
+        value = item[pos]
+
+        if not case_sensitive:
+            value = ignore_case(value)
+
+        return value
+
+    return sorted(value.items(), key=sort_func, reverse=reverse)
+
+
+@pass_environment
+def do_sort(
+    environment: "Environment",
+    value: "t.Iterable[V]",
+    reverse: bool = False,
+    case_sensitive: bool = False,
+    attribute: t.Optional[t.Union[str, int]] = None,
+) -> "t.List[V]":
+    """Sort an iterable using Python's :func:`sorted`.
+
+    .. sourcecode:: jinja
+
+        {% for city in cities|sort %}
+            ...
+        {% endfor %}
+
+    :param reverse: Sort descending instead of ascending.
+    :param case_sensitive: When sorting strings, sort upper and lower
+        case separately.
+    :param attribute: When sorting objects or dicts, an attribute or
+        key to sort by. Can use dot notation like ``"address.city"``.
+        Can be a list of attributes like ``"age,name"``.
+
+    The sort is stable, it does not change the relative order of
+    elements that compare equal. This makes it is possible to chain
+    sorts on different attributes and ordering.
+
+    .. sourcecode:: jinja
+
+        {% for user in users|sort(attribute="name")
+            |sort(reverse=true, attribute="age") %}
+            ...
+        {% endfor %}
+
+    As a shortcut to chaining when the direction is the same for all
+    attributes, pass a comma separate list of attributes.
+
+    .. sourcecode:: jinja
+
+        {% for user users|sort(attribute="age,name") %}
+            ...
+        {% endfor %}
+
+    .. versionchanged:: 2.11.0
+        The ``attribute`` parameter can be a comma separated list of
+        attributes, e.g. ``"age,name"``.
+
+    .. versionchanged:: 2.6
+       The ``attribute`` parameter was added.
+    """
+    key_func = make_multi_attrgetter(
+        environment, attribute, postprocess=ignore_case if not case_sensitive else None
+    )
+    return sorted(value, key=key_func, reverse=reverse)
+
+
+@pass_environment
+def do_unique(
+    environment: "Environment",
+    value: "t.Iterable[V]",
+    case_sensitive: bool = False,
+    attribute: t.Optional[t.Union[str, int]] = None,
+) -> "t.Iterator[V]":
+    """Returns a list of unique items from the given iterable.
+
+    .. sourcecode:: jinja
+
+        {{ ['foo', 'bar', 'foobar', 'FooBar']|unique|list }}
+            -> ['foo', 'bar', 'foobar']
+
+    The unique items are yielded in the same order as their first occurrence in
+    the iterable passed to the filter.
+
+    :param case_sensitive: Treat upper and lower case strings as distinct.
+    :param attribute: Filter objects with unique values for this attribute.
+    """
+    getter = make_attrgetter(
+        environment, attribute, postprocess=ignore_case if not case_sensitive else None
+    )
+    seen = set()
+
+    for item in value:
+        key = getter(item)
+
+        if key not in seen:
+            seen.add(key)
+            yield item
+
+
+def _min_or_max(
+    environment: "Environment",
+    value: "t.Iterable[V]",
+    func: "t.Callable[..., V]",
+    case_sensitive: bool,
+    attribute: t.Optional[t.Union[str, int]],
+) -> "t.Union[V, Undefined]":
+    it = iter(value)
+
+    try:
+        first = next(it)
+    except StopIteration:
+        return environment.undefined("No aggregated item, sequence was empty.")
+
+    key_func = make_attrgetter(
+        environment, attribute, postprocess=ignore_case if not case_sensitive else None
+    )
+    return func(chain([first], it), key=key_func)
+
+
+@pass_environment
+def do_min(
+    environment: "Environment",
+    value: "t.Iterable[V]",
+    case_sensitive: bool = False,
+    attribute: t.Optional[t.Union[str, int]] = None,
+) -> "t.Union[V, Undefined]":
+    """Return the smallest item from the sequence.
+
+    .. sourcecode:: jinja
+
+        {{ [1, 2, 3]|min }}
+            -> 1
+
+    :param case_sensitive: Treat upper and lower case strings as distinct.
+    :param attribute: Get the object with the min value of this attribute.
+    """
+    return _min_or_max(environment, value, min, case_sensitive, attribute)
+
+
+@pass_environment
+def do_max(
+    environment: "Environment",
+    value: "t.Iterable[V]",
+    case_sensitive: bool = False,
+    attribute: t.Optional[t.Union[str, int]] = None,
+) -> "t.Union[V, Undefined]":
+    """Return the largest item from the sequence.
+
+    .. sourcecode:: jinja
+
+        {{ [1, 2, 3]|max }}
+            -> 3
+
+    :param case_sensitive: Treat upper and lower case strings as distinct.
+    :param attribute: Get the object with the max value of this attribute.
+    """
+    return _min_or_max(environment, value, max, case_sensitive, attribute)
+
+
+def do_default(
+    value: V,
+    default_value: V = "",  # type: ignore
+    boolean: bool = False,
+) -> V:
+    """If the value is undefined it will return the passed default value,
+    otherwise the value of the variable:
+
+    .. sourcecode:: jinja
+
+        {{ my_variable|default('my_variable is not defined') }}
+
+    This will output the value of ``my_variable`` if the variable was
+    defined, otherwise ``'my_variable is not defined'``. If you want
+    to use default with variables that evaluate to false you have to
+    set the second parameter to `true`:
+
+    .. sourcecode:: jinja
+
+        {{ ''|default('the string was empty', true) }}
+
+    .. versionchanged:: 2.11
+       It's now possible to configure the :class:`~jinja2.Environment` with
+       :class:`~jinja2.ChainableUndefined` to make the `default` filter work
+       on nested elements and attributes that may contain undefined values
+       in the chain without getting an :exc:`~jinja2.UndefinedError`.
+    """
+    if isinstance(value, Undefined) or (boolean and not value):
+        return default_value
+
+    return value
+
+
+@pass_eval_context
+def sync_do_join(
+    eval_ctx: "EvalContext",
+    value: t.Iterable,
+    d: str = "",
+    attribute: t.Optional[t.Union[str, int]] = None,
+) -> str:
+    """Return a string which is the concatenation of the strings in the
+    sequence. The separator between elements is an empty string per
+    default, you can define it with the optional parameter:
+
+    .. sourcecode:: jinja
+
+        {{ [1, 2, 3]|join('|') }}
+            -> 1|2|3
+
+        {{ [1, 2, 3]|join }}
+            -> 123
+
+    It is also possible to join certain attributes of an object:
+
+    .. sourcecode:: jinja
+
+        {{ users|join(', ', attribute='username') }}
+
+    .. versionadded:: 2.6
+       The `attribute` parameter was added.
+    """
+    if attribute is not None:
+        value = map(make_attrgetter(eval_ctx.environment, attribute), value)
+
+    # no automatic escaping?  joining is a lot easier then
+    if not eval_ctx.autoescape:
+        return str(d).join(map(str, value))
+
+    # if the delimiter doesn't have an html representation we check
+    # if any of the items has.  If yes we do a coercion to Markup
+    if not hasattr(d, "__html__"):
+        value = list(value)
+        do_escape = False
+
+        for idx, item in enumerate(value):
+            if hasattr(item, "__html__"):
+                do_escape = True
+            else:
+                value[idx] = str(item)
+
+        if do_escape:
+            d = escape(d)
+        else:
+            d = str(d)
+
+        return d.join(value)
+
+    # no html involved, to normal joining
+    return soft_str(d).join(map(soft_str, value))
+
+
+@async_variant(sync_do_join)  # type: ignore
+async def do_join(
+    eval_ctx: "EvalContext",
+    value: t.Union[t.AsyncIterable, t.Iterable],
+    d: str = "",
+    attribute: t.Optional[t.Union[str, int]] = None,
+) -> str:
+    return sync_do_join(eval_ctx, await auto_to_list(value), d, attribute)
+
+
+def do_center(value: str, width: int = 80) -> str:
+    """Centers the value in a field of a given width."""
+    return soft_str(value).center(width)
+
+
+@pass_environment
+def sync_do_first(
+    environment: "Environment", seq: "t.Iterable[V]"
+) -> "t.Union[V, Undefined]":
+    """Return the first item of a sequence."""
+    try:
+        return next(iter(seq))
+    except StopIteration:
+        return environment.undefined("No first item, sequence was empty.")
+
+
+@async_variant(sync_do_first)  # type: ignore
+async def do_first(
+    environment: "Environment", seq: "t.Union[t.AsyncIterable[V], t.Iterable[V]]"
+) -> "t.Union[V, Undefined]":
+    try:
+        return await auto_aiter(seq).__anext__()
+    except StopAsyncIteration:
+        return environment.undefined("No first item, sequence was empty.")
+
+
+@pass_environment
+def do_last(
+    environment: "Environment", seq: "t.Reversible[V]"
+) -> "t.Union[V, Undefined]":
+    """Return the last item of a sequence.
+
+    Note: Does not work with generators. You may want to explicitly
+    convert it to a list:
+
+    .. sourcecode:: jinja
+
+        {{ data | selectattr('name', '==', 'Jinja') | list | last }}
+    """
+    try:
+        return next(iter(reversed(seq)))
+    except StopIteration:
+        return environment.undefined("No last item, sequence was empty.")
+
+
+# No async do_last, it may not be safe in async mode.
+
+
+@pass_context
+def do_random(context: "Context", seq: "t.Sequence[V]") -> "t.Union[V, Undefined]":
+    """Return a random item from the sequence."""
+    try:
+        return random.choice(seq)
+    except IndexError:
+        return context.environment.undefined("No random item, sequence was empty.")
+
+
+def do_filesizeformat(value: t.Union[str, float, int], binary: bool = False) -> str:
+    """Format the value like a 'human-readable' file size (i.e. 13 kB,
+    4.1 MB, 102 Bytes, etc).  Per default decimal prefixes are used (Mega,
+    Giga, etc.), if the second parameter is set to `True` the binary
+    prefixes are used (Mebi, Gibi).
+    """
+    bytes = float(value)
+    base = 1024 if binary else 1000
+    prefixes = [
+        ("KiB" if binary else "kB"),
+        ("MiB" if binary else "MB"),
+        ("GiB" if binary else "GB"),
+        ("TiB" if binary else "TB"),
+        ("PiB" if binary else "PB"),
+        ("EiB" if binary else "EB"),
+        ("ZiB" if binary else "ZB"),
+        ("YiB" if binary else "YB"),
+    ]
+
+    if bytes == 1:
+        return "1 Byte"
+    elif bytes < base:
+        return f"{int(bytes)} Bytes"
+    else:
+        for i, prefix in enumerate(prefixes):
+            unit = base ** (i + 2)
+
+            if bytes < unit:
+                return f"{base * bytes / unit:.1f} {prefix}"
+
+        return f"{base * bytes / unit:.1f} {prefix}"
+
+
+def do_pprint(value: t.Any) -> str:
+    """Pretty print a variable. Useful for debugging."""
+    return pformat(value)
+
+
+_uri_scheme_re = re.compile(r"^([\w.+-]{2,}:(/){0,2})$")
+
+
+@pass_eval_context
+def do_urlize(
+    eval_ctx: "EvalContext",
+    value: str,
+    trim_url_limit: t.Optional[int] = None,
+    nofollow: bool = False,
+    target: t.Optional[str] = None,
+    rel: t.Optional[str] = None,
+    extra_schemes: t.Optional[t.Iterable[str]] = None,
+) -> str:
+    """Convert URLs in text into clickable links.
+
+    This may not recognize links in some situations. Usually, a more
+    comprehensive formatter, such as a Markdown library, is a better
+    choice.
+
+    Works on ``http://``, ``https://``, ``www.``, ``mailto:``, and email
+    addresses. Links with trailing punctuation (periods, commas, closing
+    parentheses) and leading punctuation (opening parentheses) are
+    recognized excluding the punctuation. Email addresses that include
+    header fields are not recognized (for example,
+    ``mailto:address@example.com?cc=copy@example.com``).
+
+    :param value: Original text containing URLs to link.
+    :param trim_url_limit: Shorten displayed URL values to this length.
+    :param nofollow: Add the ``rel=nofollow`` attribute to links.
+    :param target: Add the ``target`` attribute to links.
+    :param rel: Add the ``rel`` attribute to links.
+    :param extra_schemes: Recognize URLs that start with these schemes
+        in addition to the default behavior. Defaults to
+        ``env.policies["urlize.extra_schemes"]``, which defaults to no
+        extra schemes.
+
+    .. versionchanged:: 3.0
+        The ``extra_schemes`` parameter was added.
+
+    .. versionchanged:: 3.0
+        Generate ``https://`` links for URLs without a scheme.
+
+    .. versionchanged:: 3.0
+        The parsing rules were updated. Recognize email addresses with
+        or without the ``mailto:`` scheme. Validate IP addresses. Ignore
+        parentheses and brackets in more cases.
+
+    .. versionchanged:: 2.8
+       The ``target`` parameter was added.
+    """
+    policies = eval_ctx.environment.policies
+    rel_parts = set((rel or "").split())
+
+    if nofollow:
+        rel_parts.add("nofollow")
+
+    rel_parts.update((policies["urlize.rel"] or "").split())
+    rel = " ".join(sorted(rel_parts)) or None
+
+    if target is None:
+        target = policies["urlize.target"]
+
+    if extra_schemes is None:
+        extra_schemes = policies["urlize.extra_schemes"] or ()
+
+    for scheme in extra_schemes:
+        if _uri_scheme_re.fullmatch(scheme) is None:
+            raise FilterArgumentError(f"{scheme!r} is not a valid URI scheme prefix.")
+
+    rv = urlize(
+        value,
+        trim_url_limit=trim_url_limit,
+        rel=rel,
+        target=target,
+        extra_schemes=extra_schemes,
+    )
+
+    if eval_ctx.autoescape:
+        rv = Markup(rv)
+
+    return rv
+
+
+def do_indent(
+    s: str, width: t.Union[int, str] = 4, first: bool = False, blank: bool = False
+) -> str:
+    """Return a copy of the string with each line indented by 4 spaces. The
+    first line and blank lines are not indented by default.
+
+    :param width: Number of spaces, or a string, to indent by.
+    :param first: Don't skip indenting the first line.
+    :param blank: Don't skip indenting empty lines.
+
+    .. versionchanged:: 3.0
+        ``width`` can be a string.
+
+    .. versionchanged:: 2.10
+        Blank lines are not indented by default.
+
+        Rename the ``indentfirst`` argument to ``first``.
+    """
+    if isinstance(width, str):
+        indention = width
+    else:
+        indention = " " * width
+
+    newline = "\n"
+
+    if isinstance(s, Markup):
+        indention = Markup(indention)
+        newline = Markup(newline)
+
+    s += newline  # this quirk is necessary for splitlines method
+
+    if blank:
+        rv = (newline + indention).join(s.splitlines())
+    else:
+        lines = s.splitlines()
+        rv = lines.pop(0)
+
+        if lines:
+            rv += newline + newline.join(
+                indention + line if line else line for line in lines
+            )
+
+    if first:
+        rv = indention + rv
+
+    return rv
+
+
+@pass_environment
+def do_truncate(
+    env: "Environment",
+    s: str,
+    length: int = 255,
+    killwords: bool = False,
+    end: str = "...",
+    leeway: t.Optional[int] = None,
+) -> str:
+    """Return a truncated copy of the string. The length is specified
+    with the first parameter which defaults to ``255``. If the second
+    parameter is ``true`` the filter will cut the text at length. Otherwise
+    it will discard the last word. If the text was in fact
+    truncated it will append an ellipsis sign (``"..."``). If you want a
+    different ellipsis sign than ``"..."`` you can specify it using the
+    third parameter. Strings that only exceed the length by the tolerance
+    margin given in the fourth parameter will not be truncated.
+
+    .. sourcecode:: jinja
+
+        {{ "foo bar baz qux"|truncate(9) }}
+            -> "foo..."
+        {{ "foo bar baz qux"|truncate(9, True) }}
+            -> "foo ba..."
+        {{ "foo bar baz qux"|truncate(11) }}
+            -> "foo bar baz qux"
+        {{ "foo bar baz qux"|truncate(11, False, '...', 0) }}
+            -> "foo bar..."
+
+    The default leeway on newer Jinja versions is 5 and was 0 before but
+    can be reconfigured globally.
+    """
+    if leeway is None:
+        leeway = env.policies["truncate.leeway"]
+
+    assert length >= len(end), f"expected length >= {len(end)}, got {length}"
+    assert leeway >= 0, f"expected leeway >= 0, got {leeway}"
+
+    if len(s) <= length + leeway:
+        return s
+
+    if killwords:
+        return s[: length - len(end)] + end
+
+    result = s[: length - len(end)].rsplit(" ", 1)[0]
+    return result + end
+
+
+@pass_environment
+def do_wordwrap(
+    environment: "Environment",
+    s: str,
+    width: int = 79,
+    break_long_words: bool = True,
+    wrapstring: t.Optional[str] = None,
+    break_on_hyphens: bool = True,
+) -> str:
+    """Wrap a string to the given width. Existing newlines are treated
+    as paragraphs to be wrapped separately.
+
+    :param s: Original text to wrap.
+    :param width: Maximum length of wrapped lines.
+    :param break_long_words: If a word is longer than ``width``, break
+        it across lines.
+    :param break_on_hyphens: If a word contains hyphens, it may be split
+        across lines.
+    :param wrapstring: String to join each wrapped line. Defaults to
+        :attr:`Environment.newline_sequence`.
+
+    .. versionchanged:: 2.11
+        Existing newlines are treated as paragraphs wrapped separately.
+
+    .. versionchanged:: 2.11
+        Added the ``break_on_hyphens`` parameter.
+
+    .. versionchanged:: 2.7
+        Added the ``wrapstring`` parameter.
+    """
+    import textwrap
+
+    if wrapstring is None:
+        wrapstring = environment.newline_sequence
+
+    # textwrap.wrap doesn't consider existing newlines when wrapping.
+    # If the string has a newline before width, wrap will still insert
+    # a newline at width, resulting in a short line. Instead, split and
+    # wrap each paragraph individually.
+    return wrapstring.join(
+        [
+            wrapstring.join(
+                textwrap.wrap(
+                    line,
+                    width=width,
+                    expand_tabs=False,
+                    replace_whitespace=False,
+                    break_long_words=break_long_words,
+                    break_on_hyphens=break_on_hyphens,
+                )
+            )
+            for line in s.splitlines()
+        ]
+    )
+
+
+_word_re = re.compile(r"\w+")
+
+
+def do_wordcount(s: str) -> int:
+    """Count the words in that string."""
+    return len(_word_re.findall(soft_str(s)))
+
+
+def do_int(value: t.Any, default: int = 0, base: int = 10) -> int:
+    """Convert the value into an integer. If the
+    conversion doesn't work it will return ``0``. You can
+    override this default using the first parameter. You
+    can also override the default base (10) in the second
+    parameter, which handles input with prefixes such as
+    0b, 0o and 0x for bases 2, 8 and 16 respectively.
+    The base is ignored for decimal numbers and non-string values.
+    """
+    try:
+        if isinstance(value, str):
+            return int(value, base)
+
+        return int(value)
+    except (TypeError, ValueError):
+        # this quirk is necessary so that "42.23"|int gives 42.
+        try:
+            return int(float(value))
+        except (TypeError, ValueError):
+            return default
+
+
+def do_float(value: t.Any, default: float = 0.0) -> float:
+    """Convert the value into a floating point number. If the
+    conversion doesn't work it will return ``0.0``. You can
+    override this default using the first parameter.
+    """
+    try:
+        return float(value)
+    except (TypeError, ValueError):
+        return default
+
+
+def do_format(value: str, *args: t.Any, **kwargs: t.Any) -> str:
+    """Apply the given values to a `printf-style`_ format string, like
+    ``string % values``.
+
+    .. sourcecode:: jinja
+
+        {{ "%s, %s!"|format(greeting, name) }}
+        Hello, World!
+
+    In most cases it should be more convenient and efficient to use the
+    ``%`` operator or :meth:`str.format`.
+
+    .. code-block:: text
+
+        {{ "%s, %s!" % (greeting, name) }}
+        {{ "{}, {}!".format(greeting, name) }}
+
+    .. _printf-style: https://docs.python.org/library/stdtypes.html
+        #printf-style-string-formatting
+    """
+    if args and kwargs:
+        raise FilterArgumentError(
+            "can't handle positional and keyword arguments at the same time"
+        )
+
+    return soft_str(value) % (kwargs or args)
+
+
+def do_trim(value: str, chars: t.Optional[str] = None) -> str:
+    """Strip leading and trailing characters, by default whitespace."""
+    return soft_str(value).strip(chars)
+
+
+def do_striptags(value: "t.Union[str, HasHTML]") -> str:
+    """Strip SGML/XML tags and replace adjacent whitespace by one space."""
+    if hasattr(value, "__html__"):
+        value = t.cast("HasHTML", value).__html__()
+
+    return Markup(str(value)).striptags()
+
+
+def sync_do_slice(
+    value: "t.Collection[V]", slices: int, fill_with: "t.Optional[V]" = None
+) -> "t.Iterator[t.List[V]]":
+    """Slice an iterator and return a list of lists containing
+    those items. Useful if you want to create a div containing
+    three ul tags that represent columns:
+
+    .. sourcecode:: html+jinja
+
+        <div class="columnwrapper">
+          {%- for column in items|slice(3) %}
+            <ul class="column-{{ loop.index }}">
+            {%- for item in column %}
+              <li>{{ item }}</li>
+            {%- endfor %}
+            </ul>
+          {%- endfor %}
+        </div>
+
+    If you pass it a second argument it's used to fill missing
+    values on the last iteration.
+    """
+    seq = list(value)
+    length = len(seq)
+    items_per_slice = length // slices
+    slices_with_extra = length % slices
+    offset = 0
+
+    for slice_number in range(slices):
+        start = offset + slice_number * items_per_slice
+
+        if slice_number < slices_with_extra:
+            offset += 1
+
+        end = offset + (slice_number + 1) * items_per_slice
+        tmp = seq[start:end]
+
+        if fill_with is not None and slice_number >= slices_with_extra:
+            tmp.append(fill_with)
+
+        yield tmp
+
+
+@async_variant(sync_do_slice)  # type: ignore
+async def do_slice(
+    value: "t.Union[t.AsyncIterable[V], t.Iterable[V]]",
+    slices: int,
+    fill_with: t.Optional[t.Any] = None,
+) -> "t.Iterator[t.List[V]]":
+    return sync_do_slice(await auto_to_list(value), slices, fill_with)
+
+
+def do_batch(
+    value: "t.Iterable[V]", linecount: int, fill_with: "t.Optional[V]" = None
+) -> "t.Iterator[t.List[V]]":
+    """
+    A filter that batches items. It works pretty much like `slice`
+    just the other way round. It returns a list of lists with the
+    given number of items. If you provide a second parameter this
+    is used to fill up missing items. See this example:
+
+    .. sourcecode:: html+jinja
+
+        <table>
+        {%- for row in items|batch(3, '&nbsp;') %}
+          <tr>
+          {%- for column in row %}
+            <td>{{ column }}</td>
+          {%- endfor %}
+          </tr>
+        {%- endfor %}
+        </table>
+    """
+    tmp: "t.List[V]" = []
+
+    for item in value:
+        if len(tmp) == linecount:
+            yield tmp
+            tmp = []
+
+        tmp.append(item)
+
+    if tmp:
+        if fill_with is not None and len(tmp) < linecount:
+            tmp += [fill_with] * (linecount - len(tmp))
+
+        yield tmp
+
+
+def do_round(
+    value: float,
+    precision: int = 0,
+    method: 'te.Literal["common", "ceil", "floor"]' = "common",
+) -> float:
+    """Round the number to a given precision. The first
+    parameter specifies the precision (default is ``0``), the
+    second the rounding method:
+
+    - ``'common'`` rounds either up or down
+    - ``'ceil'`` always rounds up
+    - ``'floor'`` always rounds down
+
+    If you don't specify a method ``'common'`` is used.
+
+    .. sourcecode:: jinja
+
+        {{ 42.55|round }}
+            -> 43.0
+        {{ 42.55|round(1, 'floor') }}
+            -> 42.5
+
+    Note that even if rounded to 0 precision, a float is returned.  If
+    you need a real integer, pipe it through `int`:
+
+    .. sourcecode:: jinja
+
+        {{ 42.55|round|int }}
+            -> 43
+    """
+    if method not in {"common", "ceil", "floor"}:
+        raise FilterArgumentError("method must be common, ceil or floor")
+
+    if method == "common":
+        return round(value, precision)
+
+    func = getattr(math, method)
+    return t.cast(float, func(value * (10 ** precision)) / (10 ** precision))
+
+
+class _GroupTuple(t.NamedTuple):
+    grouper: t.Any
+    list: t.List
+
+    # Use the regular tuple repr to hide this subclass if users print
+    # out the value during debugging.
+    def __repr__(self) -> str:
+        return tuple.__repr__(self)
+
+    def __str__(self) -> str:
+        return tuple.__str__(self)
+
+
+@pass_environment
+def sync_do_groupby(
+    environment: "Environment",
+    value: "t.Iterable[V]",
+    attribute: t.Union[str, int],
+    default: t.Optional[t.Any] = None,
+) -> "t.List[t.Tuple[t.Any, t.List[V]]]":
+    """Group a sequence of objects by an attribute using Python's
+    :func:`itertools.groupby`. The attribute can use dot notation for
+    nested access, like ``"address.city"``. Unlike Python's ``groupby``,
+    the values are sorted first so only one group is returned for each
+    unique value.
+
+    For example, a list of ``User`` objects with a ``city`` attribute
+    can be rendered in groups. In this example, ``grouper`` refers to
+    the ``city`` value of the group.
+
+    .. sourcecode:: html+jinja
+
+        <ul>{% for city, items in users|groupby("city") %}
+          <li>{{ city }}
+            <ul>{% for user in items %}
+              <li>{{ user.name }}
+            {% endfor %}</ul>
+          </li>
+        {% endfor %}</ul>
+
+    ``groupby`` yields namedtuples of ``(grouper, list)``, which
+    can be used instead of the tuple unpacking above. ``grouper`` is the
+    value of the attribute, and ``list`` is the items with that value.
+
+    .. sourcecode:: html+jinja
+
+        <ul>{% for group in users|groupby("city") %}
+          <li>{{ group.grouper }}: {{ group.list|join(", ") }}
+        {% endfor %}</ul>
+
+    You can specify a ``default`` value to use if an object in the list
+    does not have the given attribute.
+
+    .. sourcecode:: jinja
+
+        <ul>{% for city, items in users|groupby("city", default="NY") %}
+          <li>{{ city }}: {{ items|map(attribute="name")|join(", ") }}</li>
+        {% endfor %}</ul>
+
+    .. versionchanged:: 3.0
+        Added the ``default`` parameter.
+
+    .. versionchanged:: 2.6
+        The attribute supports dot notation for nested access.
+    """
+    expr = make_attrgetter(environment, attribute, default=default)
+    return [
+        _GroupTuple(key, list(values))
+        for key, values in groupby(sorted(value, key=expr), expr)
+    ]
+
+
+@async_variant(sync_do_groupby)  # type: ignore
+async def do_groupby(
+    environment: "Environment",
+    value: "t.Union[t.AsyncIterable[V], t.Iterable[V]]",
+    attribute: t.Union[str, int],
+    default: t.Optional[t.Any] = None,
+) -> "t.List[t.Tuple[t.Any, t.List[V]]]":
+    expr = make_attrgetter(environment, attribute, default=default)
+    return [
+        _GroupTuple(key, await auto_to_list(values))
+        for key, values in groupby(sorted(await auto_to_list(value), key=expr), expr)
+    ]
+
+
+@pass_environment
+def sync_do_sum(
+    environment: "Environment",
+    iterable: "t.Iterable[V]",
+    attribute: t.Optional[t.Union[str, int]] = None,
+    start: V = 0,  # type: ignore
+) -> V:
+    """Returns the sum of a sequence of numbers plus the value of parameter
+    'start' (which defaults to 0).  When the sequence is empty it returns
+    start.
+
+    It is also possible to sum up only certain attributes:
+
+    .. sourcecode:: jinja
+
+        Total: {{ items|sum(attribute='price') }}
+
+    .. versionchanged:: 2.6
+       The `attribute` parameter was added to allow suming up over
+       attributes.  Also the `start` parameter was moved on to the right.
+    """
+    if attribute is not None:
+        iterable = map(make_attrgetter(environment, attribute), iterable)
+
+    return sum(iterable, start)
+
+
+@async_variant(sync_do_sum)  # type: ignore
+async def do_sum(
+    environment: "Environment",
+    iterable: "t.Union[t.AsyncIterable[V], t.Iterable[V]]",
+    attribute: t.Optional[t.Union[str, int]] = None,
+    start: V = 0,  # type: ignore
+) -> V:
+    rv = start
+
+    if attribute is not None:
+        func = make_attrgetter(environment, attribute)
+    else:
+
+        def func(x: V) -> V:
+            return x
+
+    async for item in auto_aiter(iterable):
+        rv += func(item)
+
+    return rv
+
+
+def sync_do_list(value: "t.Iterable[V]") -> "t.List[V]":
+    """Convert the value into a list.  If it was a string the returned list
+    will be a list of characters.
+    """
+    return list(value)
+
+
+@async_variant(sync_do_list)  # type: ignore
+async def do_list(value: "t.Union[t.AsyncIterable[V], t.Iterable[V]]") -> "t.List[V]":
+    return await auto_to_list(value)
+
+
+def do_mark_safe(value: str) -> Markup:
+    """Mark the value as safe which means that in an environment with automatic
+    escaping enabled this variable will not be escaped.
+    """
+    return Markup(value)
+
+
+def do_mark_unsafe(value: str) -> str:
+    """Mark a value as unsafe.  This is the reverse operation for :func:`safe`."""
+    return str(value)
+
+
+@typing.overload
+def do_reverse(value: str) -> str:
+    ...
+
+
+@typing.overload
+def do_reverse(value: "t.Iterable[V]") -> "t.Iterable[V]":
+    ...
+
+
+def do_reverse(value: t.Union[str, t.Iterable[V]]) -> t.Union[str, t.Iterable[V]]:
+    """Reverse the object or return an iterator that iterates over it the other
+    way round.
+    """
+    if isinstance(value, str):
+        return value[::-1]
+
+    try:
+        return reversed(value)  # type: ignore
+    except TypeError:
+        try:
+            rv = list(value)
+            rv.reverse()
+            return rv
+        except TypeError as e:
+            raise FilterArgumentError("argument must be iterable") from e
+
+
+@pass_environment
+def do_attr(
+    environment: "Environment", obj: t.Any, name: str
+) -> t.Union[Undefined, t.Any]:
+    """Get an attribute of an object.  ``foo|attr("bar")`` works like
+    ``foo.bar`` just that always an attribute is returned and items are not
+    looked up.
+
+    See :ref:`Notes on subscriptions <notes-on-subscriptions>` for more details.
+    """
+    try:
+        name = str(name)
+    except UnicodeError:
+        pass
+    else:
+        try:
+            value = getattr(obj, name)
+        except AttributeError:
+            pass
+        else:
+            if environment.sandboxed:
+                environment = t.cast("SandboxedEnvironment", environment)
+
+                if not environment.is_safe_attribute(obj, name, value):
+                    return environment.unsafe_undefined(obj, name)
+
+            return value
+
+    return environment.undefined(obj=obj, name=name)
+
+
+@typing.overload
+def sync_do_map(
+    context: "Context", value: t.Iterable, name: str, *args: t.Any, **kwargs: t.Any
+) -> t.Iterable:
+    ...
+
+
+@typing.overload
+def sync_do_map(
+    context: "Context",
+    value: t.Iterable,
+    *,
+    attribute: str = ...,
+    default: t.Optional[t.Any] = None,
+) -> t.Iterable:
+    ...
+
+
+@pass_context
+def sync_do_map(
+    context: "Context", value: t.Iterable, *args: t.Any, **kwargs: t.Any
+) -> t.Iterable:
+    """Applies a filter on a sequence of objects or looks up an attribute.
+    This is useful when dealing with lists of objects but you are really
+    only interested in a certain value of it.
+
+    The basic usage is mapping on an attribute.  Imagine you have a list
+    of users but you are only interested in a list of usernames:
+
+    .. sourcecode:: jinja
+
+        Users on this page: {{ users|map(attribute='username')|join(', ') }}
+
+    You can specify a ``default`` value to use if an object in the list
+    does not have the given attribute.
+
+    .. sourcecode:: jinja
+
+        {{ users|map(attribute="username", default="Anonymous")|join(", ") }}
+
+    Alternatively you can let it invoke a filter by passing the name of the
+    filter and the arguments afterwards.  A good example would be applying a
+    text conversion filter on a sequence:
+
+    .. sourcecode:: jinja
+
+        Users on this page: {{ titles|map('lower')|join(', ') }}
+
+    Similar to a generator comprehension such as:
+
+    .. code-block:: python
+
+        (u.username for u in users)
+        (getattr(u, "username", "Anonymous") for u in users)
+        (do_lower(x) for x in titles)
+
+    .. versionchanged:: 2.11.0
+        Added the ``default`` parameter.
+
+    .. versionadded:: 2.7
+    """
+    if value:
+        func = prepare_map(context, args, kwargs)
+
+        for item in value:
+            yield func(item)
+
+
+@typing.overload
+def do_map(
+    context: "Context",
+    value: t.Union[t.AsyncIterable, t.Iterable],
+    name: str,
+    *args: t.Any,
+    **kwargs: t.Any,
+) -> t.Iterable:
+    ...
+
+
+@typing.overload
+def do_map(
+    context: "Context",
+    value: t.Union[t.AsyncIterable, t.Iterable],
+    *,
+    attribute: str = ...,
+    default: t.Optional[t.Any] = None,
+) -> t.Iterable:
+    ...
+
+
+@async_variant(sync_do_map)  # type: ignore
+async def do_map(
+    context: "Context",
+    value: t.Union[t.AsyncIterable, t.Iterable],
+    *args: t.Any,
+    **kwargs: t.Any,
+) -> t.AsyncIterable:
+    if value:
+        func = prepare_map(context, args, kwargs)
+
+        async for item in auto_aiter(value):
+            yield await auto_await(func(item))
+
+
+@pass_context
+def sync_do_select(
+    context: "Context", value: "t.Iterable[V]", *args: t.Any, **kwargs: t.Any
+) -> "t.Iterator[V]":
+    """Filters a sequence of objects by applying a test to each object,
+    and only selecting the objects with the test succeeding.
+
+    If no test is specified, each object will be evaluated as a boolean.
+
+    Example usage:
+
+    .. sourcecode:: jinja
+
+        {{ numbers|select("odd") }}
+        {{ numbers|select("odd") }}
+        {{ numbers|select("divisibleby", 3) }}
+        {{ numbers|select("lessthan", 42) }}
+        {{ strings|select("equalto", "mystring") }}
+
+    Similar to a generator comprehension such as:
+
+    .. code-block:: python
+
+        (n for n in numbers if test_odd(n))
+        (n for n in numbers if test_divisibleby(n, 3))
+
+    .. versionadded:: 2.7
+    """
+    return select_or_reject(context, value, args, kwargs, lambda x: x, False)
+
+
+@async_variant(sync_do_select)  # type: ignore
+async def do_select(
+    context: "Context",
+    value: "t.Union[t.AsyncIterable[V], t.Iterable[V]]",
+    *args: t.Any,
+    **kwargs: t.Any,
+) -> "t.AsyncIterator[V]":
+    return async_select_or_reject(context, value, args, kwargs, lambda x: x, False)
+
+
+@pass_context
+def sync_do_reject(
+    context: "Context", value: "t.Iterable[V]", *args: t.Any, **kwargs: t.Any
+) -> "t.Iterator[V]":
+    """Filters a sequence of objects by applying a test to each object,
+    and rejecting the objects with the test succeeding.
+
+    If no test is specified, each object will be evaluated as a boolean.
+
+    Example usage:
+
+    .. sourcecode:: jinja
+
+        {{ numbers|reject("odd") }}
+
+    Similar to a generator comprehension such as:
+
+    .. code-block:: python
+
+        (n for n in numbers if not test_odd(n))
+
+    .. versionadded:: 2.7
+    """
+    return select_or_reject(context, value, args, kwargs, lambda x: not x, False)
+
+
+@async_variant(sync_do_reject)  # type: ignore
+async def do_reject(
+    context: "Context",
+    value: "t.Union[t.AsyncIterable[V], t.Iterable[V]]",
+    *args: t.Any,
+    **kwargs: t.Any,
+) -> "t.AsyncIterator[V]":
+    return async_select_or_reject(context, value, args, kwargs, lambda x: not x, False)
+
+
+@pass_context
+def sync_do_selectattr(
+    context: "Context", value: "t.Iterable[V]", *args: t.Any, **kwargs: t.Any
+) -> "t.Iterator[V]":
+    """Filters a sequence of objects by applying a test to the specified
+    attribute of each object, and only selecting the objects with the
+    test succeeding.
+
+    If no test is specified, the attribute's value will be evaluated as
+    a boolean.
+
+    Example usage:
+
+    .. sourcecode:: jinja
+
+        {{ users|selectattr("is_active") }}
+        {{ users|selectattr("email", "none") }}
+
+    Similar to a generator comprehension such as:
+
+    .. code-block:: python
+
+        (u for user in users if user.is_active)
+        (u for user in users if test_none(user.email))
+
+    .. versionadded:: 2.7
+    """
+    return select_or_reject(context, value, args, kwargs, lambda x: x, True)
+
+
+@async_variant(sync_do_selectattr)  # type: ignore
+async def do_selectattr(
+    context: "Context",
+    value: "t.Union[t.AsyncIterable[V], t.Iterable[V]]",
+    *args: t.Any,
+    **kwargs: t.Any,
+) -> "t.AsyncIterator[V]":
+    return async_select_or_reject(context, value, args, kwargs, lambda x: x, True)
+
+
+@pass_context
+def sync_do_rejectattr(
+    context: "Context", value: "t.Iterable[V]", *args: t.Any, **kwargs: t.Any
+) -> "t.Iterator[V]":
+    """Filters a sequence of objects by applying a test to the specified
+    attribute of each object, and rejecting the objects with the test
+    succeeding.
+
+    If no test is specified, the attribute's value will be evaluated as
+    a boolean.
+
+    .. sourcecode:: jinja
+
+        {{ users|rejectattr("is_active") }}
+        {{ users|rejectattr("email", "none") }}
+
+    Similar to a generator comprehension such as:
+
+    .. code-block:: python
+
+        (u for user in users if not user.is_active)
+        (u for user in users if not test_none(user.email))
+
+    .. versionadded:: 2.7
+    """
+    return select_or_reject(context, value, args, kwargs, lambda x: not x, True)
+
+
+@async_variant(sync_do_rejectattr)  # type: ignore
+async def do_rejectattr(
+    context: "Context",
+    value: "t.Union[t.AsyncIterable[V], t.Iterable[V]]",
+    *args: t.Any,
+    **kwargs: t.Any,
+) -> "t.AsyncIterator[V]":
+    return async_select_or_reject(context, value, args, kwargs, lambda x: not x, True)
+
+
+@pass_eval_context
+def do_tojson(
+    eval_ctx: "EvalContext", value: t.Any, indent: t.Optional[int] = None
+) -> Markup:
+    """Serialize an object to a string of JSON, and mark it safe to
+    render in HTML. This filter is only for use in HTML documents.
+
+    The returned string is safe to render in HTML documents and
+    ``<script>`` tags. The exception is in HTML attributes that are
+    double quoted; either use single quotes or the ``|forceescape``
+    filter.
+
+    :param value: The object to serialize to JSON.
+    :param indent: The ``indent`` parameter passed to ``dumps``, for
+        pretty-printing the value.
+
+    .. versionadded:: 2.9
+    """
+    policies = eval_ctx.environment.policies
+    dumps = policies["json.dumps_function"]
+    kwargs = policies["json.dumps_kwargs"]
+
+    if indent is not None:
+        kwargs = kwargs.copy()
+        kwargs["indent"] = indent
+
+    return htmlsafe_json_dumps(value, dumps=dumps, **kwargs)
+
+
+def prepare_map(
+    context: "Context", args: t.Tuple, kwargs: t.Dict[str, t.Any]
+) -> t.Callable[[t.Any], t.Any]:
+    if not args and "attribute" in kwargs:
+        attribute = kwargs.pop("attribute")
+        default = kwargs.pop("default", None)
+
+        if kwargs:
+            raise FilterArgumentError(
+                f"Unexpected keyword argument {next(iter(kwargs))!r}"
+            )
+
+        func = make_attrgetter(context.environment, attribute, default=default)
+    else:
+        try:
+            name = args[0]
+            args = args[1:]
+        except LookupError:
+            raise FilterArgumentError("map requires a filter argument") from None
+
+        def func(item: t.Any) -> t.Any:
+            return context.environment.call_filter(
+                name, item, args, kwargs, context=context
+            )
+
+    return func
+
+
+def prepare_select_or_reject(
+    context: "Context",
+    args: t.Tuple,
+    kwargs: t.Dict[str, t.Any],
+    modfunc: t.Callable[[t.Any], t.Any],
+    lookup_attr: bool,
+) -> t.Callable[[t.Any], t.Any]:
+    if lookup_attr:
+        try:
+            attr = args[0]
+        except LookupError:
+            raise FilterArgumentError("Missing parameter for attribute name") from None
+
+        transfunc = make_attrgetter(context.environment, attr)
+        off = 1
+    else:
+        off = 0
+
+        def transfunc(x: V) -> V:
+            return x
+
+    try:
+        name = args[off]
+        args = args[1 + off :]
+
+        def func(item: t.Any) -> t.Any:
+            return context.environment.call_test(name, item, args, kwargs)
+
+    except LookupError:
+        func = bool  # type: ignore
+
+    return lambda item: modfunc(func(transfunc(item)))
+
+
+def select_or_reject(
+    context: "Context",
+    value: "t.Iterable[V]",
+    args: t.Tuple,
+    kwargs: t.Dict[str, t.Any],
+    modfunc: t.Callable[[t.Any], t.Any],
+    lookup_attr: bool,
+) -> "t.Iterator[V]":
+    if value:
+        func = prepare_select_or_reject(context, args, kwargs, modfunc, lookup_attr)
+
+        for item in value:
+            if func(item):
+                yield item
+
+
+async def async_select_or_reject(
+    context: "Context",
+    value: "t.Union[t.AsyncIterable[V], t.Iterable[V]]",
+    args: t.Tuple,
+    kwargs: t.Dict[str, t.Any],
+    modfunc: t.Callable[[t.Any], t.Any],
+    lookup_attr: bool,
+) -> "t.AsyncIterator[V]":
+    if value:
+        func = prepare_select_or_reject(context, args, kwargs, modfunc, lookup_attr)
+
+        async for item in auto_aiter(value):
+            if func(item):
+                yield item
+
+
+FILTERS = {
+    "abs": abs,
+    "attr": do_attr,
+    "batch": do_batch,
+    "capitalize": do_capitalize,
+    "center": do_center,
+    "count": len,
+    "d": do_default,
+    "default": do_default,
+    "dictsort": do_dictsort,
+    "e": escape,
+    "escape": escape,
+    "filesizeformat": do_filesizeformat,
+    "first": do_first,
+    "float": do_float,
+    "forceescape": do_forceescape,
+    "format": do_format,
+    "groupby": do_groupby,
+    "indent": do_indent,
+    "int": do_int,
+    "join": do_join,
+    "last": do_last,
+    "length": len,
+    "list": do_list,
+    "lower": do_lower,
+    "map": do_map,
+    "min": do_min,
+    "max": do_max,
+    "pprint": do_pprint,
+    "random": do_random,
+    "reject": do_reject,
+    "rejectattr": do_rejectattr,
+    "replace": do_replace,
+    "reverse": do_reverse,
+    "round": do_round,
+    "safe": do_mark_safe,
+    "select": do_select,
+    "selectattr": do_selectattr,
+    "slice": do_slice,
+    "sort": do_sort,
+    "string": soft_str,
+    "striptags": do_striptags,
+    "sum": do_sum,
+    "title": do_title,
+    "trim": do_trim,
+    "truncate": do_truncate,
+    "unique": do_unique,
+    "upper": do_upper,
+    "urlencode": do_urlencode,
+    "urlize": do_urlize,
+    "wordcount": do_wordcount,
+    "wordwrap": do_wordwrap,
+    "xmlattr": do_xmlattr,
+    "tojson": do_tojson,
+}
diff --git a/lib/spack/external/_vendoring/jinja2/idtracking.py b/lib/spack/external/_vendoring/jinja2/idtracking.py
new file mode 100644
index 0000000000..38c525ee31
--- /dev/null
+++ b/lib/spack/external/_vendoring/jinja2/idtracking.py
@@ -0,0 +1,318 @@
+import typing as t
+
+from . import nodes
+from .visitor import NodeVisitor
+
+VAR_LOAD_PARAMETER = "param"
+VAR_LOAD_RESOLVE = "resolve"
+VAR_LOAD_ALIAS = "alias"
+VAR_LOAD_UNDEFINED = "undefined"
+
+
+def find_symbols(
+    nodes: t.Iterable[nodes.Node], parent_symbols: t.Optional["Symbols"] = None
+) -> "Symbols":
+    sym = Symbols(parent=parent_symbols)
+    visitor = FrameSymbolVisitor(sym)
+    for node in nodes:
+        visitor.visit(node)
+    return sym
+
+
+def symbols_for_node(
+    node: nodes.Node, parent_symbols: t.Optional["Symbols"] = None
+) -> "Symbols":
+    sym = Symbols(parent=parent_symbols)
+    sym.analyze_node(node)
+    return sym
+
+
+class Symbols:
+    def __init__(
+        self, parent: t.Optional["Symbols"] = None, level: t.Optional[int] = None
+    ) -> None:
+        if level is None:
+            if parent is None:
+                level = 0
+            else:
+                level = parent.level + 1
+
+        self.level: int = level
+        self.parent = parent
+        self.refs: t.Dict[str, str] = {}
+        self.loads: t.Dict[str, t.Any] = {}
+        self.stores: t.Set[str] = set()
+
+    def analyze_node(self, node: nodes.Node, **kwargs: t.Any) -> None:
+        visitor = RootVisitor(self)
+        visitor.visit(node, **kwargs)
+
+    def _define_ref(
+        self, name: str, load: t.Optional[t.Tuple[str, t.Optional[str]]] = None
+    ) -> str:
+        ident = f"l_{self.level}_{name}"
+        self.refs[name] = ident
+        if load is not None:
+            self.loads[ident] = load
+        return ident
+
+    def find_load(self, target: str) -> t.Optional[t.Any]:
+        if target in self.loads:
+            return self.loads[target]
+
+        if self.parent is not None:
+            return self.parent.find_load(target)
+
+        return None
+
+    def find_ref(self, name: str) -> t.Optional[str]:
+        if name in self.refs:
+            return self.refs[name]
+
+        if self.parent is not None:
+            return self.parent.find_ref(name)
+
+        return None
+
+    def ref(self, name: str) -> str:
+        rv = self.find_ref(name)
+        if rv is None:
+            raise AssertionError(
+                "Tried to resolve a name to a reference that was"
+                f" unknown to the frame ({name!r})"
+            )
+        return rv
+
+    def copy(self) -> "Symbols":
+        rv = t.cast(Symbols, object.__new__(self.__class__))
+        rv.__dict__.update(self.__dict__)
+        rv.refs = self.refs.copy()
+        rv.loads = self.loads.copy()
+        rv.stores = self.stores.copy()
+        return rv
+
+    def store(self, name: str) -> None:
+        self.stores.add(name)
+
+        # If we have not see the name referenced yet, we need to figure
+        # out what to set it to.
+        if name not in self.refs:
+            # If there is a parent scope we check if the name has a
+            # reference there.  If it does it means we might have to alias
+            # to a variable there.
+            if self.parent is not None:
+                outer_ref = self.parent.find_ref(name)
+                if outer_ref is not None:
+                    self._define_ref(name, load=(VAR_LOAD_ALIAS, outer_ref))
+                    return
+
+            # Otherwise we can just set it to undefined.
+            self._define_ref(name, load=(VAR_LOAD_UNDEFINED, None))
+
+    def declare_parameter(self, name: str) -> str:
+        self.stores.add(name)
+        return self._define_ref(name, load=(VAR_LOAD_PARAMETER, None))
+
+    def load(self, name: str) -> None:
+        if self.find_ref(name) is None:
+            self._define_ref(name, load=(VAR_LOAD_RESOLVE, name))
+
+    def branch_update(self, branch_symbols: t.Sequence["Symbols"]) -> None:
+        stores: t.Dict[str, int] = {}
+        for branch in branch_symbols:
+            for target in branch.stores:
+                if target in self.stores:
+                    continue
+                stores[target] = stores.get(target, 0) + 1
+
+        for sym in branch_symbols:
+            self.refs.update(sym.refs)
+            self.loads.update(sym.loads)
+            self.stores.update(sym.stores)
+
+        for name, branch_count in stores.items():
+            if branch_count == len(branch_symbols):
+                continue
+
+            target = self.find_ref(name)  # type: ignore
+            assert target is not None, "should not happen"
+
+            if self.parent is not None:
+                outer_target = self.parent.find_ref(name)
+                if outer_target is not None:
+                    self.loads[target] = (VAR_LOAD_ALIAS, outer_target)
+                    continue
+            self.loads[target] = (VAR_LOAD_RESOLVE, name)
+
+    def dump_stores(self) -> t.Dict[str, str]:
+        rv: t.Dict[str, str] = {}
+        node: t.Optional["Symbols"] = self
+
+        while node is not None:
+            for name in sorted(node.stores):
+                if name not in rv:
+                    rv[name] = self.find_ref(name)  # type: ignore
+
+            node = node.parent
+
+        return rv
+
+    def dump_param_targets(self) -> t.Set[str]:
+        rv = set()
+        node: t.Optional["Symbols"] = self
+
+        while node is not None:
+            for target, (instr, _) in self.loads.items():
+                if instr == VAR_LOAD_PARAMETER:
+                    rv.add(target)
+
+            node = node.parent
+
+        return rv
+
+
+class RootVisitor(NodeVisitor):
+    def __init__(self, symbols: "Symbols") -> None:
+        self.sym_visitor = FrameSymbolVisitor(symbols)
+
+    def _simple_visit(self, node: nodes.Node, **kwargs: t.Any) -> None:
+        for child in node.iter_child_nodes():
+            self.sym_visitor.visit(child)
+
+    visit_Template = _simple_visit
+    visit_Block = _simple_visit
+    visit_Macro = _simple_visit
+    visit_FilterBlock = _simple_visit
+    visit_Scope = _simple_visit
+    visit_If = _simple_visit
+    visit_ScopedEvalContextModifier = _simple_visit
+
+    def visit_AssignBlock(self, node: nodes.AssignBlock, **kwargs: t.Any) -> None:
+        for child in node.body:
+            self.sym_visitor.visit(child)
+
+    def visit_CallBlock(self, node: nodes.CallBlock, **kwargs: t.Any) -> None:
+        for child in node.iter_child_nodes(exclude=("call",)):
+            self.sym_visitor.visit(child)
+
+    def visit_OverlayScope(self, node: nodes.OverlayScope, **kwargs: t.Any) -> None:
+        for child in node.body:
+            self.sym_visitor.visit(child)
+
+    def visit_For(
+        self, node: nodes.For, for_branch: str = "body", **kwargs: t.Any
+    ) -> None:
+        if for_branch == "body":
+            self.sym_visitor.visit(node.target, store_as_param=True)
+            branch = node.body
+        elif for_branch == "else":
+            branch = node.else_
+        elif for_branch == "test":
+            self.sym_visitor.visit(node.target, store_as_param=True)
+            if node.test is not None:
+                self.sym_visitor.visit(node.test)
+            return
+        else:
+            raise RuntimeError("Unknown for branch")
+
+        if branch:
+            for item in branch:
+                self.sym_visitor.visit(item)
+
+    def visit_With(self, node: nodes.With, **kwargs: t.Any) -> None:
+        for target in node.targets:
+            self.sym_visitor.visit(target)
+        for child in node.body:
+            self.sym_visitor.visit(child)
+
+    def generic_visit(self, node: nodes.Node, *args: t.Any, **kwargs: t.Any) -> None:
+        raise NotImplementedError(f"Cannot find symbols for {type(node).__name__!r}")
+
+
+class FrameSymbolVisitor(NodeVisitor):
+    """A visitor for `Frame.inspect`."""
+
+    def __init__(self, symbols: "Symbols") -> None:
+        self.symbols = symbols
+
+    def visit_Name(
+        self, node: nodes.Name, store_as_param: bool = False, **kwargs: t.Any
+    ) -> None:
+        """All assignments to names go through this function."""
+        if store_as_param or node.ctx == "param":
+            self.symbols.declare_parameter(node.name)
+        elif node.ctx == "store":
+            self.symbols.store(node.name)
+        elif node.ctx == "load":
+            self.symbols.load(node.name)
+
+    def visit_NSRef(self, node: nodes.NSRef, **kwargs: t.Any) -> None:
+        self.symbols.load(node.name)
+
+    def visit_If(self, node: nodes.If, **kwargs: t.Any) -> None:
+        self.visit(node.test, **kwargs)
+        original_symbols = self.symbols
+
+        def inner_visit(nodes: t.Iterable[nodes.Node]) -> "Symbols":
+            self.symbols = rv = original_symbols.copy()
+
+            for subnode in nodes:
+                self.visit(subnode, **kwargs)
+
+            self.symbols = original_symbols
+            return rv
+
+        body_symbols = inner_visit(node.body)
+        elif_symbols = inner_visit(node.elif_)
+        else_symbols = inner_visit(node.else_ or ())
+        self.symbols.branch_update([body_symbols, elif_symbols, else_symbols])
+
+    def visit_Macro(self, node: nodes.Macro, **kwargs: t.Any) -> None:
+        self.symbols.store(node.name)
+
+    def visit_Import(self, node: nodes.Import, **kwargs: t.Any) -> None:
+        self.generic_visit(node, **kwargs)
+        self.symbols.store(node.target)
+
+    def visit_FromImport(self, node: nodes.FromImport, **kwargs: t.Any) -> None:
+        self.generic_visit(node, **kwargs)
+
+        for name in node.names:
+            if isinstance(name, tuple):
+                self.symbols.store(name[1])
+            else:
+                self.symbols.store(name)
+
+    def visit_Assign(self, node: nodes.Assign, **kwargs: t.Any) -> None:
+        """Visit assignments in the correct order."""
+        self.visit(node.node, **kwargs)
+        self.visit(node.target, **kwargs)
+
+    def visit_For(self, node: nodes.For, **kwargs: t.Any) -> None:
+        """Visiting stops at for blocks.  However the block sequence
+        is visited as part of the outer scope.
+        """
+        self.visit(node.iter, **kwargs)
+
+    def visit_CallBlock(self, node: nodes.CallBlock, **kwargs: t.Any) -> None:
+        self.visit(node.call, **kwargs)
+
+    def visit_FilterBlock(self, node: nodes.FilterBlock, **kwargs: t.Any) -> None:
+        self.visit(node.filter, **kwargs)
+
+    def visit_With(self, node: nodes.With, **kwargs: t.Any) -> None:
+        for target in node.values:
+            self.visit(target)
+
+    def visit_AssignBlock(self, node: nodes.AssignBlock, **kwargs: t.Any) -> None:
+        """Stop visiting at block assigns."""
+        self.visit(node.target, **kwargs)
+
+    def visit_Scope(self, node: nodes.Scope, **kwargs: t.Any) -> None:
+        """Stop visiting at scopes."""
+
+    def visit_Block(self, node: nodes.Block, **kwargs: t.Any) -> None:
+        """Stop visiting at blocks."""
+
+    def visit_OverlayScope(self, node: nodes.OverlayScope, **kwargs: t.Any) -> None:
+        """Do not visit into overlay scopes."""
diff --git a/lib/spack/external/_vendoring/jinja2/lexer.py b/lib/spack/external/_vendoring/jinja2/lexer.py
new file mode 100644
index 0000000000..c25ab0f690
--- /dev/null
+++ b/lib/spack/external/_vendoring/jinja2/lexer.py
@@ -0,0 +1,869 @@
+"""Implements a Jinja / Python combination lexer. The ``Lexer`` class
+is used to do some preprocessing. It filters out invalid operators like
+the bitshift operators we don't allow in templates. It separates
+template code and python code in expressions.
+"""
+import re
+import typing as t
+from ast import literal_eval
+from collections import deque
+from sys import intern
+
+from ._identifier import pattern as name_re
+from .exceptions import TemplateSyntaxError
+from .utils import LRUCache
+
+if t.TYPE_CHECKING:
+    import typing_extensions as te
+    from .environment import Environment
+
+# cache for the lexers. Exists in order to be able to have multiple
+# environments with the same lexer
+_lexer_cache: t.MutableMapping[t.Tuple, "Lexer"] = LRUCache(50)  # type: ignore
+
+# static regular expressions
+whitespace_re = re.compile(r"\s+")
+newline_re = re.compile(r"(\r\n|\r|\n)")
+string_re = re.compile(
+    r"('([^'\\]*(?:\\.[^'\\]*)*)'" r'|"([^"\\]*(?:\\.[^"\\]*)*)")', re.S
+)
+integer_re = re.compile(
+    r"""
+    (
+        0b(_?[0-1])+ # binary
+    |
+        0o(_?[0-7])+ # octal
+    |
+        0x(_?[\da-f])+ # hex
+    |
+        [1-9](_?\d)* # decimal
+    |
+        0(_?0)* # decimal zero
+    )
+    """,
+    re.IGNORECASE | re.VERBOSE,
+)
+float_re = re.compile(
+    r"""
+    (?<!\.)  # doesn't start with a .
+    (\d+_)*\d+  # digits, possibly _ separated
+    (
+        (\.(\d+_)*\d+)?  # optional fractional part
+        e[+\-]?(\d+_)*\d+  # exponent part
+    |
+        \.(\d+_)*\d+  # required fractional part
+    )
+    """,
+    re.IGNORECASE | re.VERBOSE,
+)
+
+# internal the tokens and keep references to them
+TOKEN_ADD = intern("add")
+TOKEN_ASSIGN = intern("assign")
+TOKEN_COLON = intern("colon")
+TOKEN_COMMA = intern("comma")
+TOKEN_DIV = intern("div")
+TOKEN_DOT = intern("dot")
+TOKEN_EQ = intern("eq")
+TOKEN_FLOORDIV = intern("floordiv")
+TOKEN_GT = intern("gt")
+TOKEN_GTEQ = intern("gteq")
+TOKEN_LBRACE = intern("lbrace")
+TOKEN_LBRACKET = intern("lbracket")
+TOKEN_LPAREN = intern("lparen")
+TOKEN_LT = intern("lt")
+TOKEN_LTEQ = intern("lteq")
+TOKEN_MOD = intern("mod")
+TOKEN_MUL = intern("mul")
+TOKEN_NE = intern("ne")
+TOKEN_PIPE = intern("pipe")
+TOKEN_POW = intern("pow")
+TOKEN_RBRACE = intern("rbrace")
+TOKEN_RBRACKET = intern("rbracket")
+TOKEN_RPAREN = intern("rparen")
+TOKEN_SEMICOLON = intern("semicolon")
+TOKEN_SUB = intern("sub")
+TOKEN_TILDE = intern("tilde")
+TOKEN_WHITESPACE = intern("whitespace")
+TOKEN_FLOAT = intern("float")
+TOKEN_INTEGER = intern("integer")
+TOKEN_NAME = intern("name")
+TOKEN_STRING = intern("string")
+TOKEN_OPERATOR = intern("operator")
+TOKEN_BLOCK_BEGIN = intern("block_begin")
+TOKEN_BLOCK_END = intern("block_end")
+TOKEN_VARIABLE_BEGIN = intern("variable_begin")
+TOKEN_VARIABLE_END = intern("variable_end")
+TOKEN_RAW_BEGIN = intern("raw_begin")
+TOKEN_RAW_END = intern("raw_end")
+TOKEN_COMMENT_BEGIN = intern("comment_begin")
+TOKEN_COMMENT_END = intern("comment_end")
+TOKEN_COMMENT = intern("comment")
+TOKEN_LINESTATEMENT_BEGIN = intern("linestatement_begin")
+TOKEN_LINESTATEMENT_END = intern("linestatement_end")
+TOKEN_LINECOMMENT_BEGIN = intern("linecomment_begin")
+TOKEN_LINECOMMENT_END = intern("linecomment_end")
+TOKEN_LINECOMMENT = intern("linecomment")
+TOKEN_DATA = intern("data")
+TOKEN_INITIAL = intern("initial")
+TOKEN_EOF = intern("eof")
+
+# bind operators to token types
+operators = {
+    "+": TOKEN_ADD,
+    "-": TOKEN_SUB,
+    "/": TOKEN_DIV,
+    "//": TOKEN_FLOORDIV,
+    "*": TOKEN_MUL,
+    "%": TOKEN_MOD,
+    "**": TOKEN_POW,
+    "~": TOKEN_TILDE,
+    "[": TOKEN_LBRACKET,
+    "]": TOKEN_RBRACKET,
+    "(": TOKEN_LPAREN,
+    ")": TOKEN_RPAREN,
+    "{": TOKEN_LBRACE,
+    "}": TOKEN_RBRACE,
+    "==": TOKEN_EQ,
+    "!=": TOKEN_NE,
+    ">": TOKEN_GT,
+    ">=": TOKEN_GTEQ,
+    "<": TOKEN_LT,
+    "<=": TOKEN_LTEQ,
+    "=": TOKEN_ASSIGN,
+    ".": TOKEN_DOT,
+    ":": TOKEN_COLON,
+    "|": TOKEN_PIPE,
+    ",": TOKEN_COMMA,
+    ";": TOKEN_SEMICOLON,
+}
+
+reverse_operators = {v: k for k, v in operators.items()}
+assert len(operators) == len(reverse_operators), "operators dropped"
+operator_re = re.compile(
+    f"({'|'.join(re.escape(x) for x in sorted(operators, key=lambda x: -len(x)))})"
+)
+
+ignored_tokens = frozenset(
+    [
+        TOKEN_COMMENT_BEGIN,
+        TOKEN_COMMENT,
+        TOKEN_COMMENT_END,
+        TOKEN_WHITESPACE,
+        TOKEN_LINECOMMENT_BEGIN,
+        TOKEN_LINECOMMENT_END,
+        TOKEN_LINECOMMENT,
+    ]
+)
+ignore_if_empty = frozenset(
+    [TOKEN_WHITESPACE, TOKEN_DATA, TOKEN_COMMENT, TOKEN_LINECOMMENT]
+)
+
+
+def _describe_token_type(token_type: str) -> str:
+    if token_type in reverse_operators:
+        return reverse_operators[token_type]
+
+    return {
+        TOKEN_COMMENT_BEGIN: "begin of comment",
+        TOKEN_COMMENT_END: "end of comment",
+        TOKEN_COMMENT: "comment",
+        TOKEN_LINECOMMENT: "comment",
+        TOKEN_BLOCK_BEGIN: "begin of statement block",
+        TOKEN_BLOCK_END: "end of statement block",
+        TOKEN_VARIABLE_BEGIN: "begin of print statement",
+        TOKEN_VARIABLE_END: "end of print statement",
+        TOKEN_LINESTATEMENT_BEGIN: "begin of line statement",
+        TOKEN_LINESTATEMENT_END: "end of line statement",
+        TOKEN_DATA: "template data / text",
+        TOKEN_EOF: "end of template",
+    }.get(token_type, token_type)
+
+
+def describe_token(token: "Token") -> str:
+    """Returns a description of the token."""
+    if token.type == TOKEN_NAME:
+        return token.value
+
+    return _describe_token_type(token.type)
+
+
+def describe_token_expr(expr: str) -> str:
+    """Like `describe_token` but for token expressions."""
+    if ":" in expr:
+        type, value = expr.split(":", 1)
+
+        if type == TOKEN_NAME:
+            return value
+    else:
+        type = expr
+
+    return _describe_token_type(type)
+
+
+def count_newlines(value: str) -> int:
+    """Count the number of newline characters in the string.  This is
+    useful for extensions that filter a stream.
+    """
+    return len(newline_re.findall(value))
+
+
+def compile_rules(environment: "Environment") -> t.List[t.Tuple[str, str]]:
+    """Compiles all the rules from the environment into a list of rules."""
+    e = re.escape
+    rules = [
+        (
+            len(environment.comment_start_string),
+            TOKEN_COMMENT_BEGIN,
+            e(environment.comment_start_string),
+        ),
+        (
+            len(environment.block_start_string),
+            TOKEN_BLOCK_BEGIN,
+            e(environment.block_start_string),
+        ),
+        (
+            len(environment.variable_start_string),
+            TOKEN_VARIABLE_BEGIN,
+            e(environment.variable_start_string),
+        ),
+    ]
+
+    if environment.line_statement_prefix is not None:
+        rules.append(
+            (
+                len(environment.line_statement_prefix),
+                TOKEN_LINESTATEMENT_BEGIN,
+                r"^[ \t\v]*" + e(environment.line_statement_prefix),
+            )
+        )
+    if environment.line_comment_prefix is not None:
+        rules.append(
+            (
+                len(environment.line_comment_prefix),
+                TOKEN_LINECOMMENT_BEGIN,
+                r"(?:^|(?<=\S))[^\S\r\n]*" + e(environment.line_comment_prefix),
+            )
+        )
+
+    return [x[1:] for x in sorted(rules, reverse=True)]
+
+
+class Failure:
+    """Class that raises a `TemplateSyntaxError` if called.
+    Used by the `Lexer` to specify known errors.
+    """
+
+    def __init__(
+        self, message: str, cls: t.Type[TemplateSyntaxError] = TemplateSyntaxError
+    ) -> None:
+        self.message = message
+        self.error_class = cls
+
+    def __call__(self, lineno: int, filename: str) -> "te.NoReturn":
+        raise self.error_class(self.message, lineno, filename)
+
+
+class Token(t.NamedTuple):
+    lineno: int
+    type: str
+    value: str
+
+    def __str__(self) -> str:
+        return describe_token(self)
+
+    def test(self, expr: str) -> bool:
+        """Test a token against a token expression.  This can either be a
+        token type or ``'token_type:token_value'``.  This can only test
+        against string values and types.
+        """
+        # here we do a regular string equality check as test_any is usually
+        # passed an iterable of not interned strings.
+        if self.type == expr:
+            return True
+
+        if ":" in expr:
+            return expr.split(":", 1) == [self.type, self.value]
+
+        return False
+
+    def test_any(self, *iterable: str) -> bool:
+        """Test against multiple token expressions."""
+        return any(self.test(expr) for expr in iterable)
+
+
+class TokenStreamIterator:
+    """The iterator for tokenstreams.  Iterate over the stream
+    until the eof token is reached.
+    """
+
+    def __init__(self, stream: "TokenStream") -> None:
+        self.stream = stream
+
+    def __iter__(self) -> "TokenStreamIterator":
+        return self
+
+    def __next__(self) -> Token:
+        token = self.stream.current
+
+        if token.type is TOKEN_EOF:
+            self.stream.close()
+            raise StopIteration
+
+        next(self.stream)
+        return token
+
+
+class TokenStream:
+    """A token stream is an iterable that yields :class:`Token`\\s.  The
+    parser however does not iterate over it but calls :meth:`next` to go
+    one token ahead.  The current active token is stored as :attr:`current`.
+    """
+
+    def __init__(
+        self,
+        generator: t.Iterable[Token],
+        name: t.Optional[str],
+        filename: t.Optional[str],
+    ):
+        self._iter = iter(generator)
+        self._pushed: "te.Deque[Token]" = deque()
+        self.name = name
+        self.filename = filename
+        self.closed = False
+        self.current = Token(1, TOKEN_INITIAL, "")
+        next(self)
+
+    def __iter__(self) -> TokenStreamIterator:
+        return TokenStreamIterator(self)
+
+    def __bool__(self) -> bool:
+        return bool(self._pushed) or self.current.type is not TOKEN_EOF
+
+    @property
+    def eos(self) -> bool:
+        """Are we at the end of the stream?"""
+        return not self
+
+    def push(self, token: Token) -> None:
+        """Push a token back to the stream."""
+        self._pushed.append(token)
+
+    def look(self) -> Token:
+        """Look at the next token."""
+        old_token = next(self)
+        result = self.current
+        self.push(result)
+        self.current = old_token
+        return result
+
+    def skip(self, n: int = 1) -> None:
+        """Got n tokens ahead."""
+        for _ in range(n):
+            next(self)
+
+    def next_if(self, expr: str) -> t.Optional[Token]:
+        """Perform the token test and return the token if it matched.
+        Otherwise the return value is `None`.
+        """
+        if self.current.test(expr):
+            return next(self)
+
+        return None
+
+    def skip_if(self, expr: str) -> bool:
+        """Like :meth:`next_if` but only returns `True` or `False`."""
+        return self.next_if(expr) is not None
+
+    def __next__(self) -> Token:
+        """Go one token ahead and return the old one.
+
+        Use the built-in :func:`next` instead of calling this directly.
+        """
+        rv = self.current
+
+        if self._pushed:
+            self.current = self._pushed.popleft()
+        elif self.current.type is not TOKEN_EOF:
+            try:
+                self.current = next(self._iter)
+            except StopIteration:
+                self.close()
+
+        return rv
+
+    def close(self) -> None:
+        """Close the stream."""
+        self.current = Token(self.current.lineno, TOKEN_EOF, "")
+        self._iter = iter(())
+        self.closed = True
+
+    def expect(self, expr: str) -> Token:
+        """Expect a given token type and return it.  This accepts the same
+        argument as :meth:`jinja2.lexer.Token.test`.
+        """
+        if not self.current.test(expr):
+            expr = describe_token_expr(expr)
+
+            if self.current.type is TOKEN_EOF:
+                raise TemplateSyntaxError(
+                    f"unexpected end of template, expected {expr!r}.",
+                    self.current.lineno,
+                    self.name,
+                    self.filename,
+                )
+
+            raise TemplateSyntaxError(
+                f"expected token {expr!r}, got {describe_token(self.current)!r}",
+                self.current.lineno,
+                self.name,
+                self.filename,
+            )
+
+        return next(self)
+
+
+def get_lexer(environment: "Environment") -> "Lexer":
+    """Return a lexer which is probably cached."""
+    key = (
+        environment.block_start_string,
+        environment.block_end_string,
+        environment.variable_start_string,
+        environment.variable_end_string,
+        environment.comment_start_string,
+        environment.comment_end_string,
+        environment.line_statement_prefix,
+        environment.line_comment_prefix,
+        environment.trim_blocks,
+        environment.lstrip_blocks,
+        environment.newline_sequence,
+        environment.keep_trailing_newline,
+    )
+    lexer = _lexer_cache.get(key)
+
+    if lexer is None:
+        _lexer_cache[key] = lexer = Lexer(environment)
+
+    return lexer
+
+
+class OptionalLStrip(tuple):
+    """A special tuple for marking a point in the state that can have
+    lstrip applied.
+    """
+
+    __slots__ = ()
+
+    # Even though it looks like a no-op, creating instances fails
+    # without this.
+    def __new__(cls, *members, **kwargs):  # type: ignore
+        return super().__new__(cls, members)
+
+
+class _Rule(t.NamedTuple):
+    pattern: t.Pattern[str]
+    tokens: t.Union[str, t.Tuple[str, ...], t.Tuple[Failure]]
+    command: t.Optional[str]
+
+
+class Lexer:
+    """Class that implements a lexer for a given environment. Automatically
+    created by the environment class, usually you don't have to do that.
+
+    Note that the lexer is not automatically bound to an environment.
+    Multiple environments can share the same lexer.
+    """
+
+    def __init__(self, environment: "Environment") -> None:
+        # shortcuts
+        e = re.escape
+
+        def c(x: str) -> t.Pattern[str]:
+            return re.compile(x, re.M | re.S)
+
+        # lexing rules for tags
+        tag_rules: t.List[_Rule] = [
+            _Rule(whitespace_re, TOKEN_WHITESPACE, None),
+            _Rule(float_re, TOKEN_FLOAT, None),
+            _Rule(integer_re, TOKEN_INTEGER, None),
+            _Rule(name_re, TOKEN_NAME, None),
+            _Rule(string_re, TOKEN_STRING, None),
+            _Rule(operator_re, TOKEN_OPERATOR, None),
+        ]
+
+        # assemble the root lexing rule. because "|" is ungreedy
+        # we have to sort by length so that the lexer continues working
+        # as expected when we have parsing rules like <% for block and
+        # <%= for variables. (if someone wants asp like syntax)
+        # variables are just part of the rules if variable processing
+        # is required.
+        root_tag_rules = compile_rules(environment)
+
+        block_start_re = e(environment.block_start_string)
+        block_end_re = e(environment.block_end_string)
+        comment_end_re = e(environment.comment_end_string)
+        variable_end_re = e(environment.variable_end_string)
+
+        # block suffix if trimming is enabled
+        block_suffix_re = "\\n?" if environment.trim_blocks else ""
+
+        # If lstrip is enabled, it should not be applied if there is any
+        # non-whitespace between the newline and block.
+        self.lstrip_unless_re = c(r"[^ \t]") if environment.lstrip_blocks else None
+
+        self.newline_sequence = environment.newline_sequence
+        self.keep_trailing_newline = environment.keep_trailing_newline
+
+        root_raw_re = (
+            fr"(?P<raw_begin>{block_start_re}(\-|\+|)\s*raw\s*"
+            fr"(?:\-{block_end_re}\s*|{block_end_re}))"
+        )
+        root_parts_re = "|".join(
+            [root_raw_re] + [fr"(?P<{n}>{r}(\-|\+|))" for n, r in root_tag_rules]
+        )
+
+        # global lexing rules
+        self.rules: t.Dict[str, t.List[_Rule]] = {
+            "root": [
+                # directives
+                _Rule(
+                    c(fr"(.*?)(?:{root_parts_re})"),
+                    OptionalLStrip(TOKEN_DATA, "#bygroup"),  # type: ignore
+                    "#bygroup",
+                ),
+                # data
+                _Rule(c(".+"), TOKEN_DATA, None),
+            ],
+            # comments
+            TOKEN_COMMENT_BEGIN: [
+                _Rule(
+                    c(
+                        fr"(.*?)((?:\+{comment_end_re}|\-{comment_end_re}\s*"
+                        fr"|{comment_end_re}{block_suffix_re}))"
+                    ),
+                    (TOKEN_COMMENT, TOKEN_COMMENT_END),
+                    "#pop",
+                ),
+                _Rule(c(r"(.)"), (Failure("Missing end of comment tag"),), None),
+            ],
+            # blocks
+            TOKEN_BLOCK_BEGIN: [
+                _Rule(
+                    c(
+                        fr"(?:\+{block_end_re}|\-{block_end_re}\s*"
+                        fr"|{block_end_re}{block_suffix_re})"
+                    ),
+                    TOKEN_BLOCK_END,
+                    "#pop",
+                ),
+            ]
+            + tag_rules,
+            # variables
+            TOKEN_VARIABLE_BEGIN: [
+                _Rule(
+                    c(fr"\-{variable_end_re}\s*|{variable_end_re}"),
+                    TOKEN_VARIABLE_END,
+                    "#pop",
+                )
+            ]
+            + tag_rules,
+            # raw block
+            TOKEN_RAW_BEGIN: [
+                _Rule(
+                    c(
+                        fr"(.*?)((?:{block_start_re}(\-|\+|))\s*endraw\s*"
+                        fr"(?:\+{block_end_re}|\-{block_end_re}\s*"
+                        fr"|{block_end_re}{block_suffix_re}))"
+                    ),
+                    OptionalLStrip(TOKEN_DATA, TOKEN_RAW_END),  # type: ignore
+                    "#pop",
+                ),
+                _Rule(c(r"(.)"), (Failure("Missing end of raw directive"),), None),
+            ],
+            # line statements
+            TOKEN_LINESTATEMENT_BEGIN: [
+                _Rule(c(r"\s*(\n|$)"), TOKEN_LINESTATEMENT_END, "#pop")
+            ]
+            + tag_rules,
+            # line comments
+            TOKEN_LINECOMMENT_BEGIN: [
+                _Rule(
+                    c(r"(.*?)()(?=\n|$)"),
+                    (TOKEN_LINECOMMENT, TOKEN_LINECOMMENT_END),
+                    "#pop",
+                )
+            ],
+        }
+
+    def _normalize_newlines(self, value: str) -> str:
+        """Replace all newlines with the configured sequence in strings
+        and template data.
+        """
+        return newline_re.sub(self.newline_sequence, value)
+
+    def tokenize(
+        self,
+        source: str,
+        name: t.Optional[str] = None,
+        filename: t.Optional[str] = None,
+        state: t.Optional[str] = None,
+    ) -> TokenStream:
+        """Calls tokeniter + tokenize and wraps it in a token stream."""
+        stream = self.tokeniter(source, name, filename, state)
+        return TokenStream(self.wrap(stream, name, filename), name, filename)
+
+    def wrap(
+        self,
+        stream: t.Iterable[t.Tuple[int, str, str]],
+        name: t.Optional[str] = None,
+        filename: t.Optional[str] = None,
+    ) -> t.Iterator[Token]:
+        """This is called with the stream as returned by `tokenize` and wraps
+        every token in a :class:`Token` and converts the value.
+        """
+        for lineno, token, value_str in stream:
+            if token in ignored_tokens:
+                continue
+
+            value: t.Any = value_str
+
+            if token == TOKEN_LINESTATEMENT_BEGIN:
+                token = TOKEN_BLOCK_BEGIN
+            elif token == TOKEN_LINESTATEMENT_END:
+                token = TOKEN_BLOCK_END
+            # we are not interested in those tokens in the parser
+            elif token in (TOKEN_RAW_BEGIN, TOKEN_RAW_END):
+                continue
+            elif token == TOKEN_DATA:
+                value = self._normalize_newlines(value_str)
+            elif token == "keyword":
+                token = value_str
+            elif token == TOKEN_NAME:
+                value = value_str
+
+                if not value.isidentifier():
+                    raise TemplateSyntaxError(
+                        "Invalid character in identifier", lineno, name, filename
+                    )
+            elif token == TOKEN_STRING:
+                # try to unescape string
+                try:
+                    value = (
+                        self._normalize_newlines(value_str[1:-1])
+                        .encode("ascii", "backslashreplace")
+                        .decode("unicode-escape")
+                    )
+                except Exception as e:
+                    msg = str(e).split(":")[-1].strip()
+                    raise TemplateSyntaxError(msg, lineno, name, filename) from e
+            elif token == TOKEN_INTEGER:
+                value = int(value_str.replace("_", ""), 0)
+            elif token == TOKEN_FLOAT:
+                # remove all "_" first to support more Python versions
+                value = literal_eval(value_str.replace("_", ""))
+            elif token == TOKEN_OPERATOR:
+                token = operators[value_str]
+
+            yield Token(lineno, token, value)
+
+    def tokeniter(
+        self,
+        source: str,
+        name: t.Optional[str],
+        filename: t.Optional[str] = None,
+        state: t.Optional[str] = None,
+    ) -> t.Iterator[t.Tuple[int, str, str]]:
+        """This method tokenizes the text and returns the tokens in a
+        generator. Use this method if you just want to tokenize a template.
+
+        .. versionchanged:: 3.0
+            Only ``\\n``, ``\\r\\n`` and ``\\r`` are treated as line
+            breaks.
+        """
+        lines = newline_re.split(source)[::2]
+
+        if not self.keep_trailing_newline and lines[-1] == "":
+            del lines[-1]
+
+        source = "\n".join(lines)
+        pos = 0
+        lineno = 1
+        stack = ["root"]
+
+        if state is not None and state != "root":
+            assert state in ("variable", "block"), "invalid state"
+            stack.append(state + "_begin")
+
+        statetokens = self.rules[stack[-1]]
+        source_length = len(source)
+        balancing_stack: t.List[str] = []
+        lstrip_unless_re = self.lstrip_unless_re
+        newlines_stripped = 0
+        line_starting = True
+
+        while True:
+            # tokenizer loop
+            for regex, tokens, new_state in statetokens:
+                m = regex.match(source, pos)
+
+                # if no match we try again with the next rule
+                if m is None:
+                    continue
+
+                # we only match blocks and variables if braces / parentheses
+                # are balanced. continue parsing with the lower rule which
+                # is the operator rule. do this only if the end tags look
+                # like operators
+                if balancing_stack and tokens in (
+                    TOKEN_VARIABLE_END,
+                    TOKEN_BLOCK_END,
+                    TOKEN_LINESTATEMENT_END,
+                ):
+                    continue
+
+                # tuples support more options
+                if isinstance(tokens, tuple):
+                    groups = m.groups()
+
+                    if isinstance(tokens, OptionalLStrip):
+                        # Rule supports lstrip. Match will look like
+                        # text, block type, whitespace control, type, control, ...
+                        text = groups[0]
+                        # Skipping the text and first type, every other group is the
+                        # whitespace control for each type. One of the groups will be
+                        # -, +, or empty string instead of None.
+                        strip_sign = next(g for g in groups[2::2] if g is not None)
+
+                        if strip_sign == "-":
+                            # Strip all whitespace between the text and the tag.
+                            stripped = text.rstrip()
+                            newlines_stripped = text[len(stripped) :].count("\n")
+                            groups = [stripped, *groups[1:]]
+                        elif (
+                            # Not marked for preserving whitespace.
+                            strip_sign != "+"
+                            # lstrip is enabled.
+                            and lstrip_unless_re is not None
+                            # Not a variable expression.
+                            and not m.groupdict().get(TOKEN_VARIABLE_BEGIN)
+                        ):
+                            # The start of text between the last newline and the tag.
+                            l_pos = text.rfind("\n") + 1
+
+                            if l_pos > 0 or line_starting:
+                                # If there's only whitespace between the newline and the
+                                # tag, strip it.
+                                if not lstrip_unless_re.search(text, l_pos):
+                                    groups = [text[:l_pos], *groups[1:]]
+
+                    for idx, token in enumerate(tokens):
+                        # failure group
+                        if token.__class__ is Failure:
+                            raise token(lineno, filename)
+                        # bygroup is a bit more complex, in that case we
+                        # yield for the current token the first named
+                        # group that matched
+                        elif token == "#bygroup":
+                            for key, value in m.groupdict().items():
+                                if value is not None:
+                                    yield lineno, key, value
+                                    lineno += value.count("\n")
+                                    break
+                            else:
+                                raise RuntimeError(
+                                    f"{regex!r} wanted to resolve the token dynamically"
+                                    " but no group matched"
+                                )
+                        # normal group
+                        else:
+                            data = groups[idx]
+
+                            if data or token not in ignore_if_empty:
+                                yield lineno, token, data
+
+                            lineno += data.count("\n") + newlines_stripped
+                            newlines_stripped = 0
+
+                # strings as token just are yielded as it.
+                else:
+                    data = m.group()
+
+                    # update brace/parentheses balance
+                    if tokens == TOKEN_OPERATOR:
+                        if data == "{":
+                            balancing_stack.append("}")
+                        elif data == "(":
+                            balancing_stack.append(")")
+                        elif data == "[":
+                            balancing_stack.append("]")
+                        elif data in ("}", ")", "]"):
+                            if not balancing_stack:
+                                raise TemplateSyntaxError(
+                                    f"unexpected '{data}'", lineno, name, filename
+                                )
+
+                            expected_op = balancing_stack.pop()
+
+                            if expected_op != data:
+                                raise TemplateSyntaxError(
+                                    f"unexpected '{data}', expected '{expected_op}'",
+                                    lineno,
+                                    name,
+                                    filename,
+                                )
+
+                    # yield items
+                    if data or tokens not in ignore_if_empty:
+                        yield lineno, tokens, data
+
+                    lineno += data.count("\n")
+
+                line_starting = m.group()[-1:] == "\n"
+                # fetch new position into new variable so that we can check
+                # if there is a internal parsing error which would result
+                # in an infinite loop
+                pos2 = m.end()
+
+                # handle state changes
+                if new_state is not None:
+                    # remove the uppermost state
+                    if new_state == "#pop":
+                        stack.pop()
+                    # resolve the new state by group checking
+                    elif new_state == "#bygroup":
+                        for key, value in m.groupdict().items():
+                            if value is not None:
+                                stack.append(key)
+                                break
+                        else:
+                            raise RuntimeError(
+                                f"{regex!r} wanted to resolve the new state dynamically"
+                                f" but no group matched"
+                            )
+                    # direct state name given
+                    else:
+                        stack.append(new_state)
+
+                    statetokens = self.rules[stack[-1]]
+                # we are still at the same position and no stack change.
+                # this means a loop without break condition, avoid that and
+                # raise error
+                elif pos2 == pos:
+                    raise RuntimeError(
+                        f"{regex!r} yielded empty string without stack change"
+                    )
+
+                # publish new function and start again
+                pos = pos2
+                break
+            # if loop terminated without break we haven't found a single match
+            # either we are at the end of the file or we have a problem
+            else:
+                # end of text
+                if pos >= source_length:
+                    return
+
+                # something went wrong
+                raise TemplateSyntaxError(
+                    f"unexpected char {source[pos]!r} at {pos}", lineno, name, filename
+                )
diff --git a/lib/spack/external/_vendoring/jinja2/loaders.py b/lib/spack/external/_vendoring/jinja2/loaders.py
new file mode 100644
index 0000000000..4fac3a0966
--- /dev/null
+++ b/lib/spack/external/_vendoring/jinja2/loaders.py
@@ -0,0 +1,652 @@
+"""API and implementations for loading templates from different data
+sources.
+"""
+import importlib.util
+import os
+import sys
+import typing as t
+import weakref
+import zipimport
+from collections import abc
+from hashlib import sha1
+from importlib import import_module
+from types import ModuleType
+
+from .exceptions import TemplateNotFound
+from .utils import internalcode
+from .utils import open_if_exists
+
+if t.TYPE_CHECKING:
+    from .environment import Environment
+    from .environment import Template
+
+
+def split_template_path(template: str) -> t.List[str]:
+    """Split a path into segments and perform a sanity check.  If it detects
+    '..' in the path it will raise a `TemplateNotFound` error.
+    """
+    pieces = []
+    for piece in template.split("/"):
+        if (
+            os.path.sep in piece
+            or (os.path.altsep and os.path.altsep in piece)
+            or piece == os.path.pardir
+        ):
+            raise TemplateNotFound(template)
+        elif piece and piece != ".":
+            pieces.append(piece)
+    return pieces
+
+
+class BaseLoader:
+    """Baseclass for all loaders.  Subclass this and override `get_source` to
+    implement a custom loading mechanism.  The environment provides a
+    `get_template` method that calls the loader's `load` method to get the
+    :class:`Template` object.
+
+    A very basic example for a loader that looks up templates on the file
+    system could look like this::
+
+        from jinja2 import BaseLoader, TemplateNotFound
+        from os.path import join, exists, getmtime
+
+        class MyLoader(BaseLoader):
+
+            def __init__(self, path):
+                self.path = path
+
+            def get_source(self, environment, template):
+                path = join(self.path, template)
+                if not exists(path):
+                    raise TemplateNotFound(template)
+                mtime = getmtime(path)
+                with open(path) as f:
+                    source = f.read()
+                return source, path, lambda: mtime == getmtime(path)
+    """
+
+    #: if set to `False` it indicates that the loader cannot provide access
+    #: to the source of templates.
+    #:
+    #: .. versionadded:: 2.4
+    has_source_access = True
+
+    def get_source(
+        self, environment: "Environment", template: str
+    ) -> t.Tuple[str, t.Optional[str], t.Optional[t.Callable[[], bool]]]:
+        """Get the template source, filename and reload helper for a template.
+        It's passed the environment and template name and has to return a
+        tuple in the form ``(source, filename, uptodate)`` or raise a
+        `TemplateNotFound` error if it can't locate the template.
+
+        The source part of the returned tuple must be the source of the
+        template as a string. The filename should be the name of the
+        file on the filesystem if it was loaded from there, otherwise
+        ``None``. The filename is used by Python for the tracebacks
+        if no loader extension is used.
+
+        The last item in the tuple is the `uptodate` function.  If auto
+        reloading is enabled it's always called to check if the template
+        changed.  No arguments are passed so the function must store the
+        old state somewhere (for example in a closure).  If it returns `False`
+        the template will be reloaded.
+        """
+        if not self.has_source_access:
+            raise RuntimeError(
+                f"{type(self).__name__} cannot provide access to the source"
+            )
+        raise TemplateNotFound(template)
+
+    def list_templates(self) -> t.List[str]:
+        """Iterates over all templates.  If the loader does not support that
+        it should raise a :exc:`TypeError` which is the default behavior.
+        """
+        raise TypeError("this loader cannot iterate over all templates")
+
+    @internalcode
+    def load(
+        self,
+        environment: "Environment",
+        name: str,
+        globals: t.Optional[t.MutableMapping[str, t.Any]] = None,
+    ) -> "Template":
+        """Loads a template.  This method looks up the template in the cache
+        or loads one by calling :meth:`get_source`.  Subclasses should not
+        override this method as loaders working on collections of other
+        loaders (such as :class:`PrefixLoader` or :class:`ChoiceLoader`)
+        will not call this method but `get_source` directly.
+        """
+        code = None
+        if globals is None:
+            globals = {}
+
+        # first we try to get the source for this template together
+        # with the filename and the uptodate function.
+        source, filename, uptodate = self.get_source(environment, name)
+
+        # try to load the code from the bytecode cache if there is a
+        # bytecode cache configured.
+        bcc = environment.bytecode_cache
+        if bcc is not None:
+            bucket = bcc.get_bucket(environment, name, filename, source)
+            code = bucket.code
+
+        # if we don't have code so far (not cached, no longer up to
+        # date) etc. we compile the template
+        if code is None:
+            code = environment.compile(source, name, filename)
+
+        # if the bytecode cache is available and the bucket doesn't
+        # have a code so far, we give the bucket the new code and put
+        # it back to the bytecode cache.
+        if bcc is not None and bucket.code is None:
+            bucket.code = code
+            bcc.set_bucket(bucket)
+
+        return environment.template_class.from_code(
+            environment, code, globals, uptodate
+        )
+
+
+class FileSystemLoader(BaseLoader):
+    """Load templates from a directory in the file system.
+
+    The path can be relative or absolute. Relative paths are relative to
+    the current working directory.
+
+    .. code-block:: python
+
+        loader = FileSystemLoader("templates")
+
+    A list of paths can be given. The directories will be searched in
+    order, stopping at the first matching template.
+
+    .. code-block:: python
+
+        loader = FileSystemLoader(["/override/templates", "/default/templates"])
+
+    :param searchpath: A path, or list of paths, to the directory that
+        contains the templates.
+    :param encoding: Use this encoding to read the text from template
+        files.
+    :param followlinks: Follow symbolic links in the path.
+
+    .. versionchanged:: 2.8
+        Added the ``followlinks`` parameter.
+    """
+
+    def __init__(
+        self,
+        searchpath: t.Union[str, os.PathLike, t.Sequence[t.Union[str, os.PathLike]]],
+        encoding: str = "utf-8",
+        followlinks: bool = False,
+    ) -> None:
+        if not isinstance(searchpath, abc.Iterable) or isinstance(searchpath, str):
+            searchpath = [searchpath]
+
+        self.searchpath = [os.fspath(p) for p in searchpath]
+        self.encoding = encoding
+        self.followlinks = followlinks
+
+    def get_source(
+        self, environment: "Environment", template: str
+    ) -> t.Tuple[str, str, t.Callable[[], bool]]:
+        pieces = split_template_path(template)
+        for searchpath in self.searchpath:
+            filename = os.path.join(searchpath, *pieces)
+            f = open_if_exists(filename)
+            if f is None:
+                continue
+            try:
+                contents = f.read().decode(self.encoding)
+            finally:
+                f.close()
+
+            mtime = os.path.getmtime(filename)
+
+            def uptodate() -> bool:
+                try:
+                    return os.path.getmtime(filename) == mtime
+                except OSError:
+                    return False
+
+            return contents, filename, uptodate
+        raise TemplateNotFound(template)
+
+    def list_templates(self) -> t.List[str]:
+        found = set()
+        for searchpath in self.searchpath:
+            walk_dir = os.walk(searchpath, followlinks=self.followlinks)
+            for dirpath, _, filenames in walk_dir:
+                for filename in filenames:
+                    template = (
+                        os.path.join(dirpath, filename)[len(searchpath) :]
+                        .strip(os.path.sep)
+                        .replace(os.path.sep, "/")
+                    )
+                    if template[:2] == "./":
+                        template = template[2:]
+                    if template not in found:
+                        found.add(template)
+        return sorted(found)
+
+
+class PackageLoader(BaseLoader):
+    """Load templates from a directory in a Python package.
+
+    :param package_name: Import name of the package that contains the
+        template directory.
+    :param package_path: Directory within the imported package that
+        contains the templates.
+    :param encoding: Encoding of template files.
+
+    The following example looks up templates in the ``pages`` directory
+    within the ``project.ui`` package.
+
+    .. code-block:: python
+
+        loader = PackageLoader("project.ui", "pages")
+
+    Only packages installed as directories (standard pip behavior) or
+    zip/egg files (less common) are supported. The Python API for
+    introspecting data in packages is too limited to support other
+    installation methods the way this loader requires.
+
+    There is limited support for :pep:`420` namespace packages. The
+    template directory is assumed to only be in one namespace
+    contributor. Zip files contributing to a namespace are not
+    supported.
+
+    .. versionchanged:: 3.0
+        No longer uses ``setuptools`` as a dependency.
+
+    .. versionchanged:: 3.0
+        Limited PEP 420 namespace package support.
+    """
+
+    def __init__(
+        self,
+        package_name: str,
+        package_path: "str" = "templates",
+        encoding: str = "utf-8",
+    ) -> None:
+        package_path = os.path.normpath(package_path).rstrip(os.path.sep)
+
+        # normpath preserves ".", which isn't valid in zip paths.
+        if package_path == os.path.curdir:
+            package_path = ""
+        elif package_path[:2] == os.path.curdir + os.path.sep:
+            package_path = package_path[2:]
+
+        self.package_path = package_path
+        self.package_name = package_name
+        self.encoding = encoding
+
+        # Make sure the package exists. This also makes namespace
+        # packages work, otherwise get_loader returns None.
+        import_module(package_name)
+        spec = importlib.util.find_spec(package_name)
+        assert spec is not None, "An import spec was not found for the package."
+        loader = spec.loader
+        assert loader is not None, "A loader was not found for the package."
+        self._loader = loader
+        self._archive = None
+        template_root = None
+
+        if isinstance(loader, zipimport.zipimporter):
+            self._archive = loader.archive
+            pkgdir = next(iter(spec.submodule_search_locations))  # type: ignore
+            template_root = os.path.join(pkgdir, package_path)
+        else:
+            roots: t.List[str] = []
+
+            # One element for regular packages, multiple for namespace
+            # packages, or None for single module file.
+            if spec.submodule_search_locations:
+                roots.extend(spec.submodule_search_locations)
+            # A single module file, use the parent directory instead.
+            elif spec.origin is not None:
+                roots.append(os.path.dirname(spec.origin))
+
+            for root in roots:
+                root = os.path.join(root, package_path)
+
+                if os.path.isdir(root):
+                    template_root = root
+                    break
+
+        if template_root is None:
+            raise ValueError(
+                f"The {package_name!r} package was not installed in a"
+                " way that PackageLoader understands."
+            )
+
+        self._template_root = template_root
+
+    def get_source(
+        self, environment: "Environment", template: str
+    ) -> t.Tuple[str, str, t.Optional[t.Callable[[], bool]]]:
+        p = os.path.join(self._template_root, *split_template_path(template))
+        up_to_date: t.Optional[t.Callable[[], bool]]
+
+        if self._archive is None:
+            # Package is a directory.
+            if not os.path.isfile(p):
+                raise TemplateNotFound(template)
+
+            with open(p, "rb") as f:
+                source = f.read()
+
+            mtime = os.path.getmtime(p)
+
+            def up_to_date() -> bool:
+                return os.path.isfile(p) and os.path.getmtime(p) == mtime
+
+        else:
+            # Package is a zip file.
+            try:
+                source = self._loader.get_data(p)  # type: ignore
+            except OSError as e:
+                raise TemplateNotFound(template) from e
+
+            # Could use the zip's mtime for all template mtimes, but
+            # would need to safely reload the module if it's out of
+            # date, so just report it as always current.
+            up_to_date = None
+
+        return source.decode(self.encoding), p, up_to_date
+
+    def list_templates(self) -> t.List[str]:
+        results: t.List[str] = []
+
+        if self._archive is None:
+            # Package is a directory.
+            offset = len(self._template_root)
+
+            for dirpath, _, filenames in os.walk(self._template_root):
+                dirpath = dirpath[offset:].lstrip(os.path.sep)
+                results.extend(
+                    os.path.join(dirpath, name).replace(os.path.sep, "/")
+                    for name in filenames
+                )
+        else:
+            if not hasattr(self._loader, "_files"):
+                raise TypeError(
+                    "This zip import does not have the required"
+                    " metadata to list templates."
+                )
+
+            # Package is a zip file.
+            prefix = (
+                self._template_root[len(self._archive) :].lstrip(os.path.sep)
+                + os.path.sep
+            )
+            offset = len(prefix)
+
+            for name in self._loader._files.keys():  # type: ignore
+                # Find names under the templates directory that aren't directories.
+                if name.startswith(prefix) and name[-1] != os.path.sep:
+                    results.append(name[offset:].replace(os.path.sep, "/"))
+
+        results.sort()
+        return results
+
+
+class DictLoader(BaseLoader):
+    """Loads a template from a Python dict mapping template names to
+    template source.  This loader is useful for unittesting:
+
+    >>> loader = DictLoader({'index.html': 'source here'})
+
+    Because auto reloading is rarely useful this is disabled per default.
+    """
+
+    def __init__(self, mapping: t.Mapping[str, str]) -> None:
+        self.mapping = mapping
+
+    def get_source(
+        self, environment: "Environment", template: str
+    ) -> t.Tuple[str, None, t.Callable[[], bool]]:
+        if template in self.mapping:
+            source = self.mapping[template]
+            return source, None, lambda: source == self.mapping.get(template)
+        raise TemplateNotFound(template)
+
+    def list_templates(self) -> t.List[str]:
+        return sorted(self.mapping)
+
+
+class FunctionLoader(BaseLoader):
+    """A loader that is passed a function which does the loading.  The
+    function receives the name of the template and has to return either
+    a string with the template source, a tuple in the form ``(source,
+    filename, uptodatefunc)`` or `None` if the template does not exist.
+
+    >>> def load_template(name):
+    ...     if name == 'index.html':
+    ...         return '...'
+    ...
+    >>> loader = FunctionLoader(load_template)
+
+    The `uptodatefunc` is a function that is called if autoreload is enabled
+    and has to return `True` if the template is still up to date.  For more
+    details have a look at :meth:`BaseLoader.get_source` which has the same
+    return value.
+    """
+
+    def __init__(
+        self,
+        load_func: t.Callable[
+            [str],
+            t.Optional[
+                t.Union[
+                    str, t.Tuple[str, t.Optional[str], t.Optional[t.Callable[[], bool]]]
+                ]
+            ],
+        ],
+    ) -> None:
+        self.load_func = load_func
+
+    def get_source(
+        self, environment: "Environment", template: str
+    ) -> t.Tuple[str, t.Optional[str], t.Optional[t.Callable[[], bool]]]:
+        rv = self.load_func(template)
+
+        if rv is None:
+            raise TemplateNotFound(template)
+
+        if isinstance(rv, str):
+            return rv, None, None
+
+        return rv
+
+
+class PrefixLoader(BaseLoader):
+    """A loader that is passed a dict of loaders where each loader is bound
+    to a prefix.  The prefix is delimited from the template by a slash per
+    default, which can be changed by setting the `delimiter` argument to
+    something else::
+
+        loader = PrefixLoader({
+            'app1':     PackageLoader('mypackage.app1'),
+            'app2':     PackageLoader('mypackage.app2')
+        })
+
+    By loading ``'app1/index.html'`` the file from the app1 package is loaded,
+    by loading ``'app2/index.html'`` the file from the second.
+    """
+
+    def __init__(
+        self, mapping: t.Mapping[str, BaseLoader], delimiter: str = "/"
+    ) -> None:
+        self.mapping = mapping
+        self.delimiter = delimiter
+
+    def get_loader(self, template: str) -> t.Tuple[BaseLoader, str]:
+        try:
+            prefix, name = template.split(self.delimiter, 1)
+            loader = self.mapping[prefix]
+        except (ValueError, KeyError) as e:
+            raise TemplateNotFound(template) from e
+        return loader, name
+
+    def get_source(
+        self, environment: "Environment", template: str
+    ) -> t.Tuple[str, t.Optional[str], t.Optional[t.Callable[[], bool]]]:
+        loader, name = self.get_loader(template)
+        try:
+            return loader.get_source(environment, name)
+        except TemplateNotFound as e:
+            # re-raise the exception with the correct filename here.
+            # (the one that includes the prefix)
+            raise TemplateNotFound(template) from e
+
+    @internalcode
+    def load(
+        self,
+        environment: "Environment",
+        name: str,
+        globals: t.Optional[t.MutableMapping[str, t.Any]] = None,
+    ) -> "Template":
+        loader, local_name = self.get_loader(name)
+        try:
+            return loader.load(environment, local_name, globals)
+        except TemplateNotFound as e:
+            # re-raise the exception with the correct filename here.
+            # (the one that includes the prefix)
+            raise TemplateNotFound(name) from e
+
+    def list_templates(self) -> t.List[str]:
+        result = []
+        for prefix, loader in self.mapping.items():
+            for template in loader.list_templates():
+                result.append(prefix + self.delimiter + template)
+        return result
+
+
+class ChoiceLoader(BaseLoader):
+    """This loader works like the `PrefixLoader` just that no prefix is
+    specified.  If a template could not be found by one loader the next one
+    is tried.
+
+    >>> loader = ChoiceLoader([
+    ...     FileSystemLoader('/path/to/user/templates'),
+    ...     FileSystemLoader('/path/to/system/templates')
+    ... ])
+
+    This is useful if you want to allow users to override builtin templates
+    from a different location.
+    """
+
+    def __init__(self, loaders: t.Sequence[BaseLoader]) -> None:
+        self.loaders = loaders
+
+    def get_source(
+        self, environment: "Environment", template: str
+    ) -> t.Tuple[str, t.Optional[str], t.Optional[t.Callable[[], bool]]]:
+        for loader in self.loaders:
+            try:
+                return loader.get_source(environment, template)
+            except TemplateNotFound:
+                pass
+        raise TemplateNotFound(template)
+
+    @internalcode
+    def load(
+        self,
+        environment: "Environment",
+        name: str,
+        globals: t.Optional[t.MutableMapping[str, t.Any]] = None,
+    ) -> "Template":
+        for loader in self.loaders:
+            try:
+                return loader.load(environment, name, globals)
+            except TemplateNotFound:
+                pass
+        raise TemplateNotFound(name)
+
+    def list_templates(self) -> t.List[str]:
+        found = set()
+        for loader in self.loaders:
+            found.update(loader.list_templates())
+        return sorted(found)
+
+
+class _TemplateModule(ModuleType):
+    """Like a normal module but with support for weak references"""
+
+
+class ModuleLoader(BaseLoader):
+    """This loader loads templates from precompiled templates.
+
+    Example usage:
+
+    >>> loader = ChoiceLoader([
+    ...     ModuleLoader('/path/to/compiled/templates'),
+    ...     FileSystemLoader('/path/to/templates')
+    ... ])
+
+    Templates can be precompiled with :meth:`Environment.compile_templates`.
+    """
+
+    has_source_access = False
+
+    def __init__(
+        self, path: t.Union[str, os.PathLike, t.Sequence[t.Union[str, os.PathLike]]]
+    ) -> None:
+        package_name = f"_jinja2_module_templates_{id(self):x}"
+
+        # create a fake module that looks for the templates in the
+        # path given.
+        mod = _TemplateModule(package_name)
+
+        if not isinstance(path, abc.Iterable) or isinstance(path, str):
+            path = [path]
+
+        mod.__path__ = [os.fspath(p) for p in path]  # type: ignore
+
+        sys.modules[package_name] = weakref.proxy(
+            mod, lambda x: sys.modules.pop(package_name, None)
+        )
+
+        # the only strong reference, the sys.modules entry is weak
+        # so that the garbage collector can remove it once the
+        # loader that created it goes out of business.
+        self.module = mod
+        self.package_name = package_name
+
+    @staticmethod
+    def get_template_key(name: str) -> str:
+        return "tmpl_" + sha1(name.encode("utf-8")).hexdigest()
+
+    @staticmethod
+    def get_module_filename(name: str) -> str:
+        return ModuleLoader.get_template_key(name) + ".py"
+
+    @internalcode
+    def load(
+        self,
+        environment: "Environment",
+        name: str,
+        globals: t.Optional[t.MutableMapping[str, t.Any]] = None,
+    ) -> "Template":
+        key = self.get_template_key(name)
+        module = f"{self.package_name}.{key}"
+        mod = getattr(self.module, module, None)
+
+        if mod is None:
+            try:
+                mod = __import__(module, None, None, ["root"])
+            except ImportError as e:
+                raise TemplateNotFound(name) from e
+
+            # remove the entry from sys.modules, we only want the attribute
+            # on the module object we have stored on the loader.
+            sys.modules.pop(module, None)
+
+        if globals is None:
+            globals = {}
+
+        return environment.template_class.from_module_dict(
+            environment, mod.__dict__, globals
+        )
diff --git a/lib/spack/external/_vendoring/jinja2/meta.py b/lib/spack/external/_vendoring/jinja2/meta.py
new file mode 100644
index 0000000000..0057d6eaba
--- /dev/null
+++ b/lib/spack/external/_vendoring/jinja2/meta.py
@@ -0,0 +1,111 @@
+"""Functions that expose information about templates that might be
+interesting for introspection.
+"""
+import typing as t
+
+from . import nodes
+from .compiler import CodeGenerator
+from .compiler import Frame
+
+if t.TYPE_CHECKING:
+    from .environment import Environment
+
+
+class TrackingCodeGenerator(CodeGenerator):
+    """We abuse the code generator for introspection."""
+
+    def __init__(self, environment: "Environment") -> None:
+        super().__init__(environment, "<introspection>", "<introspection>")
+        self.undeclared_identifiers: t.Set[str] = set()
+
+    def write(self, x: str) -> None:
+        """Don't write."""
+
+    def enter_frame(self, frame: Frame) -> None:
+        """Remember all undeclared identifiers."""
+        super().enter_frame(frame)
+
+        for _, (action, param) in frame.symbols.loads.items():
+            if action == "resolve" and param not in self.environment.globals:
+                self.undeclared_identifiers.add(param)
+
+
+def find_undeclared_variables(ast: nodes.Template) -> t.Set[str]:
+    """Returns a set of all variables in the AST that will be looked up from
+    the context at runtime.  Because at compile time it's not known which
+    variables will be used depending on the path the execution takes at
+    runtime, all variables are returned.
+
+    >>> from jinja2 import Environment, meta
+    >>> env = Environment()
+    >>> ast = env.parse('{% set foo = 42 %}{{ bar + foo }}')
+    >>> meta.find_undeclared_variables(ast) == {'bar'}
+    True
+
+    .. admonition:: Implementation
+
+       Internally the code generator is used for finding undeclared variables.
+       This is good to know because the code generator might raise a
+       :exc:`TemplateAssertionError` during compilation and as a matter of
+       fact this function can currently raise that exception as well.
+    """
+    codegen = TrackingCodeGenerator(ast.environment)  # type: ignore
+    codegen.visit(ast)
+    return codegen.undeclared_identifiers
+
+
+_ref_types = (nodes.Extends, nodes.FromImport, nodes.Import, nodes.Include)
+_RefType = t.Union[nodes.Extends, nodes.FromImport, nodes.Import, nodes.Include]
+
+
+def find_referenced_templates(ast: nodes.Template) -> t.Iterator[t.Optional[str]]:
+    """Finds all the referenced templates from the AST.  This will return an
+    iterator over all the hardcoded template extensions, inclusions and
+    imports.  If dynamic inheritance or inclusion is used, `None` will be
+    yielded.
+
+    >>> from jinja2 import Environment, meta
+    >>> env = Environment()
+    >>> ast = env.parse('{% extends "layout.html" %}{% include helper %}')
+    >>> list(meta.find_referenced_templates(ast))
+    ['layout.html', None]
+
+    This function is useful for dependency tracking.  For example if you want
+    to rebuild parts of the website after a layout template has changed.
+    """
+    template_name: t.Any
+
+    for node in ast.find_all(_ref_types):
+        template: nodes.Expr = node.template  # type: ignore
+
+        if not isinstance(template, nodes.Const):
+            # a tuple with some non consts in there
+            if isinstance(template, (nodes.Tuple, nodes.List)):
+                for template_name in template.items:
+                    # something const, only yield the strings and ignore
+                    # non-string consts that really just make no sense
+                    if isinstance(template_name, nodes.Const):
+                        if isinstance(template_name.value, str):
+                            yield template_name.value
+                    # something dynamic in there
+                    else:
+                        yield None
+            # something dynamic we don't know about here
+            else:
+                yield None
+            continue
+        # constant is a basestring, direct template name
+        if isinstance(template.value, str):
+            yield template.value
+        # a tuple or list (latter *should* not happen) made of consts,
+        # yield the consts that are strings.  We could warn here for
+        # non string values
+        elif isinstance(node, nodes.Include) and isinstance(
+            template.value, (tuple, list)
+        ):
+            for template_name in template.value:
+                if isinstance(template_name, str):
+                    yield template_name
+        # something else we don't care about, we could warn here
+        else:
+            yield None
diff --git a/lib/spack/external/_vendoring/jinja2/nativetypes.py b/lib/spack/external/_vendoring/jinja2/nativetypes.py
new file mode 100644
index 0000000000..20597d50ab
--- /dev/null
+++ b/lib/spack/external/_vendoring/jinja2/nativetypes.py
@@ -0,0 +1,124 @@
+import typing as t
+from ast import literal_eval
+from ast import parse
+from itertools import chain
+from itertools import islice
+
+from . import nodes
+from .compiler import CodeGenerator
+from .compiler import Frame
+from .compiler import has_safe_repr
+from .environment import Environment
+from .environment import Template
+
+
+def native_concat(values: t.Iterable[t.Any]) -> t.Optional[t.Any]:
+    """Return a native Python type from the list of compiled nodes. If
+    the result is a single node, its value is returned. Otherwise, the
+    nodes are concatenated as strings. If the result can be parsed with
+    :func:`ast.literal_eval`, the parsed value is returned. Otherwise,
+    the string is returned.
+
+    :param values: Iterable of outputs to concatenate.
+    """
+    head = list(islice(values, 2))
+
+    if not head:
+        return None
+
+    if len(head) == 1:
+        raw = head[0]
+        if not isinstance(raw, str):
+            return raw
+    else:
+        raw = "".join([str(v) for v in chain(head, values)])
+
+    try:
+        return literal_eval(
+            # In Python 3.10+ ast.literal_eval removes leading spaces/tabs
+            # from the given string. For backwards compatibility we need to
+            # parse the string ourselves without removing leading spaces/tabs.
+            parse(raw, mode="eval")
+        )
+    except (ValueError, SyntaxError, MemoryError):
+        return raw
+
+
+class NativeCodeGenerator(CodeGenerator):
+    """A code generator which renders Python types by not adding
+    ``str()`` around output nodes.
+    """
+
+    @staticmethod
+    def _default_finalize(value: t.Any) -> t.Any:
+        return value
+
+    def _output_const_repr(self, group: t.Iterable[t.Any]) -> str:
+        return repr("".join([str(v) for v in group]))
+
+    def _output_child_to_const(
+        self, node: nodes.Expr, frame: Frame, finalize: CodeGenerator._FinalizeInfo
+    ) -> t.Any:
+        const = node.as_const(frame.eval_ctx)
+
+        if not has_safe_repr(const):
+            raise nodes.Impossible()
+
+        if isinstance(node, nodes.TemplateData):
+            return const
+
+        return finalize.const(const)  # type: ignore
+
+    def _output_child_pre(
+        self, node: nodes.Expr, frame: Frame, finalize: CodeGenerator._FinalizeInfo
+    ) -> None:
+        if finalize.src is not None:
+            self.write(finalize.src)
+
+    def _output_child_post(
+        self, node: nodes.Expr, frame: Frame, finalize: CodeGenerator._FinalizeInfo
+    ) -> None:
+        if finalize.src is not None:
+            self.write(")")
+
+
+class NativeEnvironment(Environment):
+    """An environment that renders templates to native Python types."""
+
+    code_generator_class = NativeCodeGenerator
+
+
+class NativeTemplate(Template):
+    environment_class = NativeEnvironment
+
+    def render(self, *args: t.Any, **kwargs: t.Any) -> t.Any:
+        """Render the template to produce a native Python type. If the
+        result is a single node, its value is returned. Otherwise, the
+        nodes are concatenated as strings. If the result can be parsed
+        with :func:`ast.literal_eval`, the parsed value is returned.
+        Otherwise, the string is returned.
+        """
+        ctx = self.new_context(dict(*args, **kwargs))
+
+        try:
+            return native_concat(self.root_render_func(ctx))  # type: ignore
+        except Exception:
+            return self.environment.handle_exception()
+
+    async def render_async(self, *args: t.Any, **kwargs: t.Any) -> t.Any:
+        if not self.environment.is_async:
+            raise RuntimeError(
+                "The environment was not created with async mode enabled."
+            )
+
+        ctx = self.new_context(dict(*args, **kwargs))
+
+        try:
+            return native_concat(
+                [n async for n in self.root_render_func(ctx)]  # type: ignore
+            )
+        except Exception:
+            return self.environment.handle_exception()
+
+
+NativeEnvironment.template_class = NativeTemplate
diff --git a/lib/spack/external/_vendoring/jinja2/nodes.py b/lib/spack/external/_vendoring/jinja2/nodes.py
new file mode 100644
index 0000000000..b2f88d9d9c
--- /dev/null
+++ b/lib/spack/external/_vendoring/jinja2/nodes.py
@@ -0,0 +1,1204 @@
+"""AST nodes generated by the parser for the compiler. Also provides
+some node tree helper functions used by the parser and compiler in order
+to normalize nodes.
+"""
+import inspect
+import operator
+import typing as t
+from collections import deque
+
+from markupsafe import Markup
+
+from .utils import _PassArg
+
+if t.TYPE_CHECKING:
+    import typing_extensions as te
+    from .environment import Environment
+
+_NodeBound = t.TypeVar("_NodeBound", bound="Node")
+
+_binop_to_func: t.Dict[str, t.Callable[[t.Any, t.Any], t.Any]] = {
+    "*": operator.mul,
+    "/": operator.truediv,
+    "//": operator.floordiv,
+    "**": operator.pow,
+    "%": operator.mod,
+    "+": operator.add,
+    "-": operator.sub,
+}
+
+_uaop_to_func: t.Dict[str, t.Callable[[t.Any], t.Any]] = {
+    "not": operator.not_,
+    "+": operator.pos,
+    "-": operator.neg,
+}
+
+_cmpop_to_func: t.Dict[str, t.Callable[[t.Any, t.Any], t.Any]] = {
+    "eq": operator.eq,
+    "ne": operator.ne,
+    "gt": operator.gt,
+    "gteq": operator.ge,
+    "lt": operator.lt,
+    "lteq": operator.le,
+    "in": lambda a, b: a in b,
+    "notin": lambda a, b: a not in b,
+}
+
+
+class Impossible(Exception):
+    """Raised if the node could not perform a requested action."""
+
+
+class NodeType(type):
+    """A metaclass for nodes that handles the field and attribute
+    inheritance.  fields and attributes from the parent class are
+    automatically forwarded to the child."""
+
+    def __new__(mcs, name, bases, d):  # type: ignore
+        for attr in "fields", "attributes":
+            storage = []
+            storage.extend(getattr(bases[0] if bases else object, attr, ()))
+            storage.extend(d.get(attr, ()))
+            assert len(bases) <= 1, "multiple inheritance not allowed"
+            assert len(storage) == len(set(storage)), "layout conflict"
+            d[attr] = tuple(storage)
+        d.setdefault("abstract", False)
+        return type.__new__(mcs, name, bases, d)
+
+
+class EvalContext:
+    """Holds evaluation time information.  Custom attributes can be attached
+    to it in extensions.
+    """
+
+    def __init__(
+        self, environment: "Environment", template_name: t.Optional[str] = None
+    ) -> None:
+        self.environment = environment
+        if callable(environment.autoescape):
+            self.autoescape = environment.autoescape(template_name)
+        else:
+            self.autoescape = environment.autoescape
+        self.volatile = False
+
+    def save(self) -> t.Mapping[str, t.Any]:
+        return self.__dict__.copy()
+
+    def revert(self, old: t.Mapping[str, t.Any]) -> None:
+        self.__dict__.clear()
+        self.__dict__.update(old)
+
+
+def get_eval_context(node: "Node", ctx: t.Optional[EvalContext]) -> EvalContext:
+    if ctx is None:
+        if node.environment is None:
+            raise RuntimeError(
+                "if no eval context is passed, the node must have an"
+                " attached environment."
+            )
+        return EvalContext(node.environment)
+    return ctx
+
+
+class Node(metaclass=NodeType):
+    """Baseclass for all Jinja nodes.  There are a number of nodes available
+    of different types.  There are four major types:
+
+    -   :class:`Stmt`: statements
+    -   :class:`Expr`: expressions
+    -   :class:`Helper`: helper nodes
+    -   :class:`Template`: the outermost wrapper node
+
+    All nodes have fields and attributes.  Fields may be other nodes, lists,
+    or arbitrary values.  Fields are passed to the constructor as regular
+    positional arguments, attributes as keyword arguments.  Each node has
+    two attributes: `lineno` (the line number of the node) and `environment`.
+    The `environment` attribute is set at the end of the parsing process for
+    all nodes automatically.
+    """
+
+    fields: t.Tuple[str, ...] = ()
+    attributes: t.Tuple[str, ...] = ("lineno", "environment")
+    abstract = True
+
+    lineno: int
+    environment: t.Optional["Environment"]
+
+    def __init__(self, *fields: t.Any, **attributes: t.Any) -> None:
+        if self.abstract:
+            raise TypeError("abstract nodes are not instantiable")
+        if fields:
+            if len(fields) != len(self.fields):
+                if not self.fields:
+                    raise TypeError(f"{type(self).__name__!r} takes 0 arguments")
+                raise TypeError(
+                    f"{type(self).__name__!r} takes 0 or {len(self.fields)}"
+                    f" argument{'s' if len(self.fields) != 1 else ''}"
+                )
+            for name, arg in zip(self.fields, fields):
+                setattr(self, name, arg)
+        for attr in self.attributes:
+            setattr(self, attr, attributes.pop(attr, None))
+        if attributes:
+            raise TypeError(f"unknown attribute {next(iter(attributes))!r}")
+
+    def iter_fields(
+        self,
+        exclude: t.Optional[t.Container[str]] = None,
+        only: t.Optional[t.Container[str]] = None,
+    ) -> t.Iterator[t.Tuple[str, t.Any]]:
+        """This method iterates over all fields that are defined and yields
+        ``(key, value)`` tuples.  Per default all fields are returned, but
+        it's possible to limit that to some fields by providing the `only`
+        parameter or to exclude some using the `exclude` parameter.  Both
+        should be sets or tuples of field names.
+        """
+        for name in self.fields:
+            if (
+                (exclude is None and only is None)
+                or (exclude is not None and name not in exclude)
+                or (only is not None and name in only)
+            ):
+                try:
+                    yield name, getattr(self, name)
+                except AttributeError:
+                    pass
+
+    def iter_child_nodes(
+        self,
+        exclude: t.Optional[t.Container[str]] = None,
+        only: t.Optional[t.Container[str]] = None,
+    ) -> t.Iterator["Node"]:
+        """Iterates over all direct child nodes of the node.  This iterates
+        over all fields and yields the values of they are nodes.  If the value
+        of a field is a list all the nodes in that list are returned.
+        """
+        for _, item in self.iter_fields(exclude, only):
+            if isinstance(item, list):
+                for n in item:
+                    if isinstance(n, Node):
+                        yield n
+            elif isinstance(item, Node):
+                yield item
+
+    def find(self, node_type: t.Type[_NodeBound]) -> t.Optional[_NodeBound]:
+        """Find the first node of a given type.  If no such node exists the
+        return value is `None`.
+        """
+        for result in self.find_all(node_type):
+            return result
+
+        return None
+
+    def find_all(
+        self, node_type: t.Union[t.Type[_NodeBound], t.Tuple[t.Type[_NodeBound], ...]]
+    ) -> t.Iterator[_NodeBound]:
+        """Find all the nodes of a given type.  If the type is a tuple,
+        the check is performed for any of the tuple items.
+        """
+        for child in self.iter_child_nodes():
+            if isinstance(child, node_type):
+                yield child  # type: ignore
+            yield from child.find_all(node_type)
+
+    def set_ctx(self, ctx: str) -> "Node":
+        """Reset the context of a node and all child nodes.  Per default the
+        parser will all generate nodes that have a 'load' context as it's the
+        most common one.  This method is used in the parser to set assignment
+        targets and other nodes to a store context.
+        """
+        todo = deque([self])
+        while todo:
+            node = todo.popleft()
+            if "ctx" in node.fields:
+                node.ctx = ctx  # type: ignore
+            todo.extend(node.iter_child_nodes())
+        return self
+
+    def set_lineno(self, lineno: int, override: bool = False) -> "Node":
+        """Set the line numbers of the node and children."""
+        todo = deque([self])
+        while todo:
+            node = todo.popleft()
+            if "lineno" in node.attributes:
+                if node.lineno is None or override:
+                    node.lineno = lineno
+            todo.extend(node.iter_child_nodes())
+        return self
+
+    def set_environment(self, environment: "Environment") -> "Node":
+        """Set the environment for all nodes."""
+        todo = deque([self])
+        while todo:
+            node = todo.popleft()
+            node.environment = environment
+            todo.extend(node.iter_child_nodes())
+        return self
+
+    def __eq__(self, other: t.Any) -> bool:
+        if type(self) is not type(other):
+            return NotImplemented
+
+        return tuple(self.iter_fields()) == tuple(other.iter_fields())
+
+    __hash__ = object.__hash__
+
+    def __repr__(self) -> str:
+        args_str = ", ".join(f"{a}={getattr(self, a, None)!r}" for a in self.fields)
+        return f"{type(self).__name__}({args_str})"
+
+    def dump(self) -> str:
+        def _dump(node: t.Union[Node, t.Any]) -> None:
+            if not isinstance(node, Node):
+                buf.append(repr(node))
+                return
+
+            buf.append(f"nodes.{type(node).__name__}(")
+            if not node.fields:
+                buf.append(")")
+                return
+            for idx, field in enumerate(node.fields):
+                if idx:
+                    buf.append(", ")
+                value = getattr(node, field)
+                if isinstance(value, list):
+                    buf.append("[")
+                    for idx, item in enumerate(value):
+                        if idx:
+                            buf.append(", ")
+                        _dump(item)
+                    buf.append("]")
+                else:
+                    _dump(value)
+            buf.append(")")
+
+        buf: t.List[str] = []
+        _dump(self)
+        return "".join(buf)
+
+
+class Stmt(Node):
+    """Base node for all statements."""
+
+    abstract = True
+
+
+class Helper(Node):
+    """Nodes that exist in a specific context only."""
+
+    abstract = True
+
+
+class Template(Node):
+    """Node that represents a template.  This must be the outermost node that
+    is passed to the compiler.
+    """
+
+    fields = ("body",)
+    body: t.List[Node]
+
+
+class Output(Stmt):
+    """A node that holds multiple expressions which are then printed out.
+    This is used both for the `print` statement and the regular template data.
+    """
+
+    fields = ("nodes",)
+    nodes: t.List["Expr"]
+
+
+class Extends(Stmt):
+    """Represents an extends statement."""
+
+    fields = ("template",)
+    template: "Expr"
+
+
+class For(Stmt):
+    """The for loop.  `target` is the target for the iteration (usually a
+    :class:`Name` or :class:`Tuple`), `iter` the iterable.  `body` is a list
+    of nodes that are used as loop-body, and `else_` a list of nodes for the
+    `else` block.  If no else node exists it has to be an empty list.
+
+    For filtered nodes an expression can be stored as `test`, otherwise `None`.
+    """
+
+    fields = ("target", "iter", "body", "else_", "test", "recursive")
+    target: Node
+    iter: Node
+    body: t.List[Node]
+    else_: t.List[Node]
+    test: t.Optional[Node]
+    recursive: bool
+
+
+class If(Stmt):
+    """If `test` is true, `body` is rendered, else `else_`."""
+
+    fields = ("test", "body", "elif_", "else_")
+    test: Node
+    body: t.List[Node]
+    elif_: t.List["If"]
+    else_: t.List[Node]
+
+
+class Macro(Stmt):
+    """A macro definition.  `name` is the name of the macro, `args` a list of
+    arguments and `defaults` a list of defaults if there are any.  `body` is
+    a list of nodes for the macro body.
+    """
+
+    fields = ("name", "args", "defaults", "body")
+    name: str
+    args: t.List["Name"]
+    defaults: t.List["Expr"]
+    body: t.List[Node]
+
+
+class CallBlock(Stmt):
+    """Like a macro without a name but a call instead.  `call` is called with
+    the unnamed macro as `caller` argument this node holds.
+    """
+
+    fields = ("call", "args", "defaults", "body")
+    call: "Call"
+    args: t.List["Name"]
+    defaults: t.List["Expr"]
+    body: t.List[Node]
+
+
+class FilterBlock(Stmt):
+    """Node for filter sections."""
+
+    fields = ("body", "filter")
+    body: t.List[Node]
+    filter: "Filter"
+
+
+class With(Stmt):
+    """Specific node for with statements.  In older versions of Jinja the
+    with statement was implemented on the base of the `Scope` node instead.
+
+    .. versionadded:: 2.9.3
+    """
+
+    fields = ("targets", "values", "body")
+    targets: t.List["Expr"]
+    values: t.List["Expr"]
+    body: t.List[Node]
+
+
+class Block(Stmt):
+    """A node that represents a block.
+
+    .. versionchanged:: 3.0.0
+        the `required` field was added.
+    """
+
+    fields = ("name", "body", "scoped", "required")
+    name: str
+    body: t.List[Node]
+    scoped: bool
+    required: bool
+
+
+class Include(Stmt):
+    """A node that represents the include tag."""
+
+    fields = ("template", "with_context", "ignore_missing")
+    template: "Expr"
+    with_context: bool
+    ignore_missing: bool
+
+
+class Import(Stmt):
+    """A node that represents the import tag."""
+
+    fields = ("template", "target", "with_context")
+    template: "Expr"
+    target: str
+    with_context: bool
+
+
+class FromImport(Stmt):
+    """A node that represents the from import tag.  It's important to not
+    pass unsafe names to the name attribute.  The compiler translates the
+    attribute lookups directly into getattr calls and does *not* use the
+    subscript callback of the interface.  As exported variables may not
+    start with double underscores (which the parser asserts) this is not a
+    problem for regular Jinja code, but if this node is used in an extension
+    extra care must be taken.
+
+    The list of names may contain tuples if aliases are wanted.
+    """
+
+    fields = ("template", "names", "with_context")
+    template: "Expr"
+    names: t.List[t.Union[str, t.Tuple[str, str]]]
+    with_context: bool
+
+
+class ExprStmt(Stmt):
+    """A statement that evaluates an expression and discards the result."""
+
+    fields = ("node",)
+    node: Node
+
+
+class Assign(Stmt):
+    """Assigns an expression to a target."""
+
+    fields = ("target", "node")
+    target: "Expr"
+    node: Node
+
+
+class AssignBlock(Stmt):
+    """Assigns a block to a target."""
+
+    fields = ("target", "filter", "body")
+    target: "Expr"
+    filter: t.Optional["Filter"]
+    body: t.List[Node]
+
+
+class Expr(Node):
+    """Baseclass for all expressions."""
+
+    abstract = True
+
+    def as_const(self, eval_ctx: t.Optional[EvalContext] = None) -> t.Any:
+        """Return the value of the expression as constant or raise
+        :exc:`Impossible` if this was not possible.
+
+        An :class:`EvalContext` can be provided, if none is given
+        a default context is created which requires the nodes to have
+        an attached environment.
+
+        .. versionchanged:: 2.4
+           the `eval_ctx` parameter was added.
+        """
+        raise Impossible()
+
+    def can_assign(self) -> bool:
+        """Check if it's possible to assign something to this node."""
+        return False
+
+
+class BinExpr(Expr):
+    """Baseclass for all binary expressions."""
+
+    fields = ("left", "right")
+    left: Expr
+    right: Expr
+    operator: str
+    abstract = True
+
+    def as_const(self, eval_ctx: t.Optional[EvalContext] = None) -> t.Any:
+        eval_ctx = get_eval_context(self, eval_ctx)
+
+        # intercepted operators cannot be folded at compile time
+        if (
+            eval_ctx.environment.sandboxed
+            and self.operator in eval_ctx.environment.intercepted_binops  # type: ignore
+        ):
+            raise Impossible()
+        f = _binop_to_func[self.operator]
+        try:
+            return f(self.left.as_const(eval_ctx), self.right.as_const(eval_ctx))
+        except Exception as e:
+            raise Impossible() from e
+
+
+class UnaryExpr(Expr):
+    """Baseclass for all unary expressions."""
+
+    fields = ("node",)
+    node: Expr
+    operator: str
+    abstract = True
+
+    def as_const(self, eval_ctx: t.Optional[EvalContext] = None) -> t.Any:
+        eval_ctx = get_eval_context(self, eval_ctx)
+
+        # intercepted operators cannot be folded at compile time
+        if (
+            eval_ctx.environment.sandboxed
+            and self.operator in eval_ctx.environment.intercepted_unops  # type: ignore
+        ):
+            raise Impossible()
+        f = _uaop_to_func[self.operator]
+        try:
+            return f(self.node.as_const(eval_ctx))
+        except Exception as e:
+            raise Impossible() from e
+
+
+class Name(Expr):
+    """Looks up a name or stores a value in a name.
+    The `ctx` of the node can be one of the following values:
+
+    -   `store`: store a value in the name
+    -   `load`: load that name
+    -   `param`: like `store` but if the name was defined as function parameter.
+    """
+
+    fields = ("name", "ctx")
+    name: str
+    ctx: str
+
+    def can_assign(self) -> bool:
+        return self.name not in {"true", "false", "none", "True", "False", "None"}
+
+
+class NSRef(Expr):
+    """Reference to a namespace value assignment"""
+
+    fields = ("name", "attr")
+    name: str
+    attr: str
+
+    def can_assign(self) -> bool:
+        # We don't need any special checks here; NSRef assignments have a
+        # runtime check to ensure the target is a namespace object which will
+        # have been checked already as it is created using a normal assignment
+        # which goes through a `Name` node.
+        return True
+
+
+class Literal(Expr):
+    """Baseclass for literals."""
+
+    abstract = True
+
+
+class Const(Literal):
+    """All constant values.  The parser will return this node for simple
+    constants such as ``42`` or ``"foo"`` but it can be used to store more
+    complex values such as lists too.  Only constants with a safe
+    representation (objects where ``eval(repr(x)) == x`` is true).
+    """
+
+    fields = ("value",)
+    value: t.Any
+
+    def as_const(self, eval_ctx: t.Optional[EvalContext] = None) -> t.Any:
+        return self.value
+
+    @classmethod
+    def from_untrusted(
+        cls,
+        value: t.Any,
+        lineno: t.Optional[int] = None,
+        environment: "t.Optional[Environment]" = None,
+    ) -> "Const":
+        """Return a const object if the value is representable as
+        constant value in the generated code, otherwise it will raise
+        an `Impossible` exception.
+        """
+        from .compiler import has_safe_repr
+
+        if not has_safe_repr(value):
+            raise Impossible()
+        return cls(value, lineno=lineno, environment=environment)
+
+
+class TemplateData(Literal):
+    """A constant template string."""
+
+    fields = ("data",)
+    data: str
+
+    def as_const(self, eval_ctx: t.Optional[EvalContext] = None) -> str:
+        eval_ctx = get_eval_context(self, eval_ctx)
+        if eval_ctx.volatile:
+            raise Impossible()
+        if eval_ctx.autoescape:
+            return Markup(self.data)
+        return self.data
+
+
+class Tuple(Literal):
+    """For loop unpacking and some other things like multiple arguments
+    for subscripts.  Like for :class:`Name` `ctx` specifies if the tuple
+    is used for loading the names or storing.
+    """
+
+    fields = ("items", "ctx")
+    items: t.List[Expr]
+    ctx: str
+
+    def as_const(self, eval_ctx: t.Optional[EvalContext] = None) -> t.Tuple[t.Any, ...]:
+        eval_ctx = get_eval_context(self, eval_ctx)
+        return tuple(x.as_const(eval_ctx) for x in self.items)
+
+    def can_assign(self) -> bool:
+        for item in self.items:
+            if not item.can_assign():
+                return False
+        return True
+
+
+class List(Literal):
+    """Any list literal such as ``[1, 2, 3]``"""
+
+    fields = ("items",)
+    items: t.List[Expr]
+
+    def as_const(self, eval_ctx: t.Optional[EvalContext] = None) -> t.List[t.Any]:
+        eval_ctx = get_eval_context(self, eval_ctx)
+        return [x.as_const(eval_ctx) for x in self.items]
+
+
+class Dict(Literal):
+    """Any dict literal such as ``{1: 2, 3: 4}``.  The items must be a list of
+    :class:`Pair` nodes.
+    """
+
+    fields = ("items",)
+    items: t.List["Pair"]
+
+    def as_const(
+        self, eval_ctx: t.Optional[EvalContext] = None
+    ) -> t.Dict[t.Any, t.Any]:
+        eval_ctx = get_eval_context(self, eval_ctx)
+        return dict(x.as_const(eval_ctx) for x in self.items)
+
+
+class Pair(Helper):
+    """A key, value pair for dicts."""
+
+    fields = ("key", "value")
+    key: Expr
+    value: Expr
+
+    def as_const(
+        self, eval_ctx: t.Optional[EvalContext] = None
+    ) -> t.Tuple[t.Any, t.Any]:
+        eval_ctx = get_eval_context(self, eval_ctx)
+        return self.key.as_const(eval_ctx), self.value.as_const(eval_ctx)
+
+
+class Keyword(Helper):
+    """A key, value pair for keyword arguments where key is a string."""
+
+    fields = ("key", "value")
+    key: str
+    value: Expr
+
+    def as_const(self, eval_ctx: t.Optional[EvalContext] = None) -> t.Tuple[str, t.Any]:
+        eval_ctx = get_eval_context(self, eval_ctx)
+        return self.key, self.value.as_const(eval_ctx)
+
+
+class CondExpr(Expr):
+    """A conditional expression (inline if expression).  (``{{
+    foo if bar else baz }}``)
+    """
+
+    fields = ("test", "expr1", "expr2")
+    test: Expr
+    expr1: Expr
+    expr2: t.Optional[Expr]
+
+    def as_const(self, eval_ctx: t.Optional[EvalContext] = None) -> t.Any:
+        eval_ctx = get_eval_context(self, eval_ctx)
+        if self.test.as_const(eval_ctx):
+            return self.expr1.as_const(eval_ctx)
+
+        # if we evaluate to an undefined object, we better do that at runtime
+        if self.expr2 is None:
+            raise Impossible()
+
+        return self.expr2.as_const(eval_ctx)
+
+
+def args_as_const(
+    node: t.Union["_FilterTestCommon", "Call"], eval_ctx: t.Optional[EvalContext]
+) -> t.Tuple[t.List[t.Any], t.Dict[t.Any, t.Any]]:
+    args = [x.as_const(eval_ctx) for x in node.args]
+    kwargs = dict(x.as_const(eval_ctx) for x in node.kwargs)
+
+    if node.dyn_args is not None:
+        try:
+            args.extend(node.dyn_args.as_const(eval_ctx))
+        except Exception as e:
+            raise Impossible() from e
+
+    if node.dyn_kwargs is not None:
+        try:
+            kwargs.update(node.dyn_kwargs.as_const(eval_ctx))
+        except Exception as e:
+            raise Impossible() from e
+
+    return args, kwargs
+
+
+class _FilterTestCommon(Expr):
+    fields = ("node", "name", "args", "kwargs", "dyn_args", "dyn_kwargs")
+    node: Expr
+    name: str
+    args: t.List[Expr]
+    kwargs: t.List[Pair]
+    dyn_args: t.Optional[Expr]
+    dyn_kwargs: t.Optional[Expr]
+    abstract = True
+    _is_filter = True
+
+    def as_const(self, eval_ctx: t.Optional[EvalContext] = None) -> t.Any:
+        eval_ctx = get_eval_context(self, eval_ctx)
+
+        if eval_ctx.volatile:
+            raise Impossible()
+
+        if self._is_filter:
+            env_map = eval_ctx.environment.filters
+        else:
+            env_map = eval_ctx.environment.tests
+
+        func = env_map.get(self.name)
+        pass_arg = _PassArg.from_obj(func)  # type: ignore
+
+        if func is None or pass_arg is _PassArg.context:
+            raise Impossible()
+
+        if eval_ctx.environment.is_async and (
+            getattr(func, "jinja_async_variant", False) is True
+            or inspect.iscoroutinefunction(func)
+        ):
+            raise Impossible()
+
+        args, kwargs = args_as_const(self, eval_ctx)
+        args.insert(0, self.node.as_const(eval_ctx))
+
+        if pass_arg is _PassArg.eval_context:
+            args.insert(0, eval_ctx)
+        elif pass_arg is _PassArg.environment:
+            args.insert(0, eval_ctx.environment)
+
+        try:
+            return func(*args, **kwargs)
+        except Exception as e:
+            raise Impossible() from e
+
+
+class Filter(_FilterTestCommon):
+    """Apply a filter to an expression. ``name`` is the name of the
+    filter, the other fields are the same as :class:`Call`.
+
+    If ``node`` is ``None``, the filter is being used in a filter block
+    and is applied to the content of the block.
+    """
+
+    node: t.Optional[Expr]  # type: ignore
+
+    def as_const(self, eval_ctx: t.Optional[EvalContext] = None) -> t.Any:
+        if self.node is None:
+            raise Impossible()
+
+        return super().as_const(eval_ctx=eval_ctx)
+
+
+class Test(_FilterTestCommon):
+    """Apply a test to an expression. ``name`` is the name of the test,
+    the other field are the same as :class:`Call`.
+
+    .. versionchanged:: 3.0
+        ``as_const`` shares the same logic for filters and tests. Tests
+        check for volatile, async, and ``@pass_context`` etc.
+        decorators.
+    """
+
+    _is_filter = False
+
+
+class Call(Expr):
+    """Calls an expression.  `args` is a list of arguments, `kwargs` a list
+    of keyword arguments (list of :class:`Keyword` nodes), and `dyn_args`
+    and `dyn_kwargs` has to be either `None` or a node that is used as
+    node for dynamic positional (``*args``) or keyword (``**kwargs``)
+    arguments.
+    """
+
+    fields = ("node", "args", "kwargs", "dyn_args", "dyn_kwargs")
+    node: Expr
+    args: t.List[Expr]
+    kwargs: t.List[Keyword]
+    dyn_args: t.Optional[Expr]
+    dyn_kwargs: t.Optional[Expr]
+
+
+class Getitem(Expr):
+    """Get an attribute or item from an expression and prefer the item."""
+
+    fields = ("node", "arg", "ctx")
+    node: Expr
+    arg: Expr
+    ctx: str
+
+    def as_const(self, eval_ctx: t.Optional[EvalContext] = None) -> t.Any:
+        if self.ctx != "load":
+            raise Impossible()
+
+        eval_ctx = get_eval_context(self, eval_ctx)
+
+        try:
+            return eval_ctx.environment.getitem(
+                self.node.as_const(eval_ctx), self.arg.as_const(eval_ctx)
+            )
+        except Exception as e:
+            raise Impossible() from e
+
+
+class Getattr(Expr):
+    """Get an attribute or item from an expression that is a ascii-only
+    bytestring and prefer the attribute.
+    """
+
+    fields = ("node", "attr", "ctx")
+    node: Expr
+    attr: str
+    ctx: str
+
+    def as_const(self, eval_ctx: t.Optional[EvalContext] = None) -> t.Any:
+        if self.ctx != "load":
+            raise Impossible()
+
+        eval_ctx = get_eval_context(self, eval_ctx)
+
+        try:
+            return eval_ctx.environment.getattr(self.node.as_const(eval_ctx), self.attr)
+        except Exception as e:
+            raise Impossible() from e
+
+
+class Slice(Expr):
+    """Represents a slice object.  This must only be used as argument for
+    :class:`Subscript`.
+    """
+
+    fields = ("start", "stop", "step")
+    start: t.Optional[Expr]
+    stop: t.Optional[Expr]
+    step: t.Optional[Expr]
+
+    def as_const(self, eval_ctx: t.Optional[EvalContext] = None) -> slice:
+        eval_ctx = get_eval_context(self, eval_ctx)
+
+        def const(obj: t.Optional[Expr]) -> t.Optional[t.Any]:
+            if obj is None:
+                return None
+            return obj.as_const(eval_ctx)
+
+        return slice(const(self.start), const(self.stop), const(self.step))
+
+
+class Concat(Expr):
+    """Concatenates the list of expressions provided after converting
+    them to strings.
+    """
+
+    fields = ("nodes",)
+    nodes: t.List[Expr]
+
+    def as_const(self, eval_ctx: t.Optional[EvalContext] = None) -> str:
+        eval_ctx = get_eval_context(self, eval_ctx)
+        return "".join(str(x.as_const(eval_ctx)) for x in self.nodes)
+
+
+class Compare(Expr):
+    """Compares an expression with some other expressions.  `ops` must be a
+    list of :class:`Operand`\\s.
+    """
+
+    fields = ("expr", "ops")
+    expr: Expr
+    ops: t.List["Operand"]
+
+    def as_const(self, eval_ctx: t.Optional[EvalContext] = None) -> t.Any:
+        eval_ctx = get_eval_context(self, eval_ctx)
+        result = value = self.expr.as_const(eval_ctx)
+
+        try:
+            for op in self.ops:
+                new_value = op.expr.as_const(eval_ctx)
+                result = _cmpop_to_func[op.op](value, new_value)
+
+                if not result:
+                    return False
+
+                value = new_value
+        except Exception as e:
+            raise Impossible() from e
+
+        return result
+
+
+class Operand(Helper):
+    """Holds an operator and an expression."""
+
+    fields = ("op", "expr")
+    op: str
+    expr: Expr
+
+
+class Mul(BinExpr):
+    """Multiplies the left with the right node."""
+
+    operator = "*"
+
+
+class Div(BinExpr):
+    """Divides the left by the right node."""
+
+    operator = "/"
+
+
+class FloorDiv(BinExpr):
+    """Divides the left by the right node and converts the
+    result into an integer by truncating.
+    """
+
+    operator = "//"
+
+
+class Add(BinExpr):
+    """Add the left to the right node."""
+
+    operator = "+"
+
+
+class Sub(BinExpr):
+    """Subtract the right from the left node."""
+
+    operator = "-"
+
+
+class Mod(BinExpr):
+    """Left modulo right."""
+
+    operator = "%"
+
+
+class Pow(BinExpr):
+    """Left to the power of right."""
+
+    operator = "**"
+
+
+class And(BinExpr):
+    """Short circuited AND."""
+
+    operator = "and"
+
+    def as_const(self, eval_ctx: t.Optional[EvalContext] = None) -> t.Any:
+        eval_ctx = get_eval_context(self, eval_ctx)
+        return self.left.as_const(eval_ctx) and self.right.as_const(eval_ctx)
+
+
+class Or(BinExpr):
+    """Short circuited OR."""
+
+    operator = "or"
+
+    def as_const(self, eval_ctx: t.Optional[EvalContext] = None) -> t.Any:
+        eval_ctx = get_eval_context(self, eval_ctx)
+        return self.left.as_const(eval_ctx) or self.right.as_const(eval_ctx)
+
+
+class Not(UnaryExpr):
+    """Negate the expression."""
+
+    operator = "not"
+
+
+class Neg(UnaryExpr):
+    """Make the expression negative."""
+
+    operator = "-"
+
+
+class Pos(UnaryExpr):
+    """Make the expression positive (noop for most expressions)"""
+
+    operator = "+"
+
+
+# Helpers for extensions
+
+
+class EnvironmentAttribute(Expr):
+    """Loads an attribute from the environment object.  This is useful for
+    extensions that want to call a callback stored on the environment.
+    """
+
+    fields = ("name",)
+    name: str
+
+
+class ExtensionAttribute(Expr):
+    """Returns the attribute of an extension bound to the environment.
+    The identifier is the identifier of the :class:`Extension`.
+
+    This node is usually constructed by calling the
+    :meth:`~jinja2.ext.Extension.attr` method on an extension.
+    """
+
+    fields = ("identifier", "name")
+    identifier: str
+    name: str
+
+
+class ImportedName(Expr):
+    """If created with an import name the import name is returned on node
+    access.  For example ``ImportedName('cgi.escape')`` returns the `escape`
+    function from the cgi module on evaluation.  Imports are optimized by the
+    compiler so there is no need to assign them to local variables.
+    """
+
+    fields = ("importname",)
+    importname: str
+
+
+class InternalName(Expr):
+    """An internal name in the compiler.  You cannot create these nodes
+    yourself but the parser provides a
+    :meth:`~jinja2.parser.Parser.free_identifier` method that creates
+    a new identifier for you.  This identifier is not available from the
+    template and is not treated specially by the compiler.
+    """
+
+    fields = ("name",)
+    name: str
+
+    def __init__(self) -> None:
+        raise TypeError(
+            "Can't create internal names.  Use the "
+            "`free_identifier` method on a parser."
+        )
+
+
+class MarkSafe(Expr):
+    """Mark the wrapped expression as safe (wrap it as `Markup`)."""
+
+    fields = ("expr",)
+    expr: Expr
+
+    def as_const(self, eval_ctx: t.Optional[EvalContext] = None) -> Markup:
+        eval_ctx = get_eval_context(self, eval_ctx)
+        return Markup(self.expr.as_const(eval_ctx))
+
+
+class MarkSafeIfAutoescape(Expr):
+    """Mark the wrapped expression as safe (wrap it as `Markup`) but
+    only if autoescaping is active.
+
+    .. versionadded:: 2.5
+    """
+
+    fields = ("expr",)
+    expr: Expr
+
+    def as_const(
+        self, eval_ctx: t.Optional[EvalContext] = None
+    ) -> t.Union[Markup, t.Any]:
+        eval_ctx = get_eval_context(self, eval_ctx)
+        if eval_ctx.volatile:
+            raise Impossible()
+        expr = self.expr.as_const(eval_ctx)
+        if eval_ctx.autoescape:
+            return Markup(expr)
+        return expr
+
+
+class ContextReference(Expr):
+    """Returns the current template context.  It can be used like a
+    :class:`Name` node, with a ``'load'`` ctx and will return the
+    current :class:`~jinja2.runtime.Context` object.
+
+    Here an example that assigns the current template name to a
+    variable named `foo`::
+
+        Assign(Name('foo', ctx='store'),
+               Getattr(ContextReference(), 'name'))
+
+    This is basically equivalent to using the
+    :func:`~jinja2.pass_context` decorator when using the high-level
+    API, which causes a reference to the context to be passed as the
+    first argument to a function.
+    """
+
+
+class DerivedContextReference(Expr):
+    """Return the current template context including locals. Behaves
+    exactly like :class:`ContextReference`, but includes local
+    variables, such as from a ``for`` loop.
+
+    .. versionadded:: 2.11
+    """
+
+
+class Continue(Stmt):
+    """Continue a loop."""
+
+
+class Break(Stmt):
+    """Break a loop."""
+
+
+class Scope(Stmt):
+    """An artificial scope."""
+
+    fields = ("body",)
+    body: t.List[Node]
+
+
+class OverlayScope(Stmt):
+    """An overlay scope for extensions.  This is a largely unoptimized scope
+    that however can be used to introduce completely arbitrary variables into
+    a sub scope from a dictionary or dictionary like object.  The `context`
+    field has to evaluate to a dictionary object.
+
+    Example usage::
+
+        OverlayScope(context=self.call_method('get_context'),
+                     body=[...])
+
+    .. versionadded:: 2.10
+    """
+
+    fields = ("context", "body")
+    context: Expr
+    body: t.List[Node]
+
+
+class EvalContextModifier(Stmt):
+    """Modifies the eval context.  For each option that should be modified,
+    a :class:`Keyword` has to be added to the :attr:`options` list.
+
+    Example to change the `autoescape` setting::
+
+        EvalContextModifier(options=[Keyword('autoescape', Const(True))])
+    """
+
+    fields = ("options",)
+    options: t.List[Keyword]
+
+
+class ScopedEvalContextModifier(EvalContextModifier):
+    """Modifies the eval context and reverts it later.  Works exactly like
+    :class:`EvalContextModifier` but will only modify the
+    :class:`~jinja2.nodes.EvalContext` for nodes in the :attr:`body`.
+    """
+
+    fields = ("body",)
+    body: t.List[Node]
+
+
+# make sure nobody creates custom nodes
+def _failing_new(*args: t.Any, **kwargs: t.Any) -> "te.NoReturn":
+    raise TypeError("can't create custom node types")
+
+
+NodeType.__new__ = staticmethod(_failing_new)  # type: ignore
+del _failing_new
diff --git a/lib/spack/external/_vendoring/jinja2/optimizer.py b/lib/spack/external/_vendoring/jinja2/optimizer.py
new file mode 100644
index 0000000000..fe1010705e
--- /dev/null
+++ b/lib/spack/external/_vendoring/jinja2/optimizer.py
@@ -0,0 +1,47 @@
+"""The optimizer tries to constant fold expressions and modify the AST
+in place so that it should be faster to evaluate.
+
+Because the AST does not contain all the scoping information and the
+compiler has to find that out, we cannot do all the optimizations we
+want. For example, loop unrolling doesn't work because unrolled loops
+would have a different scope. The solution would be a second syntax tree
+that stored the scoping rules.
+"""
+import typing as t
+
+from . import nodes
+from .visitor import NodeTransformer
+
+if t.TYPE_CHECKING:
+    from .environment import Environment
+
+
+def optimize(node: nodes.Node, environment: "Environment") -> nodes.Node:
+    """The context hint can be used to perform an static optimization
+    based on the context given."""
+    optimizer = Optimizer(environment)
+    return t.cast(nodes.Node, optimizer.visit(node))
+
+
+class Optimizer(NodeTransformer):
+    def __init__(self, environment: "t.Optional[Environment]") -> None:
+        self.environment = environment
+
+    def generic_visit(
+        self, node: nodes.Node, *args: t.Any, **kwargs: t.Any
+    ) -> nodes.Node:
+        node = super().generic_visit(node, *args, **kwargs)
+
+        # Do constant folding. Some other nodes besides Expr have
+        # as_const, but folding them causes errors later on.
+        if isinstance(node, nodes.Expr):
+            try:
+                return nodes.Const.from_untrusted(
+                    node.as_const(args[0] if args else None),
+                    lineno=node.lineno,
+                    environment=self.environment,
+                )
+            except nodes.Impossible:
+                pass
+
+        return node
diff --git a/lib/spack/external/_vendoring/jinja2/parser.py b/lib/spack/external/_vendoring/jinja2/parser.py
new file mode 100644
index 0000000000..7ad73fcc0f
--- /dev/null
+++ b/lib/spack/external/_vendoring/jinja2/parser.py
@@ -0,0 +1,1040 @@
+"""Parse tokens from the lexer into nodes for the compiler."""
+import typing
+import typing as t
+
+from . import nodes
+from .exceptions import TemplateAssertionError
+from .exceptions import TemplateSyntaxError
+from .lexer import describe_token
+from .lexer import describe_token_expr
+
+if t.TYPE_CHECKING:
+    import typing_extensions as te
+    from .environment import Environment
+
+_ImportInclude = t.TypeVar("_ImportInclude", nodes.Import, nodes.Include)
+_MacroCall = t.TypeVar("_MacroCall", nodes.Macro, nodes.CallBlock)
+
+_statement_keywords = frozenset(
+    [
+        "for",
+        "if",
+        "block",
+        "extends",
+        "print",
+        "macro",
+        "include",
+        "from",
+        "import",
+        "set",
+        "with",
+        "autoescape",
+    ]
+)
+_compare_operators = frozenset(["eq", "ne", "lt", "lteq", "gt", "gteq"])
+
+_math_nodes: t.Dict[str, t.Type[nodes.Expr]] = {
+    "add": nodes.Add,
+    "sub": nodes.Sub,
+    "mul": nodes.Mul,
+    "div": nodes.Div,
+    "floordiv": nodes.FloorDiv,
+    "mod": nodes.Mod,
+}
+
+
+class Parser:
+    """This is the central parsing class Jinja uses.  It's passed to
+    extensions and can be used to parse expressions or statements.
+    """
+
+    def __init__(
+        self,
+        environment: "Environment",
+        source: str,
+        name: t.Optional[str] = None,
+        filename: t.Optional[str] = None,
+        state: t.Optional[str] = None,
+    ) -> None:
+        self.environment = environment
+        self.stream = environment._tokenize(source, name, filename, state)
+        self.name = name
+        self.filename = filename
+        self.closed = False
+        self.extensions: t.Dict[
+            str, t.Callable[["Parser"], t.Union[nodes.Node, t.List[nodes.Node]]]
+        ] = {}
+        for extension in environment.iter_extensions():
+            for tag in extension.tags:
+                self.extensions[tag] = extension.parse
+        self._last_identifier = 0
+        self._tag_stack: t.List[str] = []
+        self._end_token_stack: t.List[t.Tuple[str, ...]] = []
+
+    def fail(
+        self,
+        msg: str,
+        lineno: t.Optional[int] = None,
+        exc: t.Type[TemplateSyntaxError] = TemplateSyntaxError,
+    ) -> "te.NoReturn":
+        """Convenience method that raises `exc` with the message, passed
+        line number or last line number as well as the current name and
+        filename.
+        """
+        if lineno is None:
+            lineno = self.stream.current.lineno
+        raise exc(msg, lineno, self.name, self.filename)
+
+    def _fail_ut_eof(
+        self,
+        name: t.Optional[str],
+        end_token_stack: t.List[t.Tuple[str, ...]],
+        lineno: t.Optional[int],
+    ) -> "te.NoReturn":
+        expected: t.Set[str] = set()
+        for exprs in end_token_stack:
+            expected.update(map(describe_token_expr, exprs))
+        if end_token_stack:
+            currently_looking: t.Optional[str] = " or ".join(
+                map(repr, map(describe_token_expr, end_token_stack[-1]))
+            )
+        else:
+            currently_looking = None
+
+        if name is None:
+            message = ["Unexpected end of template."]
+        else:
+            message = [f"Encountered unknown tag {name!r}."]
+
+        if currently_looking:
+            if name is not None and name in expected:
+                message.append(
+                    "You probably made a nesting mistake. Jinja is expecting this tag,"
+                    f" but currently looking for {currently_looking}."
+                )
+            else:
+                message.append(
+                    f"Jinja was looking for the following tags: {currently_looking}."
+                )
+
+        if self._tag_stack:
+            message.append(
+                "The innermost block that needs to be closed is"
+                f" {self._tag_stack[-1]!r}."
+            )
+
+        self.fail(" ".join(message), lineno)
+
+    def fail_unknown_tag(
+        self, name: str, lineno: t.Optional[int] = None
+    ) -> "te.NoReturn":
+        """Called if the parser encounters an unknown tag.  Tries to fail
+        with a human readable error message that could help to identify
+        the problem.
+        """
+        self._fail_ut_eof(name, self._end_token_stack, lineno)
+
+    def fail_eof(
+        self,
+        end_tokens: t.Optional[t.Tuple[str, ...]] = None,
+        lineno: t.Optional[int] = None,
+    ) -> "te.NoReturn":
+        """Like fail_unknown_tag but for end of template situations."""
+        stack = list(self._end_token_stack)
+        if end_tokens is not None:
+            stack.append(end_tokens)
+        self._fail_ut_eof(None, stack, lineno)
+
+    def is_tuple_end(
+        self, extra_end_rules: t.Optional[t.Tuple[str, ...]] = None
+    ) -> bool:
+        """Are we at the end of a tuple?"""
+        if self.stream.current.type in ("variable_end", "block_end", "rparen"):
+            return True
+        elif extra_end_rules is not None:
+            return self.stream.current.test_any(extra_end_rules)  # type: ignore
+        return False
+
+    def free_identifier(self, lineno: t.Optional[int] = None) -> nodes.InternalName:
+        """Return a new free identifier as :class:`~jinja2.nodes.InternalName`."""
+        self._last_identifier += 1
+        rv = object.__new__(nodes.InternalName)
+        nodes.Node.__init__(rv, f"fi{self._last_identifier}", lineno=lineno)
+        return rv  # type: ignore
+
+    def parse_statement(self) -> t.Union[nodes.Node, t.List[nodes.Node]]:
+        """Parse a single statement."""
+        token = self.stream.current
+        if token.type != "name":
+            self.fail("tag name expected", token.lineno)
+        self._tag_stack.append(token.value)
+        pop_tag = True
+        try:
+            if token.value in _statement_keywords:
+                f = getattr(self, f"parse_{self.stream.current.value}")
+                return f()  # type: ignore
+            if token.value == "call":
+                return self.parse_call_block()
+            if token.value == "filter":
+                return self.parse_filter_block()
+            ext = self.extensions.get(token.value)
+            if ext is not None:
+                return ext(self)
+
+            # did not work out, remove the token we pushed by accident
+            # from the stack so that the unknown tag fail function can
+            # produce a proper error message.
+            self._tag_stack.pop()
+            pop_tag = False
+            self.fail_unknown_tag(token.value, token.lineno)
+        finally:
+            if pop_tag:
+                self._tag_stack.pop()
+
+    def parse_statements(
+        self, end_tokens: t.Tuple[str, ...], drop_needle: bool = False
+    ) -> t.List[nodes.Node]:
+        """Parse multiple statements into a list until one of the end tokens
+        is reached.  This is used to parse the body of statements as it also
+        parses template data if appropriate.  The parser checks first if the
+        current token is a colon and skips it if there is one.  Then it checks
+        for the block end and parses until if one of the `end_tokens` is
+        reached.  Per default the active token in the stream at the end of
+        the call is the matched end token.  If this is not wanted `drop_needle`
+        can be set to `True` and the end token is removed.
+        """
+        # the first token may be a colon for python compatibility
+        self.stream.skip_if("colon")
+
+        # in the future it would be possible to add whole code sections
+        # by adding some sort of end of statement token and parsing those here.
+        self.stream.expect("block_end")
+        result = self.subparse(end_tokens)
+
+        # we reached the end of the template too early, the subparser
+        # does not check for this, so we do that now
+        if self.stream.current.type == "eof":
+            self.fail_eof(end_tokens)
+
+        if drop_needle:
+            next(self.stream)
+        return result
+
+    def parse_set(self) -> t.Union[nodes.Assign, nodes.AssignBlock]:
+        """Parse an assign statement."""
+        lineno = next(self.stream).lineno
+        target = self.parse_assign_target(with_namespace=True)
+        if self.stream.skip_if("assign"):
+            expr = self.parse_tuple()
+            return nodes.Assign(target, expr, lineno=lineno)
+        filter_node = self.parse_filter(None)
+        body = self.parse_statements(("name:endset",), drop_needle=True)
+        return nodes.AssignBlock(target, filter_node, body, lineno=lineno)
+
+    def parse_for(self) -> nodes.For:
+        """Parse a for loop."""
+        lineno = self.stream.expect("name:for").lineno
+        target = self.parse_assign_target(extra_end_rules=("name:in",))
+        self.stream.expect("name:in")
+        iter = self.parse_tuple(
+            with_condexpr=False, extra_end_rules=("name:recursive",)
+        )
+        test = None
+        if self.stream.skip_if("name:if"):
+            test = self.parse_expression()
+        recursive = self.stream.skip_if("name:recursive")
+        body = self.parse_statements(("name:endfor", "name:else"))
+        if next(self.stream).value == "endfor":
+            else_ = []
+        else:
+            else_ = self.parse_statements(("name:endfor",), drop_needle=True)
+        return nodes.For(target, iter, body, else_, test, recursive, lineno=lineno)
+
+    def parse_if(self) -> nodes.If:
+        """Parse an if construct."""
+        node = result = nodes.If(lineno=self.stream.expect("name:if").lineno)
+        while True:
+            node.test = self.parse_tuple(with_condexpr=False)
+            node.body = self.parse_statements(("name:elif", "name:else", "name:endif"))
+            node.elif_ = []
+            node.else_ = []
+            token = next(self.stream)
+            if token.test("name:elif"):
+                node = nodes.If(lineno=self.stream.current.lineno)
+                result.elif_.append(node)
+                continue
+            elif token.test("name:else"):
+                result.else_ = self.parse_statements(("name:endif",), drop_needle=True)
+            break
+        return result
+
+    def parse_with(self) -> nodes.With:
+        node = nodes.With(lineno=next(self.stream).lineno)
+        targets: t.List[nodes.Expr] = []
+        values: t.List[nodes.Expr] = []
+        while self.stream.current.type != "block_end":
+            if targets:
+                self.stream.expect("comma")
+            target = self.parse_assign_target()
+            target.set_ctx("param")
+            targets.append(target)
+            self.stream.expect("assign")
+            values.append(self.parse_expression())
+        node.targets = targets
+        node.values = values
+        node.body = self.parse_statements(("name:endwith",), drop_needle=True)
+        return node
+
+    def parse_autoescape(self) -> nodes.Scope:
+        node = nodes.ScopedEvalContextModifier(lineno=next(self.stream).lineno)
+        node.options = [nodes.Keyword("autoescape", self.parse_expression())]
+        node.body = self.parse_statements(("name:endautoescape",), drop_needle=True)
+        return nodes.Scope([node])
+
+    def parse_block(self) -> nodes.Block:
+        node = nodes.Block(lineno=next(self.stream).lineno)
+        node.name = self.stream.expect("name").value
+        node.scoped = self.stream.skip_if("name:scoped")
+        node.required = self.stream.skip_if("name:required")
+
+        # common problem people encounter when switching from django
+        # to jinja.  we do not support hyphens in block names, so let's
+        # raise a nicer error message in that case.
+        if self.stream.current.type == "sub":
+            self.fail(
+                "Block names in Jinja have to be valid Python identifiers and may not"
+                " contain hyphens, use an underscore instead."
+            )
+
+        node.body = self.parse_statements(("name:endblock",), drop_needle=True)
+
+        # enforce that required blocks only contain whitespace or comments
+        # by asserting that the body, if not empty, is just TemplateData nodes
+        # with whitespace data
+        if node.required and not all(
+            isinstance(child, nodes.TemplateData) and child.data.isspace()
+            for body in node.body
+            for child in body.nodes  # type: ignore
+        ):
+            self.fail("Required blocks can only contain comments or whitespace")
+
+        self.stream.skip_if("name:" + node.name)
+        return node
+
+    def parse_extends(self) -> nodes.Extends:
+        node = nodes.Extends(lineno=next(self.stream).lineno)
+        node.template = self.parse_expression()
+        return node
+
+    def parse_import_context(
+        self, node: _ImportInclude, default: bool
+    ) -> _ImportInclude:
+        if self.stream.current.test_any(
+            "name:with", "name:without"
+        ) and self.stream.look().test("name:context"):
+            node.with_context = next(self.stream).value == "with"
+            self.stream.skip()
+        else:
+            node.with_context = default
+        return node
+
+    def parse_include(self) -> nodes.Include:
+        node = nodes.Include(lineno=next(self.stream).lineno)
+        node.template = self.parse_expression()
+        if self.stream.current.test("name:ignore") and self.stream.look().test(
+            "name:missing"
+        ):
+            node.ignore_missing = True
+            self.stream.skip(2)
+        else:
+            node.ignore_missing = False
+        return self.parse_import_context(node, True)
+
+    def parse_import(self) -> nodes.Import:
+        node = nodes.Import(lineno=next(self.stream).lineno)
+        node.template = self.parse_expression()
+        self.stream.expect("name:as")
+        node.target = self.parse_assign_target(name_only=True).name
+        return self.parse_import_context(node, False)
+
+    def parse_from(self) -> nodes.FromImport:
+        node = nodes.FromImport(lineno=next(self.stream).lineno)
+        node.template = self.parse_expression()
+        self.stream.expect("name:import")
+        node.names = []
+
+        def parse_context() -> bool:
+            if (
+                self.stream.current.value
+                in {
+                    "with",
+                    "without",
+                }
+                and self.stream.look().test("name:context")
+            ):
+                node.with_context = next(self.stream).value == "with"
+                self.stream.skip()
+                return True
+            return False
+
+        while True:
+            if node.names:
+                self.stream.expect("comma")
+            if self.stream.current.type == "name":
+                if parse_context():
+                    break
+                target = self.parse_assign_target(name_only=True)
+                if target.name.startswith("_"):
+                    self.fail(
+                        "names starting with an underline can not be imported",
+                        target.lineno,
+                        exc=TemplateAssertionError,
+                    )
+                if self.stream.skip_if("name:as"):
+                    alias = self.parse_assign_target(name_only=True)
+                    node.names.append((target.name, alias.name))
+                else:
+                    node.names.append(target.name)
+                if parse_context() or self.stream.current.type != "comma":
+                    break
+            else:
+                self.stream.expect("name")
+        if not hasattr(node, "with_context"):
+            node.with_context = False
+        return node
+
+    def parse_signature(self, node: _MacroCall) -> None:
+        args = node.args = []
+        defaults = node.defaults = []
+        self.stream.expect("lparen")
+        while self.stream.current.type != "rparen":
+            if args:
+                self.stream.expect("comma")
+            arg = self.parse_assign_target(name_only=True)
+            arg.set_ctx("param")
+            if self.stream.skip_if("assign"):
+                defaults.append(self.parse_expression())
+            elif defaults:
+                self.fail("non-default argument follows default argument")
+            args.append(arg)
+        self.stream.expect("rparen")
+
+    def parse_call_block(self) -> nodes.CallBlock:
+        node = nodes.CallBlock(lineno=next(self.stream).lineno)
+        if self.stream.current.type == "lparen":
+            self.parse_signature(node)
+        else:
+            node.args = []
+            node.defaults = []
+
+        call_node = self.parse_expression()
+        if not isinstance(call_node, nodes.Call):
+            self.fail("expected call", node.lineno)
+        node.call = call_node
+        node.body = self.parse_statements(("name:endcall",), drop_needle=True)
+        return node
+
+    def parse_filter_block(self) -> nodes.FilterBlock:
+        node = nodes.FilterBlock(lineno=next(self.stream).lineno)
+        node.filter = self.parse_filter(None, start_inline=True)  # type: ignore
+        node.body = self.parse_statements(("name:endfilter",), drop_needle=True)
+        return node
+
+    def parse_macro(self) -> nodes.Macro:
+        node = nodes.Macro(lineno=next(self.stream).lineno)
+        node.name = self.parse_assign_target(name_only=True).name
+        self.parse_signature(node)
+        node.body = self.parse_statements(("name:endmacro",), drop_needle=True)
+        return node
+
+    def parse_print(self) -> nodes.Output:
+        node = nodes.Output(lineno=next(self.stream).lineno)
+        node.nodes = []
+        while self.stream.current.type != "block_end":
+            if node.nodes:
+                self.stream.expect("comma")
+            node.nodes.append(self.parse_expression())
+        return node
+
+    @typing.overload
+    def parse_assign_target(
+        self, with_tuple: bool = ..., name_only: "te.Literal[True]" = ...
+    ) -> nodes.Name:
+        ...
+
+    @typing.overload
+    def parse_assign_target(
+        self,
+        with_tuple: bool = True,
+        name_only: bool = False,
+        extra_end_rules: t.Optional[t.Tuple[str, ...]] = None,
+        with_namespace: bool = False,
+    ) -> t.Union[nodes.NSRef, nodes.Name, nodes.Tuple]:
+        ...
+
+    def parse_assign_target(
+        self,
+        with_tuple: bool = True,
+        name_only: bool = False,
+        extra_end_rules: t.Optional[t.Tuple[str, ...]] = None,
+        with_namespace: bool = False,
+    ) -> t.Union[nodes.NSRef, nodes.Name, nodes.Tuple]:
+        """Parse an assignment target.  As Jinja allows assignments to
+        tuples, this function can parse all allowed assignment targets.  Per
+        default assignments to tuples are parsed, that can be disable however
+        by setting `with_tuple` to `False`.  If only assignments to names are
+        wanted `name_only` can be set to `True`.  The `extra_end_rules`
+        parameter is forwarded to the tuple parsing function.  If
+        `with_namespace` is enabled, a namespace assignment may be parsed.
+        """
+        target: nodes.Expr
+
+        if with_namespace and self.stream.look().type == "dot":
+            token = self.stream.expect("name")
+            next(self.stream)  # dot
+            attr = self.stream.expect("name")
+            target = nodes.NSRef(token.value, attr.value, lineno=token.lineno)
+        elif name_only:
+            token = self.stream.expect("name")
+            target = nodes.Name(token.value, "store", lineno=token.lineno)
+        else:
+            if with_tuple:
+                target = self.parse_tuple(
+                    simplified=True, extra_end_rules=extra_end_rules
+                )
+            else:
+                target = self.parse_primary()
+
+            target.set_ctx("store")
+
+        if not target.can_assign():
+            self.fail(
+                f"can't assign to {type(target).__name__.lower()!r}", target.lineno
+            )
+
+        return target  # type: ignore
+
+    def parse_expression(self, with_condexpr: bool = True) -> nodes.Expr:
+        """Parse an expression.  Per default all expressions are parsed, if
+        the optional `with_condexpr` parameter is set to `False` conditional
+        expressions are not parsed.
+        """
+        if with_condexpr:
+            return self.parse_condexpr()
+        return self.parse_or()
+
+    def parse_condexpr(self) -> nodes.Expr:
+        lineno = self.stream.current.lineno
+        expr1 = self.parse_or()
+        expr3: t.Optional[nodes.Expr]
+
+        while self.stream.skip_if("name:if"):
+            expr2 = self.parse_or()
+            if self.stream.skip_if("name:else"):
+                expr3 = self.parse_condexpr()
+            else:
+                expr3 = None
+            expr1 = nodes.CondExpr(expr2, expr1, expr3, lineno=lineno)
+            lineno = self.stream.current.lineno
+        return expr1
+
+    def parse_or(self) -> nodes.Expr:
+        lineno = self.stream.current.lineno
+        left = self.parse_and()
+        while self.stream.skip_if("name:or"):
+            right = self.parse_and()
+            left = nodes.Or(left, right, lineno=lineno)
+            lineno = self.stream.current.lineno
+        return left
+
+    def parse_and(self) -> nodes.Expr:
+        lineno = self.stream.current.lineno
+        left = self.parse_not()
+        while self.stream.skip_if("name:and"):
+            right = self.parse_not()
+            left = nodes.And(left, right, lineno=lineno)
+            lineno = self.stream.current.lineno
+        return left
+
+    def parse_not(self) -> nodes.Expr:
+        if self.stream.current.test("name:not"):
+            lineno = next(self.stream).lineno
+            return nodes.Not(self.parse_not(), lineno=lineno)
+        return self.parse_compare()
+
+    def parse_compare(self) -> nodes.Expr:
+        lineno = self.stream.current.lineno
+        expr = self.parse_math1()
+        ops = []
+        while True:
+            token_type = self.stream.current.type
+            if token_type in _compare_operators:
+                next(self.stream)
+                ops.append(nodes.Operand(token_type, self.parse_math1()))
+            elif self.stream.skip_if("name:in"):
+                ops.append(nodes.Operand("in", self.parse_math1()))
+            elif self.stream.current.test("name:not") and self.stream.look().test(
+                "name:in"
+            ):
+                self.stream.skip(2)
+                ops.append(nodes.Operand("notin", self.parse_math1()))
+            else:
+                break
+            lineno = self.stream.current.lineno
+        if not ops:
+            return expr
+        return nodes.Compare(expr, ops, lineno=lineno)
+
+    def parse_math1(self) -> nodes.Expr:
+        lineno = self.stream.current.lineno
+        left = self.parse_concat()
+        while self.stream.current.type in ("add", "sub"):
+            cls = _math_nodes[self.stream.current.type]
+            next(self.stream)
+            right = self.parse_concat()
+            left = cls(left, right, lineno=lineno)
+            lineno = self.stream.current.lineno
+        return left
+
+    def parse_concat(self) -> nodes.Expr:
+        lineno = self.stream.current.lineno
+        args = [self.parse_math2()]
+        while self.stream.current.type == "tilde":
+            next(self.stream)
+            args.append(self.parse_math2())
+        if len(args) == 1:
+            return args[0]
+        return nodes.Concat(args, lineno=lineno)
+
+    def parse_math2(self) -> nodes.Expr:
+        lineno = self.stream.current.lineno
+        left = self.parse_pow()
+        while self.stream.current.type in ("mul", "div", "floordiv", "mod"):
+            cls = _math_nodes[self.stream.current.type]
+            next(self.stream)
+            right = self.parse_pow()
+            left = cls(left, right, lineno=lineno)
+            lineno = self.stream.current.lineno
+        return left
+
+    def parse_pow(self) -> nodes.Expr:
+        lineno = self.stream.current.lineno
+        left = self.parse_unary()
+        while self.stream.current.type == "pow":
+            next(self.stream)
+            right = self.parse_unary()
+            left = nodes.Pow(left, right, lineno=lineno)
+            lineno = self.stream.current.lineno
+        return left
+
+    def parse_unary(self, with_filter: bool = True) -> nodes.Expr:
+        token_type = self.stream.current.type
+        lineno = self.stream.current.lineno
+        node: nodes.Expr
+
+        if token_type == "sub":
+            next(self.stream)
+            node = nodes.Neg(self.parse_unary(False), lineno=lineno)
+        elif token_type == "add":
+            next(self.stream)
+            node = nodes.Pos(self.parse_unary(False), lineno=lineno)
+        else:
+            node = self.parse_primary()
+        node = self.parse_postfix(node)
+        if with_filter:
+            node = self.parse_filter_expr(node)
+        return node
+
+    def parse_primary(self) -> nodes.Expr:
+        token = self.stream.current
+        node: nodes.Expr
+        if token.type == "name":
+            if token.value in ("true", "false", "True", "False"):
+                node = nodes.Const(token.value in ("true", "True"), lineno=token.lineno)
+            elif token.value in ("none", "None"):
+                node = nodes.Const(None, lineno=token.lineno)
+            else:
+                node = nodes.Name(token.value, "load", lineno=token.lineno)
+            next(self.stream)
+        elif token.type == "string":
+            next(self.stream)
+            buf = [token.value]
+            lineno = token.lineno
+            while self.stream.current.type == "string":
+                buf.append(self.stream.current.value)
+                next(self.stream)
+            node = nodes.Const("".join(buf), lineno=lineno)
+        elif token.type in ("integer", "float"):
+            next(self.stream)
+            node = nodes.Const(token.value, lineno=token.lineno)
+        elif token.type == "lparen":
+            next(self.stream)
+            node = self.parse_tuple(explicit_parentheses=True)
+            self.stream.expect("rparen")
+        elif token.type == "lbracket":
+            node = self.parse_list()
+        elif token.type == "lbrace":
+            node = self.parse_dict()
+        else:
+            self.fail(f"unexpected {describe_token(token)!r}", token.lineno)
+        return node
+
+    def parse_tuple(
+        self,
+        simplified: bool = False,
+        with_condexpr: bool = True,
+        extra_end_rules: t.Optional[t.Tuple[str, ...]] = None,
+        explicit_parentheses: bool = False,
+    ) -> t.Union[nodes.Tuple, nodes.Expr]:
+        """Works like `parse_expression` but if multiple expressions are
+        delimited by a comma a :class:`~jinja2.nodes.Tuple` node is created.
+        This method could also return a regular expression instead of a tuple
+        if no commas where found.
+
+        The default parsing mode is a full tuple.  If `simplified` is `True`
+        only names and literals are parsed.  The `no_condexpr` parameter is
+        forwarded to :meth:`parse_expression`.
+
+        Because tuples do not require delimiters and may end in a bogus comma
+        an extra hint is needed that marks the end of a tuple.  For example
+        for loops support tuples between `for` and `in`.  In that case the
+        `extra_end_rules` is set to ``['name:in']``.
+
+        `explicit_parentheses` is true if the parsing was triggered by an
+        expression in parentheses.  This is used to figure out if an empty
+        tuple is a valid expression or not.
+        """
+        lineno = self.stream.current.lineno
+        if simplified:
+            parse = self.parse_primary
+        elif with_condexpr:
+            parse = self.parse_expression
+        else:
+
+            def parse() -> nodes.Expr:
+                return self.parse_expression(with_condexpr=False)
+
+        args: t.List[nodes.Expr] = []
+        is_tuple = False
+
+        while True:
+            if args:
+                self.stream.expect("comma")
+            if self.is_tuple_end(extra_end_rules):
+                break
+            args.append(parse())
+            if self.stream.current.type == "comma":
+                is_tuple = True
+            else:
+                break
+            lineno = self.stream.current.lineno
+
+        if not is_tuple:
+            if args:
+                return args[0]
+
+            # if we don't have explicit parentheses, an empty tuple is
+            # not a valid expression.  This would mean nothing (literally
+            # nothing) in the spot of an expression would be an empty
+            # tuple.
+            if not explicit_parentheses:
+                self.fail(
+                    "Expected an expression,"
+                    f" got {describe_token(self.stream.current)!r}"
+                )
+
+        return nodes.Tuple(args, "load", lineno=lineno)
+
+    def parse_list(self) -> nodes.List:
+        token = self.stream.expect("lbracket")
+        items: t.List[nodes.Expr] = []
+        while self.stream.current.type != "rbracket":
+            if items:
+                self.stream.expect("comma")
+            if self.stream.current.type == "rbracket":
+                break
+            items.append(self.parse_expression())
+        self.stream.expect("rbracket")
+        return nodes.List(items, lineno=token.lineno)
+
+    def parse_dict(self) -> nodes.Dict:
+        token = self.stream.expect("lbrace")
+        items: t.List[nodes.Pair] = []
+        while self.stream.current.type != "rbrace":
+            if items:
+                self.stream.expect("comma")
+            if self.stream.current.type == "rbrace":
+                break
+            key = self.parse_expression()
+            self.stream.expect("colon")
+            value = self.parse_expression()
+            items.append(nodes.Pair(key, value, lineno=key.lineno))
+        self.stream.expect("rbrace")
+        return nodes.Dict(items, lineno=token.lineno)
+
+    def parse_postfix(self, node: nodes.Expr) -> nodes.Expr:
+        while True:
+            token_type = self.stream.current.type
+            if token_type == "dot" or token_type == "lbracket":
+                node = self.parse_subscript(node)
+            # calls are valid both after postfix expressions (getattr
+            # and getitem) as well as filters and tests
+            elif token_type == "lparen":
+                node = self.parse_call(node)
+            else:
+                break
+        return node
+
+    def parse_filter_expr(self, node: nodes.Expr) -> nodes.Expr:
+        while True:
+            token_type = self.stream.current.type
+            if token_type == "pipe":
+                node = self.parse_filter(node)  # type: ignore
+            elif token_type == "name" and self.stream.current.value == "is":
+                node = self.parse_test(node)
+            # calls are valid both after postfix expressions (getattr
+            # and getitem) as well as filters and tests
+            elif token_type == "lparen":
+                node = self.parse_call(node)
+            else:
+                break
+        return node
+
+    def parse_subscript(
+        self, node: nodes.Expr
+    ) -> t.Union[nodes.Getattr, nodes.Getitem]:
+        token = next(self.stream)
+        arg: nodes.Expr
+
+        if token.type == "dot":
+            attr_token = self.stream.current
+            next(self.stream)
+            if attr_token.type == "name":
+                return nodes.Getattr(
+                    node, attr_token.value, "load", lineno=token.lineno
+                )
+            elif attr_token.type != "integer":
+                self.fail("expected name or number", attr_token.lineno)
+            arg = nodes.Const(attr_token.value, lineno=attr_token.lineno)
+            return nodes.Getitem(node, arg, "load", lineno=token.lineno)
+        if token.type == "lbracket":
+            args: t.List[nodes.Expr] = []
+            while self.stream.current.type != "rbracket":
+                if args:
+                    self.stream.expect("comma")
+                args.append(self.parse_subscribed())
+            self.stream.expect("rbracket")
+            if len(args) == 1:
+                arg = args[0]
+            else:
+                arg = nodes.Tuple(args, "load", lineno=token.lineno)
+            return nodes.Getitem(node, arg, "load", lineno=token.lineno)
+        self.fail("expected subscript expression", token.lineno)
+
+    def parse_subscribed(self) -> nodes.Expr:
+        lineno = self.stream.current.lineno
+        args: t.List[t.Optional[nodes.Expr]]
+
+        if self.stream.current.type == "colon":
+            next(self.stream)
+            args = [None]
+        else:
+            node = self.parse_expression()
+            if self.stream.current.type != "colon":
+                return node
+            next(self.stream)
+            args = [node]
+
+        if self.stream.current.type == "colon":
+            args.append(None)
+        elif self.stream.current.type not in ("rbracket", "comma"):
+            args.append(self.parse_expression())
+        else:
+            args.append(None)
+
+        if self.stream.current.type == "colon":
+            next(self.stream)
+            if self.stream.current.type not in ("rbracket", "comma"):
+                args.append(self.parse_expression())
+            else:
+                args.append(None)
+        else:
+            args.append(None)
+
+        return nodes.Slice(lineno=lineno, *args)
+
+    def parse_call_args(self) -> t.Tuple:
+        token = self.stream.expect("lparen")
+        args = []
+        kwargs = []
+        dyn_args = None
+        dyn_kwargs = None
+        require_comma = False
+
+        def ensure(expr: bool) -> None:
+            if not expr:
+                self.fail("invalid syntax for function call expression", token.lineno)
+
+        while self.stream.current.type != "rparen":
+            if require_comma:
+                self.stream.expect("comma")
+
+                # support for trailing comma
+                if self.stream.current.type == "rparen":
+                    break
+
+            if self.stream.current.type == "mul":
+                ensure(dyn_args is None and dyn_kwargs is None)
+                next(self.stream)
+                dyn_args = self.parse_expression()
+            elif self.stream.current.type == "pow":
+                ensure(dyn_kwargs is None)
+                next(self.stream)
+                dyn_kwargs = self.parse_expression()
+            else:
+                if (
+                    self.stream.current.type == "name"
+                    and self.stream.look().type == "assign"
+                ):
+                    # Parsing a kwarg
+                    ensure(dyn_kwargs is None)
+                    key = self.stream.current.value
+                    self.stream.skip(2)
+                    value = self.parse_expression()
+                    kwargs.append(nodes.Keyword(key, value, lineno=value.lineno))
+                else:
+                    # Parsing an arg
+                    ensure(dyn_args is None and dyn_kwargs is None and not kwargs)
+                    args.append(self.parse_expression())
+
+            require_comma = True
+
+        self.stream.expect("rparen")
+        return args, kwargs, dyn_args, dyn_kwargs
+
+    def parse_call(self, node: nodes.Expr) -> nodes.Call:
+        # The lparen will be expected in parse_call_args, but the lineno
+        # needs to be recorded before the stream is advanced.
+        token = self.stream.current
+        args, kwargs, dyn_args, dyn_kwargs = self.parse_call_args()
+        return nodes.Call(node, args, kwargs, dyn_args, dyn_kwargs, lineno=token.lineno)
+
+    def parse_filter(
+        self, node: t.Optional[nodes.Expr], start_inline: bool = False
+    ) -> t.Optional[nodes.Expr]:
+        while self.stream.current.type == "pipe" or start_inline:
+            if not start_inline:
+                next(self.stream)
+            token = self.stream.expect("name")
+            name = token.value
+            while self.stream.current.type == "dot":
+                next(self.stream)
+                name += "." + self.stream.expect("name").value
+            if self.stream.current.type == "lparen":
+                args, kwargs, dyn_args, dyn_kwargs = self.parse_call_args()
+            else:
+                args = []
+                kwargs = []
+                dyn_args = dyn_kwargs = None
+            node = nodes.Filter(
+                node, name, args, kwargs, dyn_args, dyn_kwargs, lineno=token.lineno
+            )
+            start_inline = False
+        return node
+
+    def parse_test(self, node: nodes.Expr) -> nodes.Expr:
+        token = next(self.stream)
+        if self.stream.current.test("name:not"):
+            next(self.stream)
+            negated = True
+        else:
+            negated = False
+        name = self.stream.expect("name").value
+        while self.stream.current.type == "dot":
+            next(self.stream)
+            name += "." + self.stream.expect("name").value
+        dyn_args = dyn_kwargs = None
+        kwargs = []
+        if self.stream.current.type == "lparen":
+            args, kwargs, dyn_args, dyn_kwargs = self.parse_call_args()
+        elif (
+            self.stream.current.type
+            in {
+                "name",
+                "string",
+                "integer",
+                "float",
+                "lparen",
+                "lbracket",
+                "lbrace",
+            }
+            and not self.stream.current.test_any("name:else", "name:or", "name:and")
+        ):
+            if self.stream.current.test("name:is"):
+                self.fail("You cannot chain multiple tests with is")
+            arg_node = self.parse_primary()
+            arg_node = self.parse_postfix(arg_node)
+            args = [arg_node]
+        else:
+            args = []
+        node = nodes.Test(
+            node, name, args, kwargs, dyn_args, dyn_kwargs, lineno=token.lineno
+        )
+        if negated:
+            node = nodes.Not(node, lineno=token.lineno)
+        return node
+
+    def subparse(
+        self, end_tokens: t.Optional[t.Tuple[str, ...]] = None
+    ) -> t.List[nodes.Node]:
+        body: t.List[nodes.Node] = []
+        data_buffer: t.List[nodes.Node] = []
+        add_data = data_buffer.append
+
+        if end_tokens is not None:
+            self._end_token_stack.append(end_tokens)
+
+        def flush_data() -> None:
+            if data_buffer:
+                lineno = data_buffer[0].lineno
+                body.append(nodes.Output(data_buffer[:], lineno=lineno))
+                del data_buffer[:]
+
+        try:
+            while self.stream:
+                token = self.stream.current
+                if token.type == "data":
+                    if token.value:
+                        add_data(nodes.TemplateData(token.value, lineno=token.lineno))
+                    next(self.stream)
+                elif token.type == "variable_begin":
+                    next(self.stream)
+                    add_data(self.parse_tuple(with_condexpr=True))
+                    self.stream.expect("variable_end")
+                elif token.type == "block_begin":
+                    flush_data()
+                    next(self.stream)
+                    if end_tokens is not None and self.stream.current.test_any(
+                        *end_tokens
+                    ):
+                        return body
+                    rv = self.parse_statement()
+                    if isinstance(rv, list):
+                        body.extend(rv)
+                    else:
+                        body.append(rv)
+                    self.stream.expect("block_end")
+                else:
+                    raise AssertionError("internal parsing error")
+
+            flush_data()
+        finally:
+            if end_tokens is not None:
+                self._end_token_stack.pop()
+        return body
+
+    def parse(self) -> nodes.Template:
+        """Parse the whole template into a `Template` node."""
+        result = nodes.Template(self.subparse(), lineno=1)
+        result.set_environment(self.environment)
+        return result
diff --git a/lib/spack/external/_vendoring/jinja2/py.typed b/lib/spack/external/_vendoring/jinja2/py.typed
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/lib/spack/external/_vendoring/jinja2/py.typed
diff --git a/lib/spack/external/_vendoring/jinja2/runtime.py b/lib/spack/external/_vendoring/jinja2/runtime.py
new file mode 100644
index 0000000000..2346cf2bac
--- /dev/null
+++ b/lib/spack/external/_vendoring/jinja2/runtime.py
@@ -0,0 +1,1104 @@
+"""The runtime functions and state used by compiled templates."""
+import functools
+import sys
+import typing as t
+from collections import abc
+from itertools import chain
+
+from markupsafe import escape  # noqa: F401
+from markupsafe import Markup
+from markupsafe import soft_str
+
+from .async_utils import auto_aiter
+from .async_utils import auto_await  # noqa: F401
+from .exceptions import TemplateNotFound  # noqa: F401
+from .exceptions import TemplateRuntimeError  # noqa: F401
+from .exceptions import UndefinedError
+from .nodes import EvalContext
+from .utils import _PassArg
+from .utils import concat
+from .utils import internalcode
+from .utils import missing
+from .utils import Namespace  # noqa: F401
+from .utils import object_type_repr
+from .utils import pass_eval_context
+
+V = t.TypeVar("V")
+F = t.TypeVar("F", bound=t.Callable[..., t.Any])
+
+if t.TYPE_CHECKING:
+    import logging
+    import typing_extensions as te
+    from .environment import Environment
+
+    class LoopRenderFunc(te.Protocol):
+        def __call__(
+            self,
+            reciter: t.Iterable[V],
+            loop_render_func: "LoopRenderFunc",
+            depth: int = 0,
+        ) -> str:
+            ...
+
+
+# these variables are exported to the template runtime
+exported = [
+    "LoopContext",
+    "TemplateReference",
+    "Macro",
+    "Markup",
+    "TemplateRuntimeError",
+    "missing",
+    "concat",
+    "escape",
+    "markup_join",
+    "str_join",
+    "identity",
+    "TemplateNotFound",
+    "Namespace",
+    "Undefined",
+    "internalcode",
+]
+async_exported = [
+    "AsyncLoopContext",
+    "auto_aiter",
+    "auto_await",
+]
+
+
+def identity(x: V) -> V:
+    """Returns its argument. Useful for certain things in the
+    environment.
+    """
+    return x
+
+
+def markup_join(seq: t.Iterable[t.Any]) -> str:
+    """Concatenation that escapes if necessary and converts to string."""
+    buf = []
+    iterator = map(soft_str, seq)
+    for arg in iterator:
+        buf.append(arg)
+        if hasattr(arg, "__html__"):
+            return Markup("").join(chain(buf, iterator))
+    return concat(buf)
+
+
+def str_join(seq: t.Iterable[t.Any]) -> str:
+    """Simple args to string conversion and concatenation."""
+    return concat(map(str, seq))
+
+
+def unicode_join(seq: t.Iterable[t.Any]) -> str:
+    import warnings
+
+    warnings.warn(
+        "This template must be recompiled with at least Jinja 3.0, or"
+        " it will fail in Jinja 3.1.",
+        DeprecationWarning,
+        stacklevel=2,
+    )
+    return str_join(seq)
+
+
+def new_context(
+    environment: "Environment",
+    template_name: t.Optional[str],
+    blocks: t.Dict[str, t.Callable[["Context"], t.Iterator[str]]],
+    vars: t.Optional[t.Dict[str, t.Any]] = None,
+    shared: bool = False,
+    globals: t.Optional[t.MutableMapping[str, t.Any]] = None,
+    locals: t.Optional[t.Mapping[str, t.Any]] = None,
+) -> "Context":
+    """Internal helper for context creation."""
+    if vars is None:
+        vars = {}
+    if shared:
+        parent = vars
+    else:
+        parent = dict(globals or (), **vars)
+    if locals:
+        # if the parent is shared a copy should be created because
+        # we don't want to modify the dict passed
+        if shared:
+            parent = dict(parent)
+        for key, value in locals.items():
+            if value is not missing:
+                parent[key] = value
+    return environment.context_class(
+        environment, parent, template_name, blocks, globals=globals
+    )
+
+
+class TemplateReference:
+    """The `self` in templates."""
+
+    def __init__(self, context: "Context") -> None:
+        self.__context = context
+
+    def __getitem__(self, name: str) -> t.Any:
+        blocks = self.__context.blocks[name]
+        return BlockReference(name, self.__context, blocks, 0)
+
+    def __repr__(self) -> str:
+        return f"<{type(self).__name__} {self.__context.name!r}>"
+
+
+def _dict_method_all(dict_method: F) -> F:
+    @functools.wraps(dict_method)
+    def f_all(self: "Context") -> t.Any:
+        return dict_method(self.get_all())
+
+    return t.cast(F, f_all)
+
+
+@abc.Mapping.register
+class Context:
+    """The template context holds the variables of a template.  It stores the
+    values passed to the template and also the names the template exports.
+    Creating instances is neither supported nor useful as it's created
+    automatically at various stages of the template evaluation and should not
+    be created by hand.
+
+    The context is immutable.  Modifications on :attr:`parent` **must not**
+    happen and modifications on :attr:`vars` are allowed from generated
+    template code only.  Template filters and global functions marked as
+    :func:`pass_context` get the active context passed as first argument
+    and are allowed to access the context read-only.
+
+    The template context supports read only dict operations (`get`,
+    `keys`, `values`, `items`, `iterkeys`, `itervalues`, `iteritems`,
+    `__getitem__`, `__contains__`).  Additionally there is a :meth:`resolve`
+    method that doesn't fail with a `KeyError` but returns an
+    :class:`Undefined` object for missing variables.
+    """
+
+    _legacy_resolve_mode: t.ClassVar[bool] = False
+
+    def __init_subclass__(cls) -> None:
+        if "resolve_or_missing" in cls.__dict__:
+            # If the subclass overrides resolve_or_missing it opts in to
+            # modern mode no matter what.
+            cls._legacy_resolve_mode = False
+        elif "resolve" in cls.__dict__ or cls._legacy_resolve_mode:
+            # If the subclass overrides resolve, or if its base is
+            # already in legacy mode, warn about legacy behavior.
+            import warnings
+
+            warnings.warn(
+                "Overriding 'resolve' is deprecated and will not have"
+                " the expected behavior in Jinja 3.1. Override"
+                " 'resolve_or_missing' instead ",
+                DeprecationWarning,
+                stacklevel=2,
+            )
+            cls._legacy_resolve_mode = True
+
+    def __init__(
+        self,
+        environment: "Environment",
+        parent: t.Dict[str, t.Any],
+        name: t.Optional[str],
+        blocks: t.Dict[str, t.Callable[["Context"], t.Iterator[str]]],
+        globals: t.Optional[t.MutableMapping[str, t.Any]] = None,
+    ):
+        self.parent = parent
+        self.vars: t.Dict[str, t.Any] = {}
+        self.environment: "Environment" = environment
+        self.eval_ctx = EvalContext(self.environment, name)
+        self.exported_vars: t.Set[str] = set()
+        self.name = name
+        self.globals_keys = set() if globals is None else set(globals)
+
+        # create the initial mapping of blocks.  Whenever template inheritance
+        # takes place the runtime will update this mapping with the new blocks
+        # from the template.
+        self.blocks = {k: [v] for k, v in blocks.items()}
+
+    def super(
+        self, name: str, current: t.Callable[["Context"], t.Iterator[str]]
+    ) -> t.Union["BlockReference", "Undefined"]:
+        """Render a parent block."""
+        try:
+            blocks = self.blocks[name]
+            index = blocks.index(current) + 1
+            blocks[index]
+        except LookupError:
+            return self.environment.undefined(
+                f"there is no parent block called {name!r}.", name="super"
+            )
+        return BlockReference(name, self, blocks, index)
+
+    def get(self, key: str, default: t.Any = None) -> t.Any:
+        """Look up a variable by name, or return a default if the key is
+        not found.
+
+        :param key: The variable name to look up.
+        :param default: The value to return if the key is not found.
+        """
+        try:
+            return self[key]
+        except KeyError:
+            return default
+
+    def resolve(self, key: str) -> t.Union[t.Any, "Undefined"]:
+        """Look up a variable by name, or return an :class:`Undefined`
+        object if the key is not found.
+
+        If you need to add custom behavior, override
+        :meth:`resolve_or_missing`, not this method. The various lookup
+        functions use that method, not this one.
+
+        :param key: The variable name to look up.
+        """
+        if self._legacy_resolve_mode:
+            if key in self.vars:
+                return self.vars[key]
+
+            if key in self.parent:
+                return self.parent[key]
+
+            return self.environment.undefined(name=key)
+
+        rv = self.resolve_or_missing(key)
+
+        if rv is missing:
+            return self.environment.undefined(name=key)
+
+        return rv
+
+    def resolve_or_missing(self, key: str) -> t.Any:
+        """Look up a variable by name, or return a ``missing`` sentinel
+        if the key is not found.
+
+        Override this method to add custom lookup behavior.
+        :meth:`resolve`, :meth:`get`, and :meth:`__getitem__` use this
+        method. Don't call this method directly.
+
+        :param key: The variable name to look up.
+        """
+        if self._legacy_resolve_mode:
+            rv = self.resolve(key)
+
+            if isinstance(rv, Undefined):
+                return missing
+
+            return rv
+
+        if key in self.vars:
+            return self.vars[key]
+
+        if key in self.parent:
+            return self.parent[key]
+
+        return missing
+
+    def get_exported(self) -> t.Dict[str, t.Any]:
+        """Get a new dict with the exported variables."""
+        return {k: self.vars[k] for k in self.exported_vars}
+
+    def get_all(self) -> t.Dict[str, t.Any]:
+        """Return the complete context as dict including the exported
+        variables.  For optimizations reasons this might not return an
+        actual copy so be careful with using it.
+        """
+        if not self.vars:
+            return self.parent
+        if not self.parent:
+            return self.vars
+        return dict(self.parent, **self.vars)
+
+    @internalcode
+    def call(
+        __self, __obj: t.Callable, *args: t.Any, **kwargs: t.Any  # noqa: B902
+    ) -> t.Union[t.Any, "Undefined"]:
+        """Call the callable with the arguments and keyword arguments
+        provided but inject the active context or environment as first
+        argument if the callable has :func:`pass_context` or
+        :func:`pass_environment`.
+        """
+        if __debug__:
+            __traceback_hide__ = True  # noqa
+
+        # Allow callable classes to take a context
+        if (
+            hasattr(__obj, "__call__")  # noqa: B004
+            and _PassArg.from_obj(__obj.__call__) is not None  # type: ignore
+        ):
+            __obj = __obj.__call__  # type: ignore
+
+        pass_arg = _PassArg.from_obj(__obj)
+
+        if pass_arg is _PassArg.context:
+            # the active context should have access to variables set in
+            # loops and blocks without mutating the context itself
+            if kwargs.get("_loop_vars"):
+                __self = __self.derived(kwargs["_loop_vars"])
+            if kwargs.get("_block_vars"):
+                __self = __self.derived(kwargs["_block_vars"])
+            args = (__self,) + args
+        elif pass_arg is _PassArg.eval_context:
+            args = (__self.eval_ctx,) + args
+        elif pass_arg is _PassArg.environment:
+            args = (__self.environment,) + args
+
+        kwargs.pop("_block_vars", None)
+        kwargs.pop("_loop_vars", None)
+
+        try:
+            return __obj(*args, **kwargs)
+        except StopIteration:
+            return __self.environment.undefined(
+                "value was undefined because a callable raised a"
+                " StopIteration exception"
+            )
+
+    def derived(self, locals: t.Optional[t.Dict[str, t.Any]] = None) -> "Context":
+        """Internal helper function to create a derived context.  This is
+        used in situations where the system needs a new context in the same
+        template that is independent.
+        """
+        context = new_context(
+            self.environment, self.name, {}, self.get_all(), True, None, locals
+        )
+        context.eval_ctx = self.eval_ctx
+        context.blocks.update((k, list(v)) for k, v in self.blocks.items())
+        return context
+
+    keys = _dict_method_all(dict.keys)
+    values = _dict_method_all(dict.values)
+    items = _dict_method_all(dict.items)
+
+    def __contains__(self, name: str) -> bool:
+        return name in self.vars or name in self.parent
+
+    def __getitem__(self, key: str) -> t.Any:
+        """Look up a variable by name with ``[]`` syntax, or raise a
+        ``KeyError`` if the key is not found.
+        """
+        item = self.resolve_or_missing(key)
+
+        if item is missing:
+            raise KeyError(key)
+
+        return item
+
+    def __repr__(self) -> str:
+        return f"<{type(self).__name__} {self.get_all()!r} of {self.name!r}>"
+
+
+class BlockReference:
+    """One block on a template reference."""
+
+    def __init__(
+        self,
+        name: str,
+        context: "Context",
+        stack: t.List[t.Callable[["Context"], t.Iterator[str]]],
+        depth: int,
+    ) -> None:
+        self.name = name
+        self._context = context
+        self._stack = stack
+        self._depth = depth
+
+    @property
+    def super(self) -> t.Union["BlockReference", "Undefined"]:
+        """Super the block."""
+        if self._depth + 1 >= len(self._stack):
+            return self._context.environment.undefined(
+                f"there is no parent block called {self.name!r}.", name="super"
+            )
+        return BlockReference(self.name, self._context, self._stack, self._depth + 1)
+
+    @internalcode
+    async def _async_call(self) -> str:
+        rv = concat(
+            [x async for x in self._stack[self._depth](self._context)]  # type: ignore
+        )
+
+        if self._context.eval_ctx.autoescape:
+            return Markup(rv)
+
+        return rv
+
+    @internalcode
+    def __call__(self) -> str:
+        if self._context.environment.is_async:
+            return self._async_call()  # type: ignore
+
+        rv = concat(self._stack[self._depth](self._context))
+
+        if self._context.eval_ctx.autoescape:
+            return Markup(rv)
+
+        return rv
+
+
+class LoopContext:
+    """A wrapper iterable for dynamic ``for`` loops, with information
+    about the loop and iteration.
+    """
+
+    #: Current iteration of the loop, starting at 0.
+    index0 = -1
+
+    _length: t.Optional[int] = None
+    _after: t.Any = missing
+    _current: t.Any = missing
+    _before: t.Any = missing
+    _last_changed_value: t.Any = missing
+
+    def __init__(
+        self,
+        iterable: t.Iterable[V],
+        undefined: t.Type["Undefined"],
+        recurse: t.Optional["LoopRenderFunc"] = None,
+        depth0: int = 0,
+    ) -> None:
+        """
+        :param iterable: Iterable to wrap.
+        :param undefined: :class:`Undefined` class to use for next and
+            previous items.
+        :param recurse: The function to render the loop body when the
+            loop is marked recursive.
+        :param depth0: Incremented when looping recursively.
+        """
+        self._iterable = iterable
+        self._iterator = self._to_iterator(iterable)
+        self._undefined = undefined
+        self._recurse = recurse
+        #: How many levels deep a recursive loop currently is, starting at 0.
+        self.depth0 = depth0
+
+    @staticmethod
+    def _to_iterator(iterable: t.Iterable[V]) -> t.Iterator[V]:
+        return iter(iterable)
+
+    @property
+    def length(self) -> int:
+        """Length of the iterable.
+
+        If the iterable is a generator or otherwise does not have a
+        size, it is eagerly evaluated to get a size.
+        """
+        if self._length is not None:
+            return self._length
+
+        try:
+            self._length = len(self._iterable)  # type: ignore
+        except TypeError:
+            iterable = list(self._iterator)
+            self._iterator = self._to_iterator(iterable)
+            self._length = len(iterable) + self.index + (self._after is not missing)
+
+        return self._length
+
+    def __len__(self) -> int:
+        return self.length
+
+    @property
+    def depth(self) -> int:
+        """How many levels deep a recursive loop currently is, starting at 1."""
+        return self.depth0 + 1
+
+    @property
+    def index(self) -> int:
+        """Current iteration of the loop, starting at 1."""
+        return self.index0 + 1
+
+    @property
+    def revindex0(self) -> int:
+        """Number of iterations from the end of the loop, ending at 0.
+
+        Requires calculating :attr:`length`.
+        """
+        return self.length - self.index
+
+    @property
+    def revindex(self) -> int:
+        """Number of iterations from the end of the loop, ending at 1.
+
+        Requires calculating :attr:`length`.
+        """
+        return self.length - self.index0
+
+    @property
+    def first(self) -> bool:
+        """Whether this is the first iteration of the loop."""
+        return self.index0 == 0
+
+    def _peek_next(self) -> t.Any:
+        """Return the next element in the iterable, or :data:`missing`
+        if the iterable is exhausted. Only peeks one item ahead, caching
+        the result in :attr:`_last` for use in subsequent checks. The
+        cache is reset when :meth:`__next__` is called.
+        """
+        if self._after is not missing:
+            return self._after
+
+        self._after = next(self._iterator, missing)
+        return self._after
+
+    @property
+    def last(self) -> bool:
+        """Whether this is the last iteration of the loop.
+
+        Causes the iterable to advance early. See
+        :func:`itertools.groupby` for issues this can cause.
+        The :func:`groupby` filter avoids that issue.
+        """
+        return self._peek_next() is missing
+
+    @property
+    def previtem(self) -> t.Union[t.Any, "Undefined"]:
+        """The item in the previous iteration. Undefined during the
+        first iteration.
+        """
+        if self.first:
+            return self._undefined("there is no previous item")
+
+        return self._before
+
+    @property
+    def nextitem(self) -> t.Union[t.Any, "Undefined"]:
+        """The item in the next iteration. Undefined during the last
+        iteration.
+
+        Causes the iterable to advance early. See
+        :func:`itertools.groupby` for issues this can cause.
+        The :func:`jinja-filters.groupby` filter avoids that issue.
+        """
+        rv = self._peek_next()
+
+        if rv is missing:
+            return self._undefined("there is no next item")
+
+        return rv
+
+    def cycle(self, *args: V) -> V:
+        """Return a value from the given args, cycling through based on
+        the current :attr:`index0`.
+
+        :param args: One or more values to cycle through.
+        """
+        if not args:
+            raise TypeError("no items for cycling given")
+
+        return args[self.index0 % len(args)]
+
+    def changed(self, *value: t.Any) -> bool:
+        """Return ``True`` if previously called with a different value
+        (including when called for the first time).
+
+        :param value: One or more values to compare to the last call.
+        """
+        if self._last_changed_value != value:
+            self._last_changed_value = value
+            return True
+
+        return False
+
+    def __iter__(self) -> "LoopContext":
+        return self
+
+    def __next__(self) -> t.Tuple[t.Any, "LoopContext"]:
+        if self._after is not missing:
+            rv = self._after
+            self._after = missing
+        else:
+            rv = next(self._iterator)
+
+        self.index0 += 1
+        self._before = self._current
+        self._current = rv
+        return rv, self
+
+    @internalcode
+    def __call__(self, iterable: t.Iterable[V]) -> str:
+        """When iterating over nested data, render the body of the loop
+        recursively with the given inner iterable data.
+
+        The loop must have the ``recursive`` marker for this to work.
+        """
+        if self._recurse is None:
+            raise TypeError(
+                "The loop must have the 'recursive' marker to be called recursively."
+            )
+
+        return self._recurse(iterable, self._recurse, depth=self.depth)
+
+    def __repr__(self) -> str:
+        return f"<{type(self).__name__} {self.index}/{self.length}>"
+
+
+class AsyncLoopContext(LoopContext):
+    _iterator: t.AsyncIterator[t.Any]  # type: ignore
+
+    @staticmethod
+    def _to_iterator(  # type: ignore
+        iterable: t.Union[t.Iterable[V], t.AsyncIterable[V]]
+    ) -> t.AsyncIterator[V]:
+        return auto_aiter(iterable)
+
+    @property
+    async def length(self) -> int:  # type: ignore
+        if self._length is not None:
+            return self._length
+
+        try:
+            self._length = len(self._iterable)  # type: ignore
+        except TypeError:
+            iterable = [x async for x in self._iterator]
+            self._iterator = self._to_iterator(iterable)
+            self._length = len(iterable) + self.index + (self._after is not missing)
+
+        return self._length
+
+    @property
+    async def revindex0(self) -> int:  # type: ignore
+        return await self.length - self.index
+
+    @property
+    async def revindex(self) -> int:  # type: ignore
+        return await self.length - self.index0
+
+    async def _peek_next(self) -> t.Any:
+        if self._after is not missing:
+            return self._after
+
+        try:
+            self._after = await self._iterator.__anext__()
+        except StopAsyncIteration:
+            self._after = missing
+
+        return self._after
+
+    @property
+    async def last(self) -> bool:  # type: ignore
+        return await self._peek_next() is missing
+
+    @property
+    async def nextitem(self) -> t.Union[t.Any, "Undefined"]:
+        rv = await self._peek_next()
+
+        if rv is missing:
+            return self._undefined("there is no next item")
+
+        return rv
+
+    def __aiter__(self) -> "AsyncLoopContext":
+        return self
+
+    async def __anext__(self) -> t.Tuple[t.Any, "AsyncLoopContext"]:
+        if self._after is not missing:
+            rv = self._after
+            self._after = missing
+        else:
+            rv = await self._iterator.__anext__()
+
+        self.index0 += 1
+        self._before = self._current
+        self._current = rv
+        return rv, self
+
+
+class Macro:
+    """Wraps a macro function."""
+
+    def __init__(
+        self,
+        environment: "Environment",
+        func: t.Callable[..., str],
+        name: str,
+        arguments: t.List[str],
+        catch_kwargs: bool,
+        catch_varargs: bool,
+        caller: bool,
+        default_autoescape: t.Optional[bool] = None,
+    ):
+        self._environment = environment
+        self._func = func
+        self._argument_count = len(arguments)
+        self.name = name
+        self.arguments = arguments
+        self.catch_kwargs = catch_kwargs
+        self.catch_varargs = catch_varargs
+        self.caller = caller
+        self.explicit_caller = "caller" in arguments
+
+        if default_autoescape is None:
+            if callable(environment.autoescape):
+                default_autoescape = environment.autoescape(None)
+            else:
+                default_autoescape = environment.autoescape
+
+        self._default_autoescape = default_autoescape
+
+    @internalcode
+    @pass_eval_context
+    def __call__(self, *args: t.Any, **kwargs: t.Any) -> str:
+        # This requires a bit of explanation,  In the past we used to
+        # decide largely based on compile-time information if a macro is
+        # safe or unsafe.  While there was a volatile mode it was largely
+        # unused for deciding on escaping.  This turns out to be
+        # problematic for macros because whether a macro is safe depends not
+        # on the escape mode when it was defined, but rather when it was used.
+        #
+        # Because however we export macros from the module system and
+        # there are historic callers that do not pass an eval context (and
+        # will continue to not pass one), we need to perform an instance
+        # check here.
+        #
+        # This is considered safe because an eval context is not a valid
+        # argument to callables otherwise anyway.  Worst case here is
+        # that if no eval context is passed we fall back to the compile
+        # time autoescape flag.
+        if args and isinstance(args[0], EvalContext):
+            autoescape = args[0].autoescape
+            args = args[1:]
+        else:
+            autoescape = self._default_autoescape
+
+        # try to consume the positional arguments
+        arguments = list(args[: self._argument_count])
+        off = len(arguments)
+
+        # For information why this is necessary refer to the handling
+        # of caller in the `macro_body` handler in the compiler.
+        found_caller = False
+
+        # if the number of arguments consumed is not the number of
+        # arguments expected we start filling in keyword arguments
+        # and defaults.
+        if off != self._argument_count:
+            for name in self.arguments[len(arguments) :]:
+                try:
+                    value = kwargs.pop(name)
+                except KeyError:
+                    value = missing
+                if name == "caller":
+                    found_caller = True
+                arguments.append(value)
+        else:
+            found_caller = self.explicit_caller
+
+        # it's important that the order of these arguments does not change
+        # if not also changed in the compiler's `function_scoping` method.
+        # the order is caller, keyword arguments, positional arguments!
+        if self.caller and not found_caller:
+            caller = kwargs.pop("caller", None)
+            if caller is None:
+                caller = self._environment.undefined("No caller defined", name="caller")
+            arguments.append(caller)
+
+        if self.catch_kwargs:
+            arguments.append(kwargs)
+        elif kwargs:
+            if "caller" in kwargs:
+                raise TypeError(
+                    f"macro {self.name!r} was invoked with two values for the special"
+                    " caller argument. This is most likely a bug."
+                )
+            raise TypeError(
+                f"macro {self.name!r} takes no keyword argument {next(iter(kwargs))!r}"
+            )
+        if self.catch_varargs:
+            arguments.append(args[self._argument_count :])
+        elif len(args) > self._argument_count:
+            raise TypeError(
+                f"macro {self.name!r} takes not more than"
+                f" {len(self.arguments)} argument(s)"
+            )
+
+        return self._invoke(arguments, autoescape)
+
+    async def _async_invoke(self, arguments: t.List[t.Any], autoescape: bool) -> str:
+        rv = await self._func(*arguments)  # type: ignore
+
+        if autoescape:
+            return Markup(rv)
+
+        return rv  # type: ignore
+
+    def _invoke(self, arguments: t.List[t.Any], autoescape: bool) -> str:
+        if self._environment.is_async:
+            return self._async_invoke(arguments, autoescape)  # type: ignore
+
+        rv = self._func(*arguments)
+
+        if autoescape:
+            rv = Markup(rv)
+
+        return rv
+
+    def __repr__(self) -> str:
+        name = "anonymous" if self.name is None else repr(self.name)
+        return f"<{type(self).__name__} {name}>"
+
+
+class Undefined:
+    """The default undefined type.  This undefined type can be printed and
+    iterated over, but every other access will raise an :exc:`UndefinedError`:
+
+    >>> foo = Undefined(name='foo')
+    >>> str(foo)
+    ''
+    >>> not foo
+    True
+    >>> foo + 42
+    Traceback (most recent call last):
+      ...
+    jinja2.exceptions.UndefinedError: 'foo' is undefined
+    """
+
+    __slots__ = (
+        "_undefined_hint",
+        "_undefined_obj",
+        "_undefined_name",
+        "_undefined_exception",
+    )
+
+    def __init__(
+        self,
+        hint: t.Optional[str] = None,
+        obj: t.Any = missing,
+        name: t.Optional[str] = None,
+        exc: t.Type[TemplateRuntimeError] = UndefinedError,
+    ) -> None:
+        self._undefined_hint = hint
+        self._undefined_obj = obj
+        self._undefined_name = name
+        self._undefined_exception = exc
+
+    @property
+    def _undefined_message(self) -> str:
+        """Build a message about the undefined value based on how it was
+        accessed.
+        """
+        if self._undefined_hint:
+            return self._undefined_hint
+
+        if self._undefined_obj is missing:
+            return f"{self._undefined_name!r} is undefined"
+
+        if not isinstance(self._undefined_name, str):
+            return (
+                f"{object_type_repr(self._undefined_obj)} has no"
+                f" element {self._undefined_name!r}"
+            )
+
+        return (
+            f"{object_type_repr(self._undefined_obj)!r} has no"
+            f" attribute {self._undefined_name!r}"
+        )
+
+    @internalcode
+    def _fail_with_undefined_error(
+        self, *args: t.Any, **kwargs: t.Any
+    ) -> "te.NoReturn":
+        """Raise an :exc:`UndefinedError` when operations are performed
+        on the undefined value.
+        """
+        raise self._undefined_exception(self._undefined_message)
+
+    @internalcode
+    def __getattr__(self, name: str) -> t.Any:
+        if name[:2] == "__":
+            raise AttributeError(name)
+
+        return self._fail_with_undefined_error()
+
+    __add__ = __radd__ = __sub__ = __rsub__ = _fail_with_undefined_error
+    __mul__ = __rmul__ = __div__ = __rdiv__ = _fail_with_undefined_error
+    __truediv__ = __rtruediv__ = _fail_with_undefined_error
+    __floordiv__ = __rfloordiv__ = _fail_with_undefined_error
+    __mod__ = __rmod__ = _fail_with_undefined_error
+    __pos__ = __neg__ = _fail_with_undefined_error
+    __call__ = __getitem__ = _fail_with_undefined_error
+    __lt__ = __le__ = __gt__ = __ge__ = _fail_with_undefined_error
+    __int__ = __float__ = __complex__ = _fail_with_undefined_error
+    __pow__ = __rpow__ = _fail_with_undefined_error
+
+    def __eq__(self, other: t.Any) -> bool:
+        return type(self) is type(other)
+
+    def __ne__(self, other: t.Any) -> bool:
+        return not self.__eq__(other)
+
+    def __hash__(self) -> int:
+        return id(type(self))
+
+    def __str__(self) -> str:
+        return ""
+
+    def __len__(self) -> int:
+        return 0
+
+    def __iter__(self) -> t.Iterator[t.Any]:
+        yield from ()
+
+    async def __aiter__(self) -> t.AsyncIterator[t.Any]:
+        for _ in ():
+            yield
+
+    def __bool__(self) -> bool:
+        return False
+
+    def __repr__(self) -> str:
+        return "Undefined"
+
+
+def make_logging_undefined(
+    logger: t.Optional["logging.Logger"] = None, base: t.Type[Undefined] = Undefined
+) -> t.Type[Undefined]:
+    """Given a logger object this returns a new undefined class that will
+    log certain failures.  It will log iterations and printing.  If no
+    logger is given a default logger is created.
+
+    Example::
+
+        logger = logging.getLogger(__name__)
+        LoggingUndefined = make_logging_undefined(
+            logger=logger,
+            base=Undefined
+        )
+
+    .. versionadded:: 2.8
+
+    :param logger: the logger to use.  If not provided, a default logger
+                   is created.
+    :param base: the base class to add logging functionality to.  This
+                 defaults to :class:`Undefined`.
+    """
+    if logger is None:
+        import logging
+
+        logger = logging.getLogger(__name__)
+        logger.addHandler(logging.StreamHandler(sys.stderr))
+
+    def _log_message(undef: Undefined) -> None:
+        logger.warning(  # type: ignore
+            "Template variable warning: %s", undef._undefined_message
+        )
+
+    class LoggingUndefined(base):  # type: ignore
+        __slots__ = ()
+
+        def _fail_with_undefined_error(  # type: ignore
+            self, *args: t.Any, **kwargs: t.Any
+        ) -> "te.NoReturn":
+            try:
+                super()._fail_with_undefined_error(*args, **kwargs)
+            except self._undefined_exception as e:
+                logger.error("Template variable error: %s", e)  # type: ignore
+                raise e
+
+        def __str__(self) -> str:
+            _log_message(self)
+            return super().__str__()  # type: ignore
+
+        def __iter__(self) -> t.Iterator[t.Any]:
+            _log_message(self)
+            return super().__iter__()  # type: ignore
+
+        def __bool__(self) -> bool:
+            _log_message(self)
+            return super().__bool__()  # type: ignore
+
+    return LoggingUndefined
+
+
+class ChainableUndefined(Undefined):
+    """An undefined that is chainable, where both ``__getattr__`` and
+    ``__getitem__`` return itself rather than raising an
+    :exc:`UndefinedError`.
+
+    >>> foo = ChainableUndefined(name='foo')
+    >>> str(foo.bar['baz'])
+    ''
+    >>> foo.bar['baz'] + 42
+    Traceback (most recent call last):
+      ...
+    jinja2.exceptions.UndefinedError: 'foo' is undefined
+
+    .. versionadded:: 2.11.0
+    """
+
+    __slots__ = ()
+
+    def __html__(self) -> str:
+        return str(self)
+
+    def __getattr__(self, _: str) -> "ChainableUndefined":
+        return self
+
+    __getitem__ = __getattr__  # type: ignore
+
+
+class DebugUndefined(Undefined):
+    """An undefined that returns the debug info when printed.
+
+    >>> foo = DebugUndefined(name='foo')
+    >>> str(foo)
+    '{{ foo }}'
+    >>> not foo
+    True
+    >>> foo + 42
+    Traceback (most recent call last):
+      ...
+    jinja2.exceptions.UndefinedError: 'foo' is undefined
+    """
+
+    __slots__ = ()
+
+    def __str__(self) -> str:
+        if self._undefined_hint:
+            message = f"undefined value printed: {self._undefined_hint}"
+
+        elif self._undefined_obj is missing:
+            message = self._undefined_name  # type: ignore
+
+        else:
+            message = (
+                f"no such element: {object_type_repr(self._undefined_obj)}"
+                f"[{self._undefined_name!r}]"
+            )
+
+        return f"{{{{ {message} }}}}"
+
+
+class StrictUndefined(Undefined):
+    """An undefined that barks on print and iteration as well as boolean
+    tests and all kinds of comparisons.  In other words: you can do nothing
+    with it except checking if it's defined using the `defined` test.
+
+    >>> foo = StrictUndefined(name='foo')
+    >>> str(foo)
+    Traceback (most recent call last):
+      ...
+    jinja2.exceptions.UndefinedError: 'foo' is undefined
+    >>> not foo
+    Traceback (most recent call last):
+      ...
+    jinja2.exceptions.UndefinedError: 'foo' is undefined
+    >>> foo + 42
+    Traceback (most recent call last):
+      ...
+    jinja2.exceptions.UndefinedError: 'foo' is undefined
+    """
+
+    __slots__ = ()
+    __iter__ = __str__ = __len__ = Undefined._fail_with_undefined_error
+    __eq__ = __ne__ = __bool__ = __hash__ = Undefined._fail_with_undefined_error
+    __contains__ = Undefined._fail_with_undefined_error
+
+
+# Remove slots attributes, after the metaclass is applied they are
+# unneeded and contain wrong data for subclasses.
+del (
+    Undefined.__slots__,
+    ChainableUndefined.__slots__,
+    DebugUndefined.__slots__,
+    StrictUndefined.__slots__,
+)
diff --git a/lib/spack/external/_vendoring/jinja2/sandbox.py b/lib/spack/external/_vendoring/jinja2/sandbox.py
new file mode 100644
index 0000000000..4294884776
--- /dev/null
+++ b/lib/spack/external/_vendoring/jinja2/sandbox.py
@@ -0,0 +1,428 @@
+"""A sandbox layer that ensures unsafe operations cannot be performed.
+Useful when the template itself comes from an untrusted source.
+"""
+import operator
+import types
+import typing as t
+from _string import formatter_field_name_split  # type: ignore
+from collections import abc
+from collections import deque
+from string import Formatter
+
+from markupsafe import EscapeFormatter
+from markupsafe import Markup
+
+from .environment import Environment
+from .exceptions import SecurityError
+from .runtime import Context
+from .runtime import Undefined
+
+F = t.TypeVar("F", bound=t.Callable[..., t.Any])
+
+#: maximum number of items a range may produce
+MAX_RANGE = 100000
+
+#: Unsafe function attributes.
+UNSAFE_FUNCTION_ATTRIBUTES: t.Set[str] = set()
+
+#: Unsafe method attributes. Function attributes are unsafe for methods too.
+UNSAFE_METHOD_ATTRIBUTES: t.Set[str] = set()
+
+#: unsafe generator attributes.
+UNSAFE_GENERATOR_ATTRIBUTES = {"gi_frame", "gi_code"}
+
+#: unsafe attributes on coroutines
+UNSAFE_COROUTINE_ATTRIBUTES = {"cr_frame", "cr_code"}
+
+#: unsafe attributes on async generators
+UNSAFE_ASYNC_GENERATOR_ATTRIBUTES = {"ag_code", "ag_frame"}
+
+_mutable_spec: t.Tuple[t.Tuple[t.Type, t.FrozenSet[str]], ...] = (
+    (
+        abc.MutableSet,
+        frozenset(
+            [
+                "add",
+                "clear",
+                "difference_update",
+                "discard",
+                "pop",
+                "remove",
+                "symmetric_difference_update",
+                "update",
+            ]
+        ),
+    ),
+    (
+        abc.MutableMapping,
+        frozenset(["clear", "pop", "popitem", "setdefault", "update"]),
+    ),
+    (
+        abc.MutableSequence,
+        frozenset(["append", "reverse", "insert", "sort", "extend", "remove"]),
+    ),
+    (
+        deque,
+        frozenset(
+            [
+                "append",
+                "appendleft",
+                "clear",
+                "extend",
+                "extendleft",
+                "pop",
+                "popleft",
+                "remove",
+                "rotate",
+            ]
+        ),
+    ),
+)
+
+
+def inspect_format_method(callable: t.Callable) -> t.Optional[str]:
+    if not isinstance(
+        callable, (types.MethodType, types.BuiltinMethodType)
+    ) or callable.__name__ not in ("format", "format_map"):
+        return None
+
+    obj = callable.__self__
+
+    if isinstance(obj, str):
+        return obj
+
+    return None
+
+
+def safe_range(*args: int) -> range:
+    """A range that can't generate ranges with a length of more than
+    MAX_RANGE items.
+    """
+    rng = range(*args)
+
+    if len(rng) > MAX_RANGE:
+        raise OverflowError(
+            "Range too big. The sandbox blocks ranges larger than"
+            f" MAX_RANGE ({MAX_RANGE})."
+        )
+
+    return rng
+
+
+def unsafe(f: F) -> F:
+    """Marks a function or method as unsafe.
+
+    .. code-block: python
+
+        @unsafe
+        def delete(self):
+            pass
+    """
+    f.unsafe_callable = True  # type: ignore
+    return f
+
+
+def is_internal_attribute(obj: t.Any, attr: str) -> bool:
+    """Test if the attribute given is an internal python attribute.  For
+    example this function returns `True` for the `func_code` attribute of
+    python objects.  This is useful if the environment method
+    :meth:`~SandboxedEnvironment.is_safe_attribute` is overridden.
+
+    >>> from jinja2.sandbox import is_internal_attribute
+    >>> is_internal_attribute(str, "mro")
+    True
+    >>> is_internal_attribute(str, "upper")
+    False
+    """
+    if isinstance(obj, types.FunctionType):
+        if attr in UNSAFE_FUNCTION_ATTRIBUTES:
+            return True
+    elif isinstance(obj, types.MethodType):
+        if attr in UNSAFE_FUNCTION_ATTRIBUTES or attr in UNSAFE_METHOD_ATTRIBUTES:
+            return True
+    elif isinstance(obj, type):
+        if attr == "mro":
+            return True
+    elif isinstance(obj, (types.CodeType, types.TracebackType, types.FrameType)):
+        return True
+    elif isinstance(obj, types.GeneratorType):
+        if attr in UNSAFE_GENERATOR_ATTRIBUTES:
+            return True
+    elif hasattr(types, "CoroutineType") and isinstance(obj, types.CoroutineType):
+        if attr in UNSAFE_COROUTINE_ATTRIBUTES:
+            return True
+    elif hasattr(types, "AsyncGeneratorType") and isinstance(
+        obj, types.AsyncGeneratorType
+    ):
+        if attr in UNSAFE_ASYNC_GENERATOR_ATTRIBUTES:
+            return True
+    return attr.startswith("__")
+
+
+def modifies_known_mutable(obj: t.Any, attr: str) -> bool:
+    """This function checks if an attribute on a builtin mutable object
+    (list, dict, set or deque) or the corresponding ABCs would modify it
+    if called.
+
+    >>> modifies_known_mutable({}, "clear")
+    True
+    >>> modifies_known_mutable({}, "keys")
+    False
+    >>> modifies_known_mutable([], "append")
+    True
+    >>> modifies_known_mutable([], "index")
+    False
+
+    If called with an unsupported object, ``False`` is returned.
+
+    >>> modifies_known_mutable("foo", "upper")
+    False
+    """
+    for typespec, unsafe in _mutable_spec:
+        if isinstance(obj, typespec):
+            return attr in unsafe
+    return False
+
+
+class SandboxedEnvironment(Environment):
+    """The sandboxed environment.  It works like the regular environment but
+    tells the compiler to generate sandboxed code.  Additionally subclasses of
+    this environment may override the methods that tell the runtime what
+    attributes or functions are safe to access.
+
+    If the template tries to access insecure code a :exc:`SecurityError` is
+    raised.  However also other exceptions may occur during the rendering so
+    the caller has to ensure that all exceptions are caught.
+    """
+
+    sandboxed = True
+
+    #: default callback table for the binary operators.  A copy of this is
+    #: available on each instance of a sandboxed environment as
+    #: :attr:`binop_table`
+    default_binop_table: t.Dict[str, t.Callable[[t.Any, t.Any], t.Any]] = {
+        "+": operator.add,
+        "-": operator.sub,
+        "*": operator.mul,
+        "/": operator.truediv,
+        "//": operator.floordiv,
+        "**": operator.pow,
+        "%": operator.mod,
+    }
+
+    #: default callback table for the unary operators.  A copy of this is
+    #: available on each instance of a sandboxed environment as
+    #: :attr:`unop_table`
+    default_unop_table: t.Dict[str, t.Callable[[t.Any], t.Any]] = {
+        "+": operator.pos,
+        "-": operator.neg,
+    }
+
+    #: a set of binary operators that should be intercepted.  Each operator
+    #: that is added to this set (empty by default) is delegated to the
+    #: :meth:`call_binop` method that will perform the operator.  The default
+    #: operator callback is specified by :attr:`binop_table`.
+    #:
+    #: The following binary operators are interceptable:
+    #: ``//``, ``%``, ``+``, ``*``, ``-``, ``/``, and ``**``
+    #:
+    #: The default operation form the operator table corresponds to the
+    #: builtin function.  Intercepted calls are always slower than the native
+    #: operator call, so make sure only to intercept the ones you are
+    #: interested in.
+    #:
+    #: .. versionadded:: 2.6
+    intercepted_binops: t.FrozenSet[str] = frozenset()
+
+    #: a set of unary operators that should be intercepted.  Each operator
+    #: that is added to this set (empty by default) is delegated to the
+    #: :meth:`call_unop` method that will perform the operator.  The default
+    #: operator callback is specified by :attr:`unop_table`.
+    #:
+    #: The following unary operators are interceptable: ``+``, ``-``
+    #:
+    #: The default operation form the operator table corresponds to the
+    #: builtin function.  Intercepted calls are always slower than the native
+    #: operator call, so make sure only to intercept the ones you are
+    #: interested in.
+    #:
+    #: .. versionadded:: 2.6
+    intercepted_unops: t.FrozenSet[str] = frozenset()
+
+    def __init__(self, *args: t.Any, **kwargs: t.Any) -> None:
+        super().__init__(*args, **kwargs)
+        self.globals["range"] = safe_range
+        self.binop_table = self.default_binop_table.copy()
+        self.unop_table = self.default_unop_table.copy()
+
+    def is_safe_attribute(self, obj: t.Any, attr: str, value: t.Any) -> bool:
+        """The sandboxed environment will call this method to check if the
+        attribute of an object is safe to access.  Per default all attributes
+        starting with an underscore are considered private as well as the
+        special attributes of internal python objects as returned by the
+        :func:`is_internal_attribute` function.
+        """
+        return not (attr.startswith("_") or is_internal_attribute(obj, attr))
+
+    def is_safe_callable(self, obj: t.Any) -> bool:
+        """Check if an object is safely callable. By default callables
+        are considered safe unless decorated with :func:`unsafe`.
+
+        This also recognizes the Django convention of setting
+        ``func.alters_data = True``.
+        """
+        return not (
+            getattr(obj, "unsafe_callable", False) or getattr(obj, "alters_data", False)
+        )
+
+    def call_binop(
+        self, context: Context, operator: str, left: t.Any, right: t.Any
+    ) -> t.Any:
+        """For intercepted binary operator calls (:meth:`intercepted_binops`)
+        this function is executed instead of the builtin operator.  This can
+        be used to fine tune the behavior of certain operators.
+
+        .. versionadded:: 2.6
+        """
+        return self.binop_table[operator](left, right)
+
+    def call_unop(self, context: Context, operator: str, arg: t.Any) -> t.Any:
+        """For intercepted unary operator calls (:meth:`intercepted_unops`)
+        this function is executed instead of the builtin operator.  This can
+        be used to fine tune the behavior of certain operators.
+
+        .. versionadded:: 2.6
+        """
+        return self.unop_table[operator](arg)
+
+    def getitem(
+        self, obj: t.Any, argument: t.Union[str, t.Any]
+    ) -> t.Union[t.Any, Undefined]:
+        """Subscribe an object from sandboxed code."""
+        try:
+            return obj[argument]
+        except (TypeError, LookupError):
+            if isinstance(argument, str):
+                try:
+                    attr = str(argument)
+                except Exception:
+                    pass
+                else:
+                    try:
+                        value = getattr(obj, attr)
+                    except AttributeError:
+                        pass
+                    else:
+                        if self.is_safe_attribute(obj, argument, value):
+                            return value
+                        return self.unsafe_undefined(obj, argument)
+        return self.undefined(obj=obj, name=argument)
+
+    def getattr(self, obj: t.Any, attribute: str) -> t.Union[t.Any, Undefined]:
+        """Subscribe an object from sandboxed code and prefer the
+        attribute.  The attribute passed *must* be a bytestring.
+        """
+        try:
+            value = getattr(obj, attribute)
+        except AttributeError:
+            try:
+                return obj[attribute]
+            except (TypeError, LookupError):
+                pass
+        else:
+            if self.is_safe_attribute(obj, attribute, value):
+                return value
+            return self.unsafe_undefined(obj, attribute)
+        return self.undefined(obj=obj, name=attribute)
+
+    def unsafe_undefined(self, obj: t.Any, attribute: str) -> Undefined:
+        """Return an undefined object for unsafe attributes."""
+        return self.undefined(
+            f"access to attribute {attribute!r} of"
+            f" {type(obj).__name__!r} object is unsafe.",
+            name=attribute,
+            obj=obj,
+            exc=SecurityError,
+        )
+
+    def format_string(
+        self,
+        s: str,
+        args: t.Tuple[t.Any, ...],
+        kwargs: t.Dict[str, t.Any],
+        format_func: t.Optional[t.Callable] = None,
+    ) -> str:
+        """If a format call is detected, then this is routed through this
+        method so that our safety sandbox can be used for it.
+        """
+        formatter: SandboxedFormatter
+        if isinstance(s, Markup):
+            formatter = SandboxedEscapeFormatter(self, escape=s.escape)
+        else:
+            formatter = SandboxedFormatter(self)
+
+        if format_func is not None and format_func.__name__ == "format_map":
+            if len(args) != 1 or kwargs:
+                raise TypeError(
+                    "format_map() takes exactly one argument"
+                    f" {len(args) + (kwargs is not None)} given"
+                )
+
+            kwargs = args[0]
+            args = ()
+
+        rv = formatter.vformat(s, args, kwargs)
+        return type(s)(rv)
+
+    def call(
+        __self,  # noqa: B902
+        __context: Context,
+        __obj: t.Any,
+        *args: t.Any,
+        **kwargs: t.Any,
+    ) -> t.Any:
+        """Call an object from sandboxed code."""
+        fmt = inspect_format_method(__obj)
+        if fmt is not None:
+            return __self.format_string(fmt, args, kwargs, __obj)
+
+        # the double prefixes are to avoid double keyword argument
+        # errors when proxying the call.
+        if not __self.is_safe_callable(__obj):
+            raise SecurityError(f"{__obj!r} is not safely callable")
+        return __context.call(__obj, *args, **kwargs)
+
+
+class ImmutableSandboxedEnvironment(SandboxedEnvironment):
+    """Works exactly like the regular `SandboxedEnvironment` but does not
+    permit modifications on the builtin mutable objects `list`, `set`, and
+    `dict` by using the :func:`modifies_known_mutable` function.
+    """
+
+    def is_safe_attribute(self, obj: t.Any, attr: str, value: t.Any) -> bool:
+        if not super().is_safe_attribute(obj, attr, value):
+            return False
+
+        return not modifies_known_mutable(obj, attr)
+
+
+class SandboxedFormatter(Formatter):
+    def __init__(self, env: Environment, **kwargs: t.Any) -> None:
+        self._env = env
+        super().__init__(**kwargs)  # type: ignore
+
+    def get_field(
+        self, field_name: str, args: t.Sequence[t.Any], kwargs: t.Mapping[str, t.Any]
+    ) -> t.Tuple[t.Any, str]:
+        first, rest = formatter_field_name_split(field_name)
+        obj = self.get_value(first, args, kwargs)
+        for is_attr, i in rest:
+            if is_attr:
+                obj = self._env.getattr(obj, i)
+            else:
+                obj = self._env.getitem(obj, i)
+        return obj, first
+
+
+class SandboxedEscapeFormatter(SandboxedFormatter, EscapeFormatter):
+    pass
diff --git a/lib/spack/external/_vendoring/jinja2/tests.py b/lib/spack/external/_vendoring/jinja2/tests.py
new file mode 100644
index 0000000000..a467cf08b5
--- /dev/null
+++ b/lib/spack/external/_vendoring/jinja2/tests.py
@@ -0,0 +1,255 @@
+"""Built-in template tests used with the ``is`` operator."""
+import operator
+import typing as t
+from collections import abc
+from numbers import Number
+
+from .runtime import Undefined
+from .utils import pass_environment
+
+if t.TYPE_CHECKING:
+    from .environment import Environment
+
+
+def test_odd(value: int) -> bool:
+    """Return true if the variable is odd."""
+    return value % 2 == 1
+
+
+def test_even(value: int) -> bool:
+    """Return true if the variable is even."""
+    return value % 2 == 0
+
+
+def test_divisibleby(value: int, num: int) -> bool:
+    """Check if a variable is divisible by a number."""
+    return value % num == 0
+
+
+def test_defined(value: t.Any) -> bool:
+    """Return true if the variable is defined:
+
+    .. sourcecode:: jinja
+
+        {% if variable is defined %}
+            value of variable: {{ variable }}
+        {% else %}
+            variable is not defined
+        {% endif %}
+
+    See the :func:`default` filter for a simple way to set undefined
+    variables.
+    """
+    return not isinstance(value, Undefined)
+
+
+def test_undefined(value: t.Any) -> bool:
+    """Like :func:`defined` but the other way round."""
+    return isinstance(value, Undefined)
+
+
+@pass_environment
+def test_filter(env: "Environment", value: str) -> bool:
+    """Check if a filter exists by name. Useful if a filter may be
+    optionally available.
+
+    .. code-block:: jinja
+
+        {% if 'markdown' is filter %}
+            {{ value | markdown }}
+        {% else %}
+            {{ value }}
+        {% endif %}
+
+    .. versionadded:: 3.0
+    """
+    return value in env.filters
+
+
+@pass_environment
+def test_test(env: "Environment", value: str) -> bool:
+    """Check if a test exists by name. Useful if a test may be
+    optionally available.
+
+    .. code-block:: jinja
+
+        {% if 'loud' is test %}
+            {% if value is loud %}
+                {{ value|upper }}
+            {% else %}
+                {{ value|lower }}
+            {% endif %}
+        {% else %}
+            {{ value }}
+        {% endif %}
+
+    .. versionadded:: 3.0
+    """
+    return value in env.tests
+
+
+def test_none(value: t.Any) -> bool:
+    """Return true if the variable is none."""
+    return value is None
+
+
+def test_boolean(value: t.Any) -> bool:
+    """Return true if the object is a boolean value.
+
+    .. versionadded:: 2.11
+    """
+    return value is True or value is False
+
+
+def test_false(value: t.Any) -> bool:
+    """Return true if the object is False.
+
+    .. versionadded:: 2.11
+    """
+    return value is False
+
+
+def test_true(value: t.Any) -> bool:
+    """Return true if the object is True.
+
+    .. versionadded:: 2.11
+    """
+    return value is True
+
+
+# NOTE: The existing 'number' test matches booleans and floats
+def test_integer(value: t.Any) -> bool:
+    """Return true if the object is an integer.
+
+    .. versionadded:: 2.11
+    """
+    return isinstance(value, int) and value is not True and value is not False
+
+
+# NOTE: The existing 'number' test matches booleans and integers
+def test_float(value: t.Any) -> bool:
+    """Return true if the object is a float.
+
+    .. versionadded:: 2.11
+    """
+    return isinstance(value, float)
+
+
+def test_lower(value: str) -> bool:
+    """Return true if the variable is lowercased."""
+    return str(value).islower()
+
+
+def test_upper(value: str) -> bool:
+    """Return true if the variable is uppercased."""
+    return str(value).isupper()
+
+
+def test_string(value: t.Any) -> bool:
+    """Return true if the object is a string."""
+    return isinstance(value, str)
+
+
+def test_mapping(value: t.Any) -> bool:
+    """Return true if the object is a mapping (dict etc.).
+
+    .. versionadded:: 2.6
+    """
+    return isinstance(value, abc.Mapping)
+
+
+def test_number(value: t.Any) -> bool:
+    """Return true if the variable is a number."""
+    return isinstance(value, Number)
+
+
+def test_sequence(value: t.Any) -> bool:
+    """Return true if the variable is a sequence. Sequences are variables
+    that are iterable.
+    """
+    try:
+        len(value)
+        value.__getitem__
+    except Exception:
+        return False
+
+    return True
+
+
+def test_sameas(value: t.Any, other: t.Any) -> bool:
+    """Check if an object points to the same memory address than another
+    object:
+
+    .. sourcecode:: jinja
+
+        {% if foo.attribute is sameas false %}
+            the foo attribute really is the `False` singleton
+        {% endif %}
+    """
+    return value is other
+
+
+def test_iterable(value: t.Any) -> bool:
+    """Check if it's possible to iterate over an object."""
+    try:
+        iter(value)
+    except TypeError:
+        return False
+
+    return True
+
+
+def test_escaped(value: t.Any) -> bool:
+    """Check if the value is escaped."""
+    return hasattr(value, "__html__")
+
+
+def test_in(value: t.Any, seq: t.Container) -> bool:
+    """Check if value is in seq.
+
+    .. versionadded:: 2.10
+    """
+    return value in seq
+
+
+TESTS = {
+    "odd": test_odd,
+    "even": test_even,
+    "divisibleby": test_divisibleby,
+    "defined": test_defined,
+    "undefined": test_undefined,
+    "filter": test_filter,
+    "test": test_test,
+    "none": test_none,
+    "boolean": test_boolean,
+    "false": test_false,
+    "true": test_true,
+    "integer": test_integer,
+    "float": test_float,
+    "lower": test_lower,
+    "upper": test_upper,
+    "string": test_string,
+    "mapping": test_mapping,
+    "number": test_number,
+    "sequence": test_sequence,
+    "iterable": test_iterable,
+    "callable": callable,
+    "sameas": test_sameas,
+    "escaped": test_escaped,
+    "in": test_in,
+    "==": operator.eq,
+    "eq": operator.eq,
+    "equalto": operator.eq,
+    "!=": operator.ne,
+    "ne": operator.ne,
+    ">": operator.gt,
+    "gt": operator.gt,
+    "greaterthan": operator.gt,
+    "ge": operator.ge,
+    ">=": operator.ge,
+    "<": operator.lt,
+    "lt": operator.lt,
+    "lessthan": operator.lt,
+    "<=": operator.le,
+    "le": operator.le,
+}
diff --git a/lib/spack/external/_vendoring/jinja2/utils.py b/lib/spack/external/_vendoring/jinja2/utils.py
new file mode 100644
index 0000000000..567185f41f
--- /dev/null
+++ b/lib/spack/external/_vendoring/jinja2/utils.py
@@ -0,0 +1,854 @@
+import enum
+import json
+import os
+import re
+import typing as t
+import warnings
+from collections import abc
+from collections import deque
+from random import choice
+from random import randrange
+from threading import Lock
+from types import CodeType
+from urllib.parse import quote_from_bytes
+
+import markupsafe
+
+if t.TYPE_CHECKING:
+    import typing_extensions as te
+
+F = t.TypeVar("F", bound=t.Callable[..., t.Any])
+
+# special singleton representing missing values for the runtime
+missing: t.Any = type("MissingType", (), {"__repr__": lambda x: "missing"})()
+
+internal_code: t.MutableSet[CodeType] = set()
+
+concat = "".join
+
+
+def pass_context(f: F) -> F:
+    """Pass the :class:`~jinja2.runtime.Context` as the first argument
+    to the decorated function when called while rendering a template.
+
+    Can be used on functions, filters, and tests.
+
+    If only ``Context.eval_context`` is needed, use
+    :func:`pass_eval_context`. If only ``Context.environment`` is
+    needed, use :func:`pass_environment`.
+
+    .. versionadded:: 3.0.0
+        Replaces ``contextfunction`` and ``contextfilter``.
+    """
+    f.jinja_pass_arg = _PassArg.context  # type: ignore
+    return f
+
+
+def pass_eval_context(f: F) -> F:
+    """Pass the :class:`~jinja2.nodes.EvalContext` as the first argument
+    to the decorated function when called while rendering a template.
+    See :ref:`eval-context`.
+
+    Can be used on functions, filters, and tests.
+
+    If only ``EvalContext.environment`` is needed, use
+    :func:`pass_environment`.
+
+    .. versionadded:: 3.0.0
+        Replaces ``evalcontextfunction`` and ``evalcontextfilter``.
+    """
+    f.jinja_pass_arg = _PassArg.eval_context  # type: ignore
+    return f
+
+
+def pass_environment(f: F) -> F:
+    """Pass the :class:`~jinja2.Environment` as the first argument to
+    the decorated function when called while rendering a template.
+
+    Can be used on functions, filters, and tests.
+
+    .. versionadded:: 3.0.0
+        Replaces ``environmentfunction`` and ``environmentfilter``.
+    """
+    f.jinja_pass_arg = _PassArg.environment  # type: ignore
+    return f
+
+
+class _PassArg(enum.Enum):
+    context = enum.auto()
+    eval_context = enum.auto()
+    environment = enum.auto()
+
+    @classmethod
+    def from_obj(cls, obj: F) -> t.Optional["_PassArg"]:
+        if hasattr(obj, "jinja_pass_arg"):
+            return obj.jinja_pass_arg  # type: ignore
+
+        for prefix in "context", "eval_context", "environment":
+            squashed = prefix.replace("_", "")
+
+            for name in f"{squashed}function", f"{squashed}filter":
+                if getattr(obj, name, False) is True:
+                    warnings.warn(
+                        f"{name!r} is deprecated and will stop working"
+                        f" in Jinja 3.1. Use 'pass_{prefix}' instead.",
+                        DeprecationWarning,
+                        stacklevel=2,
+                    )
+                    return cls[prefix]
+
+        return None
+
+
+def contextfunction(f: F) -> F:
+    """Pass the context as the first argument to the decorated function.
+
+    .. deprecated:: 3.0
+        Will be removed in Jinja 3.1. Use :func:`~jinja2.pass_context`
+        instead.
+    """
+    warnings.warn(
+        "'contextfunction' is renamed to 'pass_context', the old name"
+        " will be removed in Jinja 3.1.",
+        DeprecationWarning,
+        stacklevel=2,
+    )
+    return pass_context(f)
+
+
+def evalcontextfunction(f: F) -> F:
+    """Pass the eval context as the first argument to the decorated
+    function.
+
+    .. deprecated:: 3.0
+        Will be removed in Jinja 3.1. Use
+        :func:`~jinja2.pass_eval_context` instead.
+
+    .. versionadded:: 2.4
+    """
+    warnings.warn(
+        "'evalcontextfunction' is renamed to 'pass_eval_context', the"
+        " old name will be removed in Jinja 3.1.",
+        DeprecationWarning,
+        stacklevel=2,
+    )
+    return pass_eval_context(f)
+
+
+def environmentfunction(f: F) -> F:
+    """Pass the environment as the first argument to the decorated
+    function.
+
+    .. deprecated:: 3.0
+        Will be removed in Jinja 3.1. Use
+        :func:`~jinja2.pass_environment` instead.
+    """
+    warnings.warn(
+        "'environmentfunction' is renamed to 'pass_environment', the"
+        " old name will be removed in Jinja 3.1.",
+        DeprecationWarning,
+        stacklevel=2,
+    )
+    return pass_environment(f)
+
+
+def internalcode(f: F) -> F:
+    """Marks the function as internally used"""
+    internal_code.add(f.__code__)
+    return f
+
+
+def is_undefined(obj: t.Any) -> bool:
+    """Check if the object passed is undefined.  This does nothing more than
+    performing an instance check against :class:`Undefined` but looks nicer.
+    This can be used for custom filters or tests that want to react to
+    undefined variables.  For example a custom default filter can look like
+    this::
+
+        def default(var, default=''):
+            if is_undefined(var):
+                return default
+            return var
+    """
+    from .runtime import Undefined
+
+    return isinstance(obj, Undefined)
+
+
+def consume(iterable: t.Iterable[t.Any]) -> None:
+    """Consumes an iterable without doing anything with it."""
+    for _ in iterable:
+        pass
+
+
+def clear_caches() -> None:
+    """Jinja keeps internal caches for environments and lexers.  These are
+    used so that Jinja doesn't have to recreate environments and lexers all
+    the time.  Normally you don't have to care about that but if you are
+    measuring memory consumption you may want to clean the caches.
+    """
+    from .environment import get_spontaneous_environment
+    from .lexer import _lexer_cache
+
+    get_spontaneous_environment.cache_clear()
+    _lexer_cache.clear()
+
+
+def import_string(import_name: str, silent: bool = False) -> t.Any:
+    """Imports an object based on a string.  This is useful if you want to
+    use import paths as endpoints or something similar.  An import path can
+    be specified either in dotted notation (``xml.sax.saxutils.escape``)
+    or with a colon as object delimiter (``xml.sax.saxutils:escape``).
+
+    If the `silent` is True the return value will be `None` if the import
+    fails.
+
+    :return: imported object
+    """
+    try:
+        if ":" in import_name:
+            module, obj = import_name.split(":", 1)
+        elif "." in import_name:
+            module, _, obj = import_name.rpartition(".")
+        else:
+            return __import__(import_name)
+        return getattr(__import__(module, None, None, [obj]), obj)
+    except (ImportError, AttributeError):
+        if not silent:
+            raise
+
+
+def open_if_exists(filename: str, mode: str = "rb") -> t.Optional[t.IO]:
+    """Returns a file descriptor for the filename if that file exists,
+    otherwise ``None``.
+    """
+    if not os.path.isfile(filename):
+        return None
+
+    return open(filename, mode)
+
+
+def object_type_repr(obj: t.Any) -> str:
+    """Returns the name of the object's type.  For some recognized
+    singletons the name of the object is returned instead. (For
+    example for `None` and `Ellipsis`).
+    """
+    if obj is None:
+        return "None"
+    elif obj is Ellipsis:
+        return "Ellipsis"
+
+    cls = type(obj)
+
+    if cls.__module__ == "builtins":
+        return f"{cls.__name__} object"
+
+    return f"{cls.__module__}.{cls.__name__} object"
+
+
+def pformat(obj: t.Any) -> str:
+    """Format an object using :func:`pprint.pformat`."""
+    from pprint import pformat  # type: ignore
+
+    return pformat(obj)
+
+
+_http_re = re.compile(
+    r"""
+    ^
+    (
+        (https?://|www\.)  # scheme or www
+        (([\w%-]+\.)+)?  # subdomain
+        (
+            [a-z]{2,63}  # basic tld
+        |
+            xn--[\w%]{2,59}  # idna tld
+        )
+    |
+        ([\w%-]{2,63}\.)+  # basic domain
+        (com|net|int|edu|gov|org|info|mil)  # basic tld
+    |
+        (https?://)  # scheme
+        (
+            (([\d]{1,3})(\.[\d]{1,3}){3})  # IPv4
+        |
+            (\[([\da-f]{0,4}:){2}([\da-f]{0,4}:?){1,6}])  # IPv6
+        )
+    )
+    (?::[\d]{1,5})?  # port
+    (?:[/?#]\S*)?  # path, query, and fragment
+    $
+    """,
+    re.IGNORECASE | re.VERBOSE,
+)
+_email_re = re.compile(r"^\S+@\w[\w.-]*\.\w+$")
+
+
+def urlize(
+    text: str,
+    trim_url_limit: t.Optional[int] = None,
+    rel: t.Optional[str] = None,
+    target: t.Optional[str] = None,
+    extra_schemes: t.Optional[t.Iterable[str]] = None,
+) -> str:
+    """Convert URLs in text into clickable links.
+
+    This may not recognize links in some situations. Usually, a more
+    comprehensive formatter, such as a Markdown library, is a better
+    choice.
+
+    Works on ``http://``, ``https://``, ``www.``, ``mailto:``, and email
+    addresses. Links with trailing punctuation (periods, commas, closing
+    parentheses) and leading punctuation (opening parentheses) are
+    recognized excluding the punctuation. Email addresses that include
+    header fields are not recognized (for example,
+    ``mailto:address@example.com?cc=copy@example.com``).
+
+    :param text: Original text containing URLs to link.
+    :param trim_url_limit: Shorten displayed URL values to this length.
+    :param target: Add the ``target`` attribute to links.
+    :param rel: Add the ``rel`` attribute to links.
+    :param extra_schemes: Recognize URLs that start with these schemes
+        in addition to the default behavior.
+
+    .. versionchanged:: 3.0
+        The ``extra_schemes`` parameter was added.
+
+    .. versionchanged:: 3.0
+        Generate ``https://`` links for URLs without a scheme.
+
+    .. versionchanged:: 3.0
+        The parsing rules were updated. Recognize email addresses with
+        or without the ``mailto:`` scheme. Validate IP addresses. Ignore
+        parentheses and brackets in more cases.
+    """
+    if trim_url_limit is not None:
+
+        def trim_url(x: str) -> str:
+            if len(x) > trim_url_limit:  # type: ignore
+                return f"{x[:trim_url_limit]}..."
+
+            return x
+
+    else:
+
+        def trim_url(x: str) -> str:
+            return x
+
+    words = re.split(r"(\s+)", str(markupsafe.escape(text)))
+    rel_attr = f' rel="{markupsafe.escape(rel)}"' if rel else ""
+    target_attr = f' target="{markupsafe.escape(target)}"' if target else ""
+
+    for i, word in enumerate(words):
+        head, middle, tail = "", word, ""
+        match = re.match(r"^([(<]|&lt;)+", middle)
+
+        if match:
+            head = match.group()
+            middle = middle[match.end() :]
+
+        # Unlike lead, which is anchored to the start of the string,
+        # need to check that the string ends with any of the characters
+        # before trying to match all of them, to avoid backtracking.
+        if middle.endswith((")", ">", ".", ",", "\n", "&gt;")):
+            match = re.search(r"([)>.,\n]|&gt;)+$", middle)
+
+            if match:
+                tail = match.group()
+                middle = middle[: match.start()]
+
+        # Prefer balancing parentheses in URLs instead of ignoring a
+        # trailing character.
+        for start_char, end_char in ("(", ")"), ("<", ">"), ("&lt;", "&gt;"):
+            start_count = middle.count(start_char)
+
+            if start_count <= middle.count(end_char):
+                # Balanced, or lighter on the left
+                continue
+
+            # Move as many as possible from the tail to balance
+            for _ in range(min(start_count, tail.count(end_char))):
+                end_index = tail.index(end_char) + len(end_char)
+                # Move anything in the tail before the end char too
+                middle += tail[:end_index]
+                tail = tail[end_index:]
+
+        if _http_re.match(middle):
+            if middle.startswith("https://") or middle.startswith("http://"):
+                middle = (
+                    f'<a href="{middle}"{rel_attr}{target_attr}>{trim_url(middle)}</a>'
+                )
+            else:
+                middle = (
+                    f'<a href="https://{middle}"{rel_attr}{target_attr}>'
+                    f"{trim_url(middle)}</a>"
+                )
+
+        elif middle.startswith("mailto:") and _email_re.match(middle[7:]):
+            middle = f'<a href="{middle}">{middle[7:]}</a>'
+
+        elif (
+            "@" in middle
+            and not middle.startswith("www.")
+            and ":" not in middle
+            and _email_re.match(middle)
+        ):
+            middle = f'<a href="mailto:{middle}">{middle}</a>'
+
+        elif extra_schemes is not None:
+            for scheme in extra_schemes:
+                if middle != scheme and middle.startswith(scheme):
+                    middle = f'<a href="{middle}"{rel_attr}{target_attr}>{middle}</a>'
+
+        words[i] = f"{head}{middle}{tail}"
+
+    return "".join(words)
+
+
+def generate_lorem_ipsum(
+    n: int = 5, html: bool = True, min: int = 20, max: int = 100
+) -> str:
+    """Generate some lorem ipsum for the template."""
+    from .constants import LOREM_IPSUM_WORDS
+
+    words = LOREM_IPSUM_WORDS.split()
+    result = []
+
+    for _ in range(n):
+        next_capitalized = True
+        last_comma = last_fullstop = 0
+        word = None
+        last = None
+        p = []
+
+        # each paragraph contains out of 20 to 100 words.
+        for idx, _ in enumerate(range(randrange(min, max))):
+            while True:
+                word = choice(words)
+                if word != last:
+                    last = word
+                    break
+            if next_capitalized:
+                word = word.capitalize()
+                next_capitalized = False
+            # add commas
+            if idx - randrange(3, 8) > last_comma:
+                last_comma = idx
+                last_fullstop += 2
+                word += ","
+            # add end of sentences
+            if idx - randrange(10, 20) > last_fullstop:
+                last_comma = last_fullstop = idx
+                word += "."
+                next_capitalized = True
+            p.append(word)
+
+        # ensure that the paragraph ends with a dot.
+        p_str = " ".join(p)
+
+        if p_str.endswith(","):
+            p_str = p_str[:-1] + "."
+        elif not p_str.endswith("."):
+            p_str += "."
+
+        result.append(p_str)
+
+    if not html:
+        return "\n\n".join(result)
+    return markupsafe.Markup(
+        "\n".join(f"<p>{markupsafe.escape(x)}</p>" for x in result)
+    )
+
+
+def url_quote(obj: t.Any, charset: str = "utf-8", for_qs: bool = False) -> str:
+    """Quote a string for use in a URL using the given charset.
+
+    :param obj: String or bytes to quote. Other types are converted to
+        string then encoded to bytes using the given charset.
+    :param charset: Encode text to bytes using this charset.
+    :param for_qs: Quote "/" and use "+" for spaces.
+    """
+    if not isinstance(obj, bytes):
+        if not isinstance(obj, str):
+            obj = str(obj)
+
+        obj = obj.encode(charset)
+
+    safe = b"" if for_qs else b"/"
+    rv = quote_from_bytes(obj, safe)
+
+    if for_qs:
+        rv = rv.replace("%20", "+")
+
+    return rv
+
+
+def unicode_urlencode(obj: t.Any, charset: str = "utf-8", for_qs: bool = False) -> str:
+    import warnings
+
+    warnings.warn(
+        "'unicode_urlencode' has been renamed to 'url_quote'. The old"
+        " name will be removed in Jinja 3.1.",
+        DeprecationWarning,
+        stacklevel=2,
+    )
+    return url_quote(obj, charset=charset, for_qs=for_qs)
+
+
+@abc.MutableMapping.register
+class LRUCache:
+    """A simple LRU Cache implementation."""
+
+    # this is fast for small capacities (something below 1000) but doesn't
+    # scale.  But as long as it's only used as storage for templates this
+    # won't do any harm.
+
+    def __init__(self, capacity: int) -> None:
+        self.capacity = capacity
+        self._mapping: t.Dict[t.Any, t.Any] = {}
+        self._queue: "te.Deque[t.Any]" = deque()
+        self._postinit()
+
+    def _postinit(self) -> None:
+        # alias all queue methods for faster lookup
+        self._popleft = self._queue.popleft
+        self._pop = self._queue.pop
+        self._remove = self._queue.remove
+        self._wlock = Lock()
+        self._append = self._queue.append
+
+    def __getstate__(self) -> t.Mapping[str, t.Any]:
+        return {
+            "capacity": self.capacity,
+            "_mapping": self._mapping,
+            "_queue": self._queue,
+        }
+
+    def __setstate__(self, d: t.Mapping[str, t.Any]) -> None:
+        self.__dict__.update(d)
+        self._postinit()
+
+    def __getnewargs__(self) -> t.Tuple:
+        return (self.capacity,)
+
+    def copy(self) -> "LRUCache":
+        """Return a shallow copy of the instance."""
+        rv = self.__class__(self.capacity)
+        rv._mapping.update(self._mapping)
+        rv._queue.extend(self._queue)
+        return rv
+
+    def get(self, key: t.Any, default: t.Any = None) -> t.Any:
+        """Return an item from the cache dict or `default`"""
+        try:
+            return self[key]
+        except KeyError:
+            return default
+
+    def setdefault(self, key: t.Any, default: t.Any = None) -> t.Any:
+        """Set `default` if the key is not in the cache otherwise
+        leave unchanged. Return the value of this key.
+        """
+        try:
+            return self[key]
+        except KeyError:
+            self[key] = default
+            return default
+
+    def clear(self) -> None:
+        """Clear the cache."""
+        with self._wlock:
+            self._mapping.clear()
+            self._queue.clear()
+
+    def __contains__(self, key: t.Any) -> bool:
+        """Check if a key exists in this cache."""
+        return key in self._mapping
+
+    def __len__(self) -> int:
+        """Return the current size of the cache."""
+        return len(self._mapping)
+
+    def __repr__(self) -> str:
+        return f"<{type(self).__name__} {self._mapping!r}>"
+
+    def __getitem__(self, key: t.Any) -> t.Any:
+        """Get an item from the cache. Moves the item up so that it has the
+        highest priority then.
+
+        Raise a `KeyError` if it does not exist.
+        """
+        with self._wlock:
+            rv = self._mapping[key]
+
+            if self._queue[-1] != key:
+                try:
+                    self._remove(key)
+                except ValueError:
+                    # if something removed the key from the container
+                    # when we read, ignore the ValueError that we would
+                    # get otherwise.
+                    pass
+
+                self._append(key)
+
+            return rv
+
+    def __setitem__(self, key: t.Any, value: t.Any) -> None:
+        """Sets the value for an item. Moves the item up so that it
+        has the highest priority then.
+        """
+        with self._wlock:
+            if key in self._mapping:
+                self._remove(key)
+            elif len(self._mapping) == self.capacity:
+                del self._mapping[self._popleft()]
+
+            self._append(key)
+            self._mapping[key] = value
+
+    def __delitem__(self, key: t.Any) -> None:
+        """Remove an item from the cache dict.
+        Raise a `KeyError` if it does not exist.
+        """
+        with self._wlock:
+            del self._mapping[key]
+
+            try:
+                self._remove(key)
+            except ValueError:
+                pass
+
+    def items(self) -> t.Iterable[t.Tuple[t.Any, t.Any]]:
+        """Return a list of items."""
+        result = [(key, self._mapping[key]) for key in list(self._queue)]
+        result.reverse()
+        return result
+
+    def values(self) -> t.Iterable[t.Any]:
+        """Return a list of all values."""
+        return [x[1] for x in self.items()]
+
+    def keys(self) -> t.Iterable[t.Any]:
+        """Return a list of all keys ordered by most recent usage."""
+        return list(self)
+
+    def __iter__(self) -> t.Iterator[t.Any]:
+        return reversed(tuple(self._queue))
+
+    def __reversed__(self) -> t.Iterator[t.Any]:
+        """Iterate over the keys in the cache dict, oldest items
+        coming first.
+        """
+        return iter(tuple(self._queue))
+
+    __copy__ = copy
+
+
+def select_autoescape(
+    enabled_extensions: t.Collection[str] = ("html", "htm", "xml"),
+    disabled_extensions: t.Collection[str] = (),
+    default_for_string: bool = True,
+    default: bool = False,
+) -> t.Callable[[t.Optional[str]], bool]:
+    """Intelligently sets the initial value of autoescaping based on the
+    filename of the template.  This is the recommended way to configure
+    autoescaping if you do not want to write a custom function yourself.
+
+    If you want to enable it for all templates created from strings or
+    for all templates with `.html` and `.xml` extensions::
+
+        from jinja2 import Environment, select_autoescape
+        env = Environment(autoescape=select_autoescape(
+            enabled_extensions=('html', 'xml'),
+            default_for_string=True,
+        ))
+
+    Example configuration to turn it on at all times except if the template
+    ends with `.txt`::
+
+        from jinja2 import Environment, select_autoescape
+        env = Environment(autoescape=select_autoescape(
+            disabled_extensions=('txt',),
+            default_for_string=True,
+            default=True,
+        ))
+
+    The `enabled_extensions` is an iterable of all the extensions that
+    autoescaping should be enabled for.  Likewise `disabled_extensions` is
+    a list of all templates it should be disabled for.  If a template is
+    loaded from a string then the default from `default_for_string` is used.
+    If nothing matches then the initial value of autoescaping is set to the
+    value of `default`.
+
+    For security reasons this function operates case insensitive.
+
+    .. versionadded:: 2.9
+    """
+    enabled_patterns = tuple(f".{x.lstrip('.').lower()}" for x in enabled_extensions)
+    disabled_patterns = tuple(f".{x.lstrip('.').lower()}" for x in disabled_extensions)
+
+    def autoescape(template_name: t.Optional[str]) -> bool:
+        if template_name is None:
+            return default_for_string
+        template_name = template_name.lower()
+        if template_name.endswith(enabled_patterns):
+            return True
+        if template_name.endswith(disabled_patterns):
+            return False
+        return default
+
+    return autoescape
+
+
+def htmlsafe_json_dumps(
+    obj: t.Any, dumps: t.Optional[t.Callable[..., str]] = None, **kwargs: t.Any
+) -> markupsafe.Markup:
+    """Serialize an object to a string of JSON with :func:`json.dumps`,
+    then replace HTML-unsafe characters with Unicode escapes and mark
+    the result safe with :class:`~markupsafe.Markup`.
+
+    This is available in templates as the ``|tojson`` filter.
+
+    The following characters are escaped: ``<``, ``>``, ``&``, ``'``.
+
+    The returned string is safe to render in HTML documents and
+    ``<script>`` tags. The exception is in HTML attributes that are
+    double quoted; either use single quotes or the ``|forceescape``
+    filter.
+
+    :param obj: The object to serialize to JSON.
+    :param dumps: The ``dumps`` function to use. Defaults to
+        ``env.policies["json.dumps_function"]``, which defaults to
+        :func:`json.dumps`.
+    :param kwargs: Extra arguments to pass to ``dumps``. Merged onto
+        ``env.policies["json.dumps_kwargs"]``.
+
+    .. versionchanged:: 3.0
+        The ``dumper`` parameter is renamed to ``dumps``.
+
+    .. versionadded:: 2.9
+    """
+    if dumps is None:
+        dumps = json.dumps
+
+    return markupsafe.Markup(
+        dumps(obj, **kwargs)
+        .replace("<", "\\u003c")
+        .replace(">", "\\u003e")
+        .replace("&", "\\u0026")
+        .replace("'", "\\u0027")
+    )
+
+
+class Cycler:
+    """Cycle through values by yield them one at a time, then restarting
+    once the end is reached. Available as ``cycler`` in templates.
+
+    Similar to ``loop.cycle``, but can be used outside loops or across
+    multiple loops. For example, render a list of folders and files in a
+    list, alternating giving them "odd" and "even" classes.
+
+    .. code-block:: html+jinja
+
+        {% set row_class = cycler("odd", "even") %}
+        <ul class="browser">
+        {% for folder in folders %}
+          <li class="folder {{ row_class.next() }}">{{ folder }}
+        {% endfor %}
+        {% for file in files %}
+          <li class="file {{ row_class.next() }}">{{ file }}
+        {% endfor %}
+        </ul>
+
+    :param items: Each positional argument will be yielded in the order
+        given for each cycle.
+
+    .. versionadded:: 2.1
+    """
+
+    def __init__(self, *items: t.Any) -> None:
+        if not items:
+            raise RuntimeError("at least one item has to be provided")
+        self.items = items
+        self.pos = 0
+
+    def reset(self) -> None:
+        """Resets the current item to the first item."""
+        self.pos = 0
+
+    @property
+    def current(self) -> t.Any:
+        """Return the current item. Equivalent to the item that will be
+        returned next time :meth:`next` is called.
+        """
+        return self.items[self.pos]
+
+    def next(self) -> t.Any:
+        """Return the current item, then advance :attr:`current` to the
+        next item.
+        """
+        rv = self.current
+        self.pos = (self.pos + 1) % len(self.items)
+        return rv
+
+    __next__ = next
+
+
+class Joiner:
+    """A joining helper for templates."""
+
+    def __init__(self, sep: str = ", ") -> None:
+        self.sep = sep
+        self.used = False
+
+    def __call__(self) -> str:
+        if not self.used:
+            self.used = True
+            return ""
+        return self.sep
+
+
+class Namespace:
+    """A namespace object that can hold arbitrary attributes.  It may be
+    initialized from a dictionary or with keyword arguments."""
+
+    def __init__(*args: t.Any, **kwargs: t.Any) -> None:  # noqa: B902
+        self, args = args[0], args[1:]
+        self.__attrs = dict(*args, **kwargs)
+
+    def __getattribute__(self, name: str) -> t.Any:
+        # __class__ is needed for the awaitable check in async mode
+        if name in {"_Namespace__attrs", "__class__"}:
+            return object.__getattribute__(self, name)
+        try:
+            return self.__attrs[name]
+        except KeyError:
+            raise AttributeError(name) from None
+
+    def __setitem__(self, name: str, value: t.Any) -> None:
+        self.__attrs[name] = value
+
+    def __repr__(self) -> str:
+        return f"<Namespace {self.__attrs!r}>"
+
+
+class Markup(markupsafe.Markup):
+    def __new__(cls, base="", encoding=None, errors="strict"):  # type: ignore
+        warnings.warn(
+            "'jinja2.Markup' is deprecated and will be removed in Jinja"
+            " 3.1. Import 'markupsafe.Markup' instead.",
+            DeprecationWarning,
+            stacklevel=2,
+        )
+        return super().__new__(cls, base, encoding, errors)
+
+
+def escape(s: t.Any) -> str:
+    warnings.warn(
+        "'jinja2.escape' is deprecated and will be removed in Jinja"
+        " 3.1. Import 'markupsafe.escape' instead.",
+        DeprecationWarning,
+        stacklevel=2,
+    )
+    return markupsafe.escape(s)
diff --git a/lib/spack/external/_vendoring/jinja2/visitor.py b/lib/spack/external/_vendoring/jinja2/visitor.py
new file mode 100644
index 0000000000..b150e578a8
--- /dev/null
+++ b/lib/spack/external/_vendoring/jinja2/visitor.py
@@ -0,0 +1,92 @@
+"""API for traversing the AST nodes. Implemented by the compiler and
+meta introspection.
+"""
+import typing as t
+
+from .nodes import Node
+
+if t.TYPE_CHECKING:
+    import typing_extensions as te
+
+    class VisitCallable(te.Protocol):
+        def __call__(self, node: Node, *args: t.Any, **kwargs: t.Any) -> t.Any:
+            ...
+
+
+class NodeVisitor:
+    """Walks the abstract syntax tree and call visitor functions for every
+    node found.  The visitor functions may return values which will be
+    forwarded by the `visit` method.
+
+    Per default the visitor functions for the nodes are ``'visit_'`` +
+    class name of the node.  So a `TryFinally` node visit function would
+    be `visit_TryFinally`.  This behavior can be changed by overriding
+    the `get_visitor` function.  If no visitor function exists for a node
+    (return value `None`) the `generic_visit` visitor is used instead.
+    """
+
+    def get_visitor(self, node: Node) -> "t.Optional[VisitCallable]":
+        """Return the visitor function for this node or `None` if no visitor
+        exists for this node.  In that case the generic visit function is
+        used instead.
+        """
+        return getattr(self, f"visit_{type(node).__name__}", None)  # type: ignore
+
+    def visit(self, node: Node, *args: t.Any, **kwargs: t.Any) -> t.Any:
+        """Visit a node."""
+        f = self.get_visitor(node)
+
+        if f is not None:
+            return f(node, *args, **kwargs)
+
+        return self.generic_visit(node, *args, **kwargs)
+
+    def generic_visit(self, node: Node, *args: t.Any, **kwargs: t.Any) -> t.Any:
+        """Called if no explicit visitor function exists for a node."""
+        for node in node.iter_child_nodes():
+            self.visit(node, *args, **kwargs)
+
+
+class NodeTransformer(NodeVisitor):
+    """Walks the abstract syntax tree and allows modifications of nodes.
+
+    The `NodeTransformer` will walk the AST and use the return value of the
+    visitor functions to replace or remove the old node.  If the return
+    value of the visitor function is `None` the node will be removed
+    from the previous location otherwise it's replaced with the return
+    value.  The return value may be the original node in which case no
+    replacement takes place.
+    """
+
+    def generic_visit(self, node: Node, *args: t.Any, **kwargs: t.Any) -> Node:
+        for field, old_value in node.iter_fields():
+            if isinstance(old_value, list):
+                new_values = []
+                for value in old_value:
+                    if isinstance(value, Node):
+                        value = self.visit(value, *args, **kwargs)
+                        if value is None:
+                            continue
+                        elif not isinstance(value, Node):
+                            new_values.extend(value)
+                            continue
+                    new_values.append(value)
+                old_value[:] = new_values
+            elif isinstance(old_value, Node):
+                new_node = self.visit(old_value, *args, **kwargs)
+                if new_node is None:
+                    delattr(node, field)
+                else:
+                    setattr(node, field, new_node)
+        return node
+
+    def visit_list(self, node: Node, *args: t.Any, **kwargs: t.Any) -> t.List[Node]:
+        """As transformers may return lists in some places this method
+        can be used to enforce a list as return value.
+        """
+        rv = self.visit(node, *args, **kwargs)
+
+        if not isinstance(rv, list):
+            return [rv]
+
+        return rv
diff --git a/lib/spack/external/_vendoring/jsonschema.pyi b/lib/spack/external/_vendoring/jsonschema.pyi
new file mode 100644
index 0000000000..85b509b63f
--- /dev/null
+++ b/lib/spack/external/_vendoring/jsonschema.pyi
@@ -0,0 +1 @@
+from jsonschema import *
\ No newline at end of file
diff --git a/lib/spack/external/_vendoring/jsonschema/COPYING b/lib/spack/external/_vendoring/jsonschema/COPYING
new file mode 100644
index 0000000000..af9cfbdb13
--- /dev/null
+++ b/lib/spack/external/_vendoring/jsonschema/COPYING
@@ -0,0 +1,19 @@
+Copyright (c) 2013 Julian Berman
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.
diff --git a/lib/spack/external/_vendoring/jsonschema/__init__.py b/lib/spack/external/_vendoring/jsonschema/__init__.py
new file mode 100644
index 0000000000..1791fe7fbf
--- /dev/null
+++ b/lib/spack/external/_vendoring/jsonschema/__init__.py
@@ -0,0 +1,31 @@
+"""
+An implementation of JSON Schema for Python
+
+The main functionality is provided by the validator classes for each of the
+supported JSON Schema versions.
+
+Most commonly, `validate` is the quickest way to simply validate a given
+instance under a schema, and will create a validator for you.
+"""
+
+from jsonschema.exceptions import (
+    ErrorTree, FormatError, RefResolutionError, SchemaError, ValidationError
+)
+from jsonschema._format import (
+    FormatChecker,
+    draft3_format_checker,
+    draft4_format_checker,
+    draft6_format_checker,
+    draft7_format_checker,
+)
+from jsonschema._types import TypeChecker
+from jsonschema.validators import (
+    Draft3Validator,
+    Draft4Validator,
+    Draft6Validator,
+    Draft7Validator,
+    RefResolver,
+    validate,
+)
+
+__version__ = "3.2.0"
diff --git a/lib/spack/external/_vendoring/jsonschema/__main__.py b/lib/spack/external/_vendoring/jsonschema/__main__.py
new file mode 100644
index 0000000000..82c29fd39e
--- /dev/null
+++ b/lib/spack/external/_vendoring/jsonschema/__main__.py
@@ -0,0 +1,2 @@
+from jsonschema.cli import main
+main()
diff --git a/lib/spack/external/_vendoring/jsonschema/_format.py b/lib/spack/external/_vendoring/jsonschema/_format.py
new file mode 100644
index 0000000000..281a7cfcff
--- /dev/null
+++ b/lib/spack/external/_vendoring/jsonschema/_format.py
@@ -0,0 +1,425 @@
+import datetime
+import re
+import socket
+import struct
+
+from jsonschema.compat import str_types
+from jsonschema.exceptions import FormatError
+
+
+class FormatChecker(object):
+    """
+    A ``format`` property checker.
+
+    JSON Schema does not mandate that the ``format`` property actually do any
+    validation. If validation is desired however, instances of this class can
+    be hooked into validators to enable format validation.
+
+    `FormatChecker` objects always return ``True`` when asked about
+    formats that they do not know how to validate.
+
+    To check a custom format using a function that takes an instance and
+    returns a ``bool``, use the `FormatChecker.checks` or
+    `FormatChecker.cls_checks` decorators.
+
+    Arguments:
+
+        formats (~collections.Iterable):
+
+            The known formats to validate. This argument can be used to
+            limit which formats will be used during validation.
+    """
+
+    checkers = {}
+
+    def __init__(self, formats=None):
+        if formats is None:
+            self.checkers = self.checkers.copy()
+        else:
+            self.checkers = dict((k, self.checkers[k]) for k in formats)
+
+    def __repr__(self):
+        return "<FormatChecker checkers={}>".format(sorted(self.checkers))
+
+    def checks(self, format, raises=()):
+        """
+        Register a decorated function as validating a new format.
+
+        Arguments:
+
+            format (str):
+
+                The format that the decorated function will check.
+
+            raises (Exception):
+
+                The exception(s) raised by the decorated function when an
+                invalid instance is found.
+
+                The exception object will be accessible as the
+                `jsonschema.exceptions.ValidationError.cause` attribute of the
+                resulting validation error.
+        """
+
+        def _checks(func):
+            self.checkers[format] = (func, raises)
+            return func
+        return _checks
+
+    cls_checks = classmethod(checks)
+
+    def check(self, instance, format):
+        """
+        Check whether the instance conforms to the given format.
+
+        Arguments:
+
+            instance (*any primitive type*, i.e. str, number, bool):
+
+                The instance to check
+
+            format (str):
+
+                The format that instance should conform to
+
+
+        Raises:
+
+            FormatError: if the instance does not conform to ``format``
+        """
+
+        if format not in self.checkers:
+            return
+
+        func, raises = self.checkers[format]
+        result, cause = None, None
+        try:
+            result = func(instance)
+        except raises as e:
+            cause = e
+        if not result:
+            raise FormatError(
+                "%r is not a %r" % (instance, format), cause=cause,
+            )
+
+    def conforms(self, instance, format):
+        """
+        Check whether the instance conforms to the given format.
+
+        Arguments:
+
+            instance (*any primitive type*, i.e. str, number, bool):
+
+                The instance to check
+
+            format (str):
+
+                The format that instance should conform to
+
+        Returns:
+
+            bool: whether it conformed
+        """
+
+        try:
+            self.check(instance, format)
+        except FormatError:
+            return False
+        else:
+            return True
+
+
+draft3_format_checker = FormatChecker()
+draft4_format_checker = FormatChecker()
+draft6_format_checker = FormatChecker()
+draft7_format_checker = FormatChecker()
+
+
+_draft_checkers = dict(
+    draft3=draft3_format_checker,
+    draft4=draft4_format_checker,
+    draft6=draft6_format_checker,
+    draft7=draft7_format_checker,
+)
+
+
+def _checks_drafts(
+    name=None,
+    draft3=None,
+    draft4=None,
+    draft6=None,
+    draft7=None,
+    raises=(),
+):
+    draft3 = draft3 or name
+    draft4 = draft4 or name
+    draft6 = draft6 or name
+    draft7 = draft7 or name
+
+    def wrap(func):
+        if draft3:
+            func = _draft_checkers["draft3"].checks(draft3, raises)(func)
+        if draft4:
+            func = _draft_checkers["draft4"].checks(draft4, raises)(func)
+        if draft6:
+            func = _draft_checkers["draft6"].checks(draft6, raises)(func)
+        if draft7:
+            func = _draft_checkers["draft7"].checks(draft7, raises)(func)
+
+        # Oy. This is bad global state, but relied upon for now, until
+        # deprecation. See https://github.com/Julian/jsonschema/issues/519
+        # and test_format_checkers_come_with_defaults
+        FormatChecker.cls_checks(draft7 or draft6 or draft4 or draft3, raises)(
+            func,
+        )
+        return func
+    return wrap
+
+
+@_checks_drafts(name="idn-email")
+@_checks_drafts(name="email")
+def is_email(instance):
+    if not isinstance(instance, str_types):
+        return True
+    return "@" in instance
+
+
+_ipv4_re = re.compile(r"^\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}$")
+
+
+@_checks_drafts(
+    draft3="ip-address", draft4="ipv4", draft6="ipv4", draft7="ipv4",
+)
+def is_ipv4(instance):
+    if not isinstance(instance, str_types):
+        return True
+    if not _ipv4_re.match(instance):
+        return False
+    return all(0 <= int(component) <= 255 for component in instance.split("."))
+
+
+if hasattr(socket, "inet_pton"):
+    # FIXME: Really this only should raise struct.error, but see the sadness
+    #        that is https://twistedmatrix.com/trac/ticket/9409
+    @_checks_drafts(
+        name="ipv6", raises=(socket.error, struct.error, ValueError),
+    )
+    def is_ipv6(instance):
+        if not isinstance(instance, str_types):
+            return True
+        return socket.inet_pton(socket.AF_INET6, instance)
+
+
+_host_name_re = re.compile(r"^[A-Za-z0-9][A-Za-z0-9\.\-]{1,255}$")
+
+
+@_checks_drafts(
+    draft3="host-name",
+    draft4="hostname",
+    draft6="hostname",
+    draft7="hostname",
+)
+def is_host_name(instance):
+    if not isinstance(instance, str_types):
+        return True
+    if not _host_name_re.match(instance):
+        return False
+    components = instance.split(".")
+    for component in components:
+        if len(component) > 63:
+            return False
+    return True
+
+
+try:
+    # The built-in `idna` codec only implements RFC 3890, so we go elsewhere.
+    import idna
+except ImportError:
+    pass
+else:
+    @_checks_drafts(draft7="idn-hostname", raises=idna.IDNAError)
+    def is_idn_host_name(instance):
+        if not isinstance(instance, str_types):
+            return True
+        idna.encode(instance)
+        return True
+
+
+try:
+    import rfc3987
+except ImportError:
+    try:
+        from rfc3986_validator import validate_rfc3986
+    except ImportError:
+        pass
+    else:
+        @_checks_drafts(name="uri")
+        def is_uri(instance):
+            if not isinstance(instance, str_types):
+                return True
+            return validate_rfc3986(instance, rule="URI")
+
+        @_checks_drafts(
+            draft6="uri-reference",
+            draft7="uri-reference",
+            raises=ValueError,
+        )
+        def is_uri_reference(instance):
+            if not isinstance(instance, str_types):
+                return True
+            return validate_rfc3986(instance, rule="URI_reference")
+
+else:
+    @_checks_drafts(draft7="iri", raises=ValueError)
+    def is_iri(instance):
+        if not isinstance(instance, str_types):
+            return True
+        return rfc3987.parse(instance, rule="IRI")
+
+    @_checks_drafts(draft7="iri-reference", raises=ValueError)
+    def is_iri_reference(instance):
+        if not isinstance(instance, str_types):
+            return True
+        return rfc3987.parse(instance, rule="IRI_reference")
+
+    @_checks_drafts(name="uri", raises=ValueError)
+    def is_uri(instance):
+        if not isinstance(instance, str_types):
+            return True
+        return rfc3987.parse(instance, rule="URI")
+
+    @_checks_drafts(
+        draft6="uri-reference",
+        draft7="uri-reference",
+        raises=ValueError,
+    )
+    def is_uri_reference(instance):
+        if not isinstance(instance, str_types):
+            return True
+        return rfc3987.parse(instance, rule="URI_reference")
+
+
+try:
+    from strict_rfc3339 import validate_rfc3339
+except ImportError:
+    try:
+        from rfc3339_validator import validate_rfc3339
+    except ImportError:
+        validate_rfc3339 = None
+
+if validate_rfc3339:
+    @_checks_drafts(name="date-time")
+    def is_datetime(instance):
+        if not isinstance(instance, str_types):
+            return True
+        return validate_rfc3339(instance)
+
+    @_checks_drafts(draft7="time")
+    def is_time(instance):
+        if not isinstance(instance, str_types):
+            return True
+        return is_datetime("1970-01-01T" + instance)
+
+
+@_checks_drafts(name="regex", raises=re.error)
+def is_regex(instance):
+    if not isinstance(instance, str_types):
+        return True
+    return re.compile(instance)
+
+
+@_checks_drafts(draft3="date", draft7="date", raises=ValueError)
+def is_date(instance):
+    if not isinstance(instance, str_types):
+        return True
+    return datetime.datetime.strptime(instance, "%Y-%m-%d")
+
+
+@_checks_drafts(draft3="time", raises=ValueError)
+def is_draft3_time(instance):
+    if not isinstance(instance, str_types):
+        return True
+    return datetime.datetime.strptime(instance, "%H:%M:%S")
+
+
+try:
+    import webcolors
+except ImportError:
+    pass
+else:
+    def is_css_color_code(instance):
+        return webcolors.normalize_hex(instance)
+
+    @_checks_drafts(draft3="color", raises=(ValueError, TypeError))
+    def is_css21_color(instance):
+        if (
+            not isinstance(instance, str_types) or
+            instance.lower() in webcolors.css21_names_to_hex
+        ):
+            return True
+        return is_css_color_code(instance)
+
+    def is_css3_color(instance):
+        if instance.lower() in webcolors.css3_names_to_hex:
+            return True
+        return is_css_color_code(instance)
+
+
+try:
+    import jsonpointer
+except ImportError:
+    pass
+else:
+    @_checks_drafts(
+        draft6="json-pointer",
+        draft7="json-pointer",
+        raises=jsonpointer.JsonPointerException,
+    )
+    def is_json_pointer(instance):
+        if not isinstance(instance, str_types):
+            return True
+        return jsonpointer.JsonPointer(instance)
+
+    # TODO: I don't want to maintain this, so it
+    #       needs to go either into jsonpointer (pending
+    #       https://github.com/stefankoegl/python-json-pointer/issues/34) or
+    #       into a new external library.
+    @_checks_drafts(
+        draft7="relative-json-pointer",
+        raises=jsonpointer.JsonPointerException,
+    )
+    def is_relative_json_pointer(instance):
+        # Definition taken from:
+        # https://tools.ietf.org/html/draft-handrews-relative-json-pointer-01#section-3
+        if not isinstance(instance, str_types):
+            return True
+        non_negative_integer, rest = [], ""
+        for i, character in enumerate(instance):
+            if character.isdigit():
+                non_negative_integer.append(character)
+                continue
+
+            if not non_negative_integer:
+                return False
+
+            rest = instance[i:]
+            break
+        return (rest == "#") or jsonpointer.JsonPointer(rest)
+
+
+try:
+    import uritemplate.exceptions
+except ImportError:
+    pass
+else:
+    @_checks_drafts(
+        draft6="uri-template",
+        draft7="uri-template",
+        raises=uritemplate.exceptions.InvalidTemplate,
+    )
+    def is_uri_template(
+        instance,
+        template_validator=uritemplate.Validator().force_balanced_braces(),
+    ):
+        template = uritemplate.URITemplate(instance)
+        return template_validator.validate(template)
diff --git a/lib/spack/external/_vendoring/jsonschema/_legacy_validators.py b/lib/spack/external/_vendoring/jsonschema/_legacy_validators.py
new file mode 100644
index 0000000000..264ff7d713
--- /dev/null
+++ b/lib/spack/external/_vendoring/jsonschema/_legacy_validators.py
@@ -0,0 +1,141 @@
+from jsonschema import _utils
+from jsonschema.compat import iteritems
+from jsonschema.exceptions import ValidationError
+
+
+def dependencies_draft3(validator, dependencies, instance, schema):
+    if not validator.is_type(instance, "object"):
+        return
+
+    for property, dependency in iteritems(dependencies):
+        if property not in instance:
+            continue
+
+        if validator.is_type(dependency, "object"):
+            for error in validator.descend(
+                instance, dependency, schema_path=property,
+            ):
+                yield error
+        elif validator.is_type(dependency, "string"):
+            if dependency not in instance:
+                yield ValidationError(
+                    "%r is a dependency of %r" % (dependency, property)
+                )
+        else:
+            for each in dependency:
+                if each not in instance:
+                    message = "%r is a dependency of %r"
+                    yield ValidationError(message % (each, property))
+
+
+def disallow_draft3(validator, disallow, instance, schema):
+    for disallowed in _utils.ensure_list(disallow):
+        if validator.is_valid(instance, {"type": [disallowed]}):
+            yield ValidationError(
+                "%r is disallowed for %r" % (disallowed, instance)
+            )
+
+
+def extends_draft3(validator, extends, instance, schema):
+    if validator.is_type(extends, "object"):
+        for error in validator.descend(instance, extends):
+            yield error
+        return
+    for index, subschema in enumerate(extends):
+        for error in validator.descend(instance, subschema, schema_path=index):
+            yield error
+
+
+def items_draft3_draft4(validator, items, instance, schema):
+    if not validator.is_type(instance, "array"):
+        return
+
+    if validator.is_type(items, "object"):
+        for index, item in enumerate(instance):
+            for error in validator.descend(item, items, path=index):
+                yield error
+    else:
+        for (index, item), subschema in zip(enumerate(instance), items):
+            for error in validator.descend(
+                item, subschema, path=index, schema_path=index,
+            ):
+                yield error
+
+
+def minimum_draft3_draft4(validator, minimum, instance, schema):
+    if not validator.is_type(instance, "number"):
+        return
+
+    if schema.get("exclusiveMinimum", False):
+        failed = instance <= minimum
+        cmp = "less than or equal to"
+    else:
+        failed = instance < minimum
+        cmp = "less than"
+
+    if failed:
+        yield ValidationError(
+            "%r is %s the minimum of %r" % (instance, cmp, minimum)
+        )
+
+
+def maximum_draft3_draft4(validator, maximum, instance, schema):
+    if not validator.is_type(instance, "number"):
+        return
+
+    if schema.get("exclusiveMaximum", False):
+        failed = instance >= maximum
+        cmp = "greater than or equal to"
+    else:
+        failed = instance > maximum
+        cmp = "greater than"
+
+    if failed:
+        yield ValidationError(
+            "%r is %s the maximum of %r" % (instance, cmp, maximum)
+        )
+
+
+def properties_draft3(validator, properties, instance, schema):
+    if not validator.is_type(instance, "object"):
+        return
+
+    for property, subschema in iteritems(properties):
+        if property in instance:
+            for error in validator.descend(
+                instance[property],
+                subschema,
+                path=property,
+                schema_path=property,
+            ):
+                yield error
+        elif subschema.get("required", False):
+            error = ValidationError("%r is a required property" % property)
+            error._set(
+                validator="required",
+                validator_value=subschema["required"],
+                instance=instance,
+                schema=schema,
+            )
+            error.path.appendleft(property)
+            error.schema_path.extend([property, "required"])
+            yield error
+
+
+def type_draft3(validator, types, instance, schema):
+    types = _utils.ensure_list(types)
+
+    all_errors = []
+    for index, type in enumerate(types):
+        if validator.is_type(type, "object"):
+            errors = list(validator.descend(instance, type, schema_path=index))
+            if not errors:
+                return
+            all_errors.extend(errors)
+        else:
+            if validator.is_type(instance, type):
+                return
+    else:
+        yield ValidationError(
+            _utils.types_msg(instance, types), context=all_errors,
+        )
diff --git a/lib/spack/external/_vendoring/jsonschema/_reflect.py b/lib/spack/external/_vendoring/jsonschema/_reflect.py
new file mode 100644
index 0000000000..d09e38fbdc
--- /dev/null
+++ b/lib/spack/external/_vendoring/jsonschema/_reflect.py
@@ -0,0 +1,155 @@
+# -*- test-case-name: twisted.test.test_reflect -*-
+# Copyright (c) Twisted Matrix Laboratories.
+# See LICENSE for details.
+
+"""
+Standardized versions of various cool and/or strange things that you can do
+with Python's reflection capabilities.
+"""
+
+import sys
+
+from jsonschema.compat import PY3
+
+
+class _NoModuleFound(Exception):
+    """
+    No module was found because none exists.
+    """
+
+
+
+class InvalidName(ValueError):
+    """
+    The given name is not a dot-separated list of Python objects.
+    """
+
+
+
+class ModuleNotFound(InvalidName):
+    """
+    The module associated with the given name doesn't exist and it can't be
+    imported.
+    """
+
+
+
+class ObjectNotFound(InvalidName):
+    """
+    The object associated with the given name doesn't exist and it can't be
+    imported.
+    """
+
+
+
+if PY3:
+    def reraise(exception, traceback):
+        raise exception.with_traceback(traceback)
+else:
+    exec("""def reraise(exception, traceback):
+        raise exception.__class__, exception, traceback""")
+
+reraise.__doc__ = """
+Re-raise an exception, with an optional traceback, in a way that is compatible
+with both Python 2 and Python 3.
+
+Note that on Python 3, re-raised exceptions will be mutated, with their
+C{__traceback__} attribute being set.
+
+@param exception: The exception instance.
+@param traceback: The traceback to use, or C{None} indicating a new traceback.
+"""
+
+
+def _importAndCheckStack(importName):
+    """
+    Import the given name as a module, then walk the stack to determine whether
+    the failure was the module not existing, or some code in the module (for
+    example a dependent import) failing.  This can be helpful to determine
+    whether any actual application code was run.  For example, to distiguish
+    administrative error (entering the wrong module name), from programmer
+    error (writing buggy code in a module that fails to import).
+
+    @param importName: The name of the module to import.
+    @type importName: C{str}
+    @raise Exception: if something bad happens.  This can be any type of
+        exception, since nobody knows what loading some arbitrary code might
+        do.
+    @raise _NoModuleFound: if no module was found.
+    """
+    try:
+        return __import__(importName)
+    except ImportError:
+        excType, excValue, excTraceback = sys.exc_info()
+        while excTraceback:
+            execName = excTraceback.tb_frame.f_globals["__name__"]
+            # in Python 2 execName is None when an ImportError is encountered,
+            # where in Python 3 execName is equal to the importName.
+            if execName is None or execName == importName:
+                reraise(excValue, excTraceback)
+            excTraceback = excTraceback.tb_next
+        raise _NoModuleFound()
+
+
+
+def namedAny(name):
+    """
+    Retrieve a Python object by its fully qualified name from the global Python
+    module namespace.  The first part of the name, that describes a module,
+    will be discovered and imported.  Each subsequent part of the name is
+    treated as the name of an attribute of the object specified by all of the
+    name which came before it.  For example, the fully-qualified name of this
+    object is 'twisted.python.reflect.namedAny'.
+
+    @type name: L{str}
+    @param name: The name of the object to return.
+
+    @raise InvalidName: If the name is an empty string, starts or ends with
+        a '.', or is otherwise syntactically incorrect.
+
+    @raise ModuleNotFound: If the name is syntactically correct but the
+        module it specifies cannot be imported because it does not appear to
+        exist.
+
+    @raise ObjectNotFound: If the name is syntactically correct, includes at
+        least one '.', but the module it specifies cannot be imported because
+        it does not appear to exist.
+
+    @raise AttributeError: If an attribute of an object along the way cannot be
+        accessed, or a module along the way is not found.
+
+    @return: the Python object identified by 'name'.
+    """
+    if not name:
+        raise InvalidName('Empty module name')
+
+    names = name.split('.')
+
+    # if the name starts or ends with a '.' or contains '..', the __import__
+    # will raise an 'Empty module name' error. This will provide a better error
+    # message.
+    if '' in names:
+        raise InvalidName(
+            "name must be a string giving a '.'-separated list of Python "
+            "identifiers, not %r" % (name,))
+
+    topLevelPackage = None
+    moduleNames = names[:]
+    while not topLevelPackage:
+        if moduleNames:
+            trialname = '.'.join(moduleNames)
+            try:
+                topLevelPackage = _importAndCheckStack(trialname)
+            except _NoModuleFound:
+                moduleNames.pop()
+        else:
+            if len(names) == 1:
+                raise ModuleNotFound("No module named %r" % (name,))
+            else:
+                raise ObjectNotFound('%r does not name an object' % (name,))
+
+    obj = topLevelPackage
+    for n in names[1:]:
+        obj = getattr(obj, n)
+
+    return obj
diff --git a/lib/spack/external/_vendoring/jsonschema/_types.py b/lib/spack/external/_vendoring/jsonschema/_types.py
new file mode 100644
index 0000000000..a71a4e34bd
--- /dev/null
+++ b/lib/spack/external/_vendoring/jsonschema/_types.py
@@ -0,0 +1,188 @@
+import numbers
+
+from pyrsistent import pmap
+import attr
+
+from jsonschema.compat import int_types, str_types
+from jsonschema.exceptions import UndefinedTypeCheck
+
+
+def is_array(checker, instance):
+    return isinstance(instance, list)
+
+
+def is_bool(checker, instance):
+    return isinstance(instance, bool)
+
+
+def is_integer(checker, instance):
+    # bool inherits from int, so ensure bools aren't reported as ints
+    if isinstance(instance, bool):
+        return False
+    return isinstance(instance, int_types)
+
+
+def is_null(checker, instance):
+    return instance is None
+
+
+def is_number(checker, instance):
+    # bool inherits from int, so ensure bools aren't reported as ints
+    if isinstance(instance, bool):
+        return False
+    return isinstance(instance, numbers.Number)
+
+
+def is_object(checker, instance):
+    return isinstance(instance, dict)
+
+
+def is_string(checker, instance):
+    return isinstance(instance, str_types)
+
+
+def is_any(checker, instance):
+    return True
+
+
+@attr.s(frozen=True)
+class TypeChecker(object):
+    """
+    A ``type`` property checker.
+
+    A `TypeChecker` performs type checking for an `IValidator`. Type
+    checks to perform are updated using `TypeChecker.redefine` or
+    `TypeChecker.redefine_many` and removed via `TypeChecker.remove`.
+    Each of these return a new `TypeChecker` object.
+
+    Arguments:
+
+        type_checkers (dict):
+
+            The initial mapping of types to their checking functions.
+    """
+    _type_checkers = attr.ib(default=pmap(), converter=pmap)
+
+    def is_type(self, instance, type):
+        """
+        Check if the instance is of the appropriate type.
+
+        Arguments:
+
+            instance (object):
+
+                The instance to check
+
+            type (str):
+
+                The name of the type that is expected.
+
+        Returns:
+
+            bool: Whether it conformed.
+
+
+        Raises:
+
+            `jsonschema.exceptions.UndefinedTypeCheck`:
+                if type is unknown to this object.
+        """
+        try:
+            fn = self._type_checkers[type]
+        except KeyError:
+            raise UndefinedTypeCheck(type)
+
+        return fn(self, instance)
+
+    def redefine(self, type, fn):
+        """
+        Produce a new checker with the given type redefined.
+
+        Arguments:
+
+            type (str):
+
+                The name of the type to check.
+
+            fn (collections.Callable):
+
+                A function taking exactly two parameters - the type
+                checker calling the function and the instance to check.
+                The function should return true if instance is of this
+                type and false otherwise.
+
+        Returns:
+
+            A new `TypeChecker` instance.
+        """
+        return self.redefine_many({type: fn})
+
+    def redefine_many(self, definitions=()):
+        """
+        Produce a new checker with the given types redefined.
+
+        Arguments:
+
+            definitions (dict):
+
+                A dictionary mapping types to their checking functions.
+
+        Returns:
+
+            A new `TypeChecker` instance.
+        """
+        return attr.evolve(
+            self, type_checkers=self._type_checkers.update(definitions),
+        )
+
+    def remove(self, *types):
+        """
+        Produce a new checker with the given types forgotten.
+
+        Arguments:
+
+            types (~collections.Iterable):
+
+                the names of the types to remove.
+
+        Returns:
+
+            A new `TypeChecker` instance
+
+        Raises:
+
+            `jsonschema.exceptions.UndefinedTypeCheck`:
+
+                if any given type is unknown to this object
+        """
+
+        checkers = self._type_checkers
+        for each in types:
+            try:
+                checkers = checkers.remove(each)
+            except KeyError:
+                raise UndefinedTypeCheck(each)
+        return attr.evolve(self, type_checkers=checkers)
+
+
+draft3_type_checker = TypeChecker(
+    {
+        u"any": is_any,
+        u"array": is_array,
+        u"boolean": is_bool,
+        u"integer": is_integer,
+        u"object": is_object,
+        u"null": is_null,
+        u"number": is_number,
+        u"string": is_string,
+    },
+)
+draft4_type_checker = draft3_type_checker.remove(u"any")
+draft6_type_checker = draft4_type_checker.redefine(
+    u"integer",
+    lambda checker, instance: (
+        is_integer(checker, instance) or
+        isinstance(instance, float) and instance.is_integer()
+    ),
+)
+draft7_type_checker = draft6_type_checker
diff --git a/lib/spack/external/_vendoring/jsonschema/_utils.py b/lib/spack/external/_vendoring/jsonschema/_utils.py
new file mode 100644
index 0000000000..ceb880198d
--- /dev/null
+++ b/lib/spack/external/_vendoring/jsonschema/_utils.py
@@ -0,0 +1,212 @@
+import itertools
+import json
+import pkgutil
+import re
+
+from jsonschema.compat import MutableMapping, str_types, urlsplit
+
+
+class URIDict(MutableMapping):
+    """
+    Dictionary which uses normalized URIs as keys.
+    """
+
+    def normalize(self, uri):
+        return urlsplit(uri).geturl()
+
+    def __init__(self, *args, **kwargs):
+        self.store = dict()
+        self.store.update(*args, **kwargs)
+
+    def __getitem__(self, uri):
+        return self.store[self.normalize(uri)]
+
+    def __setitem__(self, uri, value):
+        self.store[self.normalize(uri)] = value
+
+    def __delitem__(self, uri):
+        del self.store[self.normalize(uri)]
+
+    def __iter__(self):
+        return iter(self.store)
+
+    def __len__(self):
+        return len(self.store)
+
+    def __repr__(self):
+        return repr(self.store)
+
+
+class Unset(object):
+    """
+    An as-of-yet unset attribute or unprovided default parameter.
+    """
+
+    def __repr__(self):
+        return "<unset>"
+
+
+def load_schema(name):
+    """
+    Load a schema from ./schemas/``name``.json and return it.
+    """
+
+    data = pkgutil.get_data("jsonschema", "schemas/{0}.json".format(name))
+    return json.loads(data.decode("utf-8"))
+
+
+def indent(string, times=1):
+    """
+    A dumb version of `textwrap.indent` from Python 3.3.
+    """
+
+    return "\n".join(" " * (4 * times) + line for line in string.splitlines())
+
+
+def format_as_index(indices):
+    """
+    Construct a single string containing indexing operations for the indices.
+
+    For example, [1, 2, "foo"] -> [1][2]["foo"]
+
+    Arguments:
+
+        indices (sequence):
+
+            The indices to format.
+    """
+
+    if not indices:
+        return ""
+    return "[%s]" % "][".join(repr(index) for index in indices)
+
+
+def find_additional_properties(instance, schema):
+    """
+    Return the set of additional properties for the given ``instance``.
+
+    Weeds out properties that should have been validated by ``properties`` and
+    / or ``patternProperties``.
+
+    Assumes ``instance`` is dict-like already.
+    """
+
+    properties = schema.get("properties", {})
+    patterns = "|".join(schema.get("patternProperties", {}))
+    for property in instance:
+        if property not in properties:
+            if patterns and re.search(patterns, property):
+                continue
+            yield property
+
+
+def extras_msg(extras):
+    """
+    Create an error message for extra items or properties.
+    """
+
+    if len(extras) == 1:
+        verb = "was"
+    else:
+        verb = "were"
+    return ", ".join(repr(extra) for extra in extras), verb
+
+
+def types_msg(instance, types):
+    """
+    Create an error message for a failure to match the given types.
+
+    If the ``instance`` is an object and contains a ``name`` property, it will
+    be considered to be a description of that object and used as its type.
+
+    Otherwise the message is simply the reprs of the given ``types``.
+    """
+
+    reprs = []
+    for type in types:
+        try:
+            reprs.append(repr(type["name"]))
+        except Exception:
+            reprs.append(repr(type))
+    return "%r is not of type %s" % (instance, ", ".join(reprs))
+
+
+def flatten(suitable_for_isinstance):
+    """
+    isinstance() can accept a bunch of really annoying different types:
+        * a single type
+        * a tuple of types
+        * an arbitrary nested tree of tuples
+
+    Return a flattened tuple of the given argument.
+    """
+
+    types = set()
+
+    if not isinstance(suitable_for_isinstance, tuple):
+        suitable_for_isinstance = (suitable_for_isinstance,)
+    for thing in suitable_for_isinstance:
+        if isinstance(thing, tuple):
+            types.update(flatten(thing))
+        else:
+            types.add(thing)
+    return tuple(types)
+
+
+def ensure_list(thing):
+    """
+    Wrap ``thing`` in a list if it's a single str.
+
+    Otherwise, return it unchanged.
+    """
+
+    if isinstance(thing, str_types):
+        return [thing]
+    return thing
+
+
+def equal(one, two):
+    """
+    Check if two things are equal, but evade booleans and ints being equal.
+    """
+    return unbool(one) == unbool(two)
+
+
+def unbool(element, true=object(), false=object()):
+    """
+    A hack to make True and 1 and False and 0 unique for ``uniq``.
+    """
+
+    if element is True:
+        return true
+    elif element is False:
+        return false
+    return element
+
+
+def uniq(container):
+    """
+    Check if all of a container's elements are unique.
+
+    Successively tries first to rely that the elements are hashable, then
+    falls back on them being sortable, and finally falls back on brute
+    force.
+    """
+
+    try:
+        return len(set(unbool(i) for i in container)) == len(container)
+    except TypeError:
+        try:
+            sort = sorted(unbool(i) for i in container)
+            sliced = itertools.islice(sort, 1, None)
+            for i, j in zip(sort, sliced):
+                if i == j:
+                    return False
+        except (NotImplementedError, TypeError):
+            seen = []
+            for e in container:
+                e = unbool(e)
+                if e in seen:
+                    return False
+                seen.append(e)
+    return True
diff --git a/lib/spack/external/_vendoring/jsonschema/_validators.py b/lib/spack/external/_vendoring/jsonschema/_validators.py
new file mode 100644
index 0000000000..179fec09a9
--- /dev/null
+++ b/lib/spack/external/_vendoring/jsonschema/_validators.py
@@ -0,0 +1,373 @@
+import re
+
+from jsonschema._utils import (
+    ensure_list,
+    equal,
+    extras_msg,
+    find_additional_properties,
+    types_msg,
+    unbool,
+    uniq,
+)
+from jsonschema.exceptions import FormatError, ValidationError
+from jsonschema.compat import iteritems
+
+
+def patternProperties(validator, patternProperties, instance, schema):
+    if not validator.is_type(instance, "object"):
+        return
+
+    for pattern, subschema in iteritems(patternProperties):
+        for k, v in iteritems(instance):
+            if re.search(pattern, k):
+                for error in validator.descend(
+                    v, subschema, path=k, schema_path=pattern,
+                ):
+                    yield error
+
+
+def propertyNames(validator, propertyNames, instance, schema):
+    if not validator.is_type(instance, "object"):
+        return
+
+    for property in instance:
+        for error in validator.descend(
+            instance=property,
+            schema=propertyNames,
+        ):
+            yield error
+
+
+def additionalProperties(validator, aP, instance, schema):
+    if not validator.is_type(instance, "object"):
+        return
+
+    extras = set(find_additional_properties(instance, schema))
+
+    if validator.is_type(aP, "object"):
+        for extra in extras:
+            for error in validator.descend(instance[extra], aP, path=extra):
+                yield error
+    elif not aP and extras:
+        if "patternProperties" in schema:
+            patterns = sorted(schema["patternProperties"])
+            if len(extras) == 1:
+                verb = "does"
+            else:
+                verb = "do"
+            error = "%s %s not match any of the regexes: %s" % (
+                ", ".join(map(repr, sorted(extras))),
+                verb,
+                ", ".join(map(repr, patterns)),
+            )
+            yield ValidationError(error)
+        else:
+            error = "Additional properties are not allowed (%s %s unexpected)"
+            yield ValidationError(error % extras_msg(extras))
+
+
+def items(validator, items, instance, schema):
+    if not validator.is_type(instance, "array"):
+        return
+
+    if validator.is_type(items, "array"):
+        for (index, item), subschema in zip(enumerate(instance), items):
+            for error in validator.descend(
+                item, subschema, path=index, schema_path=index,
+            ):
+                yield error
+    else:
+        for index, item in enumerate(instance):
+            for error in validator.descend(item, items, path=index):
+                yield error
+
+
+def additionalItems(validator, aI, instance, schema):
+    if (
+        not validator.is_type(instance, "array") or
+        validator.is_type(schema.get("items", {}), "object")
+    ):
+        return
+
+    len_items = len(schema.get("items", []))
+    if validator.is_type(aI, "object"):
+        for index, item in enumerate(instance[len_items:], start=len_items):
+            for error in validator.descend(item, aI, path=index):
+                yield error
+    elif not aI and len(instance) > len(schema.get("items", [])):
+        error = "Additional items are not allowed (%s %s unexpected)"
+        yield ValidationError(
+            error %
+            extras_msg(instance[len(schema.get("items", [])):])
+        )
+
+
+def const(validator, const, instance, schema):
+    if not equal(instance, const):
+        yield ValidationError("%r was expected" % (const,))
+
+
+def contains(validator, contains, instance, schema):
+    if not validator.is_type(instance, "array"):
+        return
+
+    if not any(validator.is_valid(element, contains) for element in instance):
+        yield ValidationError(
+            "None of %r are valid under the given schema" % (instance,)
+        )
+
+
+def exclusiveMinimum(validator, minimum, instance, schema):
+    if not validator.is_type(instance, "number"):
+        return
+
+    if instance <= minimum:
+        yield ValidationError(
+            "%r is less than or equal to the minimum of %r" % (
+                instance, minimum,
+            ),
+        )
+
+
+def exclusiveMaximum(validator, maximum, instance, schema):
+    if not validator.is_type(instance, "number"):
+        return
+
+    if instance >= maximum:
+        yield ValidationError(
+            "%r is greater than or equal to the maximum of %r" % (
+                instance, maximum,
+            ),
+        )
+
+
+def minimum(validator, minimum, instance, schema):
+    if not validator.is_type(instance, "number"):
+        return
+
+    if instance < minimum:
+        yield ValidationError(
+            "%r is less than the minimum of %r" % (instance, minimum)
+        )
+
+
+def maximum(validator, maximum, instance, schema):
+    if not validator.is_type(instance, "number"):
+        return
+
+    if instance > maximum:
+        yield ValidationError(
+            "%r is greater than the maximum of %r" % (instance, maximum)
+        )
+
+
+def multipleOf(validator, dB, instance, schema):
+    if not validator.is_type(instance, "number"):
+        return
+
+    if isinstance(dB, float):
+        quotient = instance / dB
+        failed = int(quotient) != quotient
+    else:
+        failed = instance % dB
+
+    if failed:
+        yield ValidationError("%r is not a multiple of %r" % (instance, dB))
+
+
+def minItems(validator, mI, instance, schema):
+    if validator.is_type(instance, "array") and len(instance) < mI:
+        yield ValidationError("%r is too short" % (instance,))
+
+
+def maxItems(validator, mI, instance, schema):
+    if validator.is_type(instance, "array") and len(instance) > mI:
+        yield ValidationError("%r is too long" % (instance,))
+
+
+def uniqueItems(validator, uI, instance, schema):
+    if (
+        uI and
+        validator.is_type(instance, "array") and
+        not uniq(instance)
+    ):
+        yield ValidationError("%r has non-unique elements" % (instance,))
+
+
+def pattern(validator, patrn, instance, schema):
+    if (
+        validator.is_type(instance, "string") and
+        not re.search(patrn, instance)
+    ):
+        yield ValidationError("%r does not match %r" % (instance, patrn))
+
+
+def format(validator, format, instance, schema):
+    if validator.format_checker is not None:
+        try:
+            validator.format_checker.check(instance, format)
+        except FormatError as error:
+            yield ValidationError(error.message, cause=error.cause)
+
+
+def minLength(validator, mL, instance, schema):
+    if validator.is_type(instance, "string") and len(instance) < mL:
+        yield ValidationError("%r is too short" % (instance,))
+
+
+def maxLength(validator, mL, instance, schema):
+    if validator.is_type(instance, "string") and len(instance) > mL:
+        yield ValidationError("%r is too long" % (instance,))
+
+
+def dependencies(validator, dependencies, instance, schema):
+    if not validator.is_type(instance, "object"):
+        return
+
+    for property, dependency in iteritems(dependencies):
+        if property not in instance:
+            continue
+
+        if validator.is_type(dependency, "array"):
+            for each in dependency:
+                if each not in instance:
+                    message = "%r is a dependency of %r"
+                    yield ValidationError(message % (each, property))
+        else:
+            for error in validator.descend(
+                instance, dependency, schema_path=property,
+            ):
+                yield error
+
+
+def enum(validator, enums, instance, schema):
+    if instance == 0 or instance == 1:
+        unbooled = unbool(instance)
+        if all(unbooled != unbool(each) for each in enums):
+            yield ValidationError("%r is not one of %r" % (instance, enums))
+    elif instance not in enums:
+        yield ValidationError("%r is not one of %r" % (instance, enums))
+
+
+def ref(validator, ref, instance, schema):
+    resolve = getattr(validator.resolver, "resolve", None)
+    if resolve is None:
+        with validator.resolver.resolving(ref) as resolved:
+            for error in validator.descend(instance, resolved):
+                yield error
+    else:
+        scope, resolved = validator.resolver.resolve(ref)
+        validator.resolver.push_scope(scope)
+
+        try:
+            for error in validator.descend(instance, resolved):
+                yield error
+        finally:
+            validator.resolver.pop_scope()
+
+
+def type(validator, types, instance, schema):
+    types = ensure_list(types)
+
+    if not any(validator.is_type(instance, type) for type in types):
+        yield ValidationError(types_msg(instance, types))
+
+
+def properties(validator, properties, instance, schema):
+    if not validator.is_type(instance, "object"):
+        return
+
+    for property, subschema in iteritems(properties):
+        if property in instance:
+            for error in validator.descend(
+                instance[property],
+                subschema,
+                path=property,
+                schema_path=property,
+            ):
+                yield error
+
+
+def required(validator, required, instance, schema):
+    if not validator.is_type(instance, "object"):
+        return
+    for property in required:
+        if property not in instance:
+            yield ValidationError("%r is a required property" % property)
+
+
+def minProperties(validator, mP, instance, schema):
+    if validator.is_type(instance, "object") and len(instance) < mP:
+        yield ValidationError(
+            "%r does not have enough properties" % (instance,)
+        )
+
+
+def maxProperties(validator, mP, instance, schema):
+    if not validator.is_type(instance, "object"):
+        return
+    if validator.is_type(instance, "object") and len(instance) > mP:
+        yield ValidationError("%r has too many properties" % (instance,))
+
+
+def allOf(validator, allOf, instance, schema):
+    for index, subschema in enumerate(allOf):
+        for error in validator.descend(instance, subschema, schema_path=index):
+            yield error
+
+
+def anyOf(validator, anyOf, instance, schema):
+    all_errors = []
+    for index, subschema in enumerate(anyOf):
+        errs = list(validator.descend(instance, subschema, schema_path=index))
+        if not errs:
+            break
+        all_errors.extend(errs)
+    else:
+        yield ValidationError(
+            "%r is not valid under any of the given schemas" % (instance,),
+            context=all_errors,
+        )
+
+
+def oneOf(validator, oneOf, instance, schema):
+    subschemas = enumerate(oneOf)
+    all_errors = []
+    for index, subschema in subschemas:
+        errs = list(validator.descend(instance, subschema, schema_path=index))
+        if not errs:
+            first_valid = subschema
+            break
+        all_errors.extend(errs)
+    else:
+        yield ValidationError(
+            "%r is not valid under any of the given schemas" % (instance,),
+            context=all_errors,
+        )
+
+    more_valid = [s for i, s in subschemas if validator.is_valid(instance, s)]
+    if more_valid:
+        more_valid.append(first_valid)
+        reprs = ", ".join(repr(schema) for schema in more_valid)
+        yield ValidationError(
+            "%r is valid under each of %s" % (instance, reprs)
+        )
+
+
+def not_(validator, not_schema, instance, schema):
+    if validator.is_valid(instance, not_schema):
+        yield ValidationError(
+            "%r is not allowed for %r" % (not_schema, instance)
+        )
+
+
+def if_(validator, if_schema, instance, schema):
+    if validator.is_valid(instance, if_schema):
+        if u"then" in schema:
+            then = schema[u"then"]
+            for error in validator.descend(instance, then, schema_path="then"):
+                yield error
+    elif u"else" in schema:
+        else_ = schema[u"else"]
+        for error in validator.descend(instance, else_, schema_path="else"):
+            yield error
diff --git a/lib/spack/external/_vendoring/jsonschema/benchmarks/__init__.py b/lib/spack/external/_vendoring/jsonschema/benchmarks/__init__.py
new file mode 100644
index 0000000000..e3dcc68993
--- /dev/null
+++ b/lib/spack/external/_vendoring/jsonschema/benchmarks/__init__.py
@@ -0,0 +1,5 @@
+"""
+Benchmarks for validation.
+
+This package is *not* public API.
+"""
diff --git a/lib/spack/external/_vendoring/jsonschema/benchmarks/issue232.py b/lib/spack/external/_vendoring/jsonschema/benchmarks/issue232.py
new file mode 100644
index 0000000000..65e3aedf79
--- /dev/null
+++ b/lib/spack/external/_vendoring/jsonschema/benchmarks/issue232.py
@@ -0,0 +1,26 @@
+#!/usr/bin/env python
+"""
+A performance benchmark using the example from issue #232.
+
+See https://github.com/Julian/jsonschema/pull/232.
+"""
+from twisted.python.filepath import FilePath
+from pyperf import Runner
+from pyrsistent import m
+
+from jsonschema.tests._suite import Version
+import jsonschema
+
+
+issue232 = Version(
+    path=FilePath(__file__).sibling("issue232"),
+    remotes=m(),
+    name="issue232",
+)
+
+
+if __name__ == "__main__":
+    issue232.benchmark(
+        runner=Runner(),
+        Validator=jsonschema.Draft4Validator,
+    )
diff --git a/lib/spack/external/_vendoring/jsonschema/benchmarks/json_schema_test_suite.py b/lib/spack/external/_vendoring/jsonschema/benchmarks/json_schema_test_suite.py
new file mode 100644
index 0000000000..5add5051df
--- /dev/null
+++ b/lib/spack/external/_vendoring/jsonschema/benchmarks/json_schema_test_suite.py
@@ -0,0 +1,14 @@
+#!/usr/bin/env python
+"""
+A performance benchmark using the official test suite.
+
+This benchmarks jsonschema using every valid example in the
+JSON-Schema-Test-Suite. It will take some time to complete.
+"""
+from pyperf import Runner
+
+from jsonschema.tests._suite import Suite
+
+
+if __name__ == "__main__":
+    Suite().benchmark(runner=Runner())
diff --git a/lib/spack/external/_vendoring/jsonschema/cli.py b/lib/spack/external/_vendoring/jsonschema/cli.py
new file mode 100644
index 0000000000..ab3335b27c
--- /dev/null
+++ b/lib/spack/external/_vendoring/jsonschema/cli.py
@@ -0,0 +1,90 @@
+"""
+The ``jsonschema`` command line.
+"""
+from __future__ import absolute_import
+import argparse
+import json
+import sys
+
+from jsonschema import __version__
+from jsonschema._reflect import namedAny
+from jsonschema.validators import validator_for
+
+
+def _namedAnyWithDefault(name):
+    if "." not in name:
+        name = "jsonschema." + name
+    return namedAny(name)
+
+
+def _json_file(path):
+    with open(path) as file:
+        return json.load(file)
+
+
+parser = argparse.ArgumentParser(
+    description="JSON Schema Validation CLI",
+)
+parser.add_argument(
+    "-i", "--instance",
+    action="append",
+    dest="instances",
+    type=_json_file,
+    help=(
+        "a path to a JSON instance (i.e. filename.json) "
+        "to validate (may be specified multiple times)"
+    ),
+)
+parser.add_argument(
+    "-F", "--error-format",
+    default="{error.instance}: {error.message}\n",
+    help=(
+        "the format to use for each error output message, specified in "
+        "a form suitable for passing to str.format, which will be called "
+        "with 'error' for each error"
+    ),
+)
+parser.add_argument(
+    "-V", "--validator",
+    type=_namedAnyWithDefault,
+    help=(
+        "the fully qualified object name of a validator to use, or, for "
+        "validators that are registered with jsonschema, simply the name "
+        "of the class."
+    ),
+)
+parser.add_argument(
+    "--version",
+    action="version",
+    version=__version__,
+)
+parser.add_argument(
+    "schema",
+    help="the JSON Schema to validate with (i.e. schema.json)",
+    type=_json_file,
+)
+
+
+def parse_args(args):
+    arguments = vars(parser.parse_args(args=args or ["--help"]))
+    if arguments["validator"] is None:
+        arguments["validator"] = validator_for(arguments["schema"])
+    return arguments
+
+
+def main(args=sys.argv[1:]):
+    sys.exit(run(arguments=parse_args(args=args)))
+
+
+def run(arguments, stdout=sys.stdout, stderr=sys.stderr):
+    error_format = arguments["error_format"]
+    validator = arguments["validator"](schema=arguments["schema"])
+
+    validator.check_schema(arguments["schema"])
+
+    errored = False
+    for instance in arguments["instances"] or ():
+        for error in validator.iter_errors(instance):
+            stderr.write(error_format.format(error=error))
+            errored = True
+    return errored
diff --git a/lib/spack/external/_vendoring/jsonschema/compat.py b/lib/spack/external/_vendoring/jsonschema/compat.py
new file mode 100644
index 0000000000..47e0980455
--- /dev/null
+++ b/lib/spack/external/_vendoring/jsonschema/compat.py
@@ -0,0 +1,55 @@
+"""
+Python 2/3 compatibility helpers.
+
+Note: This module is *not* public API.
+"""
+import contextlib
+import operator
+import sys
+
+
+try:
+    from collections.abc import MutableMapping, Sequence  # noqa
+except ImportError:
+    from collections import MutableMapping, Sequence  # noqa
+
+PY3 = sys.version_info[0] >= 3
+
+if PY3:
+    zip = zip
+    from functools import lru_cache
+    from io import StringIO as NativeIO
+    from urllib.parse import (
+        unquote, urljoin, urlunsplit, SplitResult, urlsplit
+    )
+    from urllib.request import pathname2url, urlopen
+    str_types = str,
+    int_types = int,
+    iteritems = operator.methodcaller("items")
+else:
+    from itertools import izip as zip  # noqa
+    from io import BytesIO as NativeIO
+    from urlparse import urljoin, urlunsplit, SplitResult, urlsplit
+    from urllib import pathname2url, unquote  # noqa
+    import urllib2  # noqa
+    def urlopen(*args, **kwargs):
+        return contextlib.closing(urllib2.urlopen(*args, **kwargs))
+
+    str_types = basestring
+    int_types = int, long
+    iteritems = operator.methodcaller("iteritems")
+
+    from functools32 import lru_cache
+
+
+def urldefrag(url):
+    if "#" in url:
+        s, n, p, q, frag = urlsplit(url)
+        defrag = urlunsplit((s, n, p, q, ""))
+    else:
+        defrag = url
+        frag = ""
+    return defrag, frag
+
+
+# flake8: noqa
diff --git a/lib/spack/external/_vendoring/jsonschema/exceptions.py b/lib/spack/external/_vendoring/jsonschema/exceptions.py
new file mode 100644
index 0000000000..691dcffe6c
--- /dev/null
+++ b/lib/spack/external/_vendoring/jsonschema/exceptions.py
@@ -0,0 +1,374 @@
+"""
+Validation errors, and some surrounding helpers.
+"""
+from collections import defaultdict, deque
+import itertools
+import pprint
+import textwrap
+
+import attr
+
+from jsonschema import _utils
+from jsonschema.compat import PY3, iteritems
+
+
+WEAK_MATCHES = frozenset(["anyOf", "oneOf"])
+STRONG_MATCHES = frozenset()
+
+_unset = _utils.Unset()
+
+
+class _Error(Exception):
+    def __init__(
+        self,
+        message,
+        validator=_unset,
+        path=(),
+        cause=None,
+        context=(),
+        validator_value=_unset,
+        instance=_unset,
+        schema=_unset,
+        schema_path=(),
+        parent=None,
+    ):
+        super(_Error, self).__init__(
+            message,
+            validator,
+            path,
+            cause,
+            context,
+            validator_value,
+            instance,
+            schema,
+            schema_path,
+            parent,
+        )
+        self.message = message
+        self.path = self.relative_path = deque(path)
+        self.schema_path = self.relative_schema_path = deque(schema_path)
+        self.context = list(context)
+        self.cause = self.__cause__ = cause
+        self.validator = validator
+        self.validator_value = validator_value
+        self.instance = instance
+        self.schema = schema
+        self.parent = parent
+
+        for error in context:
+            error.parent = self
+
+    def __repr__(self):
+        return "<%s: %r>" % (self.__class__.__name__, self.message)
+
+    def __unicode__(self):
+        essential_for_verbose = (
+            self.validator, self.validator_value, self.instance, self.schema,
+        )
+        if any(m is _unset for m in essential_for_verbose):
+            return self.message
+
+        pschema = pprint.pformat(self.schema, width=72)
+        pinstance = pprint.pformat(self.instance, width=72)
+        return self.message + textwrap.dedent("""
+
+            Failed validating %r in %s%s:
+            %s
+
+            On %s%s:
+            %s
+            """.rstrip()
+        ) % (
+            self.validator,
+            self._word_for_schema_in_error_message,
+            _utils.format_as_index(list(self.relative_schema_path)[:-1]),
+            _utils.indent(pschema),
+            self._word_for_instance_in_error_message,
+            _utils.format_as_index(self.relative_path),
+            _utils.indent(pinstance),
+        )
+
+    if PY3:
+        __str__ = __unicode__
+    else:
+        def __str__(self):
+            return unicode(self).encode("utf-8")
+
+    @classmethod
+    def create_from(cls, other):
+        return cls(**other._contents())
+
+    @property
+    def absolute_path(self):
+        parent = self.parent
+        if parent is None:
+            return self.relative_path
+
+        path = deque(self.relative_path)
+        path.extendleft(reversed(parent.absolute_path))
+        return path
+
+    @property
+    def absolute_schema_path(self):
+        parent = self.parent
+        if parent is None:
+            return self.relative_schema_path
+
+        path = deque(self.relative_schema_path)
+        path.extendleft(reversed(parent.absolute_schema_path))
+        return path
+
+    def _set(self, **kwargs):
+        for k, v in iteritems(kwargs):
+            if getattr(self, k) is _unset:
+                setattr(self, k, v)
+
+    def _contents(self):
+        attrs = (
+            "message", "cause", "context", "validator", "validator_value",
+            "path", "schema_path", "instance", "schema", "parent",
+        )
+        return dict((attr, getattr(self, attr)) for attr in attrs)
+
+
+class ValidationError(_Error):
+    """
+    An instance was invalid under a provided schema.
+    """
+
+    _word_for_schema_in_error_message = "schema"
+    _word_for_instance_in_error_message = "instance"
+
+
+class SchemaError(_Error):
+    """
+    A schema was invalid under its corresponding metaschema.
+    """
+
+    _word_for_schema_in_error_message = "metaschema"
+    _word_for_instance_in_error_message = "schema"
+
+
+@attr.s(hash=True)
+class RefResolutionError(Exception):
+    """
+    A ref could not be resolved.
+    """
+
+    _cause = attr.ib()
+
+    def __str__(self):
+        return str(self._cause)
+
+
+class UndefinedTypeCheck(Exception):
+    """
+    A type checker was asked to check a type it did not have registered.
+    """
+
+    def __init__(self, type):
+        self.type = type
+
+    def __unicode__(self):
+        return "Type %r is unknown to this type checker" % self.type
+
+    if PY3:
+        __str__ = __unicode__
+    else:
+        def __str__(self):
+            return unicode(self).encode("utf-8")
+
+
+class UnknownType(Exception):
+    """
+    A validator was asked to validate an instance against an unknown type.
+    """
+
+    def __init__(self, type, instance, schema):
+        self.type = type
+        self.instance = instance
+        self.schema = schema
+
+    def __unicode__(self):
+        pschema = pprint.pformat(self.schema, width=72)
+        pinstance = pprint.pformat(self.instance, width=72)
+        return textwrap.dedent("""
+            Unknown type %r for validator with schema:
+            %s
+
+            While checking instance:
+            %s
+            """.rstrip()
+        ) % (self.type, _utils.indent(pschema), _utils.indent(pinstance))
+
+    if PY3:
+        __str__ = __unicode__
+    else:
+        def __str__(self):
+            return unicode(self).encode("utf-8")
+
+
+class FormatError(Exception):
+    """
+    Validating a format failed.
+    """
+
+    def __init__(self, message, cause=None):
+        super(FormatError, self).__init__(message, cause)
+        self.message = message
+        self.cause = self.__cause__ = cause
+
+    def __unicode__(self):
+        return self.message
+
+    if PY3:
+        __str__ = __unicode__
+    else:
+        def __str__(self):
+            return self.message.encode("utf-8")
+
+
+class ErrorTree(object):
+    """
+    ErrorTrees make it easier to check which validations failed.
+    """
+
+    _instance = _unset
+
+    def __init__(self, errors=()):
+        self.errors = {}
+        self._contents = defaultdict(self.__class__)
+
+        for error in errors:
+            container = self
+            for element in error.path:
+                container = container[element]
+            container.errors[error.validator] = error
+
+            container._instance = error.instance
+
+    def __contains__(self, index):
+        """
+        Check whether ``instance[index]`` has any errors.
+        """
+
+        return index in self._contents
+
+    def __getitem__(self, index):
+        """
+        Retrieve the child tree one level down at the given ``index``.
+
+        If the index is not in the instance that this tree corresponds to and
+        is not known by this tree, whatever error would be raised by
+        ``instance.__getitem__`` will be propagated (usually this is some
+        subclass of `exceptions.LookupError`.
+        """
+
+        if self._instance is not _unset and index not in self:
+            self._instance[index]
+        return self._contents[index]
+
+    def __setitem__(self, index, value):
+        """
+        Add an error to the tree at the given ``index``.
+        """
+        self._contents[index] = value
+
+    def __iter__(self):
+        """
+        Iterate (non-recursively) over the indices in the instance with errors.
+        """
+
+        return iter(self._contents)
+
+    def __len__(self):
+        """
+        Return the `total_errors`.
+        """
+        return self.total_errors
+
+    def __repr__(self):
+        return "<%s (%s total errors)>" % (self.__class__.__name__, len(self))
+
+    @property
+    def total_errors(self):
+        """
+        The total number of errors in the entire tree, including children.
+        """
+
+        child_errors = sum(len(tree) for _, tree in iteritems(self._contents))
+        return len(self.errors) + child_errors
+
+
+def by_relevance(weak=WEAK_MATCHES, strong=STRONG_MATCHES):
+    """
+    Create a key function that can be used to sort errors by relevance.
+
+    Arguments:
+        weak (set):
+            a collection of validator names to consider to be "weak".
+            If there are two errors at the same level of the instance
+            and one is in the set of weak validator names, the other
+            error will take priority. By default, :validator:`anyOf` and
+            :validator:`oneOf` are considered weak validators and will
+            be superseded by other same-level validation errors.
+
+        strong (set):
+            a collection of validator names to consider to be "strong"
+    """
+    def relevance(error):
+        validator = error.validator
+        return -len(error.path), validator not in weak, validator in strong
+    return relevance
+
+
+relevance = by_relevance()
+
+
+def best_match(errors, key=relevance):
+    """
+    Try to find an error that appears to be the best match among given errors.
+
+    In general, errors that are higher up in the instance (i.e. for which
+    `ValidationError.path` is shorter) are considered better matches,
+    since they indicate "more" is wrong with the instance.
+
+    If the resulting match is either :validator:`oneOf` or :validator:`anyOf`,
+    the *opposite* assumption is made -- i.e. the deepest error is picked,
+    since these validators only need to match once, and any other errors may
+    not be relevant.
+
+    Arguments:
+        errors (collections.Iterable):
+
+            the errors to select from. Do not provide a mixture of
+            errors from different validation attempts (i.e. from
+            different instances or schemas), since it won't produce
+            sensical output.
+
+        key (collections.Callable):
+
+            the key to use when sorting errors. See `relevance` and
+            transitively `by_relevance` for more details (the default is
+            to sort with the defaults of that function). Changing the
+            default is only useful if you want to change the function
+            that rates errors but still want the error context descent
+            done by this function.
+
+    Returns:
+        the best matching error, or ``None`` if the iterable was empty
+
+    .. note::
+
+        This function is a heuristic. Its return value may change for a given
+        set of inputs from version to version if better heuristics are added.
+    """
+    errors = iter(errors)
+    best = next(errors, None)
+    if best is None:
+        return
+    best = max(itertools.chain([best], errors), key=key)
+
+    while best.context:
+        best = min(best.context, key=key)
+    return best
diff --git a/lib/spack/external/_vendoring/jsonschema/schemas/draft3.json b/lib/spack/external/_vendoring/jsonschema/schemas/draft3.json
new file mode 100644
index 0000000000..f8a09c563b
--- /dev/null
+++ b/lib/spack/external/_vendoring/jsonschema/schemas/draft3.json
@@ -0,0 +1,199 @@
+{
+    "$schema": "http://json-schema.org/draft-03/schema#",
+    "dependencies": {
+        "exclusiveMaximum": "maximum",
+        "exclusiveMinimum": "minimum"
+    },
+    "id": "http://json-schema.org/draft-03/schema#",
+    "properties": {
+        "$ref": {
+            "format": "uri",
+            "type": "string"
+        },
+        "$schema": {
+            "format": "uri",
+            "type": "string"
+        },
+        "additionalItems": {
+            "default": {},
+            "type": [
+                {
+                    "$ref": "#"
+                },
+                "boolean"
+            ]
+        },
+        "additionalProperties": {
+            "default": {},
+            "type": [
+                {
+                    "$ref": "#"
+                },
+                "boolean"
+            ]
+        },
+        "default": {
+            "type": "any"
+        },
+        "dependencies": {
+            "additionalProperties": {
+                "items": {
+                    "type": "string"
+                },
+                "type": [
+                    "string",
+                    "array",
+                    {
+                        "$ref": "#"
+                    }
+                ]
+            },
+            "default": {},
+            "type": [
+                "string",
+                "array",
+                "object"
+            ]
+        },
+        "description": {
+            "type": "string"
+        },
+        "disallow": {
+            "items": {
+                "type": [
+                    "string",
+                    {
+                        "$ref": "#"
+                    }
+                ]
+            },
+            "type": [
+                "string",
+                "array"
+            ],
+            "uniqueItems": true
+        },
+        "divisibleBy": {
+            "default": 1,
+            "exclusiveMinimum": true,
+            "minimum": 0,
+            "type": "number"
+        },
+        "enum": {
+            "type": "array"
+        },
+        "exclusiveMaximum": {
+            "default": false,
+            "type": "boolean"
+        },
+        "exclusiveMinimum": {
+            "default": false,
+            "type": "boolean"
+        },
+        "extends": {
+            "default": {},
+            "items": {
+                "$ref": "#"
+            },
+            "type": [
+                {
+                    "$ref": "#"
+                },
+                "array"
+            ]
+        },
+        "format": {
+            "type": "string"
+        },
+        "id": {
+            "format": "uri",
+            "type": "string"
+        },
+        "items": {
+            "default": {},
+            "items": {
+                "$ref": "#"
+            },
+            "type": [
+                {
+                    "$ref": "#"
+                },
+                "array"
+            ]
+        },
+        "maxDecimal": {
+            "minimum": 0,
+            "type": "number"
+        },
+        "maxItems": {
+            "minimum": 0,
+            "type": "integer"
+        },
+        "maxLength": {
+            "type": "integer"
+        },
+        "maximum": {
+            "type": "number"
+        },
+        "minItems": {
+            "default": 0,
+            "minimum": 0,
+            "type": "integer"
+        },
+        "minLength": {
+            "default": 0,
+            "minimum": 0,
+            "type": "integer"
+        },
+        "minimum": {
+            "type": "number"
+        },
+        "pattern": {
+            "format": "regex",
+            "type": "string"
+        },
+        "patternProperties": {
+            "additionalProperties": {
+                "$ref": "#"
+            },
+            "default": {},
+            "type": "object"
+        },
+        "properties": {
+            "additionalProperties": {
+                "$ref": "#",
+                "type": "object"
+            },
+            "default": {},
+            "type": "object"
+        },
+        "required": {
+            "default": false,
+            "type": "boolean"
+        },
+        "title": {
+            "type": "string"
+        },
+        "type": {
+            "default": "any",
+            "items": {
+                "type": [
+                    "string",
+                    {
+                        "$ref": "#"
+                    }
+                ]
+            },
+            "type": [
+                "string",
+                "array"
+            ],
+            "uniqueItems": true
+        },
+        "uniqueItems": {
+            "default": false,
+            "type": "boolean"
+        }
+    },
+    "type": "object"
+}
diff --git a/lib/spack/external/_vendoring/jsonschema/schemas/draft4.json b/lib/spack/external/_vendoring/jsonschema/schemas/draft4.json
new file mode 100644
index 0000000000..9b666cff88
--- /dev/null
+++ b/lib/spack/external/_vendoring/jsonschema/schemas/draft4.json
@@ -0,0 +1,222 @@
+{
+    "$schema": "http://json-schema.org/draft-04/schema#",
+    "default": {},
+    "definitions": {
+        "positiveInteger": {
+            "minimum": 0,
+            "type": "integer"
+        },
+        "positiveIntegerDefault0": {
+            "allOf": [
+                {
+                    "$ref": "#/definitions/positiveInteger"
+                },
+                {
+                    "default": 0
+                }
+            ]
+        },
+        "schemaArray": {
+            "items": {
+                "$ref": "#"
+            },
+            "minItems": 1,
+            "type": "array"
+        },
+        "simpleTypes": {
+            "enum": [
+                "array",
+                "boolean",
+                "integer",
+                "null",
+                "number",
+                "object",
+                "string"
+            ]
+        },
+        "stringArray": {
+            "items": {
+                "type": "string"
+            },
+            "minItems": 1,
+            "type": "array",
+            "uniqueItems": true
+        }
+    },
+    "dependencies": {
+        "exclusiveMaximum": [
+            "maximum"
+        ],
+        "exclusiveMinimum": [
+            "minimum"
+        ]
+    },
+    "description": "Core schema meta-schema",
+    "id": "http://json-schema.org/draft-04/schema#",
+    "properties": {
+        "$schema": {
+            "format": "uri",
+            "type": "string"
+        },
+        "additionalItems": {
+            "anyOf": [
+                {
+                    "type": "boolean"
+                },
+                {
+                    "$ref": "#"
+                }
+            ],
+            "default": {}
+        },
+        "additionalProperties": {
+            "anyOf": [
+                {
+                    "type": "boolean"
+                },
+                {
+                    "$ref": "#"
+                }
+            ],
+            "default": {}
+        },
+        "allOf": {
+            "$ref": "#/definitions/schemaArray"
+        },
+        "anyOf": {
+            "$ref": "#/definitions/schemaArray"
+        },
+        "default": {},
+        "definitions": {
+            "additionalProperties": {
+                "$ref": "#"
+            },
+            "default": {},
+            "type": "object"
+        },
+        "dependencies": {
+            "additionalProperties": {
+                "anyOf": [
+                    {
+                        "$ref": "#"
+                    },
+                    {
+                        "$ref": "#/definitions/stringArray"
+                    }
+                ]
+            },
+            "type": "object"
+        },
+        "description": {
+            "type": "string"
+        },
+        "enum": {
+            "type": "array"
+        },
+        "exclusiveMaximum": {
+            "default": false,
+            "type": "boolean"
+        },
+        "exclusiveMinimum": {
+            "default": false,
+            "type": "boolean"
+        },
+        "format": {
+            "type": "string"
+        },
+        "id": {
+            "format": "uri",
+            "type": "string"
+        },
+        "items": {
+            "anyOf": [
+                {
+                    "$ref": "#"
+                },
+                {
+                    "$ref": "#/definitions/schemaArray"
+                }
+            ],
+            "default": {}
+        },
+        "maxItems": {
+            "$ref": "#/definitions/positiveInteger"
+        },
+        "maxLength": {
+            "$ref": "#/definitions/positiveInteger"
+        },
+        "maxProperties": {
+            "$ref": "#/definitions/positiveInteger"
+        },
+        "maximum": {
+            "type": "number"
+        },
+        "minItems": {
+            "$ref": "#/definitions/positiveIntegerDefault0"
+        },
+        "minLength": {
+            "$ref": "#/definitions/positiveIntegerDefault0"
+        },
+        "minProperties": {
+            "$ref": "#/definitions/positiveIntegerDefault0"
+        },
+        "minimum": {
+            "type": "number"
+        },
+        "multipleOf": {
+            "exclusiveMinimum": true,
+            "minimum": 0,
+            "type": "number"
+        },
+        "not": {
+            "$ref": "#"
+        },
+        "oneOf": {
+            "$ref": "#/definitions/schemaArray"
+        },
+        "pattern": {
+            "format": "regex",
+            "type": "string"
+        },
+        "patternProperties": {
+            "additionalProperties": {
+                "$ref": "#"
+            },
+            "default": {},
+            "type": "object"
+        },
+        "properties": {
+            "additionalProperties": {
+                "$ref": "#"
+            },
+            "default": {},
+            "type": "object"
+        },
+        "required": {
+            "$ref": "#/definitions/stringArray"
+        },
+        "title": {
+            "type": "string"
+        },
+        "type": {
+            "anyOf": [
+                {
+                    "$ref": "#/definitions/simpleTypes"
+                },
+                {
+                    "items": {
+                        "$ref": "#/definitions/simpleTypes"
+                    },
+                    "minItems": 1,
+                    "type": "array",
+                    "uniqueItems": true
+                }
+            ]
+        },
+        "uniqueItems": {
+            "default": false,
+            "type": "boolean"
+        }
+    },
+    "type": "object"
+}
diff --git a/lib/spack/external/_vendoring/jsonschema/schemas/draft6.json b/lib/spack/external/_vendoring/jsonschema/schemas/draft6.json
new file mode 100644
index 0000000000..a0d2bf7896
--- /dev/null
+++ b/lib/spack/external/_vendoring/jsonschema/schemas/draft6.json
@@ -0,0 +1,153 @@
+{
+    "$schema": "http://json-schema.org/draft-06/schema#",
+    "$id": "http://json-schema.org/draft-06/schema#",
+    "title": "Core schema meta-schema",
+    "definitions": {
+        "schemaArray": {
+            "type": "array",
+            "minItems": 1,
+            "items": { "$ref": "#" }
+        },
+        "nonNegativeInteger": {
+            "type": "integer",
+            "minimum": 0
+        },
+        "nonNegativeIntegerDefault0": {
+            "allOf": [
+                { "$ref": "#/definitions/nonNegativeInteger" },
+                { "default": 0 }
+            ]
+        },
+        "simpleTypes": {
+            "enum": [
+                "array",
+                "boolean",
+                "integer",
+                "null",
+                "number",
+                "object",
+                "string"
+            ]
+        },
+        "stringArray": {
+            "type": "array",
+            "items": { "type": "string" },
+            "uniqueItems": true,
+            "default": []
+        }
+    },
+    "type": ["object", "boolean"],
+    "properties": {
+        "$id": {
+            "type": "string",
+            "format": "uri-reference"
+        },
+        "$schema": {
+            "type": "string",
+            "format": "uri"
+        },
+        "$ref": {
+            "type": "string",
+            "format": "uri-reference"
+        },
+        "title": {
+            "type": "string"
+        },
+        "description": {
+            "type": "string"
+        },
+        "default": {},
+        "examples": {
+            "type": "array",
+            "items": {}
+        },
+        "multipleOf": {
+            "type": "number",
+            "exclusiveMinimum": 0
+        },
+        "maximum": {
+            "type": "number"
+        },
+        "exclusiveMaximum": {
+            "type": "number"
+        },
+        "minimum": {
+            "type": "number"
+        },
+        "exclusiveMinimum": {
+            "type": "number"
+        },
+        "maxLength": { "$ref": "#/definitions/nonNegativeInteger" },
+        "minLength": { "$ref": "#/definitions/nonNegativeIntegerDefault0" },
+        "pattern": {
+            "type": "string",
+            "format": "regex"
+        },
+        "additionalItems": { "$ref": "#" },
+        "items": {
+            "anyOf": [
+                { "$ref": "#" },
+                { "$ref": "#/definitions/schemaArray" }
+            ],
+            "default": {}
+        },
+        "maxItems": { "$ref": "#/definitions/nonNegativeInteger" },
+        "minItems": { "$ref": "#/definitions/nonNegativeIntegerDefault0" },
+        "uniqueItems": {
+            "type": "boolean",
+            "default": false
+        },
+        "contains": { "$ref": "#" },
+        "maxProperties": { "$ref": "#/definitions/nonNegativeInteger" },
+        "minProperties": { "$ref": "#/definitions/nonNegativeIntegerDefault0" },
+        "required": { "$ref": "#/definitions/stringArray" },
+        "additionalProperties": { "$ref": "#" },
+        "definitions": {
+            "type": "object",
+            "additionalProperties": { "$ref": "#" },
+            "default": {}
+        },
+        "properties": {
+            "type": "object",
+            "additionalProperties": { "$ref": "#" },
+            "default": {}
+        },
+        "patternProperties": {
+            "type": "object",
+            "additionalProperties": { "$ref": "#" },
+            "propertyNames": { "format": "regex" },
+            "default": {}
+        },
+        "dependencies": {
+            "type": "object",
+            "additionalProperties": {
+                "anyOf": [
+                    { "$ref": "#" },
+                    { "$ref": "#/definitions/stringArray" }
+                ]
+            }
+        },
+        "propertyNames": { "$ref": "#" },
+        "const": {},
+        "enum": {
+            "type": "array"
+        },
+        "type": {
+            "anyOf": [
+                { "$ref": "#/definitions/simpleTypes" },
+                {
+                    "type": "array",
+                    "items": { "$ref": "#/definitions/simpleTypes" },
+                    "minItems": 1,
+                    "uniqueItems": true
+                }
+            ]
+        },
+        "format": { "type": "string" },
+        "allOf": { "$ref": "#/definitions/schemaArray" },
+        "anyOf": { "$ref": "#/definitions/schemaArray" },
+        "oneOf": { "$ref": "#/definitions/schemaArray" },
+        "not": { "$ref": "#" }
+    },
+    "default": {}
+}
diff --git a/lib/spack/external/_vendoring/jsonschema/schemas/draft7.json b/lib/spack/external/_vendoring/jsonschema/schemas/draft7.json
new file mode 100644
index 0000000000..746cde9690
--- /dev/null
+++ b/lib/spack/external/_vendoring/jsonschema/schemas/draft7.json
@@ -0,0 +1,166 @@
+{
+    "$schema": "http://json-schema.org/draft-07/schema#",
+    "$id": "http://json-schema.org/draft-07/schema#",
+    "title": "Core schema meta-schema",
+    "definitions": {
+        "schemaArray": {
+            "type": "array",
+            "minItems": 1,
+            "items": { "$ref": "#" }
+        },
+        "nonNegativeInteger": {
+            "type": "integer",
+            "minimum": 0
+        },
+        "nonNegativeIntegerDefault0": {
+            "allOf": [
+                { "$ref": "#/definitions/nonNegativeInteger" },
+                { "default": 0 }
+            ]
+        },
+        "simpleTypes": {
+            "enum": [
+                "array",
+                "boolean",
+                "integer",
+                "null",
+                "number",
+                "object",
+                "string"
+            ]
+        },
+        "stringArray": {
+            "type": "array",
+            "items": { "type": "string" },
+            "uniqueItems": true,
+            "default": []
+        }
+    },
+    "type": ["object", "boolean"],
+    "properties": {
+        "$id": {
+            "type": "string",
+            "format": "uri-reference"
+        },
+        "$schema": {
+            "type": "string",
+            "format": "uri"
+        },
+        "$ref": {
+            "type": "string",
+            "format": "uri-reference"
+        },
+        "$comment": {
+            "type": "string"
+        },
+        "title": {
+            "type": "string"
+        },
+        "description": {
+            "type": "string"
+        },
+        "default": true,
+        "readOnly": {
+            "type": "boolean",
+            "default": false
+        },
+        "examples": {
+            "type": "array",
+            "items": true
+        },
+        "multipleOf": {
+            "type": "number",
+            "exclusiveMinimum": 0
+        },
+        "maximum": {
+            "type": "number"
+        },
+        "exclusiveMaximum": {
+            "type": "number"
+        },
+        "minimum": {
+            "type": "number"
+        },
+        "exclusiveMinimum": {
+            "type": "number"
+        },
+        "maxLength": { "$ref": "#/definitions/nonNegativeInteger" },
+        "minLength": { "$ref": "#/definitions/nonNegativeIntegerDefault0" },
+        "pattern": {
+            "type": "string",
+            "format": "regex"
+        },
+        "additionalItems": { "$ref": "#" },
+        "items": {
+            "anyOf": [
+                { "$ref": "#" },
+                { "$ref": "#/definitions/schemaArray" }
+            ],
+            "default": true
+        },
+        "maxItems": { "$ref": "#/definitions/nonNegativeInteger" },
+        "minItems": { "$ref": "#/definitions/nonNegativeIntegerDefault0" },
+        "uniqueItems": {
+            "type": "boolean",
+            "default": false
+        },
+        "contains": { "$ref": "#" },
+        "maxProperties": { "$ref": "#/definitions/nonNegativeInteger" },
+        "minProperties": { "$ref": "#/definitions/nonNegativeIntegerDefault0" },
+        "required": { "$ref": "#/definitions/stringArray" },
+        "additionalProperties": { "$ref": "#" },
+        "definitions": {
+            "type": "object",
+            "additionalProperties": { "$ref": "#" },
+            "default": {}
+        },
+        "properties": {
+            "type": "object",
+            "additionalProperties": { "$ref": "#" },
+            "default": {}
+        },
+        "patternProperties": {
+            "type": "object",
+            "additionalProperties": { "$ref": "#" },
+            "propertyNames": { "format": "regex" },
+            "default": {}
+        },
+        "dependencies": {
+            "type": "object",
+            "additionalProperties": {
+                "anyOf": [
+                    { "$ref": "#" },
+                    { "$ref": "#/definitions/stringArray" }
+                ]
+            }
+        },
+        "propertyNames": { "$ref": "#" },
+        "const": true,
+        "enum": {
+            "type": "array",
+            "items": true
+        },
+        "type": {
+            "anyOf": [
+                { "$ref": "#/definitions/simpleTypes" },
+                {
+                    "type": "array",
+                    "items": { "$ref": "#/definitions/simpleTypes" },
+                    "minItems": 1,
+                    "uniqueItems": true
+                }
+            ]
+        },
+        "format": { "type": "string" },
+        "contentMediaType": { "type": "string" },
+        "contentEncoding": { "type": "string" },
+        "if": {"$ref": "#"},
+        "then": {"$ref": "#"},
+        "else": {"$ref": "#"},
+        "allOf": { "$ref": "#/definitions/schemaArray" },
+        "anyOf": { "$ref": "#/definitions/schemaArray" },
+        "oneOf": { "$ref": "#/definitions/schemaArray" },
+        "not": { "$ref": "#" }
+    },
+    "default": true
+}
diff --git a/lib/spack/external/_vendoring/jsonschema/tests/__init__.py b/lib/spack/external/_vendoring/jsonschema/tests/__init__.py
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/lib/spack/external/_vendoring/jsonschema/tests/__init__.py
diff --git a/lib/spack/external/_vendoring/jsonschema/tests/_helpers.py b/lib/spack/external/_vendoring/jsonschema/tests/_helpers.py
new file mode 100644
index 0000000000..70f291fe2a
--- /dev/null
+++ b/lib/spack/external/_vendoring/jsonschema/tests/_helpers.py
@@ -0,0 +1,5 @@
+def bug(issue=None):
+    message = "A known bug."
+    if issue is not None:
+        message += " See issue #{issue}.".format(issue=issue)
+    return message
diff --git a/lib/spack/external/_vendoring/jsonschema/tests/_suite.py b/lib/spack/external/_vendoring/jsonschema/tests/_suite.py
new file mode 100644
index 0000000000..b68a7b668c
--- /dev/null
+++ b/lib/spack/external/_vendoring/jsonschema/tests/_suite.py
@@ -0,0 +1,239 @@
+"""
+Python representations of the JSON Schema Test Suite tests.
+"""
+
+from functools import partial
+import json
+import os
+import re
+import subprocess
+import sys
+import unittest
+
+from twisted.python.filepath import FilePath
+import attr
+
+from jsonschema.compat import PY3
+from jsonschema.validators import validators
+import jsonschema
+
+
+def _find_suite():
+    root = os.environ.get("JSON_SCHEMA_TEST_SUITE")
+    if root is not None:
+        return FilePath(root)
+
+    root = FilePath(jsonschema.__file__).parent().sibling("json")
+    if not root.isdir():  # pragma: no cover
+        raise ValueError(
+            (
+                "Can't find the JSON-Schema-Test-Suite directory. "
+                "Set the 'JSON_SCHEMA_TEST_SUITE' environment "
+                "variable or run the tests from alongside a checkout "
+                "of the suite."
+            ),
+        )
+    return root
+
+
+@attr.s(hash=True)
+class Suite(object):
+
+    _root = attr.ib(default=attr.Factory(_find_suite))
+
+    def _remotes(self):
+        jsonschema_suite = self._root.descendant(["bin", "jsonschema_suite"])
+        remotes = subprocess.check_output(
+            [sys.executable, jsonschema_suite.path, "remotes"],
+        )
+        return {
+            "http://localhost:1234/" + name: schema
+            for name, schema in json.loads(remotes.decode("utf-8")).items()
+        }
+
+    def benchmark(self, runner):  # pragma: no cover
+        for name in validators:
+            self.version(name=name).benchmark(runner=runner)
+
+    def version(self, name):
+        return Version(
+            name=name,
+            path=self._root.descendant(["tests", name]),
+            remotes=self._remotes(),
+        )
+
+
+@attr.s(hash=True)
+class Version(object):
+
+    _path = attr.ib()
+    _remotes = attr.ib()
+
+    name = attr.ib()
+
+    def benchmark(self, runner, **kwargs):  # pragma: no cover
+        for suite in self.tests():
+            for test in suite:
+                runner.bench_func(
+                    test.fully_qualified_name,
+                    partial(test.validate_ignoring_errors, **kwargs),
+                )
+
+    def tests(self):
+        return (
+            test
+            for child in self._path.globChildren("*.json")
+            for test in self._tests_in(
+                subject=child.basename()[:-5],
+                path=child,
+            )
+        )
+
+    def format_tests(self):
+        path = self._path.descendant(["optional", "format"])
+        return (
+            test
+            for child in path.globChildren("*.json")
+            for test in self._tests_in(
+                subject=child.basename()[:-5],
+                path=child,
+            )
+        )
+
+    def tests_of(self, name):
+        return self._tests_in(
+            subject=name,
+            path=self._path.child(name + ".json"),
+        )
+
+    def optional_tests_of(self, name):
+        return self._tests_in(
+            subject=name,
+            path=self._path.descendant(["optional", name + ".json"]),
+        )
+
+    def to_unittest_testcase(self, *suites, **kwargs):
+        name = kwargs.pop("name", "Test" + self.name.title())
+        methods = {
+            test.method_name: test.to_unittest_method(**kwargs)
+            for suite in suites
+            for tests in suite
+            for test in tests
+        }
+        cls = type(name, (unittest.TestCase,), methods)
+
+        try:
+            cls.__module__ = _someone_save_us_the_module_of_the_caller()
+        except Exception:  # pragma: no cover
+            # We're doing crazy things, so if they go wrong, like a function
+            # behaving differently on some other interpreter, just make them
+            # not happen.
+            pass
+
+        return cls
+
+    def _tests_in(self, subject, path):
+        for each in json.loads(path.getContent().decode("utf-8")):
+            yield (
+                _Test(
+                    version=self,
+                    subject=subject,
+                    case_description=each["description"],
+                    schema=each["schema"],
+                    remotes=self._remotes,
+                    **test
+                ) for test in each["tests"]
+            )
+
+
+@attr.s(hash=True, repr=False)
+class _Test(object):
+
+    version = attr.ib()
+
+    subject = attr.ib()
+    case_description = attr.ib()
+    description = attr.ib()
+
+    data = attr.ib()
+    schema = attr.ib(repr=False)
+
+    valid = attr.ib()
+
+    _remotes = attr.ib()
+
+    def __repr__(self):  # pragma: no cover
+        return "<Test {}>".format(self.fully_qualified_name)
+
+    @property
+    def fully_qualified_name(self):  # pragma: no cover
+        return " > ".join(
+            [
+                self.version.name,
+                self.subject,
+                self.case_description,
+                self.description,
+            ]
+        )
+
+    @property
+    def method_name(self):
+        delimiters = r"[\W\- ]+"
+        name = "test_%s_%s_%s" % (
+            re.sub(delimiters, "_", self.subject),
+            re.sub(delimiters, "_", self.case_description),
+            re.sub(delimiters, "_", self.description),
+        )
+
+        if not PY3:  # pragma: no cover
+            name = name.encode("utf-8")
+        return name
+
+    def to_unittest_method(self, skip=lambda test: None, **kwargs):
+        if self.valid:
+            def fn(this):
+                self.validate(**kwargs)
+        else:
+            def fn(this):
+                with this.assertRaises(jsonschema.ValidationError):
+                    self.validate(**kwargs)
+
+        fn.__name__ = self.method_name
+        reason = skip(self)
+        return unittest.skipIf(reason is not None, reason)(fn)
+
+    def validate(self, Validator, **kwargs):
+        resolver = jsonschema.RefResolver.from_schema(
+            schema=self.schema,
+            store=self._remotes,
+            id_of=Validator.ID_OF,
+        )
+        jsonschema.validate(
+            instance=self.data,
+            schema=self.schema,
+            cls=Validator,
+            resolver=resolver,
+            **kwargs
+        )
+
+    def validate_ignoring_errors(self, Validator):  # pragma: no cover
+        try:
+            self.validate(Validator=Validator)
+        except jsonschema.ValidationError:
+            pass
+
+
+def _someone_save_us_the_module_of_the_caller():
+    """
+    The FQON of the module 2nd stack frames up from here.
+
+    This is intended to allow us to dynamicallly return test case classes that
+    are indistinguishable from being defined in the module that wants them.
+
+    Otherwise, trial will mis-print the FQON, and copy pasting it won't re-run
+    the class that really is running.
+
+    Save us all, this is all so so so so so terrible.
+    """
+
+    return sys._getframe(2).f_globals["__name__"]
diff --git a/lib/spack/external/_vendoring/jsonschema/tests/test_cli.py b/lib/spack/external/_vendoring/jsonschema/tests/test_cli.py
new file mode 100644
index 0000000000..ed820ba3f8
--- /dev/null
+++ b/lib/spack/external/_vendoring/jsonschema/tests/test_cli.py
@@ -0,0 +1,151 @@
+from unittest import TestCase
+import json
+import subprocess
+import sys
+
+from jsonschema import Draft4Validator, ValidationError, cli, __version__
+from jsonschema.compat import NativeIO
+from jsonschema.exceptions import SchemaError
+
+
+def fake_validator(*errors):
+    errors = list(reversed(errors))
+
+    class FakeValidator(object):
+        def __init__(self, *args, **kwargs):
+            pass
+
+        def iter_errors(self, instance):
+            if errors:
+                return errors.pop()
+            return []
+
+        def check_schema(self, schema):
+            pass
+
+    return FakeValidator
+
+
+class TestParser(TestCase):
+
+    FakeValidator = fake_validator()
+    instance_file = "foo.json"
+    schema_file = "schema.json"
+
+    def setUp(self):
+        cli.open = self.fake_open
+        self.addCleanup(delattr, cli, "open")
+
+    def fake_open(self, path):
+        if path == self.instance_file:
+            contents = ""
+        elif path == self.schema_file:
+            contents = {}
+        else:  # pragma: no cover
+            self.fail("What is {!r}".format(path))
+        return NativeIO(json.dumps(contents))
+
+    def test_find_validator_by_fully_qualified_object_name(self):
+        arguments = cli.parse_args(
+            [
+                "--validator",
+                "jsonschema.tests.test_cli.TestParser.FakeValidator",
+                "--instance", self.instance_file,
+                self.schema_file,
+            ]
+        )
+        self.assertIs(arguments["validator"], self.FakeValidator)
+
+    def test_find_validator_in_jsonschema(self):
+        arguments = cli.parse_args(
+            [
+                "--validator", "Draft4Validator",
+                "--instance", self.instance_file,
+                self.schema_file,
+            ]
+        )
+        self.assertIs(arguments["validator"], Draft4Validator)
+
+
+class TestCLI(TestCase):
+    def test_draft3_schema_draft4_validator(self):
+        stdout, stderr = NativeIO(), NativeIO()
+        with self.assertRaises(SchemaError):
+            cli.run(
+                {
+                    "validator": Draft4Validator,
+                    "schema": {
+                        "anyOf": [
+                            {"minimum": 20},
+                            {"type": "string"},
+                            {"required": True},
+                        ],
+                    },
+                    "instances": [1],
+                    "error_format": "{error.message}",
+                },
+                stdout=stdout,
+                stderr=stderr,
+            )
+
+    def test_successful_validation(self):
+        stdout, stderr = NativeIO(), NativeIO()
+        exit_code = cli.run(
+            {
+                "validator": fake_validator(),
+                "schema": {},
+                "instances": [1],
+                "error_format": "{error.message}",
+            },
+            stdout=stdout,
+            stderr=stderr,
+        )
+        self.assertFalse(stdout.getvalue())
+        self.assertFalse(stderr.getvalue())
+        self.assertEqual(exit_code, 0)
+
+    def test_unsuccessful_validation(self):
+        error = ValidationError("I am an error!", instance=1)
+        stdout, stderr = NativeIO(), NativeIO()
+        exit_code = cli.run(
+            {
+                "validator": fake_validator([error]),
+                "schema": {},
+                "instances": [1],
+                "error_format": "{error.instance} - {error.message}",
+            },
+            stdout=stdout,
+            stderr=stderr,
+        )
+        self.assertFalse(stdout.getvalue())
+        self.assertEqual(stderr.getvalue(), "1 - I am an error!")
+        self.assertEqual(exit_code, 1)
+
+    def test_unsuccessful_validation_multiple_instances(self):
+        first_errors = [
+            ValidationError("9", instance=1),
+            ValidationError("8", instance=1),
+        ]
+        second_errors = [ValidationError("7", instance=2)]
+        stdout, stderr = NativeIO(), NativeIO()
+        exit_code = cli.run(
+            {
+                "validator": fake_validator(first_errors, second_errors),
+                "schema": {},
+                "instances": [1, 2],
+                "error_format": "{error.instance} - {error.message}\t",
+            },
+            stdout=stdout,
+            stderr=stderr,
+        )
+        self.assertFalse(stdout.getvalue())
+        self.assertEqual(stderr.getvalue(), "1 - 9\t1 - 8\t2 - 7\t")
+        self.assertEqual(exit_code, 1)
+
+    def test_version(self):
+        version = subprocess.check_output(
+            [sys.executable, "-m", "jsonschema", "--version"],
+            stderr=subprocess.STDOUT,
+        )
+        version = version.decode("utf-8").strip()
+        self.assertEqual(version, __version__)
diff --git a/lib/spack/external/_vendoring/jsonschema/tests/test_exceptions.py b/lib/spack/external/_vendoring/jsonschema/tests/test_exceptions.py
new file mode 100644
index 0000000000..eae00d76d7
--- /dev/null
+++ b/lib/spack/external/_vendoring/jsonschema/tests/test_exceptions.py
@@ -0,0 +1,462 @@
+from unittest import TestCase
+import textwrap
+
+from jsonschema import Draft4Validator, exceptions
+from jsonschema.compat import PY3
+
+
+class TestBestMatch(TestCase):
+    def best_match(self, errors):
+        errors = list(errors)
+        best = exceptions.best_match(errors)
+        reversed_best = exceptions.best_match(reversed(errors))
+        msg = "Didn't return a consistent best match!\nGot: {0}\n\nThen: {1}"
+        self.assertEqual(
+            best._contents(), reversed_best._contents(),
+            msg=msg.format(best, reversed_best),
+        )
+        return best
+
+    def test_shallower_errors_are_better_matches(self):
+        validator = Draft4Validator(
+            {
+                "properties": {
+                    "foo": {
+                        "minProperties": 2,
+                        "properties": {"bar": {"type": "object"}},
+                    },
+                },
+            },
+        )
+        best = self.best_match(validator.iter_errors({"foo": {"bar": []}}))
+        self.assertEqual(best.validator, "minProperties")
+
+    def test_oneOf_and_anyOf_are_weak_matches(self):
+        """
+        A property you *must* match is probably better than one you have to
+        match a part of.
+        """
+
+        validator = Draft4Validator(
+            {
+                "minProperties": 2,
+                "anyOf": [{"type": "string"}, {"type": "number"}],
+                "oneOf": [{"type": "string"}, {"type": "number"}],
+            }
+        )
+        best = self.best_match(validator.iter_errors({}))
+        self.assertEqual(best.validator, "minProperties")
+
+    def test_if_the_most_relevant_error_is_anyOf_it_is_traversed(self):
+        """
+        If the most relevant error is an anyOf, then we traverse its context
+        and select the otherwise *least* relevant error, since in this case
+        that means the most specific, deep, error inside the instance.
+
+        I.e. since only one of the schemas must match, we look for the most
+        relevant one.
+        """
+
+        validator = Draft4Validator(
+            {
+                "properties": {
+                    "foo": {
+                        "anyOf": [
+                            {"type": "string"},
+                            {"properties": {"bar": {"type": "array"}}},
+                        ],
+                    },
+                },
+            },
+        )
+        best = self.best_match(validator.iter_errors({"foo": {"bar": 12}}))
+        self.assertEqual(best.validator_value, "array")
+
+    def test_if_the_most_relevant_error_is_oneOf_it_is_traversed(self):
+        """
+        If the most relevant error is an oneOf, then we traverse its context
+        and select the otherwise *least* relevant error, since in this case
+        that means the most specific, deep, error inside the instance.
+
+        I.e. since only one of the schemas must match, we look for the most
+        relevant one.
+        """
+
+        validator = Draft4Validator(
+            {
+                "properties": {
+                    "foo": {
+                        "oneOf": [
+                            {"type": "string"},
+                            {"properties": {"bar": {"type": "array"}}},
+                        ],
+                    },
+                },
+            },
+        )
+        best = self.best_match(validator.iter_errors({"foo": {"bar": 12}}))
+        self.assertEqual(best.validator_value, "array")
+
+    def test_if_the_most_relevant_error_is_allOf_it_is_traversed(self):
+        """
+        Now, if the error is allOf, we traverse but select the *most* relevant
+        error from the context, because all schemas here must match anyways.
+        """
+
+        validator = Draft4Validator(
+            {
+                "properties": {
+                    "foo": {
+                        "allOf": [
+                            {"type": "string"},
+                            {"properties": {"bar": {"type": "array"}}},
+                        ],
+                    },
+                },
+            },
+        )
+        best = self.best_match(validator.iter_errors({"foo": {"bar": 12}}))
+        self.assertEqual(best.validator_value, "string")
+
+    def test_nested_context_for_oneOf(self):
+        validator = Draft4Validator(
+            {
+                "properties": {
+                    "foo": {
+                        "oneOf": [
+                            {"type": "string"},
+                            {
+                                "oneOf": [
+                                    {"type": "string"},
+                                    {
+                                        "properties": {
+                                            "bar": {"type": "array"},
+                                        },
+                                    },
+                                ],
+                            },
+                        ],
+                    },
+                },
+            },
+        )
+        best = self.best_match(validator.iter_errors({"foo": {"bar": 12}}))
+        self.assertEqual(best.validator_value, "array")
+
+    def test_one_error(self):
+        validator = Draft4Validator({"minProperties": 2})
+        error, = validator.iter_errors({})
+        self.assertEqual(
+            exceptions.best_match(validator.iter_errors({})).validator,
+            "minProperties",
+        )
+
+    def test_no_errors(self):
+        validator = Draft4Validator({})
+        self.assertIsNone(exceptions.best_match(validator.iter_errors({})))
+
+
+class TestByRelevance(TestCase):
+    def test_short_paths_are_better_matches(self):
+        shallow = exceptions.ValidationError("Oh no!", path=["baz"])
+        deep = exceptions.ValidationError("Oh yes!", path=["foo", "bar"])
+        match = max([shallow, deep], key=exceptions.relevance)
+        self.assertIs(match, shallow)
+
+        match = max([deep, shallow], key=exceptions.relevance)
+        self.assertIs(match, shallow)
+
+    def test_global_errors_are_even_better_matches(self):
+        shallow = exceptions.ValidationError("Oh no!", path=[])
+        deep = exceptions.ValidationError("Oh yes!", path=["foo"])
+
+        errors = sorted([shallow, deep], key=exceptions.relevance)
+        self.assertEqual(
+            [list(error.path) for error in errors],
+            [["foo"], []],
+        )
+
+        errors = sorted([deep, shallow], key=exceptions.relevance)
+        self.assertEqual(
+            [list(error.path) for error in errors],
+            [["foo"], []],
+        )
+
+    def test_weak_validators_are_lower_priority(self):
+        weak = exceptions.ValidationError("Oh no!", path=[], validator="a")
+        normal = exceptions.ValidationError("Oh yes!", path=[], validator="b")
+
+        best_match = exceptions.by_relevance(weak="a")
+
+        match = max([weak, normal], key=best_match)
+        self.assertIs(match, normal)
+
+        match = max([normal, weak], key=best_match)
+        self.assertIs(match, normal)
+
+    def test_strong_validators_are_higher_priority(self):
+        weak = exceptions.ValidationError("Oh no!", path=[], validator="a")
+        normal = exceptions.ValidationError("Oh yes!", path=[], validator="b")
+        strong = exceptions.ValidationError("Oh fine!", path=[], validator="c")
+
+        best_match = exceptions.by_relevance(weak="a", strong="c")
+
+        match = max([weak, normal, strong], key=best_match)
+        self.assertIs(match, strong)
+
+        match = max([strong, normal, weak], key=best_match)
+        self.assertIs(match, strong)
+
+
+class TestErrorTree(TestCase):
+    def test_it_knows_how_many_total_errors_it_contains(self):
+        # FIXME: https://github.com/Julian/jsonschema/issues/442
+        errors = [
+            exceptions.ValidationError("Something", validator=i)
+            for i in range(8)
+        ]
+        tree = exceptions.ErrorTree(errors)
+        self.assertEqual(tree.total_errors, 8)
+
+    def test_it_contains_an_item_if_the_item_had_an_error(self):
+        errors = [exceptions.ValidationError("a message", path=["bar"])]
+        tree = exceptions.ErrorTree(errors)
+        self.assertIn("bar", tree)
+
+    def test_it_does_not_contain_an_item_if_the_item_had_no_error(self):
+        errors = [exceptions.ValidationError("a message", path=["bar"])]
+        tree = exceptions.ErrorTree(errors)
+        self.assertNotIn("foo", tree)
+
+    def test_validators_that_failed_appear_in_errors_dict(self):
+        error = exceptions.ValidationError("a message", validator="foo")
+        tree = exceptions.ErrorTree([error])
+        self.assertEqual(tree.errors, {"foo": error})
+
+    def test_it_creates_a_child_tree_for_each_nested_path(self):
+        errors = [
+            exceptions.ValidationError("a bar message", path=["bar"]),
+            exceptions.ValidationError("a bar -> 0 message", path=["bar", 0]),
+        ]
+        tree = exceptions.ErrorTree(errors)
+        self.assertIn(0, tree["bar"])
+        self.assertNotIn(1, tree["bar"])
+
+    def test_children_have_their_errors_dicts_built(self):
+        e1, e2 = (
+            exceptions.ValidationError("1", validator="foo", path=["bar", 0]),
+            exceptions.ValidationError("2", validator="quux", path=["bar", 0]),
+        )
+        tree = exceptions.ErrorTree([e1, e2])
+        self.assertEqual(tree["bar"][0].errors, {"foo": e1, "quux": e2})
+
+    def test_multiple_errors_with_instance(self):
+        e1, e2 = (
+            exceptions.ValidationError(
+                "1",
+                validator="foo",
+                path=["bar", "bar2"],
+                instance="i1"),
+            exceptions.ValidationError(
+                "2",
+                validator="quux",
+                path=["foobar", 2],
+                instance="i2"),
+        )
+        exceptions.ErrorTree([e1, e2])
+
+    def test_it_does_not_contain_subtrees_that_are_not_in_the_instance(self):
+        error = exceptions.ValidationError("123", validator="foo", instance=[])
+        tree = exceptions.ErrorTree([error])
+
+        with self.assertRaises(IndexError):
+            tree[0]
+
+    def test_if_its_in_the_tree_anyhow_it_does_not_raise_an_error(self):
+        """
+        If a validator is dumb (like :validator:`required` in draft 3) and
+        refers to a path that isn't in the instance, the tree still properly
+        returns a subtree for that path.
+        """
+
+        error = exceptions.ValidationError(
+            "a message", validator="foo", instance={}, path=["foo"],
+        )
+        tree = exceptions.ErrorTree([error])
+        self.assertIsInstance(tree["foo"], exceptions.ErrorTree)
+
+
+class TestErrorInitReprStr(TestCase):
+    def make_error(self, **kwargs):
+        defaults = dict(
+            message=u"hello",
+            validator=u"type",
+            validator_value=u"string",
+            instance=5,
+            schema={u"type": u"string"},
+        )
+        defaults.update(kwargs)
+        return exceptions.ValidationError(**defaults)
+
+    def assertShows(self, expected, **kwargs):
+        if PY3:  # pragma: no cover
+            expected = expected.replace("u'", "'")
+        expected = textwrap.dedent(expected).rstrip("\n")
+
+        error = self.make_error(**kwargs)
+        message_line, _, rest = str(error).partition("\n")
+        self.assertEqual(message_line, error.message)
+        self.assertEqual(rest, expected)
+
+    def test_it_calls_super_and_sets_args(self):
+        error = self.make_error()
+        self.assertGreater(len(error.args), 1)
+
+    def test_repr(self):
+        self.assertEqual(
+            repr(exceptions.ValidationError(message="Hello!")),
+            "<ValidationError: %r>" % "Hello!",
+        )
+
+    def test_unset_error(self):
+        error = exceptions.ValidationError("message")
+        self.assertEqual(str(error), "message")
+
+        kwargs = {
+            "validator": "type",
+            "validator_value": "string",
+            "instance": 5,
+            "schema": {"type": "string"},
+        }
+        # Just the message should show if any of the attributes are unset
+        for attr in kwargs:
+            k = dict(kwargs)
+            del k[attr]
+            error = exceptions.ValidationError("message", **k)
+            self.assertEqual(str(error), "message")
+
+    def test_empty_paths(self):
+        self.assertShows(
+            """
+            Failed validating u'type' in schema:
+                {u'type': u'string'}
+
+            On instance:
+                5
+            """,
+            path=[],
+            schema_path=[],
+        )
+
+    def test_one_item_paths(self):
+        self.assertShows(
+            """
+            Failed validating u'type' in schema:
+                {u'type': u'string'}
+
+            On instance[0]:
+                5
+            """,
+            path=[0],
+            schema_path=["items"],
+        )
+
+    def test_multiple_item_paths(self):
+        self.assertShows(
+            """
+            Failed validating u'type' in schema[u'items'][0]:
+                {u'type': u'string'}
+
+            On instance[0][u'a']:
+                5
+            """,
+            path=[0, u"a"],
+            schema_path=[u"items", 0, 1],
+        )
+
+    def test_uses_pprint(self):
+        self.assertShows(
+            """
+            Failed validating u'maxLength' in schema:
+                {0: 0,
+                 1: 1,
+                 2: 2,
+                 3: 3,
+                 4: 4,
+                 5: 5,
+                 6: 6,
+                 7: 7,
+                 8: 8,
+                 9: 9,
+                 10: 10,
+                 11: 11,
+                 12: 12,
+                 13: 13,
+                 14: 14,
+                 15: 15,
+                 16: 16,
+                 17: 17,
+                 18: 18,
+                 19: 19}
+
+            On instance:
+                [0,
+                 1,
+                 2,
+                 3,
+                 4,
+                 5,
+                 6,
+                 7,
+                 8,
+                 9,
+                 10,
+                 11,
+                 12,
+                 13,
+                 14,
+                 15,
+                 16,
+                 17,
+                 18,
+                 19,
+                 20,
+                 21,
+                 22,
+                 23,
+                 24]
+            """,
+            instance=list(range(25)),
+            schema=dict(zip(range(20), range(20))),
+            validator=u"maxLength",
+        )
+
+    def test_str_works_with_instances_having_overriden_eq_operator(self):
+        """
+        Check for https://github.com/Julian/jsonschema/issues/164 which
+        rendered exceptions unusable when a `ValidationError` involved
+        instances with an `__eq__` method that returned truthy values.
+        """
+
+        class DontEQMeBro(object):
+            def __eq__(this, other):  # pragma: no cover
+                self.fail("Don't!")
+
+            def __ne__(this, other):  # pragma: no cover
+                self.fail("Don't!")
+
+        instance = DontEQMeBro()
+        error = exceptions.ValidationError(
+            "a message",
+            validator="foo",
+            instance=instance,
+            validator_value="some",
+            schema="schema",
+        )
+        self.assertIn(repr(instance), str(error))
+
+
+class TestHashable(TestCase):
+    def test_hashable(self):
+        set([exceptions.ValidationError("")])
+        set([exceptions.SchemaError("")])
diff --git a/lib/spack/external/_vendoring/jsonschema/tests/test_format.py b/lib/spack/external/_vendoring/jsonschema/tests/test_format.py
new file mode 100644
index 0000000000..254985f615
--- /dev/null
+++ b/lib/spack/external/_vendoring/jsonschema/tests/test_format.py
@@ -0,0 +1,89 @@
+"""
+Tests for the parts of jsonschema related to the :validator:`format` property.
+"""
+
+from unittest import TestCase
+
+from jsonschema import FormatError, ValidationError, FormatChecker
+from jsonschema.validators import Draft4Validator
+
+
+BOOM = ValueError("Boom!")
+BANG = ZeroDivisionError("Bang!")
+
+
+def boom(thing):
+    if thing == "bang":
+        raise BANG
+    raise BOOM
+
+
+class TestFormatChecker(TestCase):
+    def test_it_can_validate_no_formats(self):
+        checker = FormatChecker(formats=())
+        self.assertFalse(checker.checkers)
+
+    def test_it_raises_a_key_error_for_unknown_formats(self):
+        with self.assertRaises(KeyError):
+            FormatChecker(formats=["o noes"])
+
+    def test_it_can_register_cls_checkers(self):
+        original = dict(FormatChecker.checkers)
+        self.addCleanup(FormatChecker.checkers.pop, "boom")
+        FormatChecker.cls_checks("boom")(boom)
+        self.assertEqual(
+            FormatChecker.checkers,
+            dict(original, boom=(boom, ())),
+        )
+
+    def test_it_can_register_checkers(self):
+        checker = FormatChecker()
+        checker.checks("boom")(boom)
+        self.assertEqual(
+            checker.checkers,
+            dict(FormatChecker.checkers, boom=(boom, ()))
+        )
+
+    def test_it_catches_registered_errors(self):
+        checker = FormatChecker()
+        checker.checks("boom", raises=type(BOOM))(boom)
+
+        with self.assertRaises(FormatError) as cm:
+            checker.check(instance=12, format="boom")
+
+        self.assertIs(cm.exception.cause, BOOM)
+        self.assertIs(cm.exception.__cause__, BOOM)
+
+        # Unregistered errors should not be caught
+        with self.assertRaises(type(BANG)):
+            checker.check(instance="bang", format="boom")
+
+    def test_format_error_causes_become_validation_error_causes(self):
+        checker = FormatChecker()
+        checker.checks("boom", raises=ValueError)(boom)
+        validator = Draft4Validator({"format": "boom"}, format_checker=checker)
+
+        with self.assertRaises(ValidationError) as cm:
+            validator.validate("BOOM")
+
+        self.assertIs(cm.exception.cause, BOOM)
+        self.assertIs(cm.exception.__cause__, BOOM)
+
+    def test_format_checkers_come_with_defaults(self):
+        # This is bad :/ but relied upon.
+        # The docs for quite awhile recommended people do things like
+        # validate(..., format_checker=FormatChecker())
+        # We should change that, but we can't without deprecation...
+        checker = FormatChecker()
+        with self.assertRaises(FormatError):
+            checker.check(instance="not-an-ipv4", format="ipv4")
+
+    def test_repr(self):
+        checker = FormatChecker(formats=())
+        checker.checks("foo")(lambda thing: True)
+        checker.checks("bar")(lambda thing: True)
+        checker.checks("baz")(lambda thing: True)
+        self.assertEqual(
+            repr(checker),
+            "<FormatChecker checkers=['bar', 'baz', 'foo']>",
+        )
diff --git a/lib/spack/external/_vendoring/jsonschema/tests/test_jsonschema_test_suite.py b/lib/spack/external/_vendoring/jsonschema/tests/test_jsonschema_test_suite.py
new file mode 100644
index 0000000000..ebccf29735
--- /dev/null
+++ b/lib/spack/external/_vendoring/jsonschema/tests/test_jsonschema_test_suite.py
@@ -0,0 +1,277 @@
+"""
+Test runner for the JSON Schema official test suite
+
+Tests comprehensive correctness of each draft's validator.
+
+See https://github.com/json-schema-org/JSON-Schema-Test-Suite for details.
+"""
+
+import sys
+import warnings
+
+from jsonschema import (
+    Draft3Validator,
+    Draft4Validator,
+    Draft6Validator,
+    Draft7Validator,
+    draft3_format_checker,
+    draft4_format_checker,
+    draft6_format_checker,
+    draft7_format_checker,
+)
+from jsonschema.tests._helpers import bug
+from jsonschema.tests._suite import Suite
+from jsonschema.validators import _DEPRECATED_DEFAULT_TYPES, create
+
+
+SUITE = Suite()
+DRAFT3 = SUITE.version(name="draft3")
+DRAFT4 = SUITE.version(name="draft4")
+DRAFT6 = SUITE.version(name="draft6")
+DRAFT7 = SUITE.version(name="draft7")
+
+
+def skip(message, **kwargs):
+    def skipper(test):
+        if all(value == getattr(test, attr) for attr, value in kwargs.items()):
+            return message
+    return skipper
+
+
+def missing_format(checker):
+    def missing_format(test):
+        schema = test.schema
+        if schema is True or schema is False or "format" not in schema:
+            return
+
+        if schema["format"] not in checker.checkers:
+            return "Format checker {0!r} not found.".format(schema["format"])
+    return missing_format
+
+
+is_narrow_build = sys.maxunicode == 2 ** 16 - 1
+if is_narrow_build:  # pragma: no cover
+    message = "Not running surrogate Unicode case, this Python is narrow."
+
+    def narrow_unicode_build(test):  # pragma: no cover
+        return skip(
+            message=message,
+            description="one supplementary Unicode code point is not long enough",
+        )(test) or skip(
+            message=message,
+            description="two supplementary Unicode code points is long enough",
+        )(test)
+else:
+    def narrow_unicode_build(test):  # pragma: no cover
+        return
+
+
+TestDraft3 = DRAFT3.to_unittest_testcase(
+    DRAFT3.tests(),
+    DRAFT3.optional_tests_of(name="bignum"),
+    DRAFT3.optional_tests_of(name="format"),
+    DRAFT3.optional_tests_of(name="zeroTerminatedFloats"),
+    Validator=Draft3Validator,
+    format_checker=draft3_format_checker,
+    skip=lambda test: (
+        narrow_unicode_build(test)
+        or missing_format(draft3_format_checker)(test)
+        or skip(
+            message="Upstream bug in strict_rfc3339",
+            subject="format",
+            description="case-insensitive T and Z",
+        )(test)
+    ),
+)
+
+
+TestDraft4 = DRAFT4.to_unittest_testcase(
+    DRAFT4.tests(),
+    DRAFT4.optional_tests_of(name="bignum"),
+    DRAFT4.optional_tests_of(name="format"),
+    DRAFT4.optional_tests_of(name="zeroTerminatedFloats"),
+    Validator=Draft4Validator,
+    format_checker=draft4_format_checker,
+    skip=lambda test: (
+        narrow_unicode_build(test)
+        or missing_format(draft4_format_checker)(test)
+        or skip(
+            message=bug(),
+            subject="ref",
+            case_description="Recursive references between schemas",
+        )(test)
+        or skip(
+            message=bug(371),
+            subject="ref",
+            case_description="Location-independent identifier",
+        )(test)
+        or skip(
+            message=bug(371),
+            subject="ref",
+            case_description=(
+                "Location-independent identifier with absolute URI"
+            ),
+        )(test)
+        or skip(
+            message=bug(371),
+            subject="ref",
+            case_description=(
+                "Location-independent identifier with base URI change in subschema"
+            ),
+        )(test)
+        or skip(
+            message=bug(),
+            subject="refRemote",
+            case_description="base URI change - change folder in subschema",
+        )(test)
+        or skip(
+            message="Upstream bug in strict_rfc3339",
+            subject="format",
+            description="case-insensitive T and Z",
+        )(test)
+    ),
+)
+
+
+TestDraft6 = DRAFT6.to_unittest_testcase(
+    DRAFT6.tests(),
+    DRAFT6.optional_tests_of(name="bignum"),
+    DRAFT6.optional_tests_of(name="format"),
+    DRAFT6.optional_tests_of(name="zeroTerminatedFloats"),
+    Validator=Draft6Validator,
+    format_checker=draft6_format_checker,
+    skip=lambda test: (
+        narrow_unicode_build(test)
+        or missing_format(draft6_format_checker)(test)
+        or skip(
+            message=bug(),
+            subject="ref",
+            case_description="Recursive references between schemas",
+        )(test)
+        or skip(
+            message=bug(371),
+            subject="ref",
+            case_description="Location-independent identifier",
+        )(test)
+        or skip(
+            message=bug(371),
+            subject="ref",
+            case_description=(
+                "Location-independent identifier with absolute URI"
+            ),
+        )(test)
+        or skip(
+            message=bug(371),
+            subject="ref",
+            case_description=(
+                "Location-independent identifier with base URI change in subschema"
+            ),
+        )(test)
+        or skip(
+            message=bug(),
+            subject="refRemote",
+            case_description="base URI change - change folder in subschema",
+        )(test)
+        or skip(
+            message="Upstream bug in strict_rfc3339",
+            subject="format",
+            description="case-insensitive T and Z",
+        )(test)
+    ),
+)
+
+
+TestDraft7 = DRAFT7.to_unittest_testcase(
+    DRAFT7.tests(),
+    DRAFT7.format_tests(),
+    DRAFT7.optional_tests_of(name="bignum"),
+    DRAFT7.optional_tests_of(name="content"),
+    DRAFT7.optional_tests_of(name="zeroTerminatedFloats"),
+    Validator=Draft7Validator,
+    format_checker=draft7_format_checker,
+    skip=lambda test: (
+        narrow_unicode_build(test)
+        or missing_format(draft7_format_checker)(test)
+        or skip(
+            message=bug(),
+            subject="ref",
+            case_description="Recursive references between schemas",
+        )(test)
+        or skip(
+            message=bug(371),
+            subject="ref",
+            case_description="Location-independent identifier",
+        )(test)
+        or skip(
+            message=bug(371),
+            subject="ref",
+            case_description=(
+                "Location-independent identifier with absolute URI"
+            ),
+        )(test)
+        or skip(
+            message=bug(371),
+            subject="ref",
+            case_description=(
+                "Location-independent identifier with base URI change in subschema"
+            ),
+        )(test)
+        or skip(
+            message=bug(),
+            subject="refRemote",
+            case_description="base URI change - change folder in subschema",
+        )(test)
+        or skip(
+            message="Upstream bug in strict_rfc3339",
+            subject="date-time",
+            description="case-insensitive T and Z",
+        )(test)
+        or skip(
+            message=bug(593),
+            subject="content",
+            case_description=(
+                "validation of string-encoded content based on media type"
+            ),
+        )(test)
+        or skip(
+            message=bug(593),
+            subject="content",
+            case_description="validation of binary string-encoding",
+        )(test)
+        or skip(
+            message=bug(593),
+            subject="content",
+            case_description=(
+                "validation of binary-encoded media type documents"
+            ),
+        )(test)
+    ),
+)
+
+
+with warnings.catch_warnings():
+    warnings.simplefilter("ignore", DeprecationWarning)
+
+    TestDraft3LegacyTypeCheck = DRAFT3.to_unittest_testcase(
+        # Interestingly the any part couldn't really be done w/the old API.
+        (
+            (test for test in each if test.schema != {"type": "any"})
+            for each in DRAFT3.tests_of(name="type")
+        ),
+        name="TestDraft3LegacyTypeCheck",
+        Validator=create(
+            meta_schema=Draft3Validator.META_SCHEMA,
+            validators=Draft3Validator.VALIDATORS,
+            default_types=_DEPRECATED_DEFAULT_TYPES,
+        ),
+    )
+
+    TestDraft4LegacyTypeCheck = DRAFT4.to_unittest_testcase(
+        DRAFT4.tests_of(name="type"),
+        name="TestDraft4LegacyTypeCheck",
+        Validator=create(
+            meta_schema=Draft4Validator.META_SCHEMA,
+            validators=Draft4Validator.VALIDATORS,
+            default_types=_DEPRECATED_DEFAULT_TYPES,
+        ),
+    )
diff --git a/lib/spack/external/_vendoring/jsonschema/tests/test_types.py b/lib/spack/external/_vendoring/jsonschema/tests/test_types.py
new file mode 100644
index 0000000000..2280cc395b
--- /dev/null
+++ b/lib/spack/external/_vendoring/jsonschema/tests/test_types.py
@@ -0,0 +1,190 @@
+"""
+Tests on the new type interface. The actual correctness of the type checking
+is handled in test_jsonschema_test_suite; these tests check that TypeChecker
+functions correctly and can facilitate extensions to type checking
+"""
+from collections import namedtuple
+from unittest import TestCase
+
+from jsonschema import ValidationError, _validators
+from jsonschema._types import TypeChecker
+from jsonschema.exceptions import UndefinedTypeCheck
+from jsonschema.validators import Draft4Validator, extend
+
+
+def equals_2(checker, instance):
+    return instance == 2
+
+
+def is_namedtuple(instance):
+    return isinstance(instance, tuple) and getattr(instance, "_fields", None)
+
+
+def is_object_or_named_tuple(checker, instance):
+    if Draft4Validator.TYPE_CHECKER.is_type(instance, "object"):
+        return True
+    return is_namedtuple(instance)
+
+
+def coerce_named_tuple(fn):
+    def coerced(validator, value, instance, schema):
+        if is_namedtuple(instance):
+            instance = instance._asdict()
+        return fn(validator, value, instance, schema)
+    return coerced
+
+
+required = coerce_named_tuple(_validators.required)
+properties = coerce_named_tuple(_validators.properties)
+
+
+class TestTypeChecker(TestCase):
+    def test_is_type(self):
+        checker = TypeChecker({"two": equals_2})
+        self.assertEqual(
+            (
+                checker.is_type(instance=2, type="two"),
+                checker.is_type(instance="bar", type="two"),
+            ),
+            (True, False),
+        )
+
+    def test_is_unknown_type(self):
+        with self.assertRaises(UndefinedTypeCheck) as context:
+            TypeChecker().is_type(4, "foobar")
+        self.assertIn("foobar", str(context.exception))
+
+    def test_checks_can_be_added_at_init(self):
+        checker = TypeChecker({"two": equals_2})
+        self.assertEqual(checker, TypeChecker().redefine("two", equals_2))
+
+    def test_redefine_existing_type(self):
+        self.assertEqual(
+            TypeChecker().redefine("two", object()).redefine("two", equals_2),
+            TypeChecker().redefine("two", equals_2),
+        )
+
+    def test_remove(self):
+        self.assertEqual(
+            TypeChecker({"two": equals_2}).remove("two"),
+            TypeChecker(),
+        )
+
+    def test_remove_unknown_type(self):
+        with self.assertRaises(UndefinedTypeCheck) as context:
+            TypeChecker().remove("foobar")
+        self.assertIn("foobar", str(context.exception))
+
+    def test_redefine_many(self):
+        self.assertEqual(
+            TypeChecker().redefine_many({"foo": int, "bar": str}),
+            TypeChecker().redefine("foo", int).redefine("bar", str),
+        )
+
+    def test_remove_multiple(self):
+        self.assertEqual(
+            TypeChecker({"foo": int, "bar": str}).remove("foo", "bar"),
+            TypeChecker(),
+        )
+
+    def test_type_check_can_raise_key_error(self):
+        """
+        Make sure no one writes:
+
+            try:
+                self._type_checkers[type](...)
+            except KeyError:
+
+        ignoring the fact that the function itself can raise that.
+        """
+
+        error = KeyError("Stuff")
+
+        def raises_keyerror(checker, instance):
+            raise error
+
+        with self.assertRaises(KeyError) as context:
+            TypeChecker({"foo": raises_keyerror}).is_type(4, "foo")
+
+        self.assertIs(context.exception, error)
+
+
+class TestCustomTypes(TestCase):
+    def test_simple_type_can_be_extended(self):
+        def int_or_str_int(checker, instance):
+            if not isinstance(instance, (int, str)):
+                return False
+            try:
+                int(instance)
+            except ValueError:
+                return False
+            return True
+
+        CustomValidator = extend(
+            Draft4Validator,
+            type_checker=Draft4Validator.TYPE_CHECKER.redefine(
+                "integer", int_or_str_int,
+            ),
+        )
+        validator = CustomValidator({"type": "integer"})
+
+        validator.validate(4)
+        validator.validate("4")
+
+        with self.assertRaises(ValidationError):
+            validator.validate(4.4)
+
+    def test_object_can_be_extended(self):
+        schema = {"type": "object"}
+
+        Point = namedtuple("Point", ["x", "y"])
+
+        type_checker = Draft4Validator.TYPE_CHECKER.redefine(
+            u"object", is_object_or_named_tuple,
+        )
+
+        CustomValidator = extend(Draft4Validator, type_checker=type_checker)
+        validator = CustomValidator(schema)
+
+        validator.validate(Point(x=4, y=5))
+
+    def test_object_extensions_require_custom_validators(self):
+        schema = {"type": "object", "required": ["x"]}
+
+        type_checker = Draft4Validator.TYPE_CHECKER.redefine(
+            u"object", is_object_or_named_tuple,
+        )
+
+        CustomValidator = extend(Draft4Validator, type_checker=type_checker)
+        validator = CustomValidator(schema)
+
+        Point = namedtuple("Point", ["x", "y"])
+        # Cannot handle required
+        with self.assertRaises(ValidationError):
+            validator.validate(Point(x=4, y=5))
+
+    def test_object_extensions_can_handle_custom_validators(self):
+        schema = {
+            "type": "object",
+            "required": ["x"],
+            "properties": {"x": {"type": "integer"}},
+        }
+
+        type_checker = Draft4Validator.TYPE_CHECKER.redefine(
+            u"object", is_object_or_named_tuple,
+        )
+
+        CustomValidator = extend(
+            Draft4Validator,
+            type_checker=type_checker,
+            validators={"required": required, "properties": properties},
+        )
+
+        validator = CustomValidator(schema)
+
+        Point = namedtuple("Point", ["x", "y"])
+        # Can now process required and properties
+        validator.validate(Point(x=4, y=5))
+
+        with self.assertRaises(ValidationError):
+            validator.validate(Point(x="not an integer", y=5))
diff --git a/lib/spack/external/_vendoring/jsonschema/tests/test_validators.py b/lib/spack/external/_vendoring/jsonschema/tests/test_validators.py
new file mode 100644
index 0000000000..07be4f08bc
--- /dev/null
+++ b/lib/spack/external/_vendoring/jsonschema/tests/test_validators.py
@@ -0,0 +1,1762 @@
+from collections import deque
+from contextlib import contextmanager
+from decimal import Decimal
+from io import BytesIO
+from unittest import TestCase
+import json
+import os
+import sys
+import tempfile
+import unittest
+
+from twisted.trial.unittest import SynchronousTestCase
+import attr
+
+from jsonschema import FormatChecker, TypeChecker, exceptions, validators
+from jsonschema.compat import PY3, pathname2url
+from jsonschema.tests._helpers import bug
+
+
+def startswith(validator, startswith, instance, schema):
+    if not instance.startswith(startswith):
+        yield exceptions.ValidationError(u"Whoops!")
+
+
+class TestCreateAndExtend(SynchronousTestCase):
+    def setUp(self):
+        self.addCleanup(
+            self.assertEqual,
+            validators.meta_schemas,
+            dict(validators.meta_schemas),
+        )
+
+        self.meta_schema = {u"$id": "some://meta/schema"}
+        self.validators = {u"startswith": startswith}
+        self.type_checker = TypeChecker()
+        self.Validator = validators.create(
+            meta_schema=self.meta_schema,
+            validators=self.validators,
+            type_checker=self.type_checker,
+        )
+
+    def test_attrs(self):
+        self.assertEqual(
+            (
+                self.Validator.VALIDATORS,
+                self.Validator.META_SCHEMA,
+                self.Validator.TYPE_CHECKER,
+            ), (
+                self.validators,
+                self.meta_schema,
+                self.type_checker,
+            ),
+        )
+
+    def test_init(self):
+        schema = {u"startswith": u"foo"}
+        self.assertEqual(self.Validator(schema).schema, schema)
+
+    def test_iter_errors(self):
+        schema = {u"startswith": u"hel"}
+        iter_errors = self.Validator(schema).iter_errors
+
+        errors = list(iter_errors(u"hello"))
+        self.assertEqual(errors, [])
+
+        expected_error = exceptions.ValidationError(
+            u"Whoops!",
+            instance=u"goodbye",
+            schema=schema,
+            validator=u"startswith",
+            validator_value=u"hel",
+            schema_path=deque([u"startswith"]),
+        )
+
+        errors = list(iter_errors(u"goodbye"))
+        self.assertEqual(len(errors), 1)
+        self.assertEqual(errors[0]._contents(), expected_error._contents())
+
+    def test_if_a_version_is_provided_it_is_registered(self):
+        Validator = validators.create(
+            meta_schema={u"$id": "something"},
+            version="my version",
+        )
+        self.addCleanup(validators.meta_schemas.pop, "something")
+        self.assertEqual(Validator.__name__, "MyVersionValidator")
+
+    def test_if_a_version_is_not_provided_it_is_not_registered(self):
+        original = dict(validators.meta_schemas)
+        validators.create(meta_schema={u"id": "id"})
+        self.assertEqual(validators.meta_schemas, original)
+
+    def test_validates_registers_meta_schema_id(self):
+        meta_schema_key = "meta schema id"
+        my_meta_schema = {u"id": meta_schema_key}
+
+        validators.create(
+            meta_schema=my_meta_schema,
+            version="my version",
+            id_of=lambda s: s.get("id", ""),
+        )
+        self.addCleanup(validators.meta_schemas.pop, meta_schema_key)
+
+        self.assertIn(meta_schema_key, validators.meta_schemas)
+
+    def test_validates_registers_meta_schema_draft6_id(self):
+        meta_schema_key = "meta schema $id"
+        my_meta_schema = {u"$id": meta_schema_key}
+
+        validators.create(
+            meta_schema=my_meta_schema,
+            version="my version",
+        )
+        self.addCleanup(validators.meta_schemas.pop, meta_schema_key)
+
+        self.assertIn(meta_schema_key, validators.meta_schemas)
+
+    def test_create_default_types(self):
+        Validator = validators.create(meta_schema={}, validators=())
+        self.assertTrue(
+            all(
+                Validator({}).is_type(instance=instance, type=type)
+                for type, instance in [
+                    (u"array", []),
+                    (u"boolean", True),
+                    (u"integer", 12),
+                    (u"null", None),
+                    (u"number", 12.0),
+                    (u"object", {}),
+                    (u"string", u"foo"),
+                ]
+            ),
+        )
+
+    def test_extend(self):
+        original = dict(self.Validator.VALIDATORS)
+        new = object()
+
+        Extended = validators.extend(
+            self.Validator,
+            validators={u"new": new},
+        )
+        self.assertEqual(
+            (
+                Extended.VALIDATORS,
+                Extended.META_SCHEMA,
+                Extended.TYPE_CHECKER,
+                self.Validator.VALIDATORS,
+            ), (
+                dict(original, new=new),
+                self.Validator.META_SCHEMA,
+                self.Validator.TYPE_CHECKER,
+                original,
+            ),
+        )
+
+    def test_extend_idof(self):
+        """
+        Extending a validator preserves its notion of schema IDs.
+        """
+        def id_of(schema):
+            return schema.get(u"__test__", self.Validator.ID_OF(schema))
+        correct_id = "the://correct/id/"
+        meta_schema = {
+            u"$id": "the://wrong/id/",
+            u"__test__": correct_id,
+        }
+        Original = validators.create(
+            meta_schema=meta_schema,
+            validators=self.validators,
+            type_checker=self.type_checker,
+            id_of=id_of,
+        )
+        self.assertEqual(Original.ID_OF(Original.META_SCHEMA), correct_id)
+
+        Derived = validators.extend(Original)
+        self.assertEqual(Derived.ID_OF(Derived.META_SCHEMA), correct_id)
+
+
+class TestLegacyTypeChecking(SynchronousTestCase):
+    def test_create_default_types(self):
+        Validator = validators.create(meta_schema={}, validators=())
+        self.assertEqual(
+            set(Validator.DEFAULT_TYPES), {
+                u"array",
+                u"boolean",
+                u"integer",
+                u"null",
+                u"number",
+                u"object", u"string",
+            },
+        )
+        self.flushWarnings()
+
+    def test_extend(self):
+        Validator = validators.create(meta_schema={}, validators=())
+        original = dict(Validator.VALIDATORS)
+        new = object()
+
+        Extended = validators.extend(
+            Validator,
+            validators={u"new": new},
+        )
+        self.assertEqual(
+            (
+                Extended.VALIDATORS,
+                Extended.META_SCHEMA,
+                Extended.TYPE_CHECKER,
+                Validator.VALIDATORS,
+
+                Extended.DEFAULT_TYPES,
+                Extended({}).DEFAULT_TYPES,
+                self.flushWarnings()[0]["message"],
+            ), (
+                dict(original, new=new),
+                Validator.META_SCHEMA,
+                Validator.TYPE_CHECKER,
+                original,
+
+                Validator.DEFAULT_TYPES,
+                Validator.DEFAULT_TYPES,
+                self.flushWarnings()[0]["message"],
+            ),
+        )
+
+    def test_types_redefines_the_validators_type_checker(self):
+        schema = {"type": "string"}
+        self.assertFalse(validators.Draft7Validator(schema).is_valid(12))
+
+        validator = validators.Draft7Validator(
+            schema,
+            types={"string": (str, int)},
+        )
+        self.assertTrue(validator.is_valid(12))
+        self.flushWarnings()
+
+    def test_providing_default_types_warns(self):
+        self.assertWarns(
+            category=DeprecationWarning,
+            message=(
+                "The default_types argument is deprecated. "
+                "Use the type_checker argument instead."
+            ),
+            # https://tm.tl/9363 :'(
+            filename=sys.modules[self.assertWarns.__module__].__file__,
+
+            f=validators.create,
+            meta_schema={},
+            validators={},
+            default_types={"foo": object},
+        )
+
+    def test_cannot_ask_for_default_types_with_non_default_type_checker(self):
+        """
+        We raise an error when you ask a validator with non-default
+        type checker for its DEFAULT_TYPES.
+
+        The type checker argument is new, so no one but this library
+        itself should be trying to use it, and doing so while then
+        asking for DEFAULT_TYPES makes no sense (not to mention is
+        deprecated), since type checkers are not strictly about Python
+        type.
+        """
+        Validator = validators.create(
+            meta_schema={},
+            validators={},
+            type_checker=TypeChecker(),
+        )
+        with self.assertRaises(validators._DontDoThat) as e:
+            Validator.DEFAULT_TYPES
+
+        self.assertIn(
+            "DEFAULT_TYPES cannot be used on Validators using TypeCheckers",
+            str(e.exception),
+        )
+        with self.assertRaises(validators._DontDoThat):
+            Validator({}).DEFAULT_TYPES
+
+        self.assertFalse(self.flushWarnings())
+
+    def test_providing_explicit_type_checker_does_not_warn(self):
+        Validator = validators.create(
+            meta_schema={},
+            validators={},
+            type_checker=TypeChecker(),
+        )
+        self.assertFalse(self.flushWarnings())
+
+        Validator({})
+        self.assertFalse(self.flushWarnings())
+
+    def test_providing_neither_does_not_warn(self):
+        Validator = validators.create(meta_schema={}, validators={})
+        self.assertFalse(self.flushWarnings())
+
+        Validator({})
+        self.assertFalse(self.flushWarnings())
+
+    def test_providing_default_types_with_type_checker_errors(self):
+        with self.assertRaises(TypeError) as e:
+            validators.create(
+                meta_schema={},
+                validators={},
+                default_types={"foo": object},
+                type_checker=TypeChecker(),
+            )
+
+        self.assertIn(
+            "Do not specify default_types when providing a type checker",
+            str(e.exception),
+        )
+        self.assertFalse(self.flushWarnings())
+
+    def test_extending_a_legacy_validator_with_a_type_checker_errors(self):
+        Validator = validators.create(
+            meta_schema={},
+            validators={},
+            default_types={u"array": list}
+        )
+        with self.assertRaises(TypeError) as e:
+            validators.extend(
+                Validator,
+                validators={},
+                type_checker=TypeChecker(),
+            )
+
+        self.assertIn(
+            (
+                "Cannot extend a validator created with default_types "
+                "with a type_checker. Update the validator to use a "
+                "type_checker when created."
+            ),
+            str(e.exception),
+        )
+        self.flushWarnings()
+
+    def test_extending_a_legacy_validator_does_not_rewarn(self):
+        Validator = validators.create(meta_schema={}, default_types={})
+        self.assertTrue(self.flushWarnings())
+
+        validators.extend(Validator)
+        self.assertFalse(self.flushWarnings())
+
+    def test_accessing_default_types_warns(self):
+        Validator = validators.create(meta_schema={}, validators={})
+        self.assertFalse(self.flushWarnings())
+
+        self.assertWarns(
+            DeprecationWarning,
+            (
+                "The DEFAULT_TYPES attribute is deprecated. "
+                "See the type checker attached to this validator instead."
+            ),
+            # https://tm.tl/9363 :'(
+            sys.modules[self.assertWarns.__module__].__file__,
+
+            getattr,
+            Validator,
+            "DEFAULT_TYPES",
+        )
+
+    def test_accessing_default_types_on_the_instance_warns(self):
+        Validator = validators.create(meta_schema={}, validators={})
+        self.assertFalse(self.flushWarnings())
+
+        self.assertWarns(
+            DeprecationWarning,
+            (
+                "The DEFAULT_TYPES attribute is deprecated. "
+                "See the type checker attached to this validator instead."
+            ),
+            # https://tm.tl/9363 :'(
+            sys.modules[self.assertWarns.__module__].__file__,
+
+            getattr,
+            Validator({}),
+            "DEFAULT_TYPES",
+        )
+
+    def test_providing_types_to_init_warns(self):
+        Validator = validators.create(meta_schema={}, validators={})
+        self.assertFalse(self.flushWarnings())
+
+        self.assertWarns(
+            category=DeprecationWarning,
+            message=(
+                "The types argument is deprecated. "
+                "Provide a type_checker to jsonschema.validators.extend "
+                "instead."
+            ),
+            # https://tm.tl/9363 :'(
+            filename=sys.modules[self.assertWarns.__module__].__file__,
+
+            f=Validator,
+            schema={},
+            types={"bar": object},
+        )
+
+
+class TestIterErrors(TestCase):
+    def setUp(self):
+        self.validator = validators.Draft3Validator({})
+
+    def test_iter_errors(self):
+        instance = [1, 2]
+        schema = {
+            u"disallow": u"array",
+            u"enum": [["a", "b", "c"], ["d", "e", "f"]],
+            u"minItems": 3,
+        }
+
+        got = (e.message for e in self.validator.iter_errors(instance, schema))
+        expected = [
+            "%r is disallowed for [1, 2]" % (schema["disallow"],),
+            "[1, 2] is too short",
+            "[1, 2] is not one of %r" % (schema["enum"],),
+        ]
+        self.assertEqual(sorted(got), sorted(expected))
+
+    def test_iter_errors_multiple_failures_one_validator(self):
+        instance = {"foo": 2, "bar": [1], "baz": 15, "quux": "spam"}
+        schema = {
+            u"properties": {
+                "foo": {u"type": "string"},
+                "bar": {u"minItems": 2},
+                "baz": {u"maximum": 10, u"enum": [2, 4, 6, 8]},
+            },
+        }
+
+        errors = list(self.validator.iter_errors(instance, schema))
+        self.assertEqual(len(errors), 4)
+
+
+class TestValidationErrorMessages(TestCase):
+    def message_for(self, instance, schema, *args, **kwargs):
+        kwargs.setdefault("cls", validators.Draft3Validator)
+        with self.assertRaises(exceptions.ValidationError) as e:
+            validators.validate(instance, schema, *args, **kwargs)
+        return e.exception.message
+
+    def test_single_type_failure(self):
+        message = self.message_for(instance=1, schema={u"type": u"string"})
+        self.assertEqual(message, "1 is not of type %r" % u"string")
+
+    def test_single_type_list_failure(self):
+        message = self.message_for(instance=1, schema={u"type": [u"string"]})
+        self.assertEqual(message, "1 is not of type %r" % u"string")
+
+    def test_multiple_type_failure(self):
+        types = u"string", u"object"
+        message = self.message_for(instance=1, schema={u"type": list(types)})
+        self.assertEqual(message, "1 is not of type %r, %r" % types)
+
+    def test_object_without_title_type_failure(self):
+        type = {u"type": [{u"minimum": 3}]}
+        message = self.message_for(instance=1, schema={u"type": [type]})
+        self.assertEqual(message, "1 is less than the minimum of 3")
+
+    def test_object_with_named_type_failure(self):
+        schema = {u"type": [{u"name": "Foo", u"minimum": 3}]}
+        message = self.message_for(instance=1, schema=schema)
+        self.assertEqual(message, "1 is less than the minimum of 3")
+
+    def test_minimum(self):
+        message = self.message_for(instance=1, schema={"minimum": 2})
+        self.assertEqual(message, "1 is less than the minimum of 2")
+
+    def test_maximum(self):
+        message = self.message_for(instance=1, schema={"maximum": 0})
+        self.assertEqual(message, "1 is greater than the maximum of 0")
+
+    def test_dependencies_single_element(self):
+        depend, on = "bar", "foo"
+        schema = {u"dependencies": {depend: on}}
+        message = self.message_for(
+            instance={"bar": 2},
+            schema=schema,
+            cls=validators.Draft3Validator,
+        )
+        self.assertEqual(message, "%r is a dependency of %r" % (on, depend))
+
+    def test_dependencies_list_draft3(self):
+        depend, on = "bar", "foo"
+        schema = {u"dependencies": {depend: [on]}}
+        message = self.message_for(
+            instance={"bar": 2},
+            schema=schema,
+            cls=validators.Draft3Validator,
+        )
+        self.assertEqual(message, "%r is a dependency of %r" % (on, depend))
+
+    def test_dependencies_list_draft7(self):
+        depend, on = "bar", "foo"
+        schema = {u"dependencies": {depend: [on]}}
+        message = self.message_for(
+            instance={"bar": 2},
+            schema=schema,
+            cls=validators.Draft7Validator,
+        )
+        self.assertEqual(message, "%r is a dependency of %r" % (on, depend))
+
+    def test_additionalItems_single_failure(self):
+        message = self.message_for(
+            instance=[2],
+            schema={u"items": [], u"additionalItems": False},
+        )
+        self.assertIn("(2 was unexpected)", message)
+
+    def test_additionalItems_multiple_failures(self):
+        message = self.message_for(
+            instance=[1, 2, 3],
+            schema={u"items": [], u"additionalItems": False}
+        )
+        self.assertIn("(1, 2, 3 were unexpected)", message)
+
+    def test_additionalProperties_single_failure(self):
+        additional = "foo"
+        schema = {u"additionalProperties": False}
+        message = self.message_for(instance={additional: 2}, schema=schema)
+        self.assertIn("(%r was unexpected)" % (additional,), message)
+
+    def test_additionalProperties_multiple_failures(self):
+        schema = {u"additionalProperties": False}
+        message = self.message_for(
+            instance=dict.fromkeys(["foo", "bar"]),
+            schema=schema,
+        )
+
+        self.assertIn(repr("foo"), message)
+        self.assertIn(repr("bar"), message)
+        self.assertIn("were unexpected)", message)
+
+    def test_const(self):
+        schema = {u"const": 12}
+        message = self.message_for(
+            instance={"foo": "bar"},
+            schema=schema,
+            cls=validators.Draft6Validator,
+        )
+        self.assertIn("12 was expected", message)
+
+    def test_contains(self):
+        schema = {u"contains": {u"const": 12}}
+        message = self.message_for(
+            instance=[2, {}, []],
+            schema=schema,
+            cls=validators.Draft6Validator,
+        )
+        self.assertIn(
+            "None of [2, {}, []] are valid under the given schema",
+            message,
+        )
+
+    def test_invalid_format_default_message(self):
+        checker = FormatChecker(formats=())
+        checker.checks(u"thing")(lambda value: False)
+
+        schema = {u"format": u"thing"}
+        message = self.message_for(
+            instance="bla",
+            schema=schema,
+            format_checker=checker,
+        )
+
+        self.assertIn(repr("bla"), message)
+        self.assertIn(repr("thing"), message)
+        self.assertIn("is not a", message)
+
+    def test_additionalProperties_false_patternProperties(self):
+        schema = {u"type": u"object",
+                  u"additionalProperties": False,
+                  u"patternProperties": {
+                      u"^abc$": {u"type": u"string"},
+                      u"^def$": {u"type": u"string"},
+                  }}
+        message = self.message_for(
+            instance={u"zebra": 123},
+            schema=schema,
+            cls=validators.Draft4Validator,
+        )
+        self.assertEqual(
+            message,
+            "{} does not match any of the regexes: {}, {}".format(
+                repr(u"zebra"), repr(u"^abc$"), repr(u"^def$"),
+            ),
+        )
+        message = self.message_for(
+            instance={u"zebra": 123, u"fish": 456},
+            schema=schema,
+            cls=validators.Draft4Validator,
+        )
+        self.assertEqual(
+            message,
+            "{}, {} do not match any of the regexes: {}, {}".format(
+                repr(u"fish"), repr(u"zebra"), repr(u"^abc$"), repr(u"^def$")
+            ),
+        )
+
+    def test_False_schema(self):
+        message = self.message_for(
+            instance="something",
+            schema=False,
+            cls=validators.Draft7Validator,
+        )
+        self.assertIn("False schema does not allow 'something'", message)
+
+
+class TestValidationErrorDetails(TestCase):
+    # TODO: These really need unit tests for each individual validator, rather
+    #       than just these higher level tests.
+    def test_anyOf(self):
+        instance = 5
+        schema = {
+            "anyOf": [
+                {"minimum": 20},
+                {"type": "string"},
+            ],
+        }
+
+        validator = validators.Draft4Validator(schema)
+        errors = list(validator.iter_errors(instance))
+        self.assertEqual(len(errors), 1)
+        e = errors[0]
+
+        self.assertEqual(e.validator, "anyOf")
+        self.assertEqual(e.validator_value, schema["anyOf"])
+        self.assertEqual(e.instance, instance)
+        self.assertEqual(e.schema, schema)
+        self.assertIsNone(e.parent)
+
+        self.assertEqual(e.path, deque([]))
+        self.assertEqual(e.relative_path, deque([]))
+        self.assertEqual(e.absolute_path, deque([]))
+
+        self.assertEqual(e.schema_path, deque(["anyOf"]))
+        self.assertEqual(e.relative_schema_path, deque(["anyOf"]))
+        self.assertEqual(e.absolute_schema_path, deque(["anyOf"]))
+
+        self.assertEqual(len(e.context), 2)
+
+        e1, e2 = sorted_errors(e.context)
+
+        self.assertEqual(e1.validator, "minimum")
+        self.assertEqual(e1.validator_value, schema["anyOf"][0]["minimum"])
+        self.assertEqual(e1.instance, instance)
+        self.assertEqual(e1.schema, schema["anyOf"][0])
+        self.assertIs(e1.parent, e)
+
+        self.assertEqual(e1.path, deque([]))
+        self.assertEqual(e1.absolute_path, deque([]))
+        self.assertEqual(e1.relative_path, deque([]))
+
+        self.assertEqual(e1.schema_path, deque([0, "minimum"]))
+        self.assertEqual(e1.relative_schema_path, deque([0, "minimum"]))
+        self.assertEqual(
+            e1.absolute_schema_path, deque(["anyOf", 0, "minimum"]),
+        )
+
+        self.assertFalse(e1.context)
+
+        self.assertEqual(e2.validator, "type")
+        self.assertEqual(e2.validator_value, schema["anyOf"][1]["type"])
+        self.assertEqual(e2.instance, instance)
+        self.assertEqual(e2.schema, schema["anyOf"][1])
+        self.assertIs(e2.parent, e)
+
+        self.assertEqual(e2.path, deque([]))
+        self.assertEqual(e2.relative_path, deque([]))
+        self.assertEqual(e2.absolute_path, deque([]))
+
+        self.assertEqual(e2.schema_path, deque([1, "type"]))
+        self.assertEqual(e2.relative_schema_path, deque([1, "type"]))
+        self.assertEqual(e2.absolute_schema_path, deque(["anyOf", 1, "type"]))
+
+        self.assertEqual(len(e2.context), 0)
+
+    def test_type(self):
+        instance = {"foo": 1}
+        schema = {
+            "type": [
+                {"type": "integer"},
+                {
+                    "type": "object",
+                    "properties": {"foo": {"enum": [2]}},
+                },
+            ],
+        }
+
+        validator = validators.Draft3Validator(schema)
+        errors = list(validator.iter_errors(instance))
+        self.assertEqual(len(errors), 1)
+        e = errors[0]
+
+        self.assertEqual(e.validator, "type")
+        self.assertEqual(e.validator_value, schema["type"])
+        self.assertEqual(e.instance, instance)
+        self.assertEqual(e.schema, schema)
+        self.assertIsNone(e.parent)
+
+        self.assertEqual(e.path, deque([]))
+        self.assertEqual(e.relative_path, deque([]))
+        self.assertEqual(e.absolute_path, deque([]))
+
+        self.assertEqual(e.schema_path, deque(["type"]))
+        self.assertEqual(e.relative_schema_path, deque(["type"]))
+        self.assertEqual(e.absolute_schema_path, deque(["type"]))
+
+        self.assertEqual(len(e.context), 2)
+
+        e1, e2 = sorted_errors(e.context)
+
+        self.assertEqual(e1.validator, "type")
+        self.assertEqual(e1.validator_value, schema["type"][0]["type"])
+        self.assertEqual(e1.instance, instance)
+        self.assertEqual(e1.schema, schema["type"][0])
+        self.assertIs(e1.parent, e)
+
+        self.assertEqual(e1.path, deque([]))
+        self.assertEqual(e1.relative_path, deque([]))
+        self.assertEqual(e1.absolute_path, deque([]))
+
+        self.assertEqual(e1.schema_path, deque([0, "type"]))
+        self.assertEqual(e1.relative_schema_path, deque([0, "type"]))
+        self.assertEqual(e1.absolute_schema_path, deque(["type", 0, "type"]))
+
+        self.assertFalse(e1.context)
+
+        self.assertEqual(e2.validator, "enum")
+        self.assertEqual(e2.validator_value, [2])
+        self.assertEqual(e2.instance, 1)
+        self.assertEqual(e2.schema, {u"enum": [2]})
+        self.assertIs(e2.parent, e)
+
+        self.assertEqual(e2.path, deque(["foo"]))
+        self.assertEqual(e2.relative_path, deque(["foo"]))
+        self.assertEqual(e2.absolute_path, deque(["foo"]))
+
+        self.assertEqual(
+            e2.schema_path, deque([1, "properties", "foo", "enum"]),
+        )
+        self.assertEqual(
+            e2.relative_schema_path, deque([1, "properties", "foo", "enum"]),
+        )
+        self.assertEqual(
+            e2.absolute_schema_path,
+            deque(["type", 1, "properties", "foo", "enum"]),
+        )
+
+        self.assertFalse(e2.context)
+
+    def test_single_nesting(self):
+        instance = {"foo": 2, "bar": [1], "baz": 15, "quux": "spam"}
+        schema = {
+            "properties": {
+                "foo": {"type": "string"},
+                "bar": {"minItems": 2},
+                "baz": {"maximum": 10, "enum": [2, 4, 6, 8]},
+            },
+        }
+
+        validator = validators.Draft3Validator(schema)
+        errors = validator.iter_errors(instance)
+        e1, e2, e3, e4 = sorted_errors(errors)
+
+        self.assertEqual(e1.path, deque(["bar"]))
+        self.assertEqual(e2.path, deque(["baz"]))
+        self.assertEqual(e3.path, deque(["baz"]))
+        self.assertEqual(e4.path, deque(["foo"]))
+
+        self.assertEqual(e1.relative_path, deque(["bar"]))
+        self.assertEqual(e2.relative_path, deque(["baz"]))
+        self.assertEqual(e3.relative_path, deque(["baz"]))
+        self.assertEqual(e4.relative_path, deque(["foo"]))
+
+        self.assertEqual(e1.absolute_path, deque(["bar"]))
+        self.assertEqual(e2.absolute_path, deque(["baz"]))
+        self.assertEqual(e3.absolute_path, deque(["baz"]))
+        self.assertEqual(e4.absolute_path, deque(["foo"]))
+
+        self.assertEqual(e1.validator, "minItems")
+        self.assertEqual(e2.validator, "enum")
+        self.assertEqual(e3.validator, "maximum")
+        self.assertEqual(e4.validator, "type")
+
+    def test_multiple_nesting(self):
+        instance = [1, {"foo": 2, "bar": {"baz": [1]}}, "quux"]
+        schema = {
+            "type": "string",
+            "items": {
+                "type": ["string", "object"],
+                "properties": {
+                    "foo": {"enum": [1, 3]},
+                    "bar": {
+                        "type": "array",
+                        "properties": {
+                            "bar": {"required": True},
+                            "baz": {"minItems": 2},
+                        },
+                    },
+                },
+            },
+        }
+
+        validator = validators.Draft3Validator(schema)
+        errors = validator.iter_errors(instance)
+        e1, e2, e3, e4, e5, e6 = sorted_errors(errors)
+
+        self.assertEqual(e1.path, deque([]))
+        self.assertEqual(e2.path, deque([0]))
+        self.assertEqual(e3.path, deque([1, "bar"]))
+        self.assertEqual(e4.path, deque([1, "bar", "bar"]))
+        self.assertEqual(e5.path, deque([1, "bar", "baz"]))
+        self.assertEqual(e6.path, deque([1, "foo"]))
+
+        self.assertEqual(e1.schema_path, deque(["type"]))
+        self.assertEqual(e2.schema_path, deque(["items", "type"]))
+        self.assertEqual(
+            list(e3.schema_path), ["items", "properties", "bar", "type"],
+        )
+        self.assertEqual(
+            list(e4.schema_path),
+            ["items", "properties", "bar", "properties", "bar", "required"],
+        )
+        self.assertEqual(
+            list(e5.schema_path),
+            ["items", "properties", "bar", "properties", "baz", "minItems"]
+        )
+        self.assertEqual(
+            list(e6.schema_path), ["items", "properties", "foo", "enum"],
+        )
+
+        self.assertEqual(e1.validator, "type")
+        self.assertEqual(e2.validator, "type")
+        self.assertEqual(e3.validator, "type")
+        self.assertEqual(e4.validator, "required")
+        self.assertEqual(e5.validator, "minItems")
+        self.assertEqual(e6.validator, "enum")
+
+    def test_recursive(self):
+        schema = {
+            "definitions": {
+                "node": {
+                    "anyOf": [{
+                        "type": "object",
+                        "required": ["name", "children"],
+                        "properties": {
+                            "name": {
+                                "type": "string",
+                            },
+                            "children": {
+                                "type": "object",
+                                "patternProperties": {
+                                    "^.*$": {
+                                        "$ref": "#/definitions/node",
+                                    },
+                                },
+                            },
+                        },
+                    }],
+                },
+            },
+            "type": "object",
+            "required": ["root"],
+            "properties": {"root": {"$ref": "#/definitions/node"}},
+        }
+
+        instance = {
+            "root": {
+                "name": "root",
+                "children": {
+                    "a": {
+                        "name": "a",
+                        "children": {
+                            "ab": {
+                                "name": "ab",
+                                # missing "children"
+                            },
+                        },
+                    },
+                },
+            },
+        }
+        validator = validators.Draft4Validator(schema)
+
+        e, = validator.iter_errors(instance)
+        self.assertEqual(e.absolute_path, deque(["root"]))
+        self.assertEqual(
+            e.absolute_schema_path, deque(["properties", "root", "anyOf"]),
+        )
+
+        e1, = e.context
+        self.assertEqual(e1.absolute_path, deque(["root", "children", "a"]))
+        self.assertEqual(
+            e1.absolute_schema_path, deque(
+                [
+                    "properties",
+                    "root",
+                    "anyOf",
+                    0,
+                    "properties",
+                    "children",
+                    "patternProperties",
+                    "^.*$",
+                    "anyOf",
+                ],
+            ),
+        )
+
+        e2, = e1.context
+        self.assertEqual(
+            e2.absolute_path, deque(
+                ["root", "children", "a", "children", "ab"],
+            ),
+        )
+        self.assertEqual(
+            e2.absolute_schema_path, deque(
+                [
+                    "properties",
+                    "root",
+                    "anyOf",
+                    0,
+                    "properties",
+                    "children",
+                    "patternProperties",
+                    "^.*$",
+                    "anyOf",
+                    0,
+                    "properties",
+                    "children",
+                    "patternProperties",
+                    "^.*$",
+                    "anyOf",
+                ],
+            ),
+        )
+
+    def test_additionalProperties(self):
+        instance = {"bar": "bar", "foo": 2}
+        schema = {"additionalProperties": {"type": "integer", "minimum": 5}}
+
+        validator = validators.Draft3Validator(schema)
+        errors = validator.iter_errors(instance)
+        e1, e2 = sorted_errors(errors)
+
+        self.assertEqual(e1.path, deque(["bar"]))
+        self.assertEqual(e2.path, deque(["foo"]))
+
+        self.assertEqual(e1.validator, "type")
+        self.assertEqual(e2.validator, "minimum")
+
+    def test_patternProperties(self):
+        instance = {"bar": 1, "foo": 2}
+        schema = {
+            "patternProperties": {
+                "bar": {"type": "string"},
+                "foo": {"minimum": 5},
+            },
+        }
+
+        validator = validators.Draft3Validator(schema)
+        errors = validator.iter_errors(instance)
+        e1, e2 = sorted_errors(errors)
+
+        self.assertEqual(e1.path, deque(["bar"]))
+        self.assertEqual(e2.path, deque(["foo"]))
+
+        self.assertEqual(e1.validator, "type")
+        self.assertEqual(e2.validator, "minimum")
+
+    def test_additionalItems(self):
+        instance = ["foo", 1]
+        schema = {
+            "items": [],
+            "additionalItems": {"type": "integer", "minimum": 5},
+        }
+
+        validator = validators.Draft3Validator(schema)
+        errors = validator.iter_errors(instance)
+        e1, e2 = sorted_errors(errors)
+
+        self.assertEqual(e1.path, deque([0]))
+        self.assertEqual(e2.path, deque([1]))
+
+        self.assertEqual(e1.validator, "type")
+        self.assertEqual(e2.validator, "minimum")
+
+    def test_additionalItems_with_items(self):
+        instance = ["foo", "bar", 1]
+        schema = {
+            "items": [{}],
+            "additionalItems": {"type": "integer", "minimum": 5},
+        }
+
+        validator = validators.Draft3Validator(schema)
+        errors = validator.iter_errors(instance)
+        e1, e2 = sorted_errors(errors)
+
+        self.assertEqual(e1.path, deque([1]))
+        self.assertEqual(e2.path, deque([2]))
+
+        self.assertEqual(e1.validator, "type")
+        self.assertEqual(e2.validator, "minimum")
+
+    def test_propertyNames(self):
+        instance = {"foo": 12}
+        schema = {"propertyNames": {"not": {"const": "foo"}}}
+
+        validator = validators.Draft7Validator(schema)
+        error, = validator.iter_errors(instance)
+
+        self.assertEqual(error.validator, "not")
+        self.assertEqual(
+            error.message,
+            "%r is not allowed for %r" % ({"const": "foo"}, "foo"),
+        )
+        self.assertEqual(error.path, deque([]))
+        self.assertEqual(error.schema_path, deque(["propertyNames", "not"]))
+
+    def test_if_then(self):
+        schema = {
+            "if": {"const": 12},
+            "then": {"const": 13},
+        }
+
+        validator = validators.Draft7Validator(schema)
+        error, = validator.iter_errors(12)
+
+        self.assertEqual(error.validator, "const")
+        self.assertEqual(error.message, "13 was expected")
+        self.assertEqual(error.path, deque([]))
+        self.assertEqual(error.schema_path, deque(["if", "then", "const"]))
+
+    def test_if_else(self):
+        schema = {
+            "if": {"const": 12},
+            "else": {"const": 13},
+        }
+
+        validator = validators.Draft7Validator(schema)
+        error, = validator.iter_errors(15)
+
+        self.assertEqual(error.validator, "const")
+        self.assertEqual(error.message, "13 was expected")
+        self.assertEqual(error.path, deque([]))
+        self.assertEqual(error.schema_path, deque(["if", "else", "const"]))
+
+    def test_boolean_schema_False(self):
+        validator = validators.Draft7Validator(False)
+        error, = validator.iter_errors(12)
+
+        self.assertEqual(
+            (
+                error.message,
+                error.validator,
+                error.validator_value,
+                error.instance,
+                error.schema,
+                error.schema_path,
+            ),
+            (
+                "False schema does not allow 12",
+                None,
+                None,
+                12,
+                False,
+                deque([]),
+            ),
+        )
+
+    def test_ref(self):
+        ref, schema = "someRef", {"additionalProperties": {"type": "integer"}}
+        validator = validators.Draft7Validator(
+            {"$ref": ref},
+            resolver=validators.RefResolver("", {}, store={ref: schema}),
+        )
+        error, = validator.iter_errors({"foo": "notAnInteger"})
+
+        self.assertEqual(
+            (
+                error.message,
+                error.validator,
+                error.validator_value,
+                error.instance,
+                error.absolute_path,
+                error.schema,
+                error.schema_path,
+            ),
+            (
+                "'notAnInteger' is not of type 'integer'",
+                "type",
+                "integer",
+                "notAnInteger",
+                deque(["foo"]),
+                {"type": "integer"},
+                deque(["additionalProperties", "type"]),
+            ),
+        )
+
+
+class MetaSchemaTestsMixin(object):
+    # TODO: These all belong upstream
+    def test_invalid_properties(self):
+        with self.assertRaises(exceptions.SchemaError):
+            self.Validator.check_schema({"properties": {"test": object()}})
+
+    def test_minItems_invalid_string(self):
+        with self.assertRaises(exceptions.SchemaError):
+            # needs to be an integer
+            self.Validator.check_schema({"minItems": "1"})
+
+    def test_enum_allows_empty_arrays(self):
+        """
+        Technically, all the spec says is they SHOULD have elements, not MUST.
+
+        See https://github.com/Julian/jsonschema/issues/529.
+        """
+        self.Validator.check_schema({"enum": []})
+
+    def test_enum_allows_non_unique_items(self):
+        """
+        Technically, all the spec says is they SHOULD be unique, not MUST.
+
+        See https://github.com/Julian/jsonschema/issues/529.
+        """
+        self.Validator.check_schema({"enum": [12, 12]})
+
+
+class ValidatorTestMixin(MetaSchemaTestsMixin, object):
+    def test_valid_instances_are_valid(self):
+        schema, instance = self.valid
+        self.assertTrue(self.Validator(schema).is_valid(instance))
+
+    def test_invalid_instances_are_not_valid(self):
+        schema, instance = self.invalid
+        self.assertFalse(self.Validator(schema).is_valid(instance))
+
+    def test_non_existent_properties_are_ignored(self):
+        self.Validator({object(): object()}).validate(instance=object())
+
+    def test_it_creates_a_ref_resolver_if_not_provided(self):
+        self.assertIsInstance(
+            self.Validator({}).resolver,
+            validators.RefResolver,
+        )
+
+    def test_it_delegates_to_a_ref_resolver(self):
+        ref, schema = "someCoolRef", {"type": "integer"}
+        resolver = validators.RefResolver("", {}, store={ref: schema})
+        validator = self.Validator({"$ref": ref}, resolver=resolver)
+
+        with self.assertRaises(exceptions.ValidationError):
+            validator.validate(None)
+
+    def test_it_delegates_to_a_legacy_ref_resolver(self):
+        """
+        Legacy RefResolvers support only the context manager form of
+        resolution.
+        """
+
+        class LegacyRefResolver(object):
+            @contextmanager
+            def resolving(this, ref):
+                self.assertEqual(ref, "the ref")
+                yield {"type": "integer"}
+
+        resolver = LegacyRefResolver()
+        schema = {"$ref": "the ref"}
+
+        with self.assertRaises(exceptions.ValidationError):
+            self.Validator(schema, resolver=resolver).validate(None)
+
+    def test_is_type_is_true_for_valid_type(self):
+        self.assertTrue(self.Validator({}).is_type("foo", "string"))
+
+    def test_is_type_is_false_for_invalid_type(self):
+        self.assertFalse(self.Validator({}).is_type("foo", "array"))
+
+    def test_is_type_evades_bool_inheriting_from_int(self):
+        self.assertFalse(self.Validator({}).is_type(True, "integer"))
+        self.assertFalse(self.Validator({}).is_type(True, "number"))
+
+    @unittest.skipIf(PY3, "In Python 3 json.load always produces unicode")
+    def test_string_a_bytestring_is_a_string(self):
+        self.Validator({"type": "string"}).validate(b"foo")
+
+    def test_patterns_can_be_native_strings(self):
+        """
+        See https://github.com/Julian/jsonschema/issues/611.
+        """
+        self.Validator({"pattern": "foo"}).validate("foo")
+
+    def test_it_can_validate_with_decimals(self):
+        schema = {"items": {"type": "number"}}
+        Validator = validators.extend(
+            self.Validator,
+            type_checker=self.Validator.TYPE_CHECKER.redefine(
+                "number",
+                lambda checker, thing: isinstance(
+                    thing, (int, float, Decimal),
+                ) and not isinstance(thing, bool),
+            )
+        )
+
+        validator = Validator(schema)
+        validator.validate([1, 1.1, Decimal(1) / Decimal(8)])
+
+        invalid = ["foo", {}, [], True, None]
+        self.assertEqual(
+            [error.instance for error in validator.iter_errors(invalid)],
+            invalid,
+        )
+
+    def test_it_returns_true_for_formats_it_does_not_know_about(self):
+        validator = self.Validator(
+            {"format": "carrot"}, format_checker=FormatChecker(),
+        )
+        validator.validate("bugs")
+
+    def test_it_does_not_validate_formats_by_default(self):
+        validator = self.Validator({})
+        self.assertIsNone(validator.format_checker)
+
+    def test_it_validates_formats_if_a_checker_is_provided(self):
+        checker = FormatChecker()
+        bad = ValueError("Bad!")
+
+        @checker.checks("foo", raises=ValueError)
+        def check(value):
+            if value == "good":
+                return True
+            elif value == "bad":
+                raise bad
+            else:  # pragma: no cover
+                self.fail("What is {}? [Baby Don't Hurt Me]".format(value))
+
+        validator = self.Validator(
+            {"format": "foo"}, format_checker=checker,
+        )
+
+        validator.validate("good")
+        with self.assertRaises(exceptions.ValidationError) as cm:
+            validator.validate("bad")
+
+        # Make sure original cause is attached
+        self.assertIs(cm.exception.cause, bad)
+
+    def test_non_string_custom_type(self):
+        non_string_type = object()
+        schema = {"type": [non_string_type]}
+        Crazy = validators.extend(
+            self.Validator,
+            type_checker=self.Validator.TYPE_CHECKER.redefine(
+                non_string_type,
+                lambda checker, thing: isinstance(thing, int),
+            )
+        )
+        Crazy(schema).validate(15)
+
+    def test_it_properly_formats_tuples_in_errors(self):
+        """
+        A tuple instance properly formats validation errors for uniqueItems.
+
+        See https://github.com/Julian/jsonschema/pull/224
+        """
+        TupleValidator = validators.extend(
+            self.Validator,
+            type_checker=self.Validator.TYPE_CHECKER.redefine(
+                "array",
+                lambda checker, thing: isinstance(thing, tuple),
+            )
+        )
+        with self.assertRaises(exceptions.ValidationError) as e:
+            TupleValidator({"uniqueItems": True}).validate((1, 1))
+        self.assertIn("(1, 1) has non-unique elements", str(e.exception))
+
+
+class AntiDraft6LeakMixin(object):
+    """
+    Make sure functionality from draft 6 doesn't leak backwards in time.
+    """
+
+    def test_True_is_not_a_schema(self):
+        with self.assertRaises(exceptions.SchemaError) as e:
+            self.Validator.check_schema(True)
+        self.assertIn("True is not of type", str(e.exception))
+
+    def test_False_is_not_a_schema(self):
+        with self.assertRaises(exceptions.SchemaError) as e:
+            self.Validator.check_schema(False)
+        self.assertIn("False is not of type", str(e.exception))
+
+    @unittest.skip(bug(523))
+    def test_True_is_not_a_schema_even_if_you_forget_to_check(self):
+        resolver = validators.RefResolver("", {})
+        with self.assertRaises(Exception) as e:
+            self.Validator(True, resolver=resolver).validate(12)
+        self.assertNotIsInstance(e.exception, exceptions.ValidationError)
+
+    @unittest.skip(bug(523))
+    def test_False_is_not_a_schema_even_if_you_forget_to_check(self):
+        resolver = validators.RefResolver("", {})
+        with self.assertRaises(Exception) as e:
+            self.Validator(False, resolver=resolver).validate(12)
+        self.assertNotIsInstance(e.exception, exceptions.ValidationError)
+
+
+class TestDraft3Validator(AntiDraft6LeakMixin, ValidatorTestMixin, TestCase):
+    Validator = validators.Draft3Validator
+    valid = {}, {}
+    invalid = {"type": "integer"}, "foo"
+
+    def test_any_type_is_valid_for_type_any(self):
+        validator = self.Validator({"type": "any"})
+        validator.validate(object())
+
+    def test_any_type_is_redefinable(self):
+        """
+        Sigh, because why not.
+        """
+        Crazy = validators.extend(
+            self.Validator,
+            type_checker=self.Validator.TYPE_CHECKER.redefine(
+                "any", lambda checker, thing: isinstance(thing, int),
+            )
+        )
+        validator = Crazy({"type": "any"})
+        validator.validate(12)
+        with self.assertRaises(exceptions.ValidationError):
+            validator.validate("foo")
+
+    def test_is_type_is_true_for_any_type(self):
+        self.assertTrue(self.Validator({}).is_valid(object(), {"type": "any"}))
+
+    def test_is_type_does_not_evade_bool_if_it_is_being_tested(self):
+        self.assertTrue(self.Validator({}).is_type(True, "boolean"))
+        self.assertTrue(self.Validator({}).is_valid(True, {"type": "any"}))
+
+
+class TestDraft4Validator(AntiDraft6LeakMixin, ValidatorTestMixin, TestCase):
+    Validator = validators.Draft4Validator
+    valid = {}, {}
+    invalid = {"type": "integer"}, "foo"
+
+
+class TestDraft6Validator(ValidatorTestMixin, TestCase):
+    Validator = validators.Draft6Validator
+    valid = {}, {}
+    invalid = {"type": "integer"}, "foo"
+
+
+class TestDraft7Validator(ValidatorTestMixin, TestCase):
+    Validator = validators.Draft7Validator
+    valid = {}, {}
+    invalid = {"type": "integer"}, "foo"
+
+
+class TestValidatorFor(SynchronousTestCase):
+    def test_draft_3(self):
+        schema = {"$schema": "http://json-schema.org/draft-03/schema"}
+        self.assertIs(
+            validators.validator_for(schema),
+            validators.Draft3Validator,
+        )
+
+        schema = {"$schema": "http://json-schema.org/draft-03/schema#"}
+        self.assertIs(
+            validators.validator_for(schema),
+            validators.Draft3Validator,
+        )
+
+    def test_draft_4(self):
+        schema = {"$schema": "http://json-schema.org/draft-04/schema"}
+        self.assertIs(
+            validators.validator_for(schema),
+            validators.Draft4Validator,
+        )
+
+        schema = {"$schema": "http://json-schema.org/draft-04/schema#"}
+        self.assertIs(
+            validators.validator_for(schema),
+            validators.Draft4Validator,
+        )
+
+    def test_draft_6(self):
+        schema = {"$schema": "http://json-schema.org/draft-06/schema"}
+        self.assertIs(
+            validators.validator_for(schema),
+            validators.Draft6Validator,
+        )
+
+        schema = {"$schema": "http://json-schema.org/draft-06/schema#"}
+        self.assertIs(
+            validators.validator_for(schema),
+            validators.Draft6Validator,
+        )
+
+    def test_draft_7(self):
+        schema = {"$schema": "http://json-schema.org/draft-07/schema"}
+        self.assertIs(
+            validators.validator_for(schema),
+            validators.Draft7Validator,
+        )
+
+        schema = {"$schema": "http://json-schema.org/draft-07/schema#"}
+        self.assertIs(
+            validators.validator_for(schema),
+            validators.Draft7Validator,
+        )
+
+    def test_True(self):
+        self.assertIs(
+            validators.validator_for(True),
+            validators._LATEST_VERSION,
+        )
+
+    def test_False(self):
+        self.assertIs(
+            validators.validator_for(False),
+            validators._LATEST_VERSION,
+        )
+
+    def test_custom_validator(self):
+        Validator = validators.create(
+            meta_schema={"id": "meta schema id"},
+            version="12",
+            id_of=lambda s: s.get("id", ""),
+        )
+        schema = {"$schema": "meta schema id"}
+        self.assertIs(
+            validators.validator_for(schema),
+            Validator,
+        )
+
+    def test_custom_validator_draft6(self):
+        Validator = validators.create(
+            meta_schema={"$id": "meta schema $id"},
+            version="13",
+        )
+        schema = {"$schema": "meta schema $id"}
+        self.assertIs(
+            validators.validator_for(schema),
+            Validator,
+        )
+
+    def test_validator_for_jsonschema_default(self):
+        self.assertIs(validators.validator_for({}), validators._LATEST_VERSION)
+
+    def test_validator_for_custom_default(self):
+        self.assertIs(validators.validator_for({}, default=None), None)
+
+    def test_warns_if_meta_schema_specified_was_not_found(self):
+        self.assertWarns(
+            category=DeprecationWarning,
+            message=(
+                "The metaschema specified by $schema was not found. "
+                "Using the latest draft to validate, but this will raise "
+                "an error in the future."
+            ),
+            # https://tm.tl/9363 :'(
+            filename=sys.modules[self.assertWarns.__module__].__file__,
+
+            f=validators.validator_for,
+            schema={u"$schema": "unknownSchema"},
+            default={},
+        )
+
+    def test_does_not_warn_if_meta_schema_is_unspecified(self):
+        validators.validator_for(schema={}, default={}),
+        self.assertFalse(self.flushWarnings())
+
+
+class TestValidate(SynchronousTestCase):
+    def assertUses(self, schema, Validator):
+        result = []
+        self.patch(Validator, "check_schema", result.append)
+        validators.validate({}, schema)
+        self.assertEqual(result, [schema])
+
+    def test_draft3_validator_is_chosen(self):
+        self.assertUses(
+            schema={"$schema": "http://json-schema.org/draft-03/schema#"},
+            Validator=validators.Draft3Validator,
+        )
+        # Make sure it works without the empty fragment
+        self.assertUses(
+            schema={"$schema": "http://json-schema.org/draft-03/schema"},
+            Validator=validators.Draft3Validator,
+        )
+
+    def test_draft4_validator_is_chosen(self):
+        self.assertUses(
+            schema={"$schema": "http://json-schema.org/draft-04/schema#"},
+            Validator=validators.Draft4Validator,
+        )
+        # Make sure it works without the empty fragment
+        self.assertUses(
+            schema={"$schema": "http://json-schema.org/draft-04/schema"},
+            Validator=validators.Draft4Validator,
+        )
+
+    def test_draft6_validator_is_chosen(self):
+        self.assertUses(
+            schema={"$schema": "http://json-schema.org/draft-06/schema#"},
+            Validator=validators.Draft6Validator,
+        )
+        # Make sure it works without the empty fragment
+        self.assertUses(
+            schema={"$schema": "http://json-schema.org/draft-06/schema"},
+            Validator=validators.Draft6Validator,
+        )
+
+    def test_draft7_validator_is_chosen(self):
+        self.assertUses(
+            schema={"$schema": "http://json-schema.org/draft-07/schema#"},
+            Validator=validators.Draft7Validator,
+        )
+        # Make sure it works without the empty fragment
+        self.assertUses(
+            schema={"$schema": "http://json-schema.org/draft-07/schema"},
+            Validator=validators.Draft7Validator,
+        )
+
+    def test_draft7_validator_is_the_default(self):
+        self.assertUses(schema={}, Validator=validators.Draft7Validator)
+
+    def test_validation_error_message(self):
+        with self.assertRaises(exceptions.ValidationError) as e:
+            validators.validate(12, {"type": "string"})
+        self.assertRegexpMatches(
+            str(e.exception),
+            "(?s)Failed validating u?'.*' in schema.*On instance",
+        )
+
+    def test_schema_error_message(self):
+        with self.assertRaises(exceptions.SchemaError) as e:
+            validators.validate(12, {"type": 12})
+        self.assertRegexpMatches(
+            str(e.exception),
+            "(?s)Failed validating u?'.*' in metaschema.*On schema",
+        )
+
+    def test_it_uses_best_match(self):
+        # This is a schema that best_match will recurse into
+        schema = {"oneOf": [{"type": "string"}, {"type": "array"}]}
+        with self.assertRaises(exceptions.ValidationError) as e:
+            validators.validate(12, schema)
+        self.assertIn("12 is not of type", str(e.exception))
+
+
+class TestRefResolver(SynchronousTestCase):
+
+    base_uri = ""
+    stored_uri = "foo://stored"
+    stored_schema = {"stored": "schema"}
+
+    def setUp(self):
+        self.referrer = {}
+        self.store = {self.stored_uri: self.stored_schema}
+        self.resolver = validators.RefResolver(
+            self.base_uri, self.referrer, self.store,
+        )
+
+    def test_it_does_not_retrieve_schema_urls_from_the_network(self):
+        ref = validators.Draft3Validator.META_SCHEMA["id"]
+        self.patch(
+            self.resolver,
+            "resolve_remote",
+            lambda *args, **kwargs: self.fail("Should not have been called!"),
+        )
+        with self.resolver.resolving(ref) as resolved:
+            pass
+        self.assertEqual(resolved, validators.Draft3Validator.META_SCHEMA)
+
+    def test_it_resolves_local_refs(self):
+        ref = "#/properties/foo"
+        self.referrer["properties"] = {"foo": object()}
+        with self.resolver.resolving(ref) as resolved:
+            self.assertEqual(resolved, self.referrer["properties"]["foo"])
+
+    def test_it_resolves_local_refs_with_id(self):
+        schema = {"id": "http://bar/schema#", "a": {"foo": "bar"}}
+        resolver = validators.RefResolver.from_schema(
+            schema,
+            id_of=lambda schema: schema.get(u"id", u""),
+        )
+        with resolver.resolving("#/a") as resolved:
+            self.assertEqual(resolved, schema["a"])
+        with resolver.resolving("http://bar/schema#/a") as resolved:
+            self.assertEqual(resolved, schema["a"])
+
+    def test_it_retrieves_stored_refs(self):
+        with self.resolver.resolving(self.stored_uri) as resolved:
+            self.assertIs(resolved, self.stored_schema)
+
+        self.resolver.store["cached_ref"] = {"foo": 12}
+        with self.resolver.resolving("cached_ref#/foo") as resolved:
+            self.assertEqual(resolved, 12)
+
+    def test_it_retrieves_unstored_refs_via_requests(self):
+        ref = "http://bar#baz"
+        schema = {"baz": 12}
+
+        if "requests" in sys.modules:
+            self.addCleanup(
+                sys.modules.__setitem__, "requests", sys.modules["requests"],
+            )
+        sys.modules["requests"] = ReallyFakeRequests({"http://bar": schema})
+
+        with self.resolver.resolving(ref) as resolved:
+            self.assertEqual(resolved, 12)
+
+    def test_it_retrieves_unstored_refs_via_urlopen(self):
+        ref = "http://bar#baz"
+        schema = {"baz": 12}
+
+        if "requests" in sys.modules:
+            self.addCleanup(
+                sys.modules.__setitem__, "requests", sys.modules["requests"],
+            )
+        sys.modules["requests"] = None
+
+        @contextmanager
+        def fake_urlopen(url):
+            self.assertEqual(url, "http://bar")
+            yield BytesIO(json.dumps(schema).encode("utf8"))
+
+        self.addCleanup(setattr, validators, "urlopen", validators.urlopen)
+        validators.urlopen = fake_urlopen
+
+        with self.resolver.resolving(ref) as resolved:
+            pass
+        self.assertEqual(resolved, 12)
+
+    def test_it_retrieves_local_refs_via_urlopen(self):
+        with tempfile.NamedTemporaryFile(delete=False, mode="wt") as tempf:
+            self.addCleanup(os.remove, tempf.name)
+            json.dump({"foo": "bar"}, tempf)
+
+        ref = "file://{}#foo".format(pathname2url(tempf.name))
+        with self.resolver.resolving(ref) as resolved:
+            self.assertEqual(resolved, "bar")
+
+    def test_it_can_construct_a_base_uri_from_a_schema(self):
+        schema = {"id": "foo"}
+        resolver = validators.RefResolver.from_schema(
+            schema,
+            id_of=lambda schema: schema.get(u"id", u""),
+        )
+        self.assertEqual(resolver.base_uri, "foo")
+        self.assertEqual(resolver.resolution_scope, "foo")
+        with resolver.resolving("") as resolved:
+            self.assertEqual(resolved, schema)
+        with resolver.resolving("#") as resolved:
+            self.assertEqual(resolved, schema)
+        with resolver.resolving("foo") as resolved:
+            self.assertEqual(resolved, schema)
+        with resolver.resolving("foo#") as resolved:
+            self.assertEqual(resolved, schema)
+
+    def test_it_can_construct_a_base_uri_from_a_schema_without_id(self):
+        schema = {}
+        resolver = validators.RefResolver.from_schema(schema)
+        self.assertEqual(resolver.base_uri, "")
+        self.assertEqual(resolver.resolution_scope, "")
+        with resolver.resolving("") as resolved:
+            self.assertEqual(resolved, schema)
+        with resolver.resolving("#") as resolved:
+            self.assertEqual(resolved, schema)
+
+    def test_custom_uri_scheme_handlers(self):
+        def handler(url):
+            self.assertEqual(url, ref)
+            return schema
+
+        schema = {"foo": "bar"}
+        ref = "foo://bar"
+        resolver = validators.RefResolver("", {}, handlers={"foo": handler})
+        with resolver.resolving(ref) as resolved:
+            self.assertEqual(resolved, schema)
+
+    def test_cache_remote_on(self):
+        response = [object()]
+
+        def handler(url):
+            try:
+                return response.pop()
+            except IndexError:  # pragma: no cover
+                self.fail("Response must not have been cached!")
+
+        ref = "foo://bar"
+        resolver = validators.RefResolver(
+            "", {}, cache_remote=True, handlers={"foo": handler},
+        )
+        with resolver.resolving(ref):
+            pass
+        with resolver.resolving(ref):
+            pass
+
+    def test_cache_remote_off(self):
+        response = [object()]
+
+        def handler(url):
+            try:
+                return response.pop()
+            except IndexError:  # pragma: no cover
+                self.fail("Handler called twice!")
+
+        ref = "foo://bar"
+        resolver = validators.RefResolver(
+            "", {}, cache_remote=False, handlers={"foo": handler},
+        )
+        with resolver.resolving(ref):
+            pass
+
+    def test_if_you_give_it_junk_you_get_a_resolution_error(self):
+        error = ValueError("Oh no! What's this?")
+
+        def handler(url):
+            raise error
+
+        ref = "foo://bar"
+        resolver = validators.RefResolver("", {}, handlers={"foo": handler})
+        with self.assertRaises(exceptions.RefResolutionError) as err:
+            with resolver.resolving(ref):
+                self.fail("Shouldn't get this far!")  # pragma: no cover
+        self.assertEqual(err.exception, exceptions.RefResolutionError(error))
+
+    def test_helpful_error_message_on_failed_pop_scope(self):
+        resolver = validators.RefResolver("", {})
+        resolver.pop_scope()
+        with self.assertRaises(exceptions.RefResolutionError) as exc:
+            resolver.pop_scope()
+        self.assertIn("Failed to pop the scope", str(exc.exception))
+
+
+def sorted_errors(errors):
+    def key(error):
+        return (
+            [str(e) for e in error.path],
+            [str(e) for e in error.schema_path],
+        )
+    return sorted(errors, key=key)
+
+
+@attr.s
+class ReallyFakeRequests(object):
+
+    _responses = attr.ib()
+
+    def get(self, url):
+        response = self._responses.get(url)
+        if url is None:  # pragma: no cover
+            raise ValueError("Unknown URL: " + repr(url))
+        return _ReallyFakeJSONResponse(json.dumps(response))
+
+
+@attr.s
+class _ReallyFakeJSONResponse(object):
+
+    _response = attr.ib()
+
+    def json(self):
+        return json.loads(self._response)
diff --git a/lib/spack/external/_vendoring/jsonschema/validators.py b/lib/spack/external/_vendoring/jsonschema/validators.py
new file mode 100644
index 0000000000..1dc420c70d
--- /dev/null
+++ b/lib/spack/external/_vendoring/jsonschema/validators.py
@@ -0,0 +1,970 @@
+"""
+Creation and extension of validators, with implementations for existing drafts.
+"""
+from __future__ import division
+
+from warnings import warn
+import contextlib
+import json
+import numbers
+
+from six import add_metaclass
+
+from jsonschema import (
+    _legacy_validators,
+    _types,
+    _utils,
+    _validators,
+    exceptions,
+)
+from jsonschema.compat import (
+    Sequence,
+    int_types,
+    iteritems,
+    lru_cache,
+    str_types,
+    unquote,
+    urldefrag,
+    urljoin,
+    urlopen,
+    urlsplit,
+)
+
+# Sigh. https://gitlab.com/pycqa/flake8/issues/280
+#       https://github.com/pyga/ebb-lint/issues/7
+# Imported for backwards compatibility.
+from jsonschema.exceptions import ErrorTree
+ErrorTree
+
+
+class _DontDoThat(Exception):
+    """
+    Raised when a Validators with non-default type checker is misused.
+
+    Asking one for DEFAULT_TYPES doesn't make sense, since type checkers
+    exist for the unrepresentable cases where DEFAULT_TYPES can't
+    represent the type relationship.
+    """
+
+    def __str__(self):
+        return "DEFAULT_TYPES cannot be used on Validators using TypeCheckers"
+
+
+validators = {}
+meta_schemas = _utils.URIDict()
+
+
+def _generate_legacy_type_checks(types=()):
+    """
+    Generate newer-style type checks out of JSON-type-name-to-type mappings.
+
+    Arguments:
+
+        types (dict):
+
+            A mapping of type names to their Python types
+
+    Returns:
+
+        A dictionary of definitions to pass to `TypeChecker`
+    """
+    types = dict(types)
+
+    def gen_type_check(pytypes):
+        pytypes = _utils.flatten(pytypes)
+
+        def type_check(checker, instance):
+            if isinstance(instance, bool):
+                if bool not in pytypes:
+                    return False
+            return isinstance(instance, pytypes)
+
+        return type_check
+
+    definitions = {}
+    for typename, pytypes in iteritems(types):
+        definitions[typename] = gen_type_check(pytypes)
+
+    return definitions
+
+
+_DEPRECATED_DEFAULT_TYPES = {
+    u"array": list,
+    u"boolean": bool,
+    u"integer": int_types,
+    u"null": type(None),
+    u"number": numbers.Number,
+    u"object": dict,
+    u"string": str_types,
+}
+_TYPE_CHECKER_FOR_DEPRECATED_DEFAULT_TYPES = _types.TypeChecker(
+    type_checkers=_generate_legacy_type_checks(_DEPRECATED_DEFAULT_TYPES),
+)
+
+
+def validates(version):
+    """
+    Register the decorated validator for a ``version`` of the specification.
+
+    Registered validators and their meta schemas will be considered when
+    parsing ``$schema`` properties' URIs.
+
+    Arguments:
+
+        version (str):
+
+            An identifier to use as the version's name
+
+    Returns:
+
+        collections.Callable:
+
+            a class decorator to decorate the validator with the version
+    """
+
+    def _validates(cls):
+        validators[version] = cls
+        meta_schema_id = cls.ID_OF(cls.META_SCHEMA)
+        if meta_schema_id:
+            meta_schemas[meta_schema_id] = cls
+        return cls
+    return _validates
+
+
+def _DEFAULT_TYPES(self):
+    if self._CREATED_WITH_DEFAULT_TYPES is None:
+        raise _DontDoThat()
+
+    warn(
+        (
+            "The DEFAULT_TYPES attribute is deprecated. "
+            "See the type checker attached to this validator instead."
+        ),
+        DeprecationWarning,
+        stacklevel=2,
+    )
+    return self._DEFAULT_TYPES
+
+
+class _DefaultTypesDeprecatingMetaClass(type):
+    DEFAULT_TYPES = property(_DEFAULT_TYPES)
+
+
+def _id_of(schema):
+    if schema is True or schema is False:
+        return u""
+    return schema.get(u"$id", u"")
+
+
+def create(
+    meta_schema,
+    validators=(),
+    version=None,
+    default_types=None,
+    type_checker=None,
+    id_of=_id_of,
+):
+    """
+    Create a new validator class.
+
+    Arguments:
+
+        meta_schema (collections.Mapping):
+
+            the meta schema for the new validator class
+
+        validators (collections.Mapping):
+
+            a mapping from names to callables, where each callable will
+            validate the schema property with the given name.
+
+            Each callable should take 4 arguments:
+
+                1. a validator instance,
+                2. the value of the property being validated within the
+                   instance
+                3. the instance
+                4. the schema
+
+        version (str):
+
+            an identifier for the version that this validator class will
+            validate. If provided, the returned validator class will
+            have its ``__name__`` set to include the version, and also
+            will have `jsonschema.validators.validates` automatically
+            called for the given version.
+
+        type_checker (jsonschema.TypeChecker):
+
+            a type checker, used when applying the :validator:`type` validator.
+
+            If unprovided, a `jsonschema.TypeChecker` will be created
+            with a set of default types typical of JSON Schema drafts.
+
+        default_types (collections.Mapping):
+
+            .. deprecated:: 3.0.0
+
+                Please use the type_checker argument instead.
+
+            If set, it provides mappings of JSON types to Python types
+            that will be converted to functions and redefined in this
+            object's `jsonschema.TypeChecker`.
+
+        id_of (collections.Callable):
+
+            A function that given a schema, returns its ID.
+
+    Returns:
+
+        a new `jsonschema.IValidator` class
+    """
+
+    if default_types is not None:
+        if type_checker is not None:
+            raise TypeError(
+                "Do not specify default_types when providing a type checker.",
+            )
+        _created_with_default_types = True
+        warn(
+            (
+                "The default_types argument is deprecated. "
+                "Use the type_checker argument instead."
+            ),
+            DeprecationWarning,
+            stacklevel=2,
+        )
+        type_checker = _types.TypeChecker(
+            type_checkers=_generate_legacy_type_checks(default_types),
+        )
+    else:
+        default_types = _DEPRECATED_DEFAULT_TYPES
+        if type_checker is None:
+            _created_with_default_types = False
+            type_checker = _TYPE_CHECKER_FOR_DEPRECATED_DEFAULT_TYPES
+        elif type_checker is _TYPE_CHECKER_FOR_DEPRECATED_DEFAULT_TYPES:
+            _created_with_default_types = False
+        else:
+            _created_with_default_types = None
+
+    @add_metaclass(_DefaultTypesDeprecatingMetaClass)
+    class Validator(object):
+
+        VALIDATORS = dict(validators)
+        META_SCHEMA = dict(meta_schema)
+        TYPE_CHECKER = type_checker
+        ID_OF = staticmethod(id_of)
+
+        DEFAULT_TYPES = property(_DEFAULT_TYPES)
+        _DEFAULT_TYPES = dict(default_types)
+        _CREATED_WITH_DEFAULT_TYPES = _created_with_default_types
+
+        def __init__(
+            self,
+            schema,
+            types=(),
+            resolver=None,
+            format_checker=None,
+        ):
+            if types:
+                warn(
+                    (
+                        "The types argument is deprecated. Provide "
+                        "a type_checker to jsonschema.validators.extend "
+                        "instead."
+                    ),
+                    DeprecationWarning,
+                    stacklevel=2,
+                )
+
+                self.TYPE_CHECKER = self.TYPE_CHECKER.redefine_many(
+                    _generate_legacy_type_checks(types),
+                )
+
+            if resolver is None:
+                resolver = RefResolver.from_schema(schema, id_of=id_of)
+
+            self.resolver = resolver
+            self.format_checker = format_checker
+            self.schema = schema
+
+        @classmethod
+        def check_schema(cls, schema):
+            for error in cls(cls.META_SCHEMA).iter_errors(schema):
+                raise exceptions.SchemaError.create_from(error)
+
+        def iter_errors(self, instance, _schema=None):
+            if _schema is None:
+                _schema = self.schema
+
+            if _schema is True:
+                return
+            elif _schema is False:
+                yield exceptions.ValidationError(
+                    "False schema does not allow %r" % (instance,),
+                    validator=None,
+                    validator_value=None,
+                    instance=instance,
+                    schema=_schema,
+                )
+                return
+
+            scope = id_of(_schema)
+            if scope:
+                self.resolver.push_scope(scope)
+            try:
+                ref = _schema.get(u"$ref")
+                if ref is not None:
+                    validators = [(u"$ref", ref)]
+                else:
+                    validators = iteritems(_schema)
+
+                for k, v in validators:
+                    validator = self.VALIDATORS.get(k)
+                    if validator is None:
+                        continue
+
+                    errors = validator(self, v, instance, _schema) or ()
+                    for error in errors:
+                        # set details if not already set by the called fn
+                        error._set(
+                            validator=k,
+                            validator_value=v,
+                            instance=instance,
+                            schema=_schema,
+                        )
+                        if k != u"$ref":
+                            error.schema_path.appendleft(k)
+                        yield error
+            finally:
+                if scope:
+                    self.resolver.pop_scope()
+
+        def descend(self, instance, schema, path=None, schema_path=None):
+            for error in self.iter_errors(instance, schema):
+                if path is not None:
+                    error.path.appendleft(path)
+                if schema_path is not None:
+                    error.schema_path.appendleft(schema_path)
+                yield error
+
+        def validate(self, *args, **kwargs):
+            for error in self.iter_errors(*args, **kwargs):
+                raise error
+
+        def is_type(self, instance, type):
+            try:
+                return self.TYPE_CHECKER.is_type(instance, type)
+            except exceptions.UndefinedTypeCheck:
+                raise exceptions.UnknownType(type, instance, self.schema)
+
+        def is_valid(self, instance, _schema=None):
+            error = next(self.iter_errors(instance, _schema), None)
+            return error is None
+
+    if version is not None:
+        Validator = validates(version)(Validator)
+        Validator.__name__ = version.title().replace(" ", "") + "Validator"
+
+    return Validator
+
+
+def extend(validator, validators=(), version=None, type_checker=None):
+    """
+    Create a new validator class by extending an existing one.
+
+    Arguments:
+
+        validator (jsonschema.IValidator):
+
+            an existing validator class
+
+        validators (collections.Mapping):
+
+            a mapping of new validator callables to extend with, whose
+            structure is as in `create`.
+
+            .. note::
+
+                Any validator callables with the same name as an
+                existing one will (silently) replace the old validator
+                callable entirely, effectively overriding any validation
+                done in the "parent" validator class.
+
+                If you wish to instead extend the behavior of a parent's
+                validator callable, delegate and call it directly in
+                the new validator function by retrieving it using
+                ``OldValidator.VALIDATORS["validator_name"]``.
+
+        version (str):
+
+            a version for the new validator class
+
+        type_checker (jsonschema.TypeChecker):
+
+            a type checker, used when applying the :validator:`type` validator.
+
+            If unprovided, the type checker of the extended
+            `jsonschema.IValidator` will be carried along.`
+
+    Returns:
+
+        a new `jsonschema.IValidator` class extending the one provided
+
+    .. note:: Meta Schemas
+
+        The new validator class will have its parent's meta schema.
+
+        If you wish to change or extend the meta schema in the new
+        validator class, modify ``META_SCHEMA`` directly on the returned
+        class. Note that no implicit copying is done, so a copy should
+        likely be made before modifying it, in order to not affect the
+        old validator.
+    """
+
+    all_validators = dict(validator.VALIDATORS)
+    all_validators.update(validators)
+
+    if type_checker is None:
+        type_checker = validator.TYPE_CHECKER
+    elif validator._CREATED_WITH_DEFAULT_TYPES:
+        raise TypeError(
+            "Cannot extend a validator created with default_types "
+            "with a type_checker. Update the validator to use a "
+            "type_checker when created."
+        )
+    return create(
+        meta_schema=validator.META_SCHEMA,
+        validators=all_validators,
+        version=version,
+        type_checker=type_checker,
+        id_of=validator.ID_OF,
+    )
+
+
+Draft3Validator = create(
+    meta_schema=_utils.load_schema("draft3"),
+    validators={
+        u"$ref": _validators.ref,
+        u"additionalItems": _validators.additionalItems,
+        u"additionalProperties": _validators.additionalProperties,
+        u"dependencies": _legacy_validators.dependencies_draft3,
+        u"disallow": _legacy_validators.disallow_draft3,
+        u"divisibleBy": _validators.multipleOf,
+        u"enum": _validators.enum,
+        u"extends": _legacy_validators.extends_draft3,
+        u"format": _validators.format,
+        u"items": _legacy_validators.items_draft3_draft4,
+        u"maxItems": _validators.maxItems,
+        u"maxLength": _validators.maxLength,
+        u"maximum": _legacy_validators.maximum_draft3_draft4,
+        u"minItems": _validators.minItems,
+        u"minLength": _validators.minLength,
+        u"minimum": _legacy_validators.minimum_draft3_draft4,
+        u"pattern": _validators.pattern,
+        u"patternProperties": _validators.patternProperties,
+        u"properties": _legacy_validators.properties_draft3,
+        u"type": _legacy_validators.type_draft3,
+        u"uniqueItems": _validators.uniqueItems,
+    },
+    type_checker=_types.draft3_type_checker,
+    version="draft3",
+    id_of=lambda schema: schema.get(u"id", ""),
+)
+
+Draft4Validator = create(
+    meta_schema=_utils.load_schema("draft4"),
+    validators={
+        u"$ref": _validators.ref,
+        u"additionalItems": _validators.additionalItems,
+        u"additionalProperties": _validators.additionalProperties,
+        u"allOf": _validators.allOf,
+        u"anyOf": _validators.anyOf,
+        u"dependencies": _validators.dependencies,
+        u"enum": _validators.enum,
+        u"format": _validators.format,
+        u"items": _legacy_validators.items_draft3_draft4,
+        u"maxItems": _validators.maxItems,
+        u"maxLength": _validators.maxLength,
+        u"maxProperties": _validators.maxProperties,
+        u"maximum": _legacy_validators.maximum_draft3_draft4,
+        u"minItems": _validators.minItems,
+        u"minLength": _validators.minLength,
+        u"minProperties": _validators.minProperties,
+        u"minimum": _legacy_validators.minimum_draft3_draft4,
+        u"multipleOf": _validators.multipleOf,
+        u"not": _validators.not_,
+        u"oneOf": _validators.oneOf,
+        u"pattern": _validators.pattern,
+        u"patternProperties": _validators.patternProperties,
+        u"properties": _validators.properties,
+        u"required": _validators.required,
+        u"type": _validators.type,
+        u"uniqueItems": _validators.uniqueItems,
+    },
+    type_checker=_types.draft4_type_checker,
+    version="draft4",
+    id_of=lambda schema: schema.get(u"id", ""),
+)
+
+Draft6Validator = create(
+    meta_schema=_utils.load_schema("draft6"),
+    validators={
+        u"$ref": _validators.ref,
+        u"additionalItems": _validators.additionalItems,
+        u"additionalProperties": _validators.additionalProperties,
+        u"allOf": _validators.allOf,
+        u"anyOf": _validators.anyOf,
+        u"const": _validators.const,
+        u"contains": _validators.contains,
+        u"dependencies": _validators.dependencies,
+        u"enum": _validators.enum,
+        u"exclusiveMaximum": _validators.exclusiveMaximum,
+        u"exclusiveMinimum": _validators.exclusiveMinimum,
+        u"format": _validators.format,
+        u"items": _validators.items,
+        u"maxItems": _validators.maxItems,
+        u"maxLength": _validators.maxLength,
+        u"maxProperties": _validators.maxProperties,
+        u"maximum": _validators.maximum,
+        u"minItems": _validators.minItems,
+        u"minLength": _validators.minLength,
+        u"minProperties": _validators.minProperties,
+        u"minimum": _validators.minimum,
+        u"multipleOf": _validators.multipleOf,
+        u"not": _validators.not_,
+        u"oneOf": _validators.oneOf,
+        u"pattern": _validators.pattern,
+        u"patternProperties": _validators.patternProperties,
+        u"properties": _validators.properties,
+        u"propertyNames": _validators.propertyNames,
+        u"required": _validators.required,
+        u"type": _validators.type,
+        u"uniqueItems": _validators.uniqueItems,
+    },
+    type_checker=_types.draft6_type_checker,
+    version="draft6",
+)
+
+Draft7Validator = create(
+    meta_schema=_utils.load_schema("draft7"),
+    validators={
+        u"$ref": _validators.ref,
+        u"additionalItems": _validators.additionalItems,
+        u"additionalProperties": _validators.additionalProperties,
+        u"allOf": _validators.allOf,
+        u"anyOf": _validators.anyOf,
+        u"const": _validators.const,
+        u"contains": _validators.contains,
+        u"dependencies": _validators.dependencies,
+        u"enum": _validators.enum,
+        u"exclusiveMaximum": _validators.exclusiveMaximum,
+        u"exclusiveMinimum": _validators.exclusiveMinimum,
+        u"format": _validators.format,
+        u"if": _validators.if_,
+        u"items": _validators.items,
+        u"maxItems": _validators.maxItems,
+        u"maxLength": _validators.maxLength,
+        u"maxProperties": _validators.maxProperties,
+        u"maximum": _validators.maximum,
+        u"minItems": _validators.minItems,
+        u"minLength": _validators.minLength,
+        u"minProperties": _validators.minProperties,
+        u"minimum": _validators.minimum,
+        u"multipleOf": _validators.multipleOf,
+        u"oneOf": _validators.oneOf,
+        u"not": _validators.not_,
+        u"pattern": _validators.pattern,
+        u"patternProperties": _validators.patternProperties,
+        u"properties": _validators.properties,
+        u"propertyNames": _validators.propertyNames,
+        u"required": _validators.required,
+        u"type": _validators.type,
+        u"uniqueItems": _validators.uniqueItems,
+    },
+    type_checker=_types.draft7_type_checker,
+    version="draft7",
+)
+
+_LATEST_VERSION = Draft7Validator
+
+
+class RefResolver(object):
+    """
+    Resolve JSON References.
+
+    Arguments:
+
+        base_uri (str):
+
+            The URI of the referring document
+
+        referrer:
+
+            The actual referring document
+
+        store (dict):
+
+            A mapping from URIs to documents to cache
+
+        cache_remote (bool):
+
+            Whether remote refs should be cached after first resolution
+
+        handlers (dict):
+
+            A mapping from URI schemes to functions that should be used
+            to retrieve them
+
+        urljoin_cache (:func:`functools.lru_cache`):
+
+            A cache that will be used for caching the results of joining
+            the resolution scope to subscopes.
+
+        remote_cache (:func:`functools.lru_cache`):
+
+            A cache that will be used for caching the results of
+            resolved remote URLs.
+
+    Attributes:
+
+        cache_remote (bool):
+
+            Whether remote refs should be cached after first resolution
+    """
+
+    def __init__(
+        self,
+        base_uri,
+        referrer,
+        store=(),
+        cache_remote=True,
+        handlers=(),
+        urljoin_cache=None,
+        remote_cache=None,
+    ):
+        if urljoin_cache is None:
+            urljoin_cache = lru_cache(1024)(urljoin)
+        if remote_cache is None:
+            remote_cache = lru_cache(1024)(self.resolve_from_url)
+
+        self.referrer = referrer
+        self.cache_remote = cache_remote
+        self.handlers = dict(handlers)
+
+        self._scopes_stack = [base_uri]
+        self.store = _utils.URIDict(
+            (id, validator.META_SCHEMA)
+            for id, validator in iteritems(meta_schemas)
+        )
+        self.store.update(store)
+        self.store[base_uri] = referrer
+
+        self._urljoin_cache = urljoin_cache
+        self._remote_cache = remote_cache
+
+    @classmethod
+    def from_schema(cls, schema, id_of=_id_of, *args, **kwargs):
+        """
+        Construct a resolver from a JSON schema object.
+
+        Arguments:
+
+            schema:
+
+                the referring schema
+
+        Returns:
+
+            `RefResolver`
+        """
+
+        return cls(base_uri=id_of(schema), referrer=schema, *args, **kwargs)
+
+    def push_scope(self, scope):
+        """
+        Enter a given sub-scope.
+
+        Treats further dereferences as being performed underneath the
+        given scope.
+        """
+        self._scopes_stack.append(
+            self._urljoin_cache(self.resolution_scope, scope),
+        )
+
+    def pop_scope(self):
+        """
+        Exit the most recent entered scope.
+
+        Treats further dereferences as being performed underneath the
+        original scope.
+
+        Don't call this method more times than `push_scope` has been
+        called.
+        """
+        try:
+            self._scopes_stack.pop()
+        except IndexError:
+            raise exceptions.RefResolutionError(
+                "Failed to pop the scope from an empty stack. "
+                "`pop_scope()` should only be called once for every "
+                "`push_scope()`"
+            )
+
+    @property
+    def resolution_scope(self):
+        """
+        Retrieve the current resolution scope.
+        """
+        return self._scopes_stack[-1]
+
+    @property
+    def base_uri(self):
+        """
+        Retrieve the current base URI, not including any fragment.
+        """
+        uri, _ = urldefrag(self.resolution_scope)
+        return uri
+
+    @contextlib.contextmanager
+    def in_scope(self, scope):
+        """
+        Temporarily enter the given scope for the duration of the context.
+        """
+        self.push_scope(scope)
+        try:
+            yield
+        finally:
+            self.pop_scope()
+
+    @contextlib.contextmanager
+    def resolving(self, ref):
+        """
+        Resolve the given ``ref`` and enter its resolution scope.
+
+        Exits the scope on exit of this context manager.
+
+        Arguments:
+
+            ref (str):
+
+                The reference to resolve
+        """
+
+        url, resolved = self.resolve(ref)
+        self.push_scope(url)
+        try:
+            yield resolved
+        finally:
+            self.pop_scope()
+
+    def resolve(self, ref):
+        """
+        Resolve the given reference.
+        """
+        url = self._urljoin_cache(self.resolution_scope, ref)
+        return url, self._remote_cache(url)
+
+    def resolve_from_url(self, url):
+        """
+        Resolve the given remote URL.
+        """
+        url, fragment = urldefrag(url)
+        try:
+            document = self.store[url]
+        except KeyError:
+            try:
+                document = self.resolve_remote(url)
+            except Exception as exc:
+                raise exceptions.RefResolutionError(exc)
+
+        return self.resolve_fragment(document, fragment)
+
+    def resolve_fragment(self, document, fragment):
+        """
+        Resolve a ``fragment`` within the referenced ``document``.
+
+        Arguments:
+
+            document:
+
+                The referent document
+
+            fragment (str):
+
+                a URI fragment to resolve within it
+        """
+
+        fragment = fragment.lstrip(u"/")
+        parts = unquote(fragment).split(u"/") if fragment else []
+
+        for part in parts:
+            part = part.replace(u"~1", u"/").replace(u"~0", u"~")
+
+            if isinstance(document, Sequence):
+                # Array indexes should be turned into integers
+                try:
+                    part = int(part)
+                except ValueError:
+                    pass
+            try:
+                document = document[part]
+            except (TypeError, LookupError):
+                raise exceptions.RefResolutionError(
+                    "Unresolvable JSON pointer: %r" % fragment
+                )
+
+        return document
+
+    def resolve_remote(self, uri):
+        """
+        Resolve a remote ``uri``.
+
+        If called directly, does not check the store first, but after
+        retrieving the document at the specified URI it will be saved in
+        the store if :attr:`cache_remote` is True.
+
+        .. note::
+
+            If the requests_ library is present, ``jsonschema`` will use it to
+            request the remote ``uri``, so that the correct encoding is
+            detected and used.
+
+            If it isn't, or if the scheme of the ``uri`` is not ``http`` or
+            ``https``, UTF-8 is assumed.
+
+        Arguments:
+
+            uri (str):
+
+                The URI to resolve
+
+        Returns:
+
+            The retrieved document
+
+        .. _requests: https://pypi.org/project/requests/
+        """
+        try:
+            import requests
+        except ImportError:
+            requests = None
+
+        scheme = urlsplit(uri).scheme
+
+        if scheme in self.handlers:
+            result = self.handlers[scheme](uri)
+        elif scheme in [u"http", u"https"] and requests:
+            # Requests has support for detecting the correct encoding of
+            # json over http
+            result = requests.get(uri).json()
+        else:
+            # Otherwise, pass off to urllib and assume utf-8
+            with urlopen(uri) as url:
+                result = json.loads(url.read().decode("utf-8"))
+
+        if self.cache_remote:
+            self.store[uri] = result
+        return result
+
+
+def validate(instance, schema, cls=None, *args, **kwargs):
+    """
+    Validate an instance under the given schema.
+
+        >>> validate([2, 3, 4], {"maxItems": 2})
+        Traceback (most recent call last):
+            ...
+        ValidationError: [2, 3, 4] is too long
+
+    :func:`validate` will first verify that the provided schema is
+    itself valid, since not doing so can lead to less obvious error
+    messages and fail in less obvious or consistent ways.
+
+    If you know you have a valid schema already, especially if you
+    intend to validate multiple instances with the same schema, you
+    likely would prefer using the `IValidator.validate` method directly
+    on a specific validator (e.g. ``Draft7Validator.validate``).
+
+
+    Arguments:
+
+        instance:
+
+            The instance to validate
+
+        schema:
+
+            The schema to validate with
+
+        cls (IValidator):
+
+            The class that will be used to validate the instance.
+
+    If the ``cls`` argument is not provided, two things will happen
+    in accordance with the specification. First, if the schema has a
+    :validator:`$schema` property containing a known meta-schema [#]_
+    then the proper validator will be used. The specification recommends
+    that all schemas contain :validator:`$schema` properties for this
+    reason. If no :validator:`$schema` property is found, the default
+    validator class is the latest released draft.
+
+    Any other provided positional and keyword arguments will be passed
+    on when instantiating the ``cls``.
+
+    Raises:
+
+        `jsonschema.exceptions.ValidationError` if the instance
+            is invalid
+
+        `jsonschema.exceptions.SchemaError` if the schema itself
+            is invalid
+
+    .. rubric:: Footnotes
+    .. [#] known by a validator registered with
+        `jsonschema.validators.validates`
+    """
+    if cls is None:
+        cls = validator_for(schema)
+
+    cls.check_schema(schema)
+    validator = cls(schema, *args, **kwargs)
+    error = exceptions.best_match(validator.iter_errors(instance))
+    if error is not None:
+        raise error
+
+
+def validator_for(schema, default=_LATEST_VERSION):
+    """
+    Retrieve the validator class appropriate for validating the given schema.
+
+    Uses the :validator:`$schema` property that should be present in the
+    given schema to look up the appropriate validator class.
+
+    Arguments:
+
+        schema (collections.Mapping or bool):
+
+            the schema to look at
+
+        default:
+
+            the default to return if the appropriate validator class
+            cannot be determined.
+
+            If unprovided, the default is to return the latest supported
+            draft.
+    """
+    if schema is True or schema is False or u"$schema" not in schema:
+        return default
+    if schema[u"$schema"] not in meta_schemas:
+        warn(
+            (
+                "The metaschema specified by $schema was not found. "
+                "Using the latest draft to validate, but this will raise "
+                "an error in the future."
+            ),
+            DeprecationWarning,
+            stacklevel=2,
+        )
+    return meta_schemas.get(schema[u"$schema"], _LATEST_VERSION)
diff --git a/lib/spack/external/_vendoring/macholib.pyi b/lib/spack/external/_vendoring/macholib.pyi
new file mode 100644
index 0000000000..62ac8a00a3
--- /dev/null
+++ b/lib/spack/external/_vendoring/macholib.pyi
@@ -0,0 +1 @@
+from macholib import *
\ No newline at end of file
diff --git a/lib/spack/external/_vendoring/macholib/LICENSE b/lib/spack/external/_vendoring/macholib/LICENSE
new file mode 100644
index 0000000000..602dbb0948
--- /dev/null
+++ b/lib/spack/external/_vendoring/macholib/LICENSE
@@ -0,0 +1,21 @@
+Copyright 2006-2010 - Bob Ippolito
+Copyright 2010-2020 - Ronald Oussoren
+
+ Permission is hereby granted, free of charge, to any person obtaining
+ a copy of this software and associated documentation files (the
+ "Software"), to deal in the Software without restriction, including
+ without limitation the rights to use, copy, modify, merge, publish,
+ distribute, sublicense, and/or sell copies of the Software, and to
+ permit persons to whom the Software is furnished to do so, subject
+ to the following conditions:
+
+ The above copyright notice and this permission notice shall be
+ included in all copies or substantial portions of the Software.
+
+ THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+ IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+ CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+ TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+ SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
diff --git a/lib/spack/external/_vendoring/macholib/MachO.py b/lib/spack/external/_vendoring/macholib/MachO.py
new file mode 100644
index 0000000000..daa36b0d3c
--- /dev/null
+++ b/lib/spack/external/_vendoring/macholib/MachO.py
@@ -0,0 +1,501 @@
+"""
+Utilities for reading and writing Mach-O headers
+"""
+from __future__ import print_function
+
+import os
+import struct
+import sys
+
+from macholib.util import fileview
+
+from .mach_o import (
+    FAT_MAGIC,
+    FAT_MAGIC_64,
+    LC_DYSYMTAB,
+    LC_ID_DYLIB,
+    LC_LOAD_DYLIB,
+    LC_LOAD_UPWARD_DYLIB,
+    LC_LOAD_WEAK_DYLIB,
+    LC_PREBOUND_DYLIB,
+    LC_REEXPORT_DYLIB,
+    LC_REGISTRY,
+    LC_SEGMENT,
+    LC_SEGMENT_64,
+    LC_SYMTAB,
+    MH_CIGAM,
+    MH_CIGAM_64,
+    MH_FILETYPE_SHORTNAMES,
+    MH_MAGIC,
+    MH_MAGIC_64,
+    S_ZEROFILL,
+    fat_arch,
+    fat_arch64,
+    fat_header,
+    load_command,
+    mach_header,
+    mach_header_64,
+    section,
+    section_64,
+)
+from .ptypes import sizeof
+
+try:
+    from macholib.compat import bytes
+except ImportError:
+    pass
+
+try:
+    unicode
+except NameError:
+    unicode = str
+
+if sys.version_info[0] == 2:
+    range = xrange  # noqa: F821
+
+__all__ = ["MachO"]
+
+_RELOCATABLE = {
+    # relocatable commands that should be used for dependency walking
+    LC_LOAD_DYLIB,
+    LC_LOAD_UPWARD_DYLIB,
+    LC_LOAD_WEAK_DYLIB,
+    LC_PREBOUND_DYLIB,
+    LC_REEXPORT_DYLIB,
+}
+
+_RELOCATABLE_NAMES = {
+    LC_LOAD_DYLIB: "load_dylib",
+    LC_LOAD_UPWARD_DYLIB: "load_upward_dylib",
+    LC_LOAD_WEAK_DYLIB: "load_weak_dylib",
+    LC_PREBOUND_DYLIB: "prebound_dylib",
+    LC_REEXPORT_DYLIB: "reexport_dylib",
+}
+
+
+def _shouldRelocateCommand(cmd):
+    """
+    Should this command id be investigated for relocation?
+    """
+    return cmd in _RELOCATABLE
+
+
+def lc_str_value(offset, cmd_info):
+    """
+    Fetch the actual value of a field of type "lc_str"
+    """
+    cmd_load, cmd_cmd, cmd_data = cmd_info
+
+    offset -= sizeof(cmd_load) + sizeof(cmd_cmd)
+    return cmd_data[offset:].strip(b"\x00")
+
+
+class MachO(object):
+    """
+    Provides reading/writing the Mach-O header of a specific existing file.
+
+    If allow_unknown_load_commands is True, allows unknown load commands.
+    Otherwise, raises ValueError if the file contains an unknown load command.
+    """
+
+    #   filename   - the original filename of this mach-o
+    #   sizediff   - the current deviation from the initial mach-o size
+    #   header     - the mach-o header
+    #   commands   - a list of (load_command, somecommand, data)
+    #                data is either a str, or a list of segment structures
+    #   total_size - the current mach-o header size (including header)
+    #   low_offset - essentially, the maximum mach-o header size
+    #   id_cmd     - the index of my id command, or None
+
+    def __init__(self, filename, allow_unknown_load_commands=False):
+
+        # supports the ObjectGraph protocol
+        self.graphident = filename
+        self.filename = filename
+        self.loader_path = os.path.dirname(filename)
+
+        # initialized by load
+        self.fat = None
+        self.headers = []
+        self.allow_unknown_load_commands = allow_unknown_load_commands
+        with open(filename, "rb") as fp:
+            self.load(fp)
+
+    def __repr__(self):
+        return "<MachO filename=%r>" % (self.filename,)
+
+    def load(self, fh):
+        assert fh.tell() == 0
+        header = struct.unpack(">I", fh.read(4))[0]
+        fh.seek(0)
+        if header in (FAT_MAGIC, FAT_MAGIC_64):
+            self.load_fat(fh)
+        else:
+            fh.seek(0, 2)
+            size = fh.tell()
+            fh.seek(0)
+            self.load_header(fh, 0, size)
+
+    def load_fat(self, fh):
+        self.fat = fat_header.from_fileobj(fh)
+        if self.fat.magic == FAT_MAGIC:
+            archs = [fat_arch.from_fileobj(fh) for i in range(self.fat.nfat_arch)]
+        elif self.fat.magic == FAT_MAGIC_64:
+            archs = [fat_arch64.from_fileobj(fh) for i in range(self.fat.nfat_arch)]
+        else:
+            raise ValueError("Unknown fat header magic: %r" % (self.fat.magic))
+
+        for arch in archs:
+            self.load_header(fh, arch.offset, arch.size)
+
+    def rewriteLoadCommands(self, *args, **kw):
+        changed = False
+        for header in self.headers:
+            if header.rewriteLoadCommands(*args, **kw):
+                changed = True
+        return changed
+
+    def load_header(self, fh, offset, size):
+        fh.seek(offset)
+        header = struct.unpack(">I", fh.read(4))[0]
+        fh.seek(offset)
+        if header == MH_MAGIC:
+            magic, hdr, endian = MH_MAGIC, mach_header, ">"
+        elif header == MH_CIGAM:
+            magic, hdr, endian = MH_CIGAM, mach_header, "<"
+        elif header == MH_MAGIC_64:
+            magic, hdr, endian = MH_MAGIC_64, mach_header_64, ">"
+        elif header == MH_CIGAM_64:
+            magic, hdr, endian = MH_CIGAM_64, mach_header_64, "<"
+        else:
+            raise ValueError("Unknown Mach-O header: 0x%08x in %r" % (header, fh))
+        hdr = MachOHeader(
+            self, fh, offset, size, magic, hdr, endian, self.allow_unknown_load_commands
+        )
+        self.headers.append(hdr)
+
+    def write(self, f):
+        for header in self.headers:
+            header.write(f)
+
+
+class MachOHeader(object):
+    """
+    Provides reading/writing the Mach-O header of a specific existing file.
+
+    If allow_unknown_load_commands is True, allows unknown load commands.
+    Otherwise, raises ValueError if the file contains an unknown load command.
+    """
+
+    #   filename   - the original filename of this mach-o
+    #   sizediff   - the current deviation from the initial mach-o size
+    #   header     - the mach-o header
+    #   commands   - a list of (load_command, somecommand, data)
+    #                data is either a str, or a list of segment structures
+    #   total_size - the current mach-o header size (including header)
+    #   low_offset - essentially, the maximum mach-o header size
+    #   id_cmd     - the index of my id command, or None
+
+    def __init__(
+        self,
+        parent,
+        fh,
+        offset,
+        size,
+        magic,
+        hdr,
+        endian,
+        allow_unknown_load_commands=False,
+    ):
+        self.MH_MAGIC = magic
+        self.mach_header = hdr
+
+        # These are all initialized by self.load()
+        self.parent = parent
+        self.offset = offset
+        self.size = size
+
+        self.endian = endian
+        self.header = None
+        self.commands = None
+        self.id_cmd = None
+        self.sizediff = None
+        self.total_size = None
+        self.low_offset = None
+        self.filetype = None
+        self.headers = []
+
+        self.allow_unknown_load_commands = allow_unknown_load_commands
+
+        self.load(fh)
+
+    def __repr__(self):
+        return "<%s filename=%r offset=%d size=%d endian=%r>" % (
+            type(self).__name__,
+            self.parent.filename,
+            self.offset,
+            self.size,
+            self.endian,
+        )
+
+    def load(self, fh):
+        fh = fileview(fh, self.offset, self.size)
+        fh.seek(0)
+
+        self.sizediff = 0
+        kw = {"_endian_": self.endian}
+        header = self.mach_header.from_fileobj(fh, **kw)
+        self.header = header
+        # if header.magic != self.MH_MAGIC:
+        #    raise ValueError("header has magic %08x, expecting %08x" % (
+        #        header.magic, self.MH_MAGIC))
+
+        cmd = self.commands = []
+
+        self.filetype = self.get_filetype_shortname(header.filetype)
+
+        read_bytes = 0
+        low_offset = sys.maxsize
+        for i in range(header.ncmds):
+            # read the load command
+            cmd_load = load_command.from_fileobj(fh, **kw)
+
+            # read the specific command
+            klass = LC_REGISTRY.get(cmd_load.cmd, None)
+            if klass is None:
+                if not self.allow_unknown_load_commands:
+                    raise ValueError("Unknown load command: %d" % (cmd_load.cmd,))
+                # No load command in the registry, so append the load command itself
+                # instead of trying to deserialize the data after the header.
+                data_size = cmd_load.cmdsize - sizeof(load_command)
+                cmd_data = fh.read(data_size)
+                cmd.append((cmd_load, cmd_load, cmd_data))
+                read_bytes += cmd_load.cmdsize
+                continue
+
+            cmd_cmd = klass.from_fileobj(fh, **kw)
+
+            if cmd_load.cmd == LC_ID_DYLIB:
+                # remember where this command was
+                if self.id_cmd is not None:
+                    raise ValueError("This dylib already has an id")
+                self.id_cmd = i
+
+            if cmd_load.cmd in (LC_SEGMENT, LC_SEGMENT_64):
+                # for segment commands, read the list of segments
+                segs = []
+                # assert that the size makes sense
+                if cmd_load.cmd == LC_SEGMENT:
+                    section_cls = section
+                else:  # LC_SEGMENT_64
+                    section_cls = section_64
+
+                expected_size = (
+                    sizeof(klass)
+                    + sizeof(load_command)
+                    + (sizeof(section_cls) * cmd_cmd.nsects)
+                )
+                if cmd_load.cmdsize != expected_size:
+                    raise ValueError("Segment size mismatch")
+                # this is a zero block or something
+                # so the beginning is wherever the fileoff of this command is
+                if cmd_cmd.nsects == 0:
+                    if cmd_cmd.filesize != 0:
+                        low_offset = min(low_offset, cmd_cmd.fileoff)
+                else:
+                    # this one has multiple segments
+                    for _j in range(cmd_cmd.nsects):
+                        # read the segment
+                        seg = section_cls.from_fileobj(fh, **kw)
+                        # if the segment has a size and is not zero filled
+                        # then its beginning is the offset of this segment
+                        not_zerofill = (seg.flags & S_ZEROFILL) != S_ZEROFILL
+                        if seg.offset > 0 and seg.size > 0 and not_zerofill:
+                            low_offset = min(low_offset, seg.offset)
+                        if not_zerofill:
+                            c = fh.tell()
+                            fh.seek(seg.offset)
+                            sd = fh.read(seg.size)
+                            seg.add_section_data(sd)
+                            fh.seek(c)
+                        segs.append(seg)
+                # data is a list of segments
+                cmd_data = segs
+
+            # These are disabled for now because writing back doesn't work
+            # elif cmd_load.cmd == LC_CODE_SIGNATURE:
+            #    c = fh.tell()
+            #    fh.seek(cmd_cmd.dataoff)
+            #    cmd_data = fh.read(cmd_cmd.datasize)
+            #    fh.seek(c)
+            # elif cmd_load.cmd == LC_SYMTAB:
+            #    c = fh.tell()
+            #    fh.seek(cmd_cmd.stroff)
+            #    cmd_data = fh.read(cmd_cmd.strsize)
+            #    fh.seek(c)
+
+            else:
+                # data is a raw str
+                data_size = cmd_load.cmdsize - sizeof(klass) - sizeof(load_command)
+                cmd_data = fh.read(data_size)
+            cmd.append((cmd_load, cmd_cmd, cmd_data))
+            read_bytes += cmd_load.cmdsize
+
+        # make sure the header made sense
+        if read_bytes != header.sizeofcmds:
+            raise ValueError(
+                "Read %d bytes, header reports %d bytes"
+                % (read_bytes, header.sizeofcmds)
+            )
+        self.total_size = sizeof(self.mach_header) + read_bytes
+        self.low_offset = low_offset
+
+    def walkRelocatables(self, shouldRelocateCommand=_shouldRelocateCommand):
+        """
+        for all relocatable commands
+        yield (command_index, command_name, filename)
+        """
+        for (idx, (lc, cmd, data)) in enumerate(self.commands):
+            if shouldRelocateCommand(lc.cmd):
+                name = _RELOCATABLE_NAMES[lc.cmd]
+                ofs = cmd.name - sizeof(lc.__class__) - sizeof(cmd.__class__)
+                yield idx, name, data[
+                    ofs : data.find(b"\x00", ofs)  # noqa: E203
+                ].decode(sys.getfilesystemencoding())
+
+    def rewriteInstallNameCommand(self, loadcmd):
+        """Rewrite the load command of this dylib"""
+        if self.id_cmd is not None:
+            self.rewriteDataForCommand(self.id_cmd, loadcmd)
+            return True
+        return False
+
+    def changedHeaderSizeBy(self, bytes):
+        self.sizediff += bytes
+        if (self.total_size + self.sizediff) > self.low_offset:
+            print(
+                "WARNING: Mach-O header in %r may be too large to relocate"
+                % (self.parent.filename,)
+            )
+
+    def rewriteLoadCommands(self, changefunc):
+        """
+        Rewrite the load commands based upon a change dictionary
+        """
+        data = changefunc(self.parent.filename)
+        changed = False
+        if data is not None:
+            if self.rewriteInstallNameCommand(data.encode(sys.getfilesystemencoding())):
+                changed = True
+        for idx, _name, filename in self.walkRelocatables():
+            data = changefunc(filename)
+            if data is not None:
+                if self.rewriteDataForCommand(
+                    idx, data.encode(sys.getfilesystemencoding())
+                ):
+                    changed = True
+        return changed
+
+    def rewriteDataForCommand(self, idx, data):
+        lc, cmd, old_data = self.commands[idx]
+        hdrsize = sizeof(lc.__class__) + sizeof(cmd.__class__)
+        align = struct.calcsize("Q")
+        data = data + (b"\x00" * (align - (len(data) % align)))
+        newsize = hdrsize + len(data)
+        self.commands[idx] = (lc, cmd, data)
+        self.changedHeaderSizeBy(newsize - lc.cmdsize)
+        lc.cmdsize, cmd.name = newsize, hdrsize
+        return True
+
+    def synchronize_size(self):
+        if (self.total_size + self.sizediff) > self.low_offset:
+            raise ValueError(
+                (
+                    "New Mach-O header is too large to relocate in %r "
+                    "(new size=%r, max size=%r, delta=%r)"
+                )
+                % (
+                    self.parent.filename,
+                    self.total_size + self.sizediff,
+                    self.low_offset,
+                    self.sizediff,
+                )
+            )
+        self.header.sizeofcmds += self.sizediff
+        self.total_size = sizeof(self.mach_header) + self.header.sizeofcmds
+        self.sizediff = 0
+
+    def write(self, fileobj):
+        fileobj = fileview(fileobj, self.offset, self.size)
+        fileobj.seek(0)
+
+        # serialize all the mach-o commands
+        self.synchronize_size()
+
+        self.header.to_fileobj(fileobj)
+        for lc, cmd, data in self.commands:
+            lc.to_fileobj(fileobj)
+            cmd.to_fileobj(fileobj)
+
+            if sys.version_info[0] == 2:
+                if isinstance(data, unicode):
+                    fileobj.write(data.encode(sys.getfilesystemencoding()))
+
+                elif isinstance(data, (bytes, str)):
+                    fileobj.write(data)
+                else:
+                    # segments..
+                    for obj in data:
+                        obj.to_fileobj(fileobj)
+            else:
+                if isinstance(data, str):
+                    fileobj.write(data.encode(sys.getfilesystemencoding()))
+
+                elif isinstance(data, bytes):
+                    fileobj.write(data)
+
+                else:
+                    # segments..
+                    for obj in data:
+                        obj.to_fileobj(fileobj)
+
+        # zero out the unused space, doubt this is strictly necessary
+        # and is generally probably already the case
+        fileobj.write(b"\x00" * (self.low_offset - fileobj.tell()))
+
+    def getSymbolTableCommand(self):
+        for lc, cmd, _data in self.commands:
+            if lc.cmd == LC_SYMTAB:
+                return cmd
+        return None
+
+    def getDynamicSymbolTableCommand(self):
+        for lc, cmd, _data in self.commands:
+            if lc.cmd == LC_DYSYMTAB:
+                return cmd
+        return None
+
+    def get_filetype_shortname(self, filetype):
+        if filetype in MH_FILETYPE_SHORTNAMES:
+            return MH_FILETYPE_SHORTNAMES[filetype]
+        else:
+            return "unknown"
+
+
+def main(fn):
+    m = MachO(fn)
+    seen = set()
+    for header in m.headers:
+        for _idx, name, other in header.walkRelocatables():
+            if other not in seen:
+                seen.add(other)
+                print("\t" + name + ": " + other)
+
+
+if __name__ == "__main__":
+    import sys
+
+    files = sys.argv[1:] or ["/bin/ls"]
+    for fn in files:
+        print(fn)
+        main(fn)
diff --git a/lib/spack/external/_vendoring/macholib/MachOGraph.py b/lib/spack/external/_vendoring/macholib/MachOGraph.py
new file mode 100644
index 0000000000..8943ed8bd3
--- /dev/null
+++ b/lib/spack/external/_vendoring/macholib/MachOGraph.py
@@ -0,0 +1,141 @@
+"""
+Utilities for reading and writing Mach-O headers
+"""
+
+import os
+import sys
+
+from altgraph.ObjectGraph import ObjectGraph
+
+from macholib.dyld import dyld_find
+from macholib.itergraphreport import itergraphreport
+from macholib.MachO import MachO
+
+__all__ = ["MachOGraph"]
+
+try:
+    unicode
+except NameError:
+    unicode = str
+
+
+class MissingMachO(object):
+    def __init__(self, filename):
+        self.graphident = filename
+        self.headers = ()
+
+    def __repr__(self):
+        return "<%s graphident=%r>" % (type(self).__name__, self.graphident)
+
+
+class MachOGraph(ObjectGraph):
+    """
+    Graph data structure of Mach-O dependencies
+    """
+
+    def __init__(self, debug=0, graph=None, env=None, executable_path=None):
+        super(MachOGraph, self).__init__(debug=debug, graph=graph)
+        self.env = env
+        self.trans_table = {}
+        self.executable_path = executable_path
+
+    def locate(self, filename, loader=None):
+        if not isinstance(filename, (str, unicode)):
+            raise TypeError("%r is not a string" % (filename,))
+        if filename.startswith("@loader_path/") and loader is not None:
+            fn = self.trans_table.get((loader.filename, filename))
+            if fn is None:
+                loader_path = loader.loader_path
+
+                try:
+                    fn = dyld_find(
+                        filename,
+                        env=self.env,
+                        executable_path=self.executable_path,
+                        loader_path=loader_path,
+                    )
+                    self.trans_table[(loader.filename, filename)] = fn
+                except ValueError:
+                    return None
+
+        else:
+            fn = self.trans_table.get(filename)
+            if fn is None:
+                try:
+                    fn = dyld_find(
+                        filename, env=self.env, executable_path=self.executable_path
+                    )
+                    self.trans_table[filename] = fn
+                except ValueError:
+                    return None
+        return fn
+
+    def findNode(self, name, loader=None):
+        assert isinstance(name, (str, unicode))
+        data = super(MachOGraph, self).findNode(name)
+        if data is not None:
+            return data
+        newname = self.locate(name, loader=loader)
+        if newname is not None and newname != name:
+            return self.findNode(newname)
+        return None
+
+    def run_file(self, pathname, caller=None):
+        assert isinstance(pathname, (str, unicode))
+        self.msgin(2, "run_file", pathname)
+        m = self.findNode(pathname, loader=caller)
+        if m is None:
+            if not os.path.exists(pathname):
+                raise ValueError("%r does not exist" % (pathname,))
+            m = self.createNode(MachO, pathname)
+            self.createReference(caller, m, edge_data="run_file")
+            self.scan_node(m)
+        self.msgout(2, "")
+        return m
+
+    def load_file(self, name, caller=None):
+        assert isinstance(name, (str, unicode))
+        self.msgin(2, "load_file", name, caller)
+        m = self.findNode(name, loader=caller)
+        if m is None:
+            newname = self.locate(name, loader=caller)
+            if newname is not None and newname != name:
+                return self.load_file(newname, caller=caller)
+            if os.path.exists(name):
+                m = self.createNode(MachO, name)
+                self.scan_node(m)
+            else:
+                m = self.createNode(MissingMachO, name)
+        self.msgout(2, "")
+        return m
+
+    def scan_node(self, node):
+        self.msgin(2, "scan_node", node)
+        for header in node.headers:
+            for _idx, name, filename in header.walkRelocatables():
+                assert isinstance(name, (str, unicode))
+                assert isinstance(filename, (str, unicode))
+                m = self.load_file(filename, caller=node)
+                self.createReference(node, m, edge_data=name)
+        self.msgout(2, "", node)
+
+    def itergraphreport(self, name="G"):
+        nodes = map(self.graph.describe_node, self.graph.iterdfs(self))
+        describe_edge = self.graph.describe_edge
+        return itergraphreport(nodes, describe_edge, name=name)
+
+    def graphreport(self, fileobj=None):
+        if fileobj is None:
+            fileobj = sys.stdout
+        fileobj.writelines(self.itergraphreport())
+
+
+def main(args):
+    g = MachOGraph()
+    for arg in args:
+        g.run_file(arg)
+    g.graphreport()
+
+
+if __name__ == "__main__":
+    main(sys.argv[1:] or ["/bin/ls"])
diff --git a/lib/spack/external/_vendoring/macholib/MachOStandalone.py b/lib/spack/external/_vendoring/macholib/MachOStandalone.py
new file mode 100644
index 0000000000..6ce154227c
--- /dev/null
+++ b/lib/spack/external/_vendoring/macholib/MachOStandalone.py
@@ -0,0 +1,173 @@
+import os
+from collections import deque
+
+from macholib.dyld import framework_info
+from macholib.MachOGraph import MachOGraph, MissingMachO
+from macholib.util import (
+    flipwritable,
+    has_filename_filter,
+    in_system_path,
+    iter_platform_files,
+    mergecopy,
+    mergetree,
+)
+
+
+class ExcludedMachO(MissingMachO):
+    pass
+
+
+class FilteredMachOGraph(MachOGraph):
+    def __init__(self, delegate, *args, **kwargs):
+        super(FilteredMachOGraph, self).__init__(*args, **kwargs)
+        self.delegate = delegate
+
+    def createNode(self, cls, name):
+        cls = self.delegate.getClass(name, cls)
+        res = super(FilteredMachOGraph, self).createNode(cls, name)
+        return self.delegate.update_node(res)
+
+    def locate(self, filename, loader=None):
+        newname = super(FilteredMachOGraph, self).locate(filename, loader)
+        if newname is None:
+            return None
+        return self.delegate.locate(newname, loader=loader)
+
+
+class MachOStandalone(object):
+    def __init__(self, base, dest=None, graph=None, env=None, executable_path=None):
+        self.base = os.path.join(os.path.abspath(base), "")
+        if dest is None:
+            dest = os.path.join(self.base, "Contents", "Frameworks")
+        self.dest = dest
+        self.mm = FilteredMachOGraph(
+            self, graph=graph, env=env, executable_path=executable_path
+        )
+        self.changemap = {}
+        self.excludes = []
+        self.pending = deque()
+
+    def update_node(self, m):
+        return m
+
+    def getClass(self, name, cls):
+        if in_system_path(name):
+            return ExcludedMachO
+        for base in self.excludes:
+            if name.startswith(base):
+                return ExcludedMachO
+        return cls
+
+    def locate(self, filename, loader=None):
+        if in_system_path(filename):
+            return filename
+        if filename.startswith(self.base):
+            return filename
+        for base in self.excludes:
+            if filename.startswith(base):
+                return filename
+        if filename in self.changemap:
+            return self.changemap[filename]
+        info = framework_info(filename)
+        if info is None:
+            res = self.copy_dylib(filename)
+            self.changemap[filename] = res
+            return res
+        else:
+            res = self.copy_framework(info)
+            self.changemap[filename] = res
+            return res
+
+    def copy_dylib(self, filename):
+        # When the filename is a symlink use the basename of the target of
+        # the link as the name in standalone bundle. This avoids problems
+        # when two libraries link to the same dylib but using different
+        # symlinks.
+        if os.path.islink(filename):
+            dest = os.path.join(self.dest, os.path.basename(os.path.realpath(filename)))
+        else:
+            dest = os.path.join(self.dest, os.path.basename(filename))
+
+        if not os.path.exists(dest):
+            self.mergecopy(filename, dest)
+        return dest
+
+    def mergecopy(self, src, dest):
+        return mergecopy(src, dest)
+
+    def mergetree(self, src, dest):
+        return mergetree(src, dest)
+
+    def copy_framework(self, info):
+        dest = os.path.join(self.dest, info["shortname"] + ".framework")
+        destfn = os.path.join(self.dest, info["name"])
+        src = os.path.join(info["location"], info["shortname"] + ".framework")
+        if not os.path.exists(dest):
+            self.mergetree(src, dest)
+            self.pending.append((destfn, iter_platform_files(dest)))
+        return destfn
+
+    def run(self, platfiles=None, contents=None):
+        mm = self.mm
+        if contents is None:
+            contents = "@executable_path/.."
+        if platfiles is None:
+            platfiles = iter_platform_files(self.base)
+
+        for fn in platfiles:
+            mm.run_file(fn)
+
+        while self.pending:
+            fmwk, files = self.pending.popleft()
+            ref = mm.findNode(fmwk)
+            for fn in files:
+                mm.run_file(fn, caller=ref)
+
+        changemap = {}
+        skipcontents = os.path.join(os.path.dirname(self.dest), "")
+        machfiles = []
+
+        for node in mm.flatten(has_filename_filter):
+            machfiles.append(node)
+            dest = os.path.join(
+                contents,
+                os.path.normpath(node.filename[len(skipcontents) :]),  # noqa: E203
+            )
+            changemap[node.filename] = dest
+
+        def changefunc(path):
+            if path.startswith("@loader_path/"):
+                # This is a quick hack for py2app: In that
+                # usecase paths like this are found in the load
+                # commands of relocatable wheels. Those don't
+                # need rewriting.
+                return path
+
+            res = mm.locate(path)
+            rv = changemap.get(res)
+            if rv is None and path.startswith("@loader_path/"):
+                rv = changemap.get(mm.locate(mm.trans_table.get((node.filename, path))))
+            return rv
+
+        for node in machfiles:
+            fn = mm.locate(node.filename)
+            if fn is None:
+                continue
+            rewroteAny = False
+            for _header in node.headers:
+                if node.rewriteLoadCommands(changefunc):
+                    rewroteAny = True
+            if rewroteAny:
+                old_mode = flipwritable(fn)
+                try:
+                    with open(fn, "rb+") as f:
+                        for _header in node.headers:
+                            f.seek(0)
+                            node.write(f)
+                        f.seek(0, 2)
+                        f.flush()
+                finally:
+                    flipwritable(fn, old_mode)
+
+        allfiles = [mm.locate(node.filename) for node in machfiles]
+        return set(filter(None, allfiles))
diff --git a/lib/spack/external/_vendoring/macholib/SymbolTable.py b/lib/spack/external/_vendoring/macholib/SymbolTable.py
new file mode 100644
index 0000000000..006abab59f
--- /dev/null
+++ b/lib/spack/external/_vendoring/macholib/SymbolTable.py
@@ -0,0 +1,104 @@
+"""
+Class to read the symbol table from a Mach-O header
+"""
+from __future__ import with_statement
+
+import sys
+
+from macholib.mach_o import (
+    MH_CIGAM_64,
+    MH_MAGIC_64,
+    dylib_module,
+    dylib_reference,
+    dylib_table_of_contents,
+    nlist,
+    nlist_64,
+    relocation_info,
+)
+
+__all__ = ["SymbolTable"]
+
+if sys.version_info[0] == 2:
+    range = xrange  # noqa: F821
+
+
+class SymbolTable(object):
+    def __init__(self, macho, header=None, openfile=None):
+        if openfile is None:
+            openfile = open
+        if header is None:
+            header = macho.headers[0]
+        self.macho_header = header
+        with openfile(macho.filename, "rb") as fh:
+            self.symtab = header.getSymbolTableCommand()
+            self.dysymtab = header.getDynamicSymbolTableCommand()
+
+            if self.symtab is not None:
+                self.nlists = self.readSymbolTable(fh)
+
+            if self.dysymtab is not None:
+                self.readDynamicSymbolTable(fh)
+
+    def readSymbolTable(self, fh):
+        cmd = self.symtab
+        fh.seek(self.macho_header.offset + cmd.stroff)
+        strtab = fh.read(cmd.strsize)
+        fh.seek(self.macho_header.offset + cmd.symoff)
+        nlists = []
+
+        if self.macho_header.MH_MAGIC in [MH_MAGIC_64, MH_CIGAM_64]:
+            cls = nlist_64
+        else:
+            cls = nlist
+
+        for _i in range(cmd.nsyms):
+            cmd = cls.from_fileobj(fh, _endian_=self.macho_header.endian)
+            if cmd.n_un == 0:
+                nlists.append((cmd, ""))
+            else:
+                nlists.append(
+                    (
+                        cmd,
+                        strtab[cmd.n_un : strtab.find(b"\x00", cmd.n_un)],  # noqa: E203
+                    )
+                )
+        return nlists
+
+    def readDynamicSymbolTable(self, fh):
+        cmd = self.dysymtab
+        nlists = self.nlists
+
+        self.localsyms = nlists[
+            cmd.ilocalsym : cmd.ilocalsym + cmd.nlocalsym  # noqa: E203
+        ]
+        self.extdefsyms = nlists[
+            cmd.iextdefsym : cmd.iextdefsym + cmd.nextdefsym  # noqa: E203
+        ]
+        self.undefsyms = nlists[
+            cmd.iundefsym : cmd.iundefsym + cmd.nundefsym  # noqa: E203
+        ]
+        if cmd.tocoff == 0:
+            self.toc = None
+        else:
+            self.toc = self.readtoc(fh, cmd.tocoff, cmd.ntoc)
+
+    def readtoc(self, fh, off, n):
+        fh.seek(self.macho_header.offset + off)
+        return [dylib_table_of_contents.from_fileobj(fh) for i in range(n)]
+
+    def readmodtab(self, fh, off, n):
+        fh.seek(self.macho_header.offset + off)
+        return [dylib_module.from_fileobj(fh) for i in range(n)]
+
+    def readsym(self, fh, off, n):
+        fh.seek(self.macho_header.offset + off)
+        refs = []
+        for _i in range(n):
+            ref = dylib_reference.from_fileobj(fh)
+            isym, flags = divmod(ref.isym_flags, 256)
+            refs.append((self.nlists[isym], flags))
+        return refs
+
+    def readrel(self, fh, off, n):
+        fh.seek(self.macho_header.offset + off)
+        return [relocation_info.from_fileobj(fh) for i in range(n)]
diff --git a/lib/spack/external/_vendoring/macholib/__init__.py b/lib/spack/external/_vendoring/macholib/__init__.py
new file mode 100644
index 0000000000..9b8d939fd5
--- /dev/null
+++ b/lib/spack/external/_vendoring/macholib/__init__.py
@@ -0,0 +1,8 @@
+"""
+Enough Mach-O to make your head spin.
+
+See the relevant header files in /usr/include/mach-o
+
+And also Apple's documentation.
+"""
+__version__ = "1.16.2"
diff --git a/lib/spack/external/_vendoring/macholib/__main__.py b/lib/spack/external/_vendoring/macholib/__main__.py
new file mode 100644
index 0000000000..dd3cc11610
--- /dev/null
+++ b/lib/spack/external/_vendoring/macholib/__main__.py
@@ -0,0 +1,80 @@
+from __future__ import absolute_import, print_function
+
+import os
+import sys
+
+from macholib import macho_dump, macho_standalone
+from macholib.util import is_platform_file
+
+gCommand = None
+
+
+def check_file(fp, path, callback):
+    if not os.path.exists(path):
+        print("%s: %s: No such file or directory" % (gCommand, path), file=sys.stderr)
+        return 1
+
+    try:
+        is_plat = is_platform_file(path)
+
+    except IOError as msg:
+        print("%s: %s: %s" % (gCommand, path, msg), file=sys.stderr)
+        return 1
+
+    else:
+        if is_plat:
+            callback(fp, path)
+    return 0
+
+
+def walk_tree(callback, paths):
+    err = 0
+
+    for base in paths:
+        if os.path.isdir(base):
+            for root, _dirs, files in os.walk(base):
+                for fn in files:
+                    err |= check_file(sys.stdout, os.path.join(root, fn), callback)
+        else:
+            err |= check_file(sys.stdout, base, callback)
+
+    return err
+
+
+def print_usage(fp):
+    print("Usage:", file=fp)
+    print("  python -mmacholib [help|--help]", file=fp)
+    print("  python -mmacholib dump FILE ...", file=fp)
+    print("  python -mmacholib find DIR ...", file=fp)
+    print("  python -mmacholib standalone DIR ...", file=fp)
+
+
+def main():
+    global gCommand
+    if len(sys.argv) < 3:
+        print_usage(sys.stderr)
+        sys.exit(1)
+
+    gCommand = sys.argv[1]
+
+    if gCommand == "dump":
+        walk_tree(macho_dump.print_file, sys.argv[2:])
+
+    elif gCommand == "find":
+        walk_tree(lambda fp, path: print(path, file=fp), sys.argv[2:])
+
+    elif gCommand == "standalone":
+        for dn in sys.argv[2:]:
+            macho_standalone.standaloneApp(dn)
+
+    elif gCommand in ("help", "--help"):
+        print_usage(sys.stdout)
+        sys.exit(0)
+
+    else:
+        print_usage(sys.stderr)
+        sys.exit(1)
+
+
+if __name__ == "__main__":
+    main()
diff --git a/lib/spack/external/_vendoring/macholib/_cmdline.py b/lib/spack/external/_vendoring/macholib/_cmdline.py
new file mode 100644
index 0000000000..9304fb6257
--- /dev/null
+++ b/lib/spack/external/_vendoring/macholib/_cmdline.py
@@ -0,0 +1,49 @@
+"""
+Internal helpers for basic commandline tools
+"""
+from __future__ import absolute_import, print_function
+
+import os
+import sys
+
+from macholib.util import is_platform_file
+
+
+def check_file(fp, path, callback):
+    if not os.path.exists(path):
+        print(
+            "%s: %s: No such file or directory" % (sys.argv[0], path), file=sys.stderr
+        )
+        return 1
+
+    try:
+        is_plat = is_platform_file(path)
+
+    except IOError as msg:
+        print("%s: %s: %s" % (sys.argv[0], path, msg), file=sys.stderr)
+        return 1
+
+    else:
+        if is_plat:
+            callback(fp, path)
+    return 0
+
+
+def main(callback):
+    args = sys.argv[1:]
+    name = os.path.basename(sys.argv[0])
+    err = 0
+
+    if not args:
+        print("Usage: %s filename..." % (name,), file=sys.stderr)
+        return 1
+
+    for base in args:
+        if os.path.isdir(base):
+            for root, _dirs, files in os.walk(base):
+                for fn in files:
+                    err |= check_file(sys.stdout, os.path.join(root, fn), callback)
+        else:
+            err |= check_file(sys.stdout, base, callback)
+
+    return err
diff --git a/lib/spack/external/_vendoring/macholib/dyld.py b/lib/spack/external/_vendoring/macholib/dyld.py
new file mode 100644
index 0000000000..fcb23198cb
--- /dev/null
+++ b/lib/spack/external/_vendoring/macholib/dyld.py
@@ -0,0 +1,228 @@
+"""
+dyld emulation
+"""
+
+import ctypes
+import os
+import platform
+import sys
+from itertools import chain
+
+from macholib.dylib import dylib_info
+from macholib.framework import framework_info
+
+__all__ = ["dyld_find", "framework_find", "framework_info", "dylib_info"]
+
+if sys.platform == "darwin" and [
+    int(x) for x in platform.mac_ver()[0].split(".")[:2]
+] >= [10, 16]:
+    try:
+        libc = ctypes.CDLL("libSystem.dylib")
+
+    except OSError:
+        _dyld_shared_cache_contains_path = None
+
+    else:
+        try:
+            _dyld_shared_cache_contains_path = libc._dyld_shared_cache_contains_path
+        except AttributeError:
+            _dyld_shared_cache_contains_path = None
+
+        else:
+            _dyld_shared_cache_contains_path.restype = ctypes.c_bool
+            _dyld_shared_cache_contains_path.argtypes = [ctypes.c_char_p]
+
+            if sys.version_info[0] != 2:
+                __dyld_shared_cache_contains_path = _dyld_shared_cache_contains_path
+
+                def _dyld_shared_cache_contains_path(path):
+                    return __dyld_shared_cache_contains_path(path.encode())
+
+else:
+    _dyld_shared_cache_contains_path = None
+
+# These are the defaults as per man dyld(1)
+#
+_DEFAULT_FRAMEWORK_FALLBACK = [
+    os.path.expanduser("~/Library/Frameworks"),
+    "/Library/Frameworks",
+    "/Network/Library/Frameworks",
+    "/System/Library/Frameworks",
+]
+
+_DEFAULT_LIBRARY_FALLBACK = [
+    os.path.expanduser("~/lib"),
+    "/usr/local/lib",
+    "/lib",
+    "/usr/lib",
+]
+
+if sys.version_info[0] == 2:
+
+    def _ensure_utf8(s):
+        if isinstance(s, unicode):  # noqa: F821
+            return s.encode("utf8")
+        return s
+
+else:
+
+    def _ensure_utf8(s):
+        if s is not None and not isinstance(s, str):
+            raise ValueError(s)
+        return s
+
+
+def _dyld_env(env, var):
+    if env is None:
+        env = os.environ
+    rval = env.get(var)
+    if rval is None or rval == "":
+        return []
+    return rval.split(":")
+
+
+def dyld_image_suffix(env=None):
+    if env is None:
+        env = os.environ
+    return env.get("DYLD_IMAGE_SUFFIX")
+
+
+def dyld_framework_path(env=None):
+    return _dyld_env(env, "DYLD_FRAMEWORK_PATH")
+
+
+def dyld_library_path(env=None):
+    return _dyld_env(env, "DYLD_LIBRARY_PATH")
+
+
+def dyld_fallback_framework_path(env=None):
+    return _dyld_env(env, "DYLD_FALLBACK_FRAMEWORK_PATH")
+
+
+def dyld_fallback_library_path(env=None):
+    return _dyld_env(env, "DYLD_FALLBACK_LIBRARY_PATH")
+
+
+def dyld_image_suffix_search(iterator, env=None):
+    """For a potential path iterator, add DYLD_IMAGE_SUFFIX semantics"""
+    suffix = dyld_image_suffix(env)
+    if suffix is None:
+        return iterator
+
+    def _inject(iterator=iterator, suffix=suffix):
+        for path in iterator:
+            if path.endswith(".dylib"):
+                yield path[: -len(".dylib")] + suffix + ".dylib"
+            else:
+                yield path + suffix
+            yield path
+
+    return _inject()
+
+
+def dyld_override_search(name, env=None):
+    # If DYLD_FRAMEWORK_PATH is set and this dylib_name is a
+    # framework name, use the first file that exists in the framework
+    # path if any.  If there is none go on to search the DYLD_LIBRARY_PATH
+    # if any.
+
+    framework = framework_info(name)
+
+    if framework is not None:
+        for path in dyld_framework_path(env):
+            yield os.path.join(path, framework["name"])
+
+    # If DYLD_LIBRARY_PATH is set then use the first file that exists
+    # in the path.  If none use the original name.
+    for path in dyld_library_path(env):
+        yield os.path.join(path, os.path.basename(name))
+
+
+def dyld_executable_path_search(name, executable_path=None):
+    # If we haven't done any searching and found a library and the
+    # dylib_name starts with "@executable_path/" then construct the
+    # library name.
+    if name.startswith("@executable_path/") and executable_path is not None:
+        yield os.path.join(
+            executable_path, name[len("@executable_path/") :]  # noqa: E203
+        )
+
+
+def dyld_loader_search(name, loader_path=None):
+    # If we haven't done any searching and found a library and the
+    # dylib_name starts with "@loader_path/" then construct the
+    # library name.
+    if name.startswith("@loader_path/") and loader_path is not None:
+        yield os.path.join(loader_path, name[len("@loader_path/") :])  # noqa: E203
+
+
+def dyld_default_search(name, env=None):
+    yield name
+
+    framework = framework_info(name)
+
+    if framework is not None:
+        fallback_framework_path = dyld_fallback_framework_path(env)
+
+        if fallback_framework_path:
+            for path in fallback_framework_path:
+                yield os.path.join(path, framework["name"])
+
+        else:
+            for path in _DEFAULT_FRAMEWORK_FALLBACK:
+                yield os.path.join(path, framework["name"])
+
+    fallback_library_path = dyld_fallback_library_path(env)
+    if fallback_library_path:
+        for path in fallback_library_path:
+            yield os.path.join(path, os.path.basename(name))
+
+    else:
+        for path in _DEFAULT_LIBRARY_FALLBACK:
+            yield os.path.join(path, os.path.basename(name))
+
+
+def dyld_find(name, executable_path=None, env=None, loader_path=None):
+    """
+    Find a library or framework using dyld semantics
+    """
+    name = _ensure_utf8(name)
+    executable_path = _ensure_utf8(executable_path)
+    for path in dyld_image_suffix_search(
+        chain(
+            dyld_override_search(name, env),
+            dyld_executable_path_search(name, executable_path),
+            dyld_loader_search(name, loader_path),
+            dyld_default_search(name, env),
+        ),
+        env,
+    ):
+        if (
+            _dyld_shared_cache_contains_path is not None
+            and _dyld_shared_cache_contains_path(path)
+        ):
+            return path
+        if os.path.isfile(path):
+            return path
+    raise ValueError("dylib %s could not be found" % (name,))
+
+
+def framework_find(fn, executable_path=None, env=None):
+    """
+    Find a framework using dyld semantics in a very loose manner.
+
+    Will take input such as:
+        Python
+        Python.framework
+        Python.framework/Versions/Current
+    """
+    try:
+        return dyld_find(fn, executable_path=executable_path, env=env)
+    except ValueError:
+        pass
+    fmwk_index = fn.rfind(".framework")
+    if fmwk_index == -1:
+        fmwk_index = len(fn)
+        fn += ".framework"
+    fn = os.path.join(fn, os.path.basename(fn[:fmwk_index]))
+    return dyld_find(fn, executable_path=executable_path, env=env)
diff --git a/lib/spack/external/_vendoring/macholib/dylib.py b/lib/spack/external/_vendoring/macholib/dylib.py
new file mode 100644
index 0000000000..72301a8f19
--- /dev/null
+++ b/lib/spack/external/_vendoring/macholib/dylib.py
@@ -0,0 +1,45 @@
+"""
+Generic dylib path manipulation
+"""
+
+import re
+
+__all__ = ["dylib_info"]
+
+_DYLIB_RE = re.compile(
+    r"""(?x)
+(?P<location>^.*)(?:^|/)
+(?P<name>
+    (?P<shortname>\w+?)
+    (?:\.(?P<version>[^._]+))?
+    (?:_(?P<suffix>[^._]+))?
+    \.dylib$
+)
+"""
+)
+
+
+def dylib_info(filename):
+    """
+    A dylib name can take one of the following four forms:
+        Location/Name.SomeVersion_Suffix.dylib
+        Location/Name.SomeVersion.dylib
+        Location/Name_Suffix.dylib
+        Location/Name.dylib
+
+    returns None if not found or a mapping equivalent to:
+        dict(
+            location='Location',
+            name='Name.SomeVersion_Suffix.dylib',
+            shortname='Name',
+            version='SomeVersion',
+            suffix='Suffix',
+        )
+
+    Note that SomeVersion and Suffix are optional and may be None
+    if not present.
+    """
+    is_dylib = _DYLIB_RE.match(filename)
+    if not is_dylib:
+        return None
+    return is_dylib.groupdict()
diff --git a/lib/spack/external/_vendoring/macholib/framework.py b/lib/spack/external/_vendoring/macholib/framework.py
new file mode 100644
index 0000000000..027001e413
--- /dev/null
+++ b/lib/spack/external/_vendoring/macholib/framework.py
@@ -0,0 +1,45 @@
+"""
+Generic framework path manipulation
+"""
+
+import re
+
+__all__ = ["framework_info"]
+
+_STRICT_FRAMEWORK_RE = re.compile(
+    r"""(?x)
+(?P<location>^.*)(?:^|/)
+(?P<name>
+    (?P<shortname>[-_A-Za-z0-9]+).framework/
+    (?:Versions/(?P<version>[^/]+)/)?
+    (?P=shortname)
+    (?:_(?P<suffix>[^_]+))?
+)$
+"""
+)
+
+
+def framework_info(filename):
+    """
+    A framework name can take one of the following four forms:
+        Location/Name.framework/Versions/SomeVersion/Name_Suffix
+        Location/Name.framework/Versions/SomeVersion/Name
+        Location/Name.framework/Name_Suffix
+        Location/Name.framework/Name
+
+    returns None if not found, or a mapping equivalent to:
+        dict(
+            location='Location',
+            name='Name.framework/Versions/SomeVersion/Name_Suffix',
+            shortname='Name',
+            version='SomeVersion',
+            suffix='Suffix',
+        )
+
+    Note that SomeVersion and Suffix are optional and may be None
+    if not present
+    """
+    is_framework = _STRICT_FRAMEWORK_RE.match(filename)
+    if not is_framework:
+        return None
+    return is_framework.groupdict()
diff --git a/lib/spack/external/_vendoring/macholib/itergraphreport.py b/lib/spack/external/_vendoring/macholib/itergraphreport.py
new file mode 100644
index 0000000000..08692c057c
--- /dev/null
+++ b/lib/spack/external/_vendoring/macholib/itergraphreport.py
@@ -0,0 +1,73 @@
+"""
+Utilities for creating dot output from a MachOGraph
+"""
+
+from collections import deque
+
+try:
+    from itertools import imap
+except ImportError:
+    imap = map
+
+__all__ = ["itergraphreport"]
+
+
+def itergraphreport(nodes, describe_edge, name="G"):
+    edges = deque()
+    nodetoident = {}
+
+    def nodevisitor(node, data, outgoing, incoming):
+        return {"label": str(node)}
+
+    def edgevisitor(edge, data, head, tail):
+        return {}
+
+    yield "digraph %s {\n" % (name,)
+    attr = {"rankdir": "LR", "concentrate": "true"}
+    cpatt = '%s="%s"'
+    for item in attr.items():
+        yield "\t%s;\n" % (cpatt % item,)
+
+    # find all packages (subgraphs)
+    for (node, data, _outgoing, _incoming) in nodes:
+        nodetoident[node] = getattr(data, "identifier", node)
+
+    # create sets for subgraph, write out descriptions
+    for (node, data, outgoing, incoming) in nodes:
+        # update edges
+        for edge in imap(describe_edge, outgoing):
+            edges.append(edge)
+
+        # describe node
+        yield '\t"%s" [%s];\n' % (
+            node,
+            ",".join(
+                [
+                    (cpatt % item)
+                    for item in nodevisitor(node, data, outgoing, incoming).items()
+                ]
+            ),
+        )
+
+    graph = []
+
+    while edges:
+        edge, data, head, tail = edges.popleft()
+        if data in ("run_file", "load_dylib"):
+            graph.append((edge, data, head, tail))
+
+    def do_graph(edges, tabs):
+        edgestr = tabs + '"%s" -> "%s" [%s];\n'
+        # describe edge
+        for (edge, data, head, tail) in edges:
+            attribs = edgevisitor(edge, data, head, tail)
+            yield edgestr % (
+                head,
+                tail,
+                ",".join([(cpatt % item) for item in attribs.items()]),
+            )
+
+    for s in do_graph(graph, "\t"):
+        yield s
+
+    yield "}\n"
diff --git a/lib/spack/external/_vendoring/macholib/mach_o.py b/lib/spack/external/_vendoring/macholib/mach_o.py
new file mode 100644
index 0000000000..bfe6157172
--- /dev/null
+++ b/lib/spack/external/_vendoring/macholib/mach_o.py
@@ -0,0 +1,1641 @@
+"""
+Other than changing the load commands in such a way that they do not
+contain the load command itself, this is largely a by-hand conversion
+of the C headers.  Hopefully everything in here should be at least as
+obvious as the C headers, and you should be using the C headers as a real
+reference because the documentation didn't come along for the ride.
+
+Doing much of anything with the symbol tables or segments is really
+not covered at this point.
+
+See /usr/include/mach-o and friends.
+"""
+
+import time
+
+from macholib.ptypes import (
+    Structure,
+    p_int32,
+    p_int64,
+    p_long,
+    p_short,
+    p_uint8,
+    p_uint32,
+    p_uint64,
+    p_ulong,
+    pypackable,
+)
+
+_CPU_ARCH_ABI64 = 0x01000000
+
+CPU_TYPE_NAMES = {
+    -1: "ANY",
+    1: "VAX",
+    6: "MC680x0",
+    7: "i386",
+    _CPU_ARCH_ABI64 | 7: "x86_64",
+    8: "MIPS",
+    10: "MC98000",
+    11: "HPPA",
+    12: "ARM",
+    _CPU_ARCH_ABI64 | 12: "ARM64",
+    13: "MC88000",
+    14: "SPARC",
+    15: "i860",
+    16: "Alpha",
+    18: "PowerPC",
+    _CPU_ARCH_ABI64 | 18: "PowerPC64",
+}
+
+INTEL64_SUBTYPE = {
+    3: "CPU_SUBTYPE_X86_64_ALL",
+    4: "CPU_SUBTYPE_X86_ARCH1",
+    8: "CPU_SUBTYPE_X86_64_H",
+}
+
+# define CPU_SUBTYPE_INTEL(f, m) ((cpu_subtype_t) (f) + ((m) << 4))
+INTEL_SUBTYPE = {
+    0: "CPU_SUBTYPE_INTEL_MODEL_ALL",
+    1: "CPU_THREADTYPE_INTEL_HTT",
+    3: "CPU_SUBTYPE_I386_ALL",
+    4: "CPU_SUBTYPE_486",
+    5: "CPU_SUBTYPE_586",
+    8: "CPU_SUBTYPE_PENTIUM_3",
+    9: "CPU_SUBTYPE_PENTIUM_M",
+    10: "CPU_SUBTYPE_PENTIUM_4",
+    11: "CPU_SUBTYPE_ITANIUM",
+    12: "CPU_SUBTYPE_XEON",
+    34: "CPU_SUBTYPE_XEON_MP",
+    42: "CPU_SUBTYPE_PENTIUM_4_M",
+    43: "CPU_SUBTYPE_ITANIUM_2",
+    38: "CPU_SUBTYPE_PENTPRO",
+    40: "CPU_SUBTYPE_PENTIUM_3_M",
+    52: "CPU_SUBTYPE_PENTIUM_3_XEON",
+    102: "CPU_SUBTYPE_PENTII_M3",
+    132: "CPU_SUBTYPE_486SX",
+    166: "CPU_SUBTYPE_PENTII_M5",
+    199: "CPU_SUBTYPE_CELERON",
+    231: "CPU_SUBTYPE_CELERON_MOBILE",
+}
+
+MC680_SUBTYPE = {
+    1: "CPU_SUBTYPE_MC680x0_ALL",
+    2: "CPU_SUBTYPE_MC68040",
+    3: "CPU_SUBTYPE_MC68030_ONLY",
+}
+
+MIPS_SUBTYPE = {
+    0: "CPU_SUBTYPE_MIPS_ALL",
+    1: "CPU_SUBTYPE_MIPS_R2300",
+    2: "CPU_SUBTYPE_MIPS_R2600",
+    3: "CPU_SUBTYPE_MIPS_R2800",
+    4: "CPU_SUBTYPE_MIPS_R2000a",
+    5: "CPU_SUBTYPE_MIPS_R2000",
+    6: "CPU_SUBTYPE_MIPS_R3000a",
+    7: "CPU_SUBTYPE_MIPS_R3000",
+}
+
+MC98000_SUBTYPE = {0: "CPU_SUBTYPE_MC98000_ALL", 1: "CPU_SUBTYPE_MC98601"}
+
+HPPA_SUBTYPE = {0: "CPU_SUBTYPE_HPPA_7100", 1: "CPU_SUBTYPE_HPPA_7100LC"}
+
+MC88_SUBTYPE = {
+    0: "CPU_SUBTYPE_MC88000_ALL",
+    1: "CPU_SUBTYPE_MC88100",
+    2: "CPU_SUBTYPE_MC88110",
+}
+
+SPARC_SUBTYPE = {0: "CPU_SUBTYPE_SPARC_ALL"}
+
+I860_SUBTYPE = {0: "CPU_SUBTYPE_I860_ALL", 1: "CPU_SUBTYPE_I860_860"}
+
+POWERPC_SUBTYPE = {
+    0: "CPU_SUBTYPE_POWERPC_ALL",
+    1: "CPU_SUBTYPE_POWERPC_601",
+    2: "CPU_SUBTYPE_POWERPC_602",
+    3: "CPU_SUBTYPE_POWERPC_603",
+    4: "CPU_SUBTYPE_POWERPC_603e",
+    5: "CPU_SUBTYPE_POWERPC_603ev",
+    6: "CPU_SUBTYPE_POWERPC_604",
+    7: "CPU_SUBTYPE_POWERPC_604e",
+    8: "CPU_SUBTYPE_POWERPC_620",
+    9: "CPU_SUBTYPE_POWERPC_750",
+    10: "CPU_SUBTYPE_POWERPC_7400",
+    11: "CPU_SUBTYPE_POWERPC_7450",
+    100: "CPU_SUBTYPE_POWERPC_970",
+}
+
+ARM_SUBTYPE = {
+    0: "CPU_SUBTYPE_ARM_ALL12",
+    5: "CPU_SUBTYPE_ARM_V4T",
+    6: "CPU_SUBTYPE_ARM_V6",
+    7: "CPU_SUBTYPE_ARM_V5TEJ",
+    8: "CPU_SUBTYPE_ARM_XSCALE",
+    9: "CPU_SUBTYPE_ARM_V7",
+    10: "CPU_SUBTYPE_ARM_V7F",
+    11: "CPU_SUBTYPE_ARM_V7S",
+    12: "CPU_SUBTYPE_ARM_V7K",
+    13: "CPU_SUBTYPE_ARM_V8",
+    14: "CPU_SUBTYPE_ARM_V6M",
+    15: "CPU_SUBTYPE_ARM_V7M",
+    16: "CPU_SUBTYPE_ARM_V7EM",
+    17: "CPU_SUBTYPE_ARM_V8M",
+}
+
+ARM64_SUBTYPE = {
+    0: "CPU_SUBTYPE_ARM64_ALL",
+    1: "CPU_SUBTYPE_ARM64_V8",
+    2: "CPU_SUBTYPE_ARM64E",
+}
+
+VAX_SUBTYPE = {
+    0: "CPU_SUBTYPE_VAX_ALL",
+    1: "CPU_SUBTYPE_VAX780",
+    2: "CPU_SUBTYPE_VAX785",
+    3: "CPU_SUBTYPE_VAX750",
+    4: "CPU_SUBTYPE_VAX730",
+    5: "CPU_SUBTYPE_UVAXI",
+    6: "CPU_SUBTYPE_UVAXII",
+    7: "CPU_SUBTYPE_VAX8200",
+    8: "CPU_SUBTYPE_VAX8500",
+    9: "CPU_SUBTYPE_VAX8600",
+    10: "CPU_SUBTYPE_VAX8650",
+    11: "CPU_SUBTYPE_VAX8800",
+    12: "CPU_SUBTYPE_UVAXIII",
+}
+
+
+def get_cpu_subtype(cpu_type, cpu_subtype):
+    st = cpu_subtype & 0x0FFFFFFF
+
+    if cpu_type == 1:
+        subtype = VAX_SUBTYPE.get(st, st)
+    elif cpu_type == 6:
+        subtype = MC680_SUBTYPE.get(st, st)
+    elif cpu_type == 7:
+        subtype = INTEL_SUBTYPE.get(st, st)
+    elif cpu_type == 7 | _CPU_ARCH_ABI64:
+        subtype = INTEL64_SUBTYPE.get(st, st)
+    elif cpu_type == 8:
+        subtype = MIPS_SUBTYPE.get(st, st)
+    elif cpu_type == 10:
+        subtype = MC98000_SUBTYPE.get(st, st)
+    elif cpu_type == 11:
+        subtype = HPPA_SUBTYPE.get(st, st)
+    elif cpu_type == 12:
+        subtype = ARM_SUBTYPE.get(st, st)
+    elif cpu_type == 12 | _CPU_ARCH_ABI64:
+        subtype = ARM64_SUBTYPE.get(st, st)
+    elif cpu_type == 13:
+        subtype = MC88_SUBTYPE.get(st, st)
+    elif cpu_type == 14:
+        subtype = SPARC_SUBTYPE.get(st, st)
+    elif cpu_type == 15:
+        subtype = I860_SUBTYPE.get(st, st)
+    elif cpu_type == 16:
+        subtype = MIPS_SUBTYPE.get(st, st)
+    elif cpu_type == 18:
+        subtype = POWERPC_SUBTYPE.get(st, st)
+    elif cpu_type == 18 | _CPU_ARCH_ABI64:
+        subtype = POWERPC_SUBTYPE.get(st, st)
+    else:
+        subtype = str(st)
+
+    return subtype
+
+
+_MH_EXECUTE_SYM = "__mh_execute_header"
+MH_EXECUTE_SYM = "_mh_execute_header"
+_MH_BUNDLE_SYM = "__mh_bundle_header"
+MH_BUNDLE_SYM = "_mh_bundle_header"
+_MH_DYLIB_SYM = "__mh_dylib_header"
+MH_DYLIB_SYM = "_mh_dylib_header"
+_MH_DYLINKER_SYM = "__mh_dylinker_header"
+MH_DYLINKER_SYM = "_mh_dylinker_header"
+
+(
+    MH_OBJECT,
+    MH_EXECUTE,
+    MH_FVMLIB,
+    MH_CORE,
+    MH_PRELOAD,
+    MH_DYLIB,
+    MH_DYLINKER,
+    MH_BUNDLE,
+    MH_DYLIB_STUB,
+    MH_DSYM,
+) = range(0x1, 0xB)
+
+MH_FILESET = 0xC
+
+(
+    MH_NOUNDEFS,
+    MH_INCRLINK,
+    MH_DYLDLINK,
+    MH_BINDATLOAD,
+    MH_PREBOUND,
+    MH_SPLIT_SEGS,
+    MH_LAZY_INIT,
+    MH_TWOLEVEL,
+    MH_FORCE_FLAT,
+    MH_NOMULTIDEFS,
+    MH_NOFIXPREBINDING,
+    MH_PREBINDABLE,
+    MH_ALLMODSBOUND,
+    MH_SUBSECTIONS_VIA_SYMBOLS,
+    MH_CANONICAL,
+    MH_WEAK_DEFINES,
+    MH_BINDS_TO_WEAK,
+    MH_ALLOW_STACK_EXECUTION,
+    MH_ROOT_SAFE,
+    MH_SETUID_SAFE,
+    MH_NO_REEXPORTED_DYLIBS,
+    MH_PIE,
+    MH_DEAD_STRIPPABLE_DYLIB,
+    MH_HAS_TLV_DESCRIPTORS,
+    MH_NO_HEAP_EXECUTION,
+    MH_APP_EXTENSION_SAFE,
+) = map((1).__lshift__, range(26))
+
+MH_MAGIC = 0xFEEDFACE
+MH_CIGAM = 0xCEFAEDFE
+MH_MAGIC_64 = 0xFEEDFACF
+MH_CIGAM_64 = 0xCFFAEDFE
+
+integer_t = p_int32
+cpu_type_t = integer_t
+cpu_subtype_t = p_uint32
+
+MH_FILETYPE_NAMES = {
+    MH_OBJECT: "relocatable object",
+    MH_EXECUTE: "demand paged executable",
+    MH_FVMLIB: "fixed vm shared library",
+    MH_CORE: "core",
+    MH_PRELOAD: "preloaded executable",
+    MH_DYLIB: "dynamically bound shared library",
+    MH_DYLINKER: "dynamic link editor",
+    MH_BUNDLE: "dynamically bound bundle",
+    MH_DYLIB_STUB: "shared library stub for static linking",
+    MH_DSYM: "symbol information",
+    MH_FILESET: "fileset object",
+}
+
+MH_FILETYPE_SHORTNAMES = {
+    MH_OBJECT: "object",
+    MH_EXECUTE: "execute",
+    MH_FVMLIB: "fvmlib",
+    MH_CORE: "core",
+    MH_PRELOAD: "preload",
+    MH_DYLIB: "dylib",
+    MH_DYLINKER: "dylinker",
+    MH_BUNDLE: "bundle",
+    MH_DYLIB_STUB: "dylib_stub",
+    MH_DSYM: "dsym",
+}
+
+MH_FLAGS_NAMES = {
+    MH_NOUNDEFS: "MH_NOUNDEFS",
+    MH_INCRLINK: "MH_INCRLINK",
+    MH_DYLDLINK: "MH_DYLDLINK",
+    MH_BINDATLOAD: "MH_BINDATLOAD",
+    MH_PREBOUND: "MH_PREBOUND",
+    MH_SPLIT_SEGS: "MH_SPLIT_SEGS",
+    MH_LAZY_INIT: "MH_LAZY_INIT",
+    MH_TWOLEVEL: "MH_TWOLEVEL",
+    MH_FORCE_FLAT: "MH_FORCE_FLAT",
+    MH_NOMULTIDEFS: "MH_NOMULTIDEFS",
+    MH_NOFIXPREBINDING: "MH_NOFIXPREBINDING",
+    MH_PREBINDABLE: "MH_PREBINDABLE",
+    MH_ALLMODSBOUND: "MH_ALLMODSBOUND",
+    MH_SUBSECTIONS_VIA_SYMBOLS: "MH_SUBSECTIONS_VIA_SYMBOLS",
+    MH_CANONICAL: "MH_CANONICAL",
+    MH_WEAK_DEFINES: "MH_WEAK_DEFINES",
+    MH_BINDS_TO_WEAK: "MH_BINDS_TO_WEAK",
+    MH_ALLOW_STACK_EXECUTION: "MH_ALLOW_STACK_EXECUTION",
+    MH_ROOT_SAFE: "MH_ROOT_SAFE",
+    MH_SETUID_SAFE: "MH_SETUID_SAFE",
+    MH_NO_REEXPORTED_DYLIBS: "MH_NO_REEXPORTED_DYLIBS",
+    MH_PIE: "MH_PIE",
+    MH_DEAD_STRIPPABLE_DYLIB: "MH_DEAD_STRIPPABLE_DYLIB",
+    MH_HAS_TLV_DESCRIPTORS: "MH_HAS_TLV_DESCRIPTORS",
+    MH_NO_HEAP_EXECUTION: "MH_NO_HEAP_EXECUTION",
+    MH_APP_EXTENSION_SAFE: "MH_APP_EXTENSION_SAFE",
+}
+
+MH_FLAGS_DESCRIPTIONS = {
+    MH_NOUNDEFS: "no undefined references",
+    MH_INCRLINK: "output of an incremental link",
+    MH_DYLDLINK: "input for the dynamic linker",
+    MH_BINDATLOAD: "undefined references bound dynamically when loaded",
+    MH_PREBOUND: "dynamic undefined references prebound",
+    MH_SPLIT_SEGS: "split read-only and read-write segments",
+    MH_LAZY_INIT: "(obsolete)",
+    MH_TWOLEVEL: "using two-level name space bindings",
+    MH_FORCE_FLAT: "forcing all imagges to use flat name space bindings",
+    MH_NOMULTIDEFS: "umbrella guarantees no multiple definitions",
+    MH_NOFIXPREBINDING: "do not notify prebinding agent about this executable",
+    MH_PREBINDABLE: "the binary is not prebound but can have its prebinding redone",
+    MH_ALLMODSBOUND: "indicates that this binary binds to all "
+    "two-level namespace modules of its dependent libraries",
+    MH_SUBSECTIONS_VIA_SYMBOLS: "safe to divide up the sections into "
+    "sub-sections via symbols for dead code stripping",
+    MH_CANONICAL: "the binary has been canonicalized via the unprebind operation",
+    MH_WEAK_DEFINES: "the final linked image contains external weak symbols",
+    MH_BINDS_TO_WEAK: "the final linked image uses weak symbols",
+    MH_ALLOW_STACK_EXECUTION: "all stacks in the task will be given "
+    "stack execution privilege",
+    MH_ROOT_SAFE: "the binary declares it is safe for use in processes with uid zero",
+    MH_SETUID_SAFE: "the binary declares it is safe for use in processes "
+    "when issetugid() is true",
+    MH_NO_REEXPORTED_DYLIBS: "the static linker does not need to examine dependent "
+    "dylibs to see if any are re-exported",
+    MH_PIE: "the OS will load the main executable at a random address",
+    MH_DEAD_STRIPPABLE_DYLIB: "the static linker will automatically not create a "
+    "LC_LOAD_DYLIB load command to the dylib if no symbols are being "
+    "referenced from the dylib",
+    MH_HAS_TLV_DESCRIPTORS: "contains a section of type S_THREAD_LOCAL_VARIABLES",
+    MH_NO_HEAP_EXECUTION: "the OS will run the main executable with a "
+    "non-executable heap even on platforms that don't require it",
+    MH_APP_EXTENSION_SAFE: "the code was linked for use in an application extension.",
+}
+
+
+class mach_version_helper(Structure):
+    _fields_ = (("_version", p_uint32),)
+
+    @property
+    def major(self):
+        return self._version >> 16 & 0xFFFF
+
+    @major.setter
+    def major(self, v):
+        self._version = (self._version & 0xFFFF) | (v << 16)
+
+    @property
+    def minor(self):
+        return self._version >> 8 & 0xFF
+
+    @minor.setter
+    def minor(self, v):
+        self._version = (self._version & 0xFFFF00FF) | (v << 8)
+
+    @property
+    def rev(self):
+        return self._version & 0xFF
+
+    @rev.setter
+    def rev(self, v):
+        return (self._version & 0xFFFFFF00) | v
+
+    def __str__(self):
+        return "%s.%s.%s" % (self.major, self.minor, self.rev)
+
+
+class mach_timestamp_helper(p_uint32):
+    def __str__(self):
+        return time.ctime(self)
+
+
+def read_struct(f, s, **kw):
+    return s.from_fileobj(f, **kw)
+
+
+class mach_header(Structure):
+    _fields_ = (
+        ("magic", p_uint32),
+        ("cputype", cpu_type_t),
+        ("cpusubtype", cpu_subtype_t),
+        ("filetype", p_uint32),
+        ("ncmds", p_uint32),
+        ("sizeofcmds", p_uint32),
+        ("flags", p_uint32),
+    )
+
+    def _describe(self):
+        bit = 1
+        flags = self.flags
+        dflags = []
+        while flags and bit < (1 << 32):
+            if flags & bit:
+                dflags.append(
+                    {
+                        "name": MH_FLAGS_NAMES.get(bit, str(bit)),
+                        "description": MH_FLAGS_DESCRIPTIONS.get(bit, str(bit)),
+                    }
+                )
+                flags = flags ^ bit
+            bit <<= 1
+        return (
+            ("magic", int(self.magic)),
+            ("cputype_string", CPU_TYPE_NAMES.get(self.cputype, self.cputype)),
+            ("cputype", int(self.cputype)),
+            ("cpusubtype_string", get_cpu_subtype(self.cputype, self.cpusubtype)),
+            ("cpusubtype", int(self.cpusubtype)),
+            ("filetype_string", MH_FILETYPE_NAMES.get(self.filetype, self.filetype)),
+            ("filetype", int(self.filetype)),
+            ("ncmds", self.ncmds),
+            ("sizeofcmds", self.sizeofcmds),
+            ("flags", dflags),
+            ("raw_flags", int(self.flags)),
+        )
+
+
+class mach_header_64(mach_header):
+    _fields_ = mach_header._fields_ + (("reserved", p_uint32),)
+
+
+class load_command(Structure):
+    _fields_ = (("cmd", p_uint32), ("cmdsize", p_uint32))
+
+    def get_cmd_name(self):
+        return LC_NAMES.get(self.cmd, self.cmd)
+
+
+LC_REQ_DYLD = 0x80000000
+
+(
+    LC_SEGMENT,
+    LC_SYMTAB,
+    LC_SYMSEG,
+    LC_THREAD,
+    LC_UNIXTHREAD,
+    LC_LOADFVMLIB,
+    LC_IDFVMLIB,
+    LC_IDENT,
+    LC_FVMFILE,
+    LC_PREPAGE,
+    LC_DYSYMTAB,
+    LC_LOAD_DYLIB,
+    LC_ID_DYLIB,
+    LC_LOAD_DYLINKER,
+    LC_ID_DYLINKER,
+    LC_PREBOUND_DYLIB,
+    LC_ROUTINES,
+    LC_SUB_FRAMEWORK,
+    LC_SUB_UMBRELLA,
+    LC_SUB_CLIENT,
+    LC_SUB_LIBRARY,
+    LC_TWOLEVEL_HINTS,
+    LC_PREBIND_CKSUM,
+) = range(0x1, 0x18)
+
+LC_LOAD_WEAK_DYLIB = LC_REQ_DYLD | 0x18
+
+LC_SEGMENT_64 = 0x19
+LC_ROUTINES_64 = 0x1A
+LC_UUID = 0x1B
+LC_RPATH = 0x1C | LC_REQ_DYLD
+LC_CODE_SIGNATURE = 0x1D
+LC_CODE_SEGMENT_SPLIT_INFO = 0x1E
+LC_REEXPORT_DYLIB = 0x1F | LC_REQ_DYLD
+LC_LAZY_LOAD_DYLIB = 0x20
+LC_ENCRYPTION_INFO = 0x21
+LC_DYLD_INFO = 0x22
+LC_DYLD_INFO_ONLY = 0x22 | LC_REQ_DYLD
+LC_LOAD_UPWARD_DYLIB = 0x23 | LC_REQ_DYLD
+LC_VERSION_MIN_MACOSX = 0x24
+LC_VERSION_MIN_IPHONEOS = 0x25
+LC_FUNCTION_STARTS = 0x26
+LC_DYLD_ENVIRONMENT = 0x27
+LC_MAIN = 0x28 | LC_REQ_DYLD
+LC_DATA_IN_CODE = 0x29
+LC_SOURCE_VERSION = 0x2A
+LC_DYLIB_CODE_SIGN_DRS = 0x2B
+LC_ENCRYPTION_INFO_64 = 0x2C
+LC_LINKER_OPTION = 0x2D
+LC_LINKER_OPTIMIZATION_HINT = 0x2E
+LC_VERSION_MIN_TVOS = 0x2F
+LC_VERSION_MIN_WATCHOS = 0x30
+LC_NOTE = 0x31
+LC_BUILD_VERSION = 0x32
+LC_DYLD_EXPORTS_TRIE = 0x33 | LC_REQ_DYLD
+LC_DYLD_CHAINED_FIXUPS = 0x34 | LC_REQ_DYLD
+LC_FILESET_ENTRY = 0x35 | LC_REQ_DYLD
+
+
+# this is really a union.. but whatever
+class lc_str(p_uint32):
+    pass
+
+
+p_str16 = pypackable("p_str16", bytes, "16s")
+
+vm_prot_t = p_int32
+
+
+class segment_command(Structure):
+    _fields_ = (
+        ("segname", p_str16),
+        ("vmaddr", p_uint32),
+        ("vmsize", p_uint32),
+        ("fileoff", p_uint32),
+        ("filesize", p_uint32),
+        ("maxprot", vm_prot_t),
+        ("initprot", vm_prot_t),
+        ("nsects", p_uint32),  # read the section structures ?
+        ("flags", p_uint32),
+    )
+
+    def describe(self):
+        s = {}
+        s["segname"] = self.segname.rstrip("\x00")
+        s["vmaddr"] = int(self.vmaddr)
+        s["vmsize"] = int(self.vmsize)
+        s["fileoff"] = int(self.fileoff)
+        s["filesize"] = int(self.filesize)
+        s["initprot"] = self.get_initial_virtual_memory_protections()
+        s["initprot_raw"] = int(self.initprot)
+        s["maxprot"] = self.get_max_virtual_memory_protections()
+        s["maxprot_raw"] = int(self.maxprot)
+        s["nsects"] = int(self.nsects)
+        s["flags"] = self.flags
+        return s
+
+    def get_initial_virtual_memory_protections(self):
+        vm = []
+        if self.initprot == 0:
+            vm.append("VM_PROT_NONE")
+        if self.initprot & 1:
+            vm.append("VM_PROT_READ")
+        if self.initprot & 2:
+            vm.append("VM_PROT_WRITE")
+        if self.initprot & 4:
+            vm.append("VM_PROT_EXECUTE")
+        return vm
+
+    def get_max_virtual_memory_protections(self):
+        vm = []
+        if self.maxprot == 0:
+            vm.append("VM_PROT_NONE")
+        if self.maxprot & 1:
+            vm.append("VM_PROT_READ")
+        if self.maxprot & 2:
+            vm.append("VM_PROT_WRITE")
+        if self.maxprot & 4:
+            vm.append("VM_PROT_EXECUTE")
+        return vm
+
+
+class segment_command_64(Structure):
+    _fields_ = (
+        ("segname", p_str16),
+        ("vmaddr", p_uint64),
+        ("vmsize", p_uint64),
+        ("fileoff", p_uint64),
+        ("filesize", p_uint64),
+        ("maxprot", vm_prot_t),
+        ("initprot", vm_prot_t),
+        ("nsects", p_uint32),  # read the section structures ?
+        ("flags", p_uint32),
+    )
+
+    def describe(self):
+        s = {}
+        s["segname"] = self.segname.rstrip("\x00")
+        s["vmaddr"] = int(self.vmaddr)
+        s["vmsize"] = int(self.vmsize)
+        s["fileoff"] = int(self.fileoff)
+        s["filesize"] = int(self.filesize)
+        s["initprot"] = self.get_initial_virtual_memory_protections()
+        s["initprot_raw"] = int(self.initprot)
+        s["maxprot"] = self.get_max_virtual_memory_protections()
+        s["maxprot_raw"] = int(self.maxprot)
+        s["nsects"] = int(self.nsects)
+        s["flags"] = self.flags
+        return s
+
+    def get_initial_virtual_memory_protections(self):
+        vm = []
+        if self.initprot == 0:
+            vm.append("VM_PROT_NONE")
+        if self.initprot & 1:
+            vm.append("VM_PROT_READ")
+        if self.initprot & 2:
+            vm.append("VM_PROT_WRITE")
+        if self.initprot & 4:
+            vm.append("VM_PROT_EXECUTE")
+        return vm
+
+    def get_max_virtual_memory_protections(self):
+        vm = []
+        if self.maxprot == 0:
+            vm.append("VM_PROT_NONE")
+        if self.maxprot & 1:
+            vm.append("VM_PROT_READ")
+        if self.maxprot & 2:
+            vm.append("VM_PROT_WRITE")
+        if self.maxprot & 4:
+            vm.append("VM_PROT_EXECUTE")
+        return vm
+
+
+SG_HIGHVM = 0x1
+SG_FVMLIB = 0x2
+SG_NORELOC = 0x4
+SG_PROTECTED_VERSION_1 = 0x8
+
+
+class section(Structure):
+    _fields_ = (
+        ("sectname", p_str16),
+        ("segname", p_str16),
+        ("addr", p_uint32),
+        ("size", p_uint32),
+        ("offset", p_uint32),
+        ("align", p_uint32),
+        ("reloff", p_uint32),
+        ("nreloc", p_uint32),
+        ("flags", p_uint32),
+        ("reserved1", p_uint32),
+        ("reserved2", p_uint32),
+    )
+
+    def describe(self):
+        s = {}
+        s["sectname"] = self.sectname.rstrip("\x00")
+        s["segname"] = self.segname.rstrip("\x00")
+        s["addr"] = int(self.addr)
+        s["size"] = int(self.size)
+        s["offset"] = int(self.offset)
+        s["align"] = int(self.align)
+        s["reloff"] = int(self.reloff)
+        s["nreloc"] = int(self.nreloc)
+        f = {}
+        f["type"] = FLAG_SECTION_TYPES[int(self.flags) & 0xFF]
+        f["attributes"] = []
+        for k in FLAG_SECTION_ATTRIBUTES:
+            if k & self.flags:
+                f["attributes"].append(FLAG_SECTION_ATTRIBUTES[k])
+        if not f["attributes"]:
+            del f["attributes"]
+        s["flags"] = f
+        s["reserved1"] = int(self.reserved1)
+        s["reserved2"] = int(self.reserved2)
+        return s
+
+    def add_section_data(self, data):
+        self.section_data = data
+
+
+class section_64(Structure):
+    _fields_ = (
+        ("sectname", p_str16),
+        ("segname", p_str16),
+        ("addr", p_uint64),
+        ("size", p_uint64),
+        ("offset", p_uint32),
+        ("align", p_uint32),
+        ("reloff", p_uint32),
+        ("nreloc", p_uint32),
+        ("flags", p_uint32),
+        ("reserved1", p_uint32),
+        ("reserved2", p_uint32),
+        ("reserved3", p_uint32),
+    )
+
+    def describe(self):
+        s = {}
+        s["sectname"] = self.sectname.rstrip("\x00")
+        s["segname"] = self.segname.rstrip("\x00")
+        s["addr"] = int(self.addr)
+        s["size"] = int(self.size)
+        s["offset"] = int(self.offset)
+        s["align"] = int(self.align)
+        s["reloff"] = int(self.reloff)
+        s["nreloc"] = int(self.nreloc)
+        f = {}
+        f["type"] = FLAG_SECTION_TYPES[int(self.flags) & 0xFF]
+        f["attributes"] = []
+        for k in FLAG_SECTION_ATTRIBUTES:
+            if k & self.flags:
+                f["attributes"].append(FLAG_SECTION_ATTRIBUTES[k])
+        if not f["attributes"]:
+            del f["attributes"]
+        s["flags"] = f
+        s["reserved1"] = int(self.reserved1)
+        s["reserved2"] = int(self.reserved2)
+        s["reserved3"] = int(self.reserved3)
+        return s
+
+    def add_section_data(self, data):
+        self.section_data = data
+
+
+SECTION_TYPE = 0xFF
+SECTION_ATTRIBUTES = 0xFFFFFF00
+S_REGULAR = 0x0
+S_ZEROFILL = 0x1
+S_CSTRING_LITERALS = 0x2
+S_4BYTE_LITERALS = 0x3
+S_8BYTE_LITERALS = 0x4
+S_LITERAL_POINTERS = 0x5
+S_NON_LAZY_SYMBOL_POINTERS = 0x6
+S_LAZY_SYMBOL_POINTERS = 0x7
+S_SYMBOL_STUBS = 0x8
+S_MOD_INIT_FUNC_POINTERS = 0x9
+S_MOD_TERM_FUNC_POINTERS = 0xA
+S_COALESCED = 0xB
+S_GB_ZEROFILL = 0xC
+S_INTERPOSING = 0xD
+S_16BYTE_LITERALS = 0xE
+S_DTRACE_DOF = 0xF
+S_LAZY_DYLIB_SYMBOL_POINTERS = 0x10
+S_THREAD_LOCAL_REGULAR = 0x11
+S_THREAD_LOCAL_ZEROFILL = 0x12
+S_THREAD_LOCAL_VARIABLES = 0x13
+S_THREAD_LOCAL_VARIABLE_POINTERS = 0x14
+S_THREAD_LOCAL_INIT_FUNCTION_POINTERS = 0x15
+
+FLAG_SECTION_TYPES = {
+    S_REGULAR: "S_REGULAR",
+    S_ZEROFILL: "S_ZEROFILL",
+    S_CSTRING_LITERALS: "S_CSTRING_LITERALS",
+    S_4BYTE_LITERALS: "S_4BYTE_LITERALS",
+    S_8BYTE_LITERALS: "S_8BYTE_LITERALS",
+    S_LITERAL_POINTERS: "S_LITERAL_POINTERS",
+    S_NON_LAZY_SYMBOL_POINTERS: "S_NON_LAZY_SYMBOL_POINTERS",
+    S_LAZY_SYMBOL_POINTERS: "S_LAZY_SYMBOL_POINTERS",
+    S_SYMBOL_STUBS: "S_SYMBOL_STUBS",
+    S_MOD_INIT_FUNC_POINTERS: "S_MOD_INIT_FUNC_POINTERS",
+    S_MOD_TERM_FUNC_POINTERS: "S_MOD_TERM_FUNC_POINTERS",
+    S_COALESCED: "S_COALESCED",
+    S_GB_ZEROFILL: "S_GB_ZEROFILL",
+    S_INTERPOSING: "S_INTERPOSING",
+    S_16BYTE_LITERALS: "S_16BYTE_LITERALS",
+    S_DTRACE_DOF: "S_DTRACE_DOF",
+    S_LAZY_DYLIB_SYMBOL_POINTERS: "S_LAZY_DYLIB_SYMBOL_POINTERS",
+    S_THREAD_LOCAL_REGULAR: "S_THREAD_LOCAL_REGULAR",
+    S_THREAD_LOCAL_ZEROFILL: "S_THREAD_LOCAL_ZEROFILL",
+    S_THREAD_LOCAL_VARIABLES: "S_THREAD_LOCAL_VARIABLES",
+    S_THREAD_LOCAL_VARIABLE_POINTERS: "S_THREAD_LOCAL_VARIABLE_POINTERS",
+    S_THREAD_LOCAL_INIT_FUNCTION_POINTERS: "S_THREAD_LOCAL_INIT_FUNCTION_POINTERS",
+}
+
+SECTION_ATTRIBUTES_USR = 0xFF000000
+S_ATTR_PURE_INSTRUCTIONS = 0x80000000
+S_ATTR_NO_TOC = 0x40000000
+S_ATTR_STRIP_STATIC_SYMS = 0x20000000
+S_ATTR_NO_DEAD_STRIP = 0x10000000
+S_ATTR_LIVE_SUPPORT = 0x08000000
+S_ATTR_SELF_MODIFYING_CODE = 0x04000000
+S_ATTR_DEBUG = 0x02000000
+
+SECTION_ATTRIBUTES_SYS = 0x00FFFF00
+S_ATTR_SOME_INSTRUCTIONS = 0x00000400
+S_ATTR_EXT_RELOC = 0x00000200
+S_ATTR_LOC_RELOC = 0x00000100
+
+FLAG_SECTION_ATTRIBUTES = {
+    S_ATTR_PURE_INSTRUCTIONS: "S_ATTR_PURE_INSTRUCTIONS",
+    S_ATTR_NO_TOC: "S_ATTR_NO_TOC",
+    S_ATTR_STRIP_STATIC_SYMS: "S_ATTR_STRIP_STATIC_SYMS",
+    S_ATTR_NO_DEAD_STRIP: "S_ATTR_NO_DEAD_STRIP",
+    S_ATTR_LIVE_SUPPORT: "S_ATTR_LIVE_SUPPORT",
+    S_ATTR_SELF_MODIFYING_CODE: "S_ATTR_SELF_MODIFYING_CODE",
+    S_ATTR_DEBUG: "S_ATTR_DEBUG",
+    S_ATTR_SOME_INSTRUCTIONS: "S_ATTR_SOME_INSTRUCTIONS",
+    S_ATTR_EXT_RELOC: "S_ATTR_EXT_RELOC",
+    S_ATTR_LOC_RELOC: "S_ATTR_LOC_RELOC",
+}
+
+SEG_PAGEZERO = "__PAGEZERO"
+SEG_TEXT = "__TEXT"
+SECT_TEXT = "__text"
+SECT_FVMLIB_INIT0 = "__fvmlib_init0"
+SECT_FVMLIB_INIT1 = "__fvmlib_init1"
+SEG_DATA = "__DATA"
+SECT_DATA = "__data"
+SECT_BSS = "__bss"
+SECT_COMMON = "__common"
+SEG_OBJC = "__OBJC"
+SECT_OBJC_SYMBOLS = "__symbol_table"
+SECT_OBJC_MODULES = "__module_info"
+SECT_OBJC_STRINGS = "__selector_strs"
+SECT_OBJC_REFS = "__selector_refs"
+SEG_ICON = "__ICON"
+SECT_ICON_HEADER = "__header"
+SECT_ICON_TIFF = "__tiff"
+SEG_LINKEDIT = "__LINKEDIT"
+SEG_UNIXSTACK = "__UNIXSTACK"
+SEG_IMPORT = "__IMPORT"
+
+#
+#  I really should remove all these _command classes because they
+#  are no different.  I decided to keep the load commands separate,
+#  so classes like fvmlib and fvmlib_command are equivalent.
+#
+
+
+class fvmlib(Structure):
+    _fields_ = (
+        ("name", lc_str),
+        ("minor_version", mach_version_helper),
+        ("header_addr", p_uint32),
+    )
+
+
+class fvmlib_command(Structure):
+    _fields_ = fvmlib._fields_
+
+    def describe(self):
+        s = {}
+        s["header_addr"] = int(self.header_addr)
+        return s
+
+
+class dylib(Structure):
+    _fields_ = (
+        ("name", lc_str),
+        ("timestamp", mach_timestamp_helper),
+        ("current_version", mach_version_helper),
+        ("compatibility_version", mach_version_helper),
+    )
+
+
+# merged dylib structure
+class dylib_command(Structure):
+    _fields_ = dylib._fields_
+
+    def describe(self):
+        s = {}
+        s["timestamp"] = str(self.timestamp)
+        s["current_version"] = str(self.current_version)
+        s["compatibility_version"] = str(self.compatibility_version)
+        return s
+
+
+class sub_framework_command(Structure):
+    _fields_ = (("umbrella", lc_str),)
+
+    def describe(self):
+        return {}
+
+
+class sub_client_command(Structure):
+    _fields_ = (("client", lc_str),)
+
+    def describe(self):
+        return {}
+
+
+class sub_umbrella_command(Structure):
+    _fields_ = (("sub_umbrella", lc_str),)
+
+    def describe(self):
+        return {}
+
+
+class sub_library_command(Structure):
+    _fields_ = (("sub_library", lc_str),)
+
+    def describe(self):
+        return {}
+
+
+class prebound_dylib_command(Structure):
+    _fields_ = (("name", lc_str), ("nmodules", p_uint32), ("linked_modules", lc_str))
+
+    def describe(self):
+        return {"nmodules": int(self.nmodules)}
+
+
+class dylinker_command(Structure):
+    _fields_ = (("name", lc_str),)
+
+    def describe(self):
+        return {}
+
+
+class thread_command(Structure):
+    _fields_ = (("flavor", p_uint32), ("count", p_uint32))
+
+    def describe(self):
+        s = {}
+        s["flavor"] = int(self.flavor)
+        s["count"] = int(self.count)
+        return s
+
+
+class entry_point_command(Structure):
+    _fields_ = (("entryoff", p_uint64), ("stacksize", p_uint64))
+
+    def describe(self):
+        s = {}
+        s["entryoff"] = int(self.entryoff)
+        s["stacksize"] = int(self.stacksize)
+        return s
+
+
+class routines_command(Structure):
+    _fields_ = (
+        ("init_address", p_uint32),
+        ("init_module", p_uint32),
+        ("reserved1", p_uint32),
+        ("reserved2", p_uint32),
+        ("reserved3", p_uint32),
+        ("reserved4", p_uint32),
+        ("reserved5", p_uint32),
+        ("reserved6", p_uint32),
+    )
+
+    def describe(self):
+        s = {}
+        s["init_address"] = int(self.init_address)
+        s["init_module"] = int(self.init_module)
+        s["reserved1"] = int(self.reserved1)
+        s["reserved2"] = int(self.reserved2)
+        s["reserved3"] = int(self.reserved3)
+        s["reserved4"] = int(self.reserved4)
+        s["reserved5"] = int(self.reserved5)
+        s["reserved6"] = int(self.reserved6)
+        return s
+
+
+class routines_command_64(Structure):
+    _fields_ = (
+        ("init_address", p_uint64),
+        ("init_module", p_uint64),
+        ("reserved1", p_uint64),
+        ("reserved2", p_uint64),
+        ("reserved3", p_uint64),
+        ("reserved4", p_uint64),
+        ("reserved5", p_uint64),
+        ("reserved6", p_uint64),
+    )
+
+    def describe(self):
+        s = {}
+        s["init_address"] = int(self.init_address)
+        s["init_module"] = int(self.init_module)
+        s["reserved1"] = int(self.reserved1)
+        s["reserved2"] = int(self.reserved2)
+        s["reserved3"] = int(self.reserved3)
+        s["reserved4"] = int(self.reserved4)
+        s["reserved5"] = int(self.reserved5)
+        s["reserved6"] = int(self.reserved6)
+        return s
+
+
+class symtab_command(Structure):
+    _fields_ = (
+        ("symoff", p_uint32),
+        ("nsyms", p_uint32),
+        ("stroff", p_uint32),
+        ("strsize", p_uint32),
+    )
+
+    def describe(self):
+        s = {}
+        s["symoff"] = int(self.symoff)
+        s["nsyms"] = int(self.nsyms)
+        s["stroff"] = int(self.stroff)
+        s["strsize"] = int(self.strsize)
+        return s
+
+
+class dysymtab_command(Structure):
+    _fields_ = (
+        ("ilocalsym", p_uint32),
+        ("nlocalsym", p_uint32),
+        ("iextdefsym", p_uint32),
+        ("nextdefsym", p_uint32),
+        ("iundefsym", p_uint32),
+        ("nundefsym", p_uint32),
+        ("tocoff", p_uint32),
+        ("ntoc", p_uint32),
+        ("modtaboff", p_uint32),
+        ("nmodtab", p_uint32),
+        ("extrefsymoff", p_uint32),
+        ("nextrefsyms", p_uint32),
+        ("indirectsymoff", p_uint32),
+        ("nindirectsyms", p_uint32),
+        ("extreloff", p_uint32),
+        ("nextrel", p_uint32),
+        ("locreloff", p_uint32),
+        ("nlocrel", p_uint32),
+    )
+
+    def describe(self):
+        dys = {}
+        dys["ilocalsym"] = int(self.ilocalsym)
+        dys["nlocalsym"] = int(self.nlocalsym)
+        dys["iextdefsym"] = int(self.iextdefsym)
+        dys["nextdefsym"] = int(self.nextdefsym)
+        dys["iundefsym"] = int(self.iundefsym)
+        dys["nundefsym"] = int(self.nundefsym)
+        dys["tocoff"] = int(self.tocoff)
+        dys["ntoc"] = int(self.ntoc)
+        dys["modtaboff"] = int(self.modtaboff)
+        dys["nmodtab"] = int(self.nmodtab)
+        dys["extrefsymoff"] = int(self.extrefsymoff)
+        dys["nextrefsyms"] = int(self.nextrefsyms)
+        dys["indirectsymoff"] = int(self.indirectsymoff)
+        dys["nindirectsyms"] = int(self.nindirectsyms)
+        dys["extreloff"] = int(self.extreloff)
+        dys["nextrel"] = int(self.nextrel)
+        dys["locreloff"] = int(self.locreloff)
+        dys["nlocrel"] = int(self.nlocrel)
+        return dys
+
+
+INDIRECT_SYMBOL_LOCAL = 0x80000000
+INDIRECT_SYMBOL_ABS = 0x40000000
+
+
+class dylib_table_of_contents(Structure):
+    _fields_ = (("symbol_index", p_uint32), ("module_index", p_uint32))
+
+
+class dylib_module(Structure):
+    _fields_ = (
+        ("module_name", p_uint32),
+        ("iextdefsym", p_uint32),
+        ("nextdefsym", p_uint32),
+        ("irefsym", p_uint32),
+        ("nrefsym", p_uint32),
+        ("ilocalsym", p_uint32),
+        ("nlocalsym", p_uint32),
+        ("iextrel", p_uint32),
+        ("nextrel", p_uint32),
+        ("iinit_iterm", p_uint32),
+        ("ninit_nterm", p_uint32),
+        ("objc_module_info_addr", p_uint32),
+        ("objc_module_info_size", p_uint32),
+    )
+
+
+class dylib_module_64(Structure):
+    _fields_ = (
+        ("module_name", p_uint32),
+        ("iextdefsym", p_uint32),
+        ("nextdefsym", p_uint32),
+        ("irefsym", p_uint32),
+        ("nrefsym", p_uint32),
+        ("ilocalsym", p_uint32),
+        ("nlocalsym", p_uint32),
+        ("iextrel", p_uint32),
+        ("nextrel", p_uint32),
+        ("iinit_iterm", p_uint32),
+        ("ninit_nterm", p_uint32),
+        ("objc_module_info_size", p_uint32),
+        ("objc_module_info_addr", p_uint64),
+    )
+
+
+class dylib_reference(Structure):
+    _fields_ = (
+        ("isym_flags", p_uint32),
+        # ('isym', p_uint8 * 3),
+        # ('flags', p_uint8),
+    )
+
+
+class twolevel_hints_command(Structure):
+    _fields_ = (("offset", p_uint32), ("nhints", p_uint32))
+
+    def describe(self):
+        s = {}
+        s["offset"] = int(self.offset)
+        s["nhints"] = int(self.nhints)
+        return s
+
+
+class twolevel_hint(Structure):
+    _fields_ = (
+        ("isub_image_itoc", p_uint32),
+        # ('isub_image', p_uint8),
+        # ('itoc', p_uint8 * 3),
+    )
+
+
+class prebind_cksum_command(Structure):
+    _fields_ = (("cksum", p_uint32),)
+
+    def describe(self):
+        return {"cksum": int(self.cksum)}
+
+
+class symseg_command(Structure):
+    _fields_ = (("offset", p_uint32), ("size", p_uint32))
+
+    def describe(self):
+        s = {}
+        s["offset"] = int(self.offset)
+        s["size"] = int(self.size)
+
+
+class ident_command(Structure):
+    _fields_ = ()
+
+    def describe(self):
+        return {}
+
+
+class fvmfile_command(Structure):
+    _fields_ = (("name", lc_str), ("header_addr", p_uint32))
+
+    def describe(self):
+        return {"header_addr": int(self.header_addr)}
+
+
+class uuid_command(Structure):
+    _fields_ = (("uuid", p_str16),)
+
+    def describe(self):
+        return {"uuid": self.uuid.rstrip("\x00")}
+
+
+class rpath_command(Structure):
+    _fields_ = (("path", lc_str),)
+
+    def describe(self):
+        return {}
+
+
+class linkedit_data_command(Structure):
+    _fields_ = (("dataoff", p_uint32), ("datasize", p_uint32))
+
+    def describe(self):
+        s = {}
+        s["dataoff"] = int(self.dataoff)
+        s["datasize"] = int(self.datasize)
+        return s
+
+
+class version_min_command(Structure):
+    _fields_ = (
+        ("version", p_uint32),  # X.Y.Z is encoded in nibbles xxxx.yy.zz
+        ("sdk", p_uint32),
+    )
+
+    def describe(self):
+        v = int(self.version)
+        v3 = v & 0xFF
+        v = v >> 8
+        v2 = v & 0xFF
+        v = v >> 8
+        v1 = v & 0xFFFF
+        s = int(self.sdk)
+        s3 = s & 0xFF
+        s = s >> 8
+        s2 = s & 0xFF
+        s = s >> 8
+        s1 = s & 0xFFFF
+        return {
+            "version": str(int(v1)) + "." + str(int(v2)) + "." + str(int(v3)),
+            "sdk": str(int(s1)) + "." + str(int(s2)) + "." + str(int(s3)),
+        }
+
+
+class source_version_command(Structure):
+    _fields_ = (("version", p_uint64),)
+
+    def describe(self):
+        v = int(self.version)
+        a = v >> 40
+        b = (v >> 30) & 0x3FF
+        c = (v >> 20) & 0x3FF
+        d = (v >> 10) & 0x3FF
+        e = v & 0x3FF
+        r = str(a) + "." + str(b) + "." + str(c) + "." + str(d) + "." + str(e)
+        return {"version": r}
+
+
+class note_command(Structure):
+    _fields_ = (("data_owner", p_str16), ("offset", p_uint64), ("size", p_uint64))
+
+
+class build_version_command(Structure):
+    _fields_ = (
+        ("platform", p_uint32),
+        ("minos", p_uint32),
+        ("sdk", p_uint32),
+        ("ntools", p_uint32),
+    )
+
+    def describe(self):
+        return {}
+
+
+class build_tool_version(Structure):
+    _fields_ = (("tool", p_uint32), ("version", p_uint32))
+
+
+class data_in_code_entry(Structure):
+    _fields_ = (("offset", p_uint32), ("length", p_uint32), ("kind", p_uint32))
+
+    def describe(self):
+        return {"offset": self.offset, "length": self.length, "kind": self.kind}
+
+
+DICE_KIND_DATA = 0x0001
+DICE_KIND_JUMP_TABLE8 = 0x0002
+DICE_KIND_JUMP_TABLE16 = 0x0003
+DICE_KIND_JUMP_TABLE32 = 0x0004
+DICE_KIND_ABS_JUMP_TABLE32 = 0x0005
+
+DATA_IN_CODE_KINDS = {
+    DICE_KIND_DATA: "DICE_KIND_DATA",
+    DICE_KIND_JUMP_TABLE8: "DICE_KIND_JUMP_TABLE8",
+    DICE_KIND_JUMP_TABLE16: "DICE_KIND_JUMP_TABLE16",
+    DICE_KIND_JUMP_TABLE32: "DICE_KIND_JUMP_TABLE32",
+    DICE_KIND_ABS_JUMP_TABLE32: "DICE_KIND_ABS_JUMP_TABLE32",
+}
+
+
+class tlv_descriptor(Structure):
+    _fields_ = (
+        ("thunk", p_long),  # Actually a pointer to a function
+        ("key", p_ulong),
+        ("offset", p_ulong),
+    )
+
+    def describe(self):
+        return {"thunk": self.thunk, "key": self.key, "offset": self.offset}
+
+
+class encryption_info_command(Structure):
+    _fields_ = (("cryptoff", p_uint32), ("cryptsize", p_uint32), ("cryptid", p_uint32))
+
+    def describe(self):
+        s = {}
+        s["cryptoff"] = int(self.cryptoff)
+        s["cryptsize"] = int(self.cryptsize)
+        s["cryptid"] = int(self.cryptid)
+        return s
+
+
+class encryption_info_command_64(Structure):
+    _fields_ = (
+        ("cryptoff", p_uint32),
+        ("cryptsize", p_uint32),
+        ("cryptid", p_uint32),
+        ("pad", p_uint32),
+    )
+
+    def describe(self):
+        s = {}
+        s["cryptoff"] = int(self.cryptoff)
+        s["cryptsize"] = int(self.cryptsize)
+        s["cryptid"] = int(self.cryptid)
+        s["pad"] = int(self.pad)
+        return s
+
+
+class dyld_info_command(Structure):
+    _fields_ = (
+        ("rebase_off", p_uint32),
+        ("rebase_size", p_uint32),
+        ("bind_off", p_uint32),
+        ("bind_size", p_uint32),
+        ("weak_bind_off", p_uint32),
+        ("weak_bind_size", p_uint32),
+        ("lazy_bind_off", p_uint32),
+        ("lazy_bind_size", p_uint32),
+        ("export_off", p_uint32),
+        ("export_size", p_uint32),
+    )
+
+    def describe(self):
+        dyld = {}
+        dyld["rebase_off"] = int(self.rebase_off)
+        dyld["rebase_size"] = int(self.rebase_size)
+        dyld["bind_off"] = int(self.bind_off)
+        dyld["bind_size"] = int(self.bind_size)
+        dyld["weak_bind_off"] = int(self.weak_bind_off)
+        dyld["weak_bind_size"] = int(self.weak_bind_size)
+        dyld["lazy_bind_off"] = int(self.lazy_bind_off)
+        dyld["lazy_bind_size"] = int(self.lazy_bind_size)
+        dyld["export_off"] = int(self.export_off)
+        dyld["export_size"] = int(self.export_size)
+        return dyld
+
+
+class linker_option_command(Structure):
+    _fields_ = (("count", p_uint32),)
+
+    def describe(self):
+        return {"count": int(self.count)}
+
+
+class fileset_entry_command(Structure):
+    _fields_ = (
+        ("vmaddr", p_uint64),
+        ("fileoff", p_uint64),
+        ("entry_id", lc_str),
+        ("reserved", p_uint32),
+    )
+
+
+LC_REGISTRY = {
+    LC_SEGMENT: segment_command,
+    LC_IDFVMLIB: fvmlib_command,
+    LC_LOADFVMLIB: fvmlib_command,
+    LC_ID_DYLIB: dylib_command,
+    LC_LOAD_DYLIB: dylib_command,
+    LC_LOAD_WEAK_DYLIB: dylib_command,
+    LC_SUB_FRAMEWORK: sub_framework_command,
+    LC_SUB_CLIENT: sub_client_command,
+    LC_SUB_UMBRELLA: sub_umbrella_command,
+    LC_SUB_LIBRARY: sub_library_command,
+    LC_PREBOUND_DYLIB: prebound_dylib_command,
+    LC_ID_DYLINKER: dylinker_command,
+    LC_LOAD_DYLINKER: dylinker_command,
+    LC_THREAD: thread_command,
+    LC_UNIXTHREAD: thread_command,
+    LC_ROUTINES: routines_command,
+    LC_SYMTAB: symtab_command,
+    LC_DYSYMTAB: dysymtab_command,
+    LC_TWOLEVEL_HINTS: twolevel_hints_command,
+    LC_PREBIND_CKSUM: prebind_cksum_command,
+    LC_SYMSEG: symseg_command,
+    LC_IDENT: ident_command,
+    LC_FVMFILE: fvmfile_command,
+    LC_SEGMENT_64: segment_command_64,
+    LC_ROUTINES_64: routines_command_64,
+    LC_UUID: uuid_command,
+    LC_RPATH: rpath_command,
+    LC_CODE_SIGNATURE: linkedit_data_command,
+    LC_CODE_SEGMENT_SPLIT_INFO: linkedit_data_command,
+    LC_REEXPORT_DYLIB: dylib_command,
+    LC_LAZY_LOAD_DYLIB: dylib_command,
+    LC_ENCRYPTION_INFO: encryption_info_command,
+    LC_DYLD_INFO: dyld_info_command,
+    LC_DYLD_INFO_ONLY: dyld_info_command,
+    LC_LOAD_UPWARD_DYLIB: dylib_command,
+    LC_VERSION_MIN_MACOSX: version_min_command,
+    LC_VERSION_MIN_IPHONEOS: version_min_command,
+    LC_FUNCTION_STARTS: linkedit_data_command,
+    LC_DYLD_ENVIRONMENT: dylinker_command,
+    LC_MAIN: entry_point_command,
+    LC_DATA_IN_CODE: linkedit_data_command,
+    LC_SOURCE_VERSION: source_version_command,
+    LC_DYLIB_CODE_SIGN_DRS: linkedit_data_command,
+    LC_ENCRYPTION_INFO_64: encryption_info_command_64,
+    LC_LINKER_OPTION: linker_option_command,
+    LC_LINKER_OPTIMIZATION_HINT: linkedit_data_command,
+    LC_VERSION_MIN_TVOS: version_min_command,
+    LC_VERSION_MIN_WATCHOS: version_min_command,
+    LC_NOTE: note_command,
+    LC_BUILD_VERSION: build_version_command,
+    LC_DYLD_EXPORTS_TRIE: linkedit_data_command,
+    LC_DYLD_CHAINED_FIXUPS: linkedit_data_command,
+    LC_FILESET_ENTRY: fileset_entry_command,
+}
+
+LC_NAMES = {
+    LC_SEGMENT: "LC_SEGMENT",
+    LC_IDFVMLIB: "LC_IDFVMLIB",
+    LC_LOADFVMLIB: "LC_LOADFVMLIB",
+    LC_ID_DYLIB: "LC_ID_DYLIB",
+    LC_LOAD_DYLIB: "LC_LOAD_DYLIB",
+    LC_LOAD_WEAK_DYLIB: "LC_LOAD_WEAK_DYLIB",
+    LC_SUB_FRAMEWORK: "LC_SUB_FRAMEWORK",
+    LC_SUB_CLIENT: "LC_SUB_CLIENT",
+    LC_SUB_UMBRELLA: "LC_SUB_UMBRELLA",
+    LC_SUB_LIBRARY: "LC_SUB_LIBRARY",
+    LC_PREBOUND_DYLIB: "LC_PREBOUND_DYLIB",
+    LC_ID_DYLINKER: "LC_ID_DYLINKER",
+    LC_LOAD_DYLINKER: "LC_LOAD_DYLINKER",
+    LC_THREAD: "LC_THREAD",
+    LC_UNIXTHREAD: "LC_UNIXTHREAD",
+    LC_ROUTINES: "LC_ROUTINES",
+    LC_SYMTAB: "LC_SYMTAB",
+    LC_DYSYMTAB: "LC_DYSYMTAB",
+    LC_TWOLEVEL_HINTS: "LC_TWOLEVEL_HINTS",
+    LC_PREBIND_CKSUM: "LC_PREBIND_CKSUM",
+    LC_SYMSEG: "LC_SYMSEG",
+    LC_IDENT: "LC_IDENT",
+    LC_FVMFILE: "LC_FVMFILE",
+    LC_SEGMENT_64: "LC_SEGMENT_64",
+    LC_ROUTINES_64: "LC_ROUTINES_64",
+    LC_UUID: "LC_UUID",
+    LC_RPATH: "LC_RPATH",
+    LC_CODE_SIGNATURE: "LC_CODE_SIGNATURE",
+    LC_CODE_SEGMENT_SPLIT_INFO: "LC_CODE_SEGMENT_SPLIT_INFO",
+    LC_REEXPORT_DYLIB: "LC_REEXPORT_DYLIB",
+    LC_LAZY_LOAD_DYLIB: "LC_LAZY_LOAD_DYLIB",
+    LC_ENCRYPTION_INFO: "LC_ENCRYPTION_INFO",
+    LC_DYLD_INFO: "LC_DYLD_INFO",
+    LC_DYLD_INFO_ONLY: "LC_DYLD_INFO_ONLY",
+    LC_LOAD_UPWARD_DYLIB: "LC_LOAD_UPWARD_DYLIB",
+    LC_VERSION_MIN_MACOSX: "LC_VERSION_MIN_MACOSX",
+    LC_VERSION_MIN_IPHONEOS: "LC_VERSION_MIN_IPHONEOS",
+    LC_FUNCTION_STARTS: "LC_FUNCTION_STARTS",
+    LC_DYLD_ENVIRONMENT: "LC_DYLD_ENVIRONMENT",
+    LC_MAIN: "LC_MAIN",
+    LC_DATA_IN_CODE: "LC_DATA_IN_CODE",
+    LC_SOURCE_VERSION: "LC_SOURCE_VERSION",
+    LC_DYLIB_CODE_SIGN_DRS: "LC_DYLIB_CODE_SIGN_DRS",
+    LC_LINKER_OPTIMIZATION_HINT: "LC_LINKER_OPTIMIZATION_HINT",
+    LC_VERSION_MIN_TVOS: "LC_VERSION_MIN_TVOS",
+    LC_VERSION_MIN_WATCHOS: "LC_VERSION_MIN_WATCHOS",
+    LC_NOTE: "LC_NOTE",
+    LC_BUILD_VERSION: "LC_BUILD_VERSION",
+    LC_DYLD_EXPORTS_TRIE: "LC_DYLD_EXPORTS_TRIE",
+    LC_DYLD_CHAINED_FIXUPS: "LC_DYLD_CHAINED_FIXUPS",
+    LC_ENCRYPTION_INFO_64: "LC_ENCRYPTION_INFO_64",
+    LC_LINKER_OPTION: "LC_LINKER_OPTION",
+    LC_PREPAGE: "LC_PREPAGE",
+    LC_FILESET_ENTRY: "LC_FILESET_ENTRY",
+}
+
+
+# this is another union.
+class n_un(p_int32):
+    pass
+
+
+class nlist(Structure):
+    _fields_ = (
+        ("n_un", n_un),
+        ("n_type", p_uint8),
+        ("n_sect", p_uint8),
+        ("n_desc", p_short),
+        ("n_value", p_uint32),
+    )
+
+
+class nlist_64(Structure):
+    _fields_ = [
+        ("n_un", n_un),
+        ("n_type", p_uint8),
+        ("n_sect", p_uint8),
+        ("n_desc", p_short),
+        ("n_value", p_int64),
+    ]
+
+
+N_STAB = 0xE0
+N_PEXT = 0x10
+N_TYPE = 0x0E
+N_EXT = 0x01
+
+N_UNDF = 0x0
+N_ABS = 0x2
+N_SECT = 0xE
+N_PBUD = 0xC
+N_INDR = 0xA
+
+NO_SECT = 0
+MAX_SECT = 255
+
+
+class relocation_info(Structure):
+    _fields_ = (("r_address", p_uint32), ("_r_bitfield", p_uint32))
+
+    def _describe(self):
+        return (("r_address", self.r_address), ("_r_bitfield", self._r_bitfield))
+
+
+def GET_COMM_ALIGN(n_desc):
+    return (n_desc >> 8) & 0x0F
+
+
+def SET_COMM_ALIGN(n_desc, align):
+    return (n_desc & 0xF0FF) | ((align & 0x0F) << 8)
+
+
+REFERENCE_TYPE = 0xF
+REFERENCE_FLAG_UNDEFINED_NON_LAZY = 0
+REFERENCE_FLAG_UNDEFINED_LAZY = 1
+REFERENCE_FLAG_DEFINED = 2
+REFERENCE_FLAG_PRIVATE_DEFINED = 3
+REFERENCE_FLAG_PRIVATE_UNDEFINED_NON_LAZY = 4
+REFERENCE_FLAG_PRIVATE_UNDEFINED_LAZY = 5
+
+REFERENCED_DYNAMICALLY = 0x0010
+
+
+def GET_LIBRARY_ORDINAL(n_desc):
+    return ((n_desc) >> 8) & 0xFF
+
+
+def SET_LIBRARY_ORDINAL(n_desc, ordinal):
+    return ((n_desc) & 0x00FF) | (((ordinal & 0xFF) << 8))
+
+
+SELF_LIBRARY_ORDINAL = 0x0
+MAX_LIBRARY_ORDINAL = 0xFD
+DYNAMIC_LOOKUP_ORDINAL = 0xFE
+EXECUTABLE_ORDINAL = 0xFF
+
+N_NO_DEAD_STRIP = 0x0020
+N_DESC_DISCARDED = 0x0020
+N_WEAK_REF = 0x0040
+N_WEAK_DEF = 0x0080
+N_REF_TO_WEAK = 0x0080
+N_ARM_THUMB_DEF = 0x0008
+N_SYMBOL_RESOLVER = 0x0100
+N_ALT_ENTRY = 0x0200
+
+# /usr/include/mach-o/fat.h
+FAT_MAGIC = 0xCAFEBABE
+FAT_CIGAM = 0xBEBAFECA
+FAT_MAGIC_64 = 0xCAFEBABF
+FAT_CIGAM_64 = 0xBFBAFECA
+
+
+class fat_header(Structure):
+    _fields_ = (("magic", p_uint32), ("nfat_arch", p_uint32))
+
+
+class fat_arch(Structure):
+    _fields_ = (
+        ("cputype", cpu_type_t),
+        ("cpusubtype", cpu_subtype_t),
+        ("offset", p_uint32),
+        ("size", p_uint32),
+        ("align", p_uint32),
+    )
+
+
+class fat_arch64(Structure):
+    _fields_ = (
+        ("cputype", cpu_type_t),
+        ("cpusubtype", cpu_subtype_t),
+        ("offset", p_uint64),
+        ("size", p_uint64),
+        ("align", p_uint32),
+        ("reserved", p_uint32),
+    )
+
+
+REBASE_TYPE_POINTER = 1  # noqa: E221
+REBASE_TYPE_TEXT_ABSOLUTE32 = 2  # noqa: E221
+REBASE_TYPE_TEXT_PCREL32 = 3  # noqa: E221
+
+REBASE_OPCODE_MASK = 0xF0  # noqa: E221
+REBASE_IMMEDIATE_MASK = 0x0F  # noqa: E221
+REBASE_OPCODE_DONE = 0x00  # noqa: E221
+REBASE_OPCODE_SET_TYPE_IMM = 0x10  # noqa: E221
+REBASE_OPCODE_SET_SEGMENT_AND_OFFSET_ULEB = 0x20  # noqa: E221
+REBASE_OPCODE_ADD_ADDR_ULEB = 0x30  # noqa: E221
+REBASE_OPCODE_ADD_ADDR_IMM_SCALED = 0x40  # noqa: E221
+REBASE_OPCODE_DO_REBASE_IMM_TIMES = 0x50  # noqa: E221
+REBASE_OPCODE_DO_REBASE_ULEB_TIMES = 0x60  # noqa: E221
+REBASE_OPCODE_DO_REBASE_ADD_ADDR_ULEB = 0x70  # noqa: E221
+REBASE_OPCODE_DO_REBASE_ULEB_TIMES_SKIPPING_ULEB = 0x80  # noqa: E221
+
+BIND_TYPE_POINTER = 1  # noqa: E221
+BIND_TYPE_TEXT_ABSOLUTE32 = 2  # noqa: E221
+BIND_TYPE_TEXT_PCREL32 = 3  # noqa: E221
+
+BIND_SPECIAL_DYLIB_SELF = 0  # noqa: E221
+BIND_SPECIAL_DYLIB_MAIN_EXECUTABLE = -1  # noqa: E221
+BIND_SPECIAL_DYLIB_FLAT_LOOKUP = -2  # noqa: E221
+
+BIND_SYMBOL_FLAGS_WEAK_IMPORT = 0x1  # noqa: E221
+BIND_SYMBOL_FLAGS_NON_WEAK_DEFINITION = 0x8  # noqa: E221
+
+BIND_OPCODE_MASK = 0xF0  # noqa: E221
+BIND_IMMEDIATE_MASK = 0x0F  # noqa: E221
+BIND_OPCODE_DONE = 0x00  # noqa: E221
+BIND_OPCODE_SET_DYLIB_ORDINAL_IMM = 0x10  # noqa: E221
+BIND_OPCODE_SET_DYLIB_ORDINAL_ULEB = 0x20  # noqa: E221
+BIND_OPCODE_SET_DYLIB_SPECIAL_IMM = 0x30  # noqa: E221
+BIND_OPCODE_SET_SYMBOL_TRAILING_FLAGS_IMM = 0x40  # noqa: E221
+BIND_OPCODE_SET_TYPE_IMM = 0x50  # noqa: E221
+BIND_OPCODE_SET_ADDEND_SLEB = 0x60  # noqa: E221
+BIND_OPCODE_SET_SEGMENT_AND_OFFSET_ULEB = 0x70  # noqa: E221
+BIND_OPCODE_ADD_ADDR_ULEB = 0x80  # noqa: E221
+BIND_OPCODE_DO_BIND = 0x90  # noqa: E221
+BIND_OPCODE_DO_BIND_ADD_ADDR_ULEB = 0xA0  # noqa: E221
+BIND_OPCODE_DO_BIND_ADD_ADDR_IMM_SCALED = 0xB0  # noqa: E221
+BIND_OPCODE_DO_BIND_ULEB_TIMES_SKIPPING_ULEB = 0xC0  # noqa: E221
+
+EXPORT_SYMBOL_FLAGS_KIND_MASK = 0x03  # noqa: E221
+EXPORT_SYMBOL_FLAGS_KIND_REGULAR = 0x00  # noqa: E221
+EXPORT_SYMBOL_FLAGS_KIND_THREAD_LOCAL = 0x01  # noqa: E221
+EXPORT_SYMBOL_FLAGS_WEAK_DEFINITION = 0x04  # noqa: E221
+EXPORT_SYMBOL_FLAGS_REEXPORT = 0x08  # noqa: E221
+EXPORT_SYMBOL_FLAGS_STUB_AND_RESOLVER = 0x10  # noqa: E221
+
+PLATFORM_MACOS = 1
+PLATFORM_IOS = 2
+PLATFORM_TVOS = 3
+PLATFORM_WATCHOS = 4
+PLATFORM_BRIDGEOS = 5
+PLATFORM_IOSMAC = 6
+PLATFORM_MACCATALYST = 6
+PLATFORM_IOSSIMULATOR = 7
+PLATFORM_TVOSSIMULATOR = 8
+PLATFORM_WATCHOSSIMULATOR = 9
+
+PLATFORM_NAMES = {
+    PLATFORM_MACOS: "macOS",
+    PLATFORM_IOS: "iOS",
+    PLATFORM_TVOS: "tvOS",
+    PLATFORM_WATCHOS: "watchOS",
+    PLATFORM_BRIDGEOS: "bridgeOS",
+    PLATFORM_MACCATALYST: "catalyst",
+    PLATFORM_IOSSIMULATOR: "iOS simulator",
+    PLATFORM_TVOSSIMULATOR: "tvOS simulator",
+    PLATFORM_WATCHOSSIMULATOR: "watchOS simulator",
+}
+
+TOOL_CLANG = 1
+TOOL_SWIFT = 2
+TOOL_LD = 3
+
+TOOL_NAMES = {TOOL_CLANG: "clang", TOOL_SWIFT: "swift", TOOL_LD: "ld"}
diff --git a/lib/spack/external/_vendoring/macholib/macho_dump.py b/lib/spack/external/_vendoring/macholib/macho_dump.py
new file mode 100644
index 0000000000..bca5d777ae
--- /dev/null
+++ b/lib/spack/external/_vendoring/macholib/macho_dump.py
@@ -0,0 +1,57 @@
+#!/usr/bin/env python
+
+from __future__ import print_function
+
+import sys
+
+from macholib._cmdline import main as _main
+from macholib.mach_o import CPU_TYPE_NAMES, MH_CIGAM_64, MH_MAGIC_64, get_cpu_subtype
+from macholib.MachO import MachO
+
+ARCH_MAP = {
+    ("<", "64-bit"): "x86_64",
+    ("<", "32-bit"): "i386",
+    (">", "64-bit"): "ppc64",
+    (">", "32-bit"): "ppc",
+}
+
+
+def print_file(fp, path):
+    print(path, file=fp)
+    m = MachO(path)
+    for header in m.headers:
+        seen = set()
+
+        if header.MH_MAGIC == MH_MAGIC_64 or header.MH_MAGIC == MH_CIGAM_64:
+            sz = "64-bit"
+        else:
+            sz = "32-bit"
+
+        arch = CPU_TYPE_NAMES.get(header.header.cputype, header.header.cputype)
+
+        subarch = get_cpu_subtype(header.header.cputype, header.header.cpusubtype)
+
+        print(
+            "    [%s endian=%r size=%r arch=%r subarch=%r]"
+            % (header.__class__.__name__, header.endian, sz, arch, subarch),
+            file=fp,
+        )
+        for _idx, _name, other in header.walkRelocatables():
+            if other not in seen:
+                seen.add(other)
+                print("\t" + other, file=fp)
+    print("", file=fp)
+
+
+def main():
+    print(
+        "WARNING: 'macho_dump' is deprecated, use 'python -mmacholib dump' " "instead"
+    )
+    _main(print_file)
+
+
+if __name__ == "__main__":
+    try:
+        sys.exit(main())
+    except KeyboardInterrupt:
+        pass
diff --git a/lib/spack/external/_vendoring/macholib/macho_find.py b/lib/spack/external/_vendoring/macholib/macho_find.py
new file mode 100644
index 0000000000..a963c36dcc
--- /dev/null
+++ b/lib/spack/external/_vendoring/macholib/macho_find.py
@@ -0,0 +1,22 @@
+#!/usr/bin/env python
+from __future__ import print_function
+
+from macholib._cmdline import main as _main
+
+
+def print_file(fp, path):
+    print(path, file=fp)
+
+
+def main():
+    print(
+        "WARNING: 'macho_find' is deprecated, " "use 'python -mmacholib dump' instead"
+    )
+    _main(print_file)
+
+
+if __name__ == "__main__":
+    try:
+        main()
+    except KeyboardInterrupt:
+        pass
diff --git a/lib/spack/external/_vendoring/macholib/macho_standalone.py b/lib/spack/external/_vendoring/macholib/macho_standalone.py
new file mode 100644
index 0000000000..0bb29e802f
--- /dev/null
+++ b/lib/spack/external/_vendoring/macholib/macho_standalone.py
@@ -0,0 +1,30 @@
+#!/usr/bin/env python
+
+import os
+import sys
+
+from macholib.MachOStandalone import MachOStandalone
+from macholib.util import strip_files
+
+
+def standaloneApp(path):
+    if not (os.path.isdir(path) and os.path.exists(os.path.join(path, "Contents"))):
+        print("%s: %s does not look like an app bundle" % (sys.argv[0], path))
+        sys.exit(1)
+    files = MachOStandalone(path).run()
+    strip_files(files)
+
+
+def main():
+    print(
+        "WARNING: 'macho_standalone' is deprecated, use "
+        "'python -mmacholib standalone' instead"
+    )
+    if not sys.argv[1:]:
+        raise SystemExit("usage: %s [appbundle ...]" % (sys.argv[0],))
+    for fn in sys.argv[1:]:
+        standaloneApp(fn)
+
+
+if __name__ == "__main__":
+    main()
diff --git a/lib/spack/external/_vendoring/macholib/ptypes.py b/lib/spack/external/_vendoring/macholib/ptypes.py
new file mode 100644
index 0000000000..248b5cb2a3
--- /dev/null
+++ b/lib/spack/external/_vendoring/macholib/ptypes.py
@@ -0,0 +1,334 @@
+"""
+This module defines packable types, that is types than can be easily
+converted to a binary format as used in MachO headers.
+"""
+import struct
+import sys
+from itertools import chain, starmap
+
+try:
+    from itertools import imap, izip
+except ImportError:
+    izip, imap = zip, map
+
+__all__ = """
+sizeof
+BasePackable
+Structure
+pypackable
+p_char
+p_byte
+p_ubyte
+p_short
+p_ushort
+p_int
+p_uint
+p_long
+p_ulong
+p_longlong
+p_ulonglong
+p_int8
+p_uint8
+p_int16
+p_uint16
+p_int32
+p_uint32
+p_int64
+p_uint64
+p_float
+p_double
+""".split()
+
+
+def sizeof(s):
+    """
+    Return the size of an object when packed
+    """
+    if hasattr(s, "_size_"):
+        return s._size_
+
+    elif isinstance(s, bytes):
+        return len(s)
+
+    raise ValueError(s)
+
+
+class MetaPackable(type):
+    """
+    Fixed size struct.unpack-able types use from_tuple as their designated
+    initializer
+    """
+
+    def from_mmap(cls, mm, ptr, **kw):
+        return cls.from_str(mm[ptr : ptr + cls._size_], **kw)  # noqa: E203
+
+    def from_fileobj(cls, f, **kw):
+        return cls.from_str(f.read(cls._size_), **kw)
+
+    def from_str(cls, s, **kw):
+        endian = kw.get("_endian_", cls._endian_)
+        return cls.from_tuple(struct.unpack(endian + cls._format_, s), **kw)
+
+    def from_tuple(cls, tpl, **kw):
+        return cls(tpl[0], **kw)
+
+
+class BasePackable(object):
+    _endian_ = ">"
+
+    def to_str(self):
+        raise NotImplementedError
+
+    def to_fileobj(self, f):
+        f.write(self.to_str())
+
+    def to_mmap(self, mm, ptr):
+        mm[ptr : ptr + self._size_] = self.to_str()  # noqa: E203
+
+
+# This defines a class with a custom metaclass, we'd normally
+# use "class Packable(BasePackable, metaclass=MetaPackage)",
+# but that syntax is not valid in Python 2 (and likewise the
+# python 2 syntax is not valid in Python 3)
+def _make():
+    def to_str(self):
+        cls = type(self)
+        endian = getattr(self, "_endian_", cls._endian_)
+        return struct.pack(endian + cls._format_, self)
+
+    return MetaPackable("Packable", (BasePackable,), {"to_str": to_str})
+
+
+Packable = _make()
+del _make
+
+
+def pypackable(name, pytype, format):
+    """
+    Create a "mix-in" class with a python type and a
+    Packable with the given struct format
+    """
+    size, items = _formatinfo(format)
+
+    def __new__(cls, *args, **kwds):
+        if "_endian_" in kwds:
+            _endian_ = kwds.pop("_endian_")
+        else:
+            _endian_ = cls._endian_
+
+        result = pytype.__new__(cls, *args, **kwds)
+        result._endian_ = _endian_
+        return result
+
+    return type(Packable)(
+        name,
+        (pytype, Packable),
+        {"_format_": format, "_size_": size, "_items_": items, "__new__": __new__},
+    )
+
+
+def _formatinfo(format):
+    """
+    Calculate the size and number of items in a struct format.
+    """
+    size = struct.calcsize(format)
+    return size, len(struct.unpack(format, b"\x00" * size))
+
+
+class MetaStructure(MetaPackable):
+    """
+    The metaclass of Structure objects that does all the magic.
+
+    Since we can assume that all Structures have a fixed size,
+    we can do a bunch of calculations up front and pack or
+    unpack the whole thing in one struct call.
+    """
+
+    def __new__(cls, clsname, bases, dct):
+        fields = dct["_fields_"]
+        names = []
+        types = []
+        structmarks = []
+        format = ""
+        items = 0
+        size = 0
+
+        def struct_property(name, typ):
+            def _get(self):
+                return self._objects_[name]
+
+            def _set(self, obj):
+                if type(obj) is not typ:
+                    obj = typ(obj)
+                self._objects_[name] = obj
+
+            return property(_get, _set, typ.__name__)
+
+        for name, typ in fields:
+            dct[name] = struct_property(name, typ)
+            names.append(name)
+            types.append(typ)
+            format += typ._format_
+            size += typ._size_
+            if typ._items_ > 1:
+                structmarks.append((items, typ._items_, typ))
+            items += typ._items_
+
+        dct["_structmarks_"] = structmarks
+        dct["_names_"] = names
+        dct["_types_"] = types
+        dct["_size_"] = size
+        dct["_items_"] = items
+        dct["_format_"] = format
+        return super(MetaStructure, cls).__new__(cls, clsname, bases, dct)
+
+    def from_tuple(cls, tpl, **kw):
+        values = []
+        current = 0
+        for begin, length, typ in cls._structmarks_:
+            if begin > current:
+                values.extend(tpl[current:begin])
+            current = begin + length
+            values.append(typ.from_tuple(tpl[begin:current], **kw))
+        values.extend(tpl[current:])
+        return cls(*values, **kw)
+
+
+# See metaclass discussion earlier in this file
+def _make():
+    class_dict = {}
+    class_dict["_fields_"] = ()
+
+    def as_method(function):
+        class_dict[function.__name__] = function
+
+    @as_method
+    def __init__(self, *args, **kwargs):
+        if len(args) == 1 and not kwargs and type(args[0]) is type(self):
+            kwargs = args[0]._objects_
+            args = ()
+        self._objects_ = {}
+        iargs = chain(izip(self._names_, args), kwargs.items())
+        for key, value in iargs:
+            if key not in self._names_ and key != "_endian_":
+                raise TypeError
+            setattr(self, key, value)
+        for key, typ in izip(self._names_, self._types_):
+            if key not in self._objects_:
+                self._objects_[key] = typ()
+
+    @as_method
+    def _get_packables(self):
+        for obj in imap(self._objects_.__getitem__, self._names_):
+            if hasattr(obj, "_get_packables"):
+                for obj in obj._get_packables():
+                    yield obj
+
+            else:
+                yield obj
+
+    @as_method
+    def to_str(self):
+        return struct.pack(self._endian_ + self._format_, *self._get_packables())
+
+    @as_method
+    def __cmp__(self, other):
+        if type(other) is not type(self):
+            raise TypeError(
+                "Cannot compare objects of type %r to objects of type %r"
+                % (type(other), type(self))
+            )
+        if sys.version_info[0] == 2:
+            _cmp = cmp  # noqa: F821
+        else:
+
+            def _cmp(a, b):
+                if a < b:
+                    return -1
+                elif a > b:
+                    return 1
+                elif a == b:
+                    return 0
+                else:
+                    raise TypeError()
+
+        for cmpval in starmap(
+            _cmp, izip(self._get_packables(), other._get_packables())
+        ):
+            if cmpval != 0:
+                return cmpval
+        return 0
+
+    @as_method
+    def __eq__(self, other):
+        r = self.__cmp__(other)
+        return r == 0
+
+    @as_method
+    def __ne__(self, other):
+        r = self.__cmp__(other)
+        return r != 0
+
+    @as_method
+    def __lt__(self, other):
+        r = self.__cmp__(other)
+        return r < 0
+
+    @as_method
+    def __le__(self, other):
+        r = self.__cmp__(other)
+        return r <= 0
+
+    @as_method
+    def __gt__(self, other):
+        r = self.__cmp__(other)
+        return r > 0
+
+    @as_method
+    def __ge__(self, other):
+        r = self.__cmp__(other)
+        return r >= 0
+
+    @as_method
+    def __repr__(self):
+        result = []
+        result.append("<")
+        result.append(type(self).__name__)
+        for nm in self._names_:
+            result.append(" %s=%r" % (nm, getattr(self, nm)))
+        result.append(">")
+        return "".join(result)
+
+    return MetaStructure("Structure", (BasePackable,), class_dict)
+
+
+Structure = _make()
+del _make
+
+try:
+    long
+except NameError:
+    long = int
+
+# export common packables with predictable names
+p_char = pypackable("p_char", bytes, "c")
+p_int8 = pypackable("p_int8", int, "b")
+p_uint8 = pypackable("p_uint8", int, "B")
+p_int16 = pypackable("p_int16", int, "h")
+p_uint16 = pypackable("p_uint16", int, "H")
+p_int32 = pypackable("p_int32", int, "i")
+p_uint32 = pypackable("p_uint32", long, "I")
+p_int64 = pypackable("p_int64", long, "q")
+p_uint64 = pypackable("p_uint64", long, "Q")
+p_float = pypackable("p_float", float, "f")
+p_double = pypackable("p_double", float, "d")
+
+# Deprecated names, need trick to emit deprecation warning.
+p_byte = p_int8
+p_ubyte = p_uint8
+p_short = p_int16
+p_ushort = p_uint16
+p_int = p_long = p_int32
+p_uint = p_ulong = p_uint32
+p_longlong = p_int64
+p_ulonglong = p_uint64
diff --git a/lib/spack/external/_vendoring/macholib/util.py b/lib/spack/external/_vendoring/macholib/util.py
new file mode 100644
index 0000000000..d5ab33544a
--- /dev/null
+++ b/lib/spack/external/_vendoring/macholib/util.py
@@ -0,0 +1,262 @@
+import os
+import shutil
+import stat
+import struct
+import sys
+
+from macholib import mach_o
+
+MAGIC = [
+    struct.pack("!L", getattr(mach_o, "MH_" + _))
+    for _ in ["MAGIC", "CIGAM", "MAGIC_64", "CIGAM_64"]
+]
+FAT_MAGIC_BYTES = struct.pack("!L", mach_o.FAT_MAGIC)
+MAGIC_LEN = 4
+STRIPCMD = ["/usr/bin/strip", "-x", "-S", "-"]
+
+try:
+    unicode
+except NameError:
+    unicode = str
+
+
+def fsencoding(s, encoding=sys.getfilesystemencoding()):  # noqa: M511,B008
+    """
+    Ensure the given argument is in filesystem encoding (not unicode)
+    """
+    if isinstance(s, unicode):
+        s = s.encode(encoding)
+    return s
+
+
+def move(src, dst):
+    """
+    move that ensures filesystem encoding of paths
+    """
+    shutil.move(fsencoding(src), fsencoding(dst))
+
+
+def copy2(src, dst):
+    """
+    copy2 that ensures filesystem encoding of paths
+    """
+    shutil.copy2(fsencoding(src), fsencoding(dst))
+
+
+def flipwritable(fn, mode=None):
+    """
+    Flip the writability of a file and return the old mode. Returns None
+    if the file is already writable.
+    """
+    if os.access(fn, os.W_OK):
+        return None
+    old_mode = os.stat(fn).st_mode
+    os.chmod(fn, stat.S_IWRITE | old_mode)
+    return old_mode
+
+
+class fileview(object):
+    """
+    A proxy for file-like objects that exposes a given view of a file
+    """
+
+    def __init__(self, fileobj, start, size):
+        self._fileobj = fileobj
+        self._start = start
+        self._end = start + size
+
+    def __repr__(self):
+        return "<fileview [%d, %d] %r>" % (self._start, self._end, self._fileobj)
+
+    def tell(self):
+        return self._fileobj.tell() - self._start
+
+    def _checkwindow(self, seekto, op):
+        if not (self._start <= seekto <= self._end):
+            raise IOError(
+                "%s to offset %d is outside window [%d, %d]"
+                % (op, seekto, self._start, self._end)
+            )
+
+    def seek(self, offset, whence=0):
+        seekto = offset
+        if whence == 0:
+            seekto += self._start
+        elif whence == 1:
+            seekto += self._fileobj.tell()
+        elif whence == 2:
+            seekto += self._end
+        else:
+            raise IOError("Invalid whence argument to seek: %r" % (whence,))
+        self._checkwindow(seekto, "seek")
+        self._fileobj.seek(seekto)
+
+    def write(self, bytes):
+        here = self._fileobj.tell()
+        self._checkwindow(here, "write")
+        self._checkwindow(here + len(bytes), "write")
+        self._fileobj.write(bytes)
+
+    def read(self, size=sys.maxsize):
+        if size < 0:
+            raise ValueError(
+                "Invalid size %s while reading from %s", size, self._fileobj
+            )
+        here = self._fileobj.tell()
+        self._checkwindow(here, "read")
+        bytes = min(size, self._end - here)
+        return self._fileobj.read(bytes)
+
+
+def mergecopy(src, dest):
+    """
+    copy2, but only if the destination isn't up to date
+    """
+    if os.path.exists(dest) and os.stat(dest).st_mtime >= os.stat(src).st_mtime:
+        return
+
+    copy2(src, dest)
+
+
+def mergetree(src, dst, condition=None, copyfn=mergecopy, srcbase=None):
+    """
+    Recursively merge a directory tree using mergecopy().
+    """
+    src = fsencoding(src)
+    dst = fsencoding(dst)
+    if srcbase is None:
+        srcbase = src
+    names = map(fsencoding, os.listdir(src))
+    try:
+        os.makedirs(dst)
+    except OSError:
+        pass
+    errors = []
+    for name in names:
+        srcname = os.path.join(src, name)
+        dstname = os.path.join(dst, name)
+        if condition is not None and not condition(srcname):
+            continue
+        try:
+            if os.path.islink(srcname):
+                realsrc = os.readlink(srcname)
+                os.symlink(realsrc, dstname)
+            elif os.path.isdir(srcname):
+                mergetree(
+                    srcname,
+                    dstname,
+                    condition=condition,
+                    copyfn=copyfn,
+                    srcbase=srcbase,
+                )
+            else:
+                copyfn(srcname, dstname)
+        except (IOError, os.error) as why:
+            errors.append((srcname, dstname, why))
+    if errors:
+        raise IOError(errors)
+
+
+def sdk_normalize(filename):
+    """
+    Normalize a path to strip out the SDK portion, normally so that it
+    can be decided whether it is in a system path or not.
+    """
+    if filename.startswith("/Developer/SDKs/"):
+        pathcomp = filename.split("/")
+        del pathcomp[1:4]
+        filename = "/".join(pathcomp)
+    return filename
+
+
+NOT_SYSTEM_FILES = []
+
+
+def in_system_path(filename):
+    """
+    Return True if the file is in a system path
+    """
+    fn = sdk_normalize(os.path.realpath(filename))
+    if fn.startswith("/usr/local/"):
+        return False
+    elif fn.startswith("/System/") or fn.startswith("/usr/"):
+        if fn in NOT_SYSTEM_FILES:
+            return False
+        return True
+    else:
+        return False
+
+
+def has_filename_filter(module):
+    """
+    Return False if the module does not have a filename attribute
+    """
+    return getattr(module, "filename", None) is not None
+
+
+def get_magic():
+    """
+    Get a list of valid Mach-O header signatures, not including the fat header
+    """
+    return MAGIC
+
+
+def is_platform_file(path):
+    """
+    Return True if the file is Mach-O
+    """
+    if not os.path.exists(path) or os.path.islink(path):
+        return False
+    # If the header is fat, we need to read into the first arch
+    with open(path, "rb") as fileobj:
+        bytes = fileobj.read(MAGIC_LEN)
+        if bytes == FAT_MAGIC_BYTES:
+            # Read in the fat header
+            fileobj.seek(0)
+            header = mach_o.fat_header.from_fileobj(fileobj, _endian_=">")
+            if header.nfat_arch < 1:
+                return False
+            # Read in the first fat arch header
+            arch = mach_o.fat_arch.from_fileobj(fileobj, _endian_=">")
+            fileobj.seek(arch.offset)
+            # Read magic off the first header
+            bytes = fileobj.read(MAGIC_LEN)
+    for magic in MAGIC:
+        if bytes == magic:
+            return True
+    return False
+
+
+def iter_platform_files(dst):
+    """
+    Walk a directory and yield each full path that is a Mach-O file
+    """
+    for root, _dirs, files in os.walk(dst):
+        for fn in files:
+            fn = os.path.join(root, fn)
+            if is_platform_file(fn):
+                yield fn
+
+
+def strip_files(files, argv_max=(256 * 1024)):
+    """
+    Strip a list of files
+    """
+    tostrip = [(fn, flipwritable(fn)) for fn in files]
+    while tostrip:
+        cmd = list(STRIPCMD)
+        flips = []
+        pathlen = sum(len(s) + 1 for s in cmd)
+        while pathlen < argv_max:
+            if not tostrip:
+                break
+            added, flip = tostrip.pop()
+            pathlen += len(added) + 1
+            cmd.append(added)
+            flips.append((added, flip))
+        else:
+            cmd.pop()
+            tostrip.append(flips.pop())
+        os.spawnv(os.P_WAIT, cmd[0], cmd)
+        for args in flips:
+            flipwritable(*args)
diff --git a/lib/spack/external/_vendoring/markupsafe/LICENSE.rst b/lib/spack/external/_vendoring/markupsafe/LICENSE.rst
new file mode 100644
index 0000000000..9d227a0cc4
--- /dev/null
+++ b/lib/spack/external/_vendoring/markupsafe/LICENSE.rst
@@ -0,0 +1,28 @@
+Copyright 2010 Pallets
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are
+met:
+
+1.  Redistributions of source code must retain the above copyright
+    notice, this list of conditions and the following disclaimer.
+
+2.  Redistributions in binary form must reproduce the above copyright
+    notice, this list of conditions and the following disclaimer in the
+    documentation and/or other materials provided with the distribution.
+
+3.  Neither the name of the copyright holder nor the names of its
+    contributors may be used to endorse or promote products derived from
+    this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
+PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
+TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
diff --git a/lib/spack/external/_vendoring/markupsafe/__init__.py b/lib/spack/external/_vendoring/markupsafe/__init__.py
new file mode 100644
index 0000000000..d331ac3622
--- /dev/null
+++ b/lib/spack/external/_vendoring/markupsafe/__init__.py
@@ -0,0 +1,288 @@
+import functools
+import re
+import string
+import typing as t
+
+if t.TYPE_CHECKING:
+    import typing_extensions as te
+
+    class HasHTML(te.Protocol):
+        def __html__(self) -> str:
+            pass
+
+
+__version__ = "2.0.1"
+
+_striptags_re = re.compile(r"(<!--.*?-->|<[^>]*>)")
+
+
+def _simple_escaping_wrapper(name: str) -> t.Callable[..., "Markup"]:
+    orig = getattr(str, name)
+
+    @functools.wraps(orig)
+    def wrapped(self: "Markup", *args: t.Any, **kwargs: t.Any) -> "Markup":
+        args = _escape_argspec(list(args), enumerate(args), self.escape)  # type: ignore
+        _escape_argspec(kwargs, kwargs.items(), self.escape)
+        return self.__class__(orig(self, *args, **kwargs))
+
+    return wrapped
+
+
+class Markup(str):
+    """A string that is ready to be safely inserted into an HTML or XML
+    document, either because it was escaped or because it was marked
+    safe.
+
+    Passing an object to the constructor converts it to text and wraps
+    it to mark it safe without escaping. To escape the text, use the
+    :meth:`escape` class method instead.
+
+    >>> Markup("Hello, <em>World</em>!")
+    Markup('Hello, <em>World</em>!')
+    >>> Markup(42)
+    Markup('42')
+    >>> Markup.escape("Hello, <em>World</em>!")
+    Markup('Hello &lt;em&gt;World&lt;/em&gt;!')
+
+    This implements the ``__html__()`` interface that some frameworks
+    use. Passing an object that implements ``__html__()`` will wrap the
+    output of that method, marking it safe.
+
+    >>> class Foo:
+    ...     def __html__(self):
+    ...         return '<a href="/foo">foo</a>'
+    ...
+    >>> Markup(Foo())
+    Markup('<a href="/foo">foo</a>')
+
+    This is a subclass of :class:`str`. It has the same methods, but
+    escapes their arguments and returns a ``Markup`` instance.
+
+    >>> Markup("<em>%s</em>") % ("foo & bar",)
+    Markup('<em>foo &amp; bar</em>')
+    >>> Markup("<em>Hello</em> ") + "<foo>"
+    Markup('<em>Hello</em> &lt;foo&gt;')
+    """
+
+    __slots__ = ()
+
+    def __new__(
+        cls, base: t.Any = "", encoding: t.Optional[str] = None, errors: str = "strict"
+    ) -> "Markup":
+        if hasattr(base, "__html__"):
+            base = base.__html__()
+
+        if encoding is None:
+            return super().__new__(cls, base)
+
+        return super().__new__(cls, base, encoding, errors)
+
+    def __html__(self) -> "Markup":
+        return self
+
+    def __add__(self, other: t.Union[str, "HasHTML"]) -> "Markup":
+        if isinstance(other, str) or hasattr(other, "__html__"):
+            return self.__class__(super().__add__(self.escape(other)))
+
+        return NotImplemented
+
+    def __radd__(self, other: t.Union[str, "HasHTML"]) -> "Markup":
+        if isinstance(other, str) or hasattr(other, "__html__"):
+            return self.escape(other).__add__(self)
+
+        return NotImplemented
+
+    def __mul__(self, num: int) -> "Markup":
+        if isinstance(num, int):
+            return self.__class__(super().__mul__(num))
+
+        return NotImplemented  # type: ignore
+
+    __rmul__ = __mul__
+
+    def __mod__(self, arg: t.Any) -> "Markup":
+        if isinstance(arg, tuple):
+            arg = tuple(_MarkupEscapeHelper(x, self.escape) for x in arg)
+        else:
+            arg = _MarkupEscapeHelper(arg, self.escape)
+
+        return self.__class__(super().__mod__(arg))
+
+    def __repr__(self) -> str:
+        return f"{self.__class__.__name__}({super().__repr__()})"
+
+    def join(self, seq: t.Iterable[t.Union[str, "HasHTML"]]) -> "Markup":
+        return self.__class__(super().join(map(self.escape, seq)))
+
+    join.__doc__ = str.join.__doc__
+
+    def split(  # type: ignore
+        self, sep: t.Optional[str] = None, maxsplit: int = -1
+    ) -> t.List["Markup"]:
+        return [self.__class__(v) for v in super().split(sep, maxsplit)]
+
+    split.__doc__ = str.split.__doc__
+
+    def rsplit(  # type: ignore
+        self, sep: t.Optional[str] = None, maxsplit: int = -1
+    ) -> t.List["Markup"]:
+        return [self.__class__(v) for v in super().rsplit(sep, maxsplit)]
+
+    rsplit.__doc__ = str.rsplit.__doc__
+
+    def splitlines(self, keepends: bool = False) -> t.List["Markup"]:  # type: ignore
+        return [self.__class__(v) for v in super().splitlines(keepends)]
+
+    splitlines.__doc__ = str.splitlines.__doc__
+
+    def unescape(self) -> str:
+        """Convert escaped markup back into a text string. This replaces
+        HTML entities with the characters they represent.
+
+        >>> Markup("Main &raquo; <em>About</em>").unescape()
+        'Main » <em>About</em>'
+        """
+        from html import unescape
+
+        return unescape(str(self))
+
+    def striptags(self) -> str:
+        """:meth:`unescape` the markup, remove tags, and normalize
+        whitespace to single spaces.
+
+        >>> Markup("Main &raquo;\t<em>About</em>").striptags()
+        'Main » About'
+        """
+        stripped = " ".join(_striptags_re.sub("", self).split())
+        return Markup(stripped).unescape()
+
+    @classmethod
+    def escape(cls, s: t.Any) -> "Markup":
+        """Escape a string. Calls :func:`escape` and ensures that for
+        subclasses the correct type is returned.
+        """
+        rv = escape(s)
+
+        if rv.__class__ is not cls:
+            return cls(rv)
+
+        return rv
+
+    for method in (
+        "__getitem__",
+        "capitalize",
+        "title",
+        "lower",
+        "upper",
+        "replace",
+        "ljust",
+        "rjust",
+        "lstrip",
+        "rstrip",
+        "center",
+        "strip",
+        "translate",
+        "expandtabs",
+        "swapcase",
+        "zfill",
+    ):
+        locals()[method] = _simple_escaping_wrapper(method)
+
+    del method
+
+    def partition(self, sep: str) -> t.Tuple["Markup", "Markup", "Markup"]:
+        l, s, r = super().partition(self.escape(sep))
+        cls = self.__class__
+        return cls(l), cls(s), cls(r)
+
+    def rpartition(self, sep: str) -> t.Tuple["Markup", "Markup", "Markup"]:
+        l, s, r = super().rpartition(self.escape(sep))
+        cls = self.__class__
+        return cls(l), cls(s), cls(r)
+
+    def format(self, *args: t.Any, **kwargs: t.Any) -> "Markup":
+        formatter = EscapeFormatter(self.escape)
+        return self.__class__(formatter.vformat(self, args, kwargs))
+
+    def __html_format__(self, format_spec: str) -> "Markup":
+        if format_spec:
+            raise ValueError("Unsupported format specification for Markup.")
+
+        return self
+
+
+class EscapeFormatter(string.Formatter):
+    __slots__ = ("escape",)
+
+    def __init__(self, escape: t.Callable[[t.Any], Markup]) -> None:
+        self.escape = escape
+        super().__init__()
+
+    def format_field(self, value: t.Any, format_spec: str) -> str:
+        if hasattr(value, "__html_format__"):
+            rv = value.__html_format__(format_spec)
+        elif hasattr(value, "__html__"):
+            if format_spec:
+                raise ValueError(
+                    f"Format specifier {format_spec} given, but {type(value)} does not"
+                    " define __html_format__. A class that defines __html__ must define"
+                    " __html_format__ to work with format specifiers."
+                )
+            rv = value.__html__()
+        else:
+            # We need to make sure the format spec is str here as
+            # otherwise the wrong callback methods are invoked.
+            rv = string.Formatter.format_field(self, value, str(format_spec))
+        return str(self.escape(rv))
+
+
+_ListOrDict = t.TypeVar("_ListOrDict", list, dict)
+
+
+def _escape_argspec(
+    obj: _ListOrDict, iterable: t.Iterable[t.Any], escape: t.Callable[[t.Any], Markup]
+) -> _ListOrDict:
+    """Helper for various string-wrapped functions."""
+    for key, value in iterable:
+        if isinstance(value, str) or hasattr(value, "__html__"):
+            obj[key] = escape(value)
+
+    return obj
+
+
+class _MarkupEscapeHelper:
+    """Helper for :meth:`Markup.__mod__`."""
+
+    __slots__ = ("obj", "escape")
+
+    def __init__(self, obj: t.Any, escape: t.Callable[[t.Any], Markup]) -> None:
+        self.obj = obj
+        self.escape = escape
+
+    def __getitem__(self, item: t.Any) -> "_MarkupEscapeHelper":
+        return _MarkupEscapeHelper(self.obj[item], self.escape)
+
+    def __str__(self) -> str:
+        return str(self.escape(self.obj))
+
+    def __repr__(self) -> str:
+        return str(self.escape(repr(self.obj)))
+
+    def __int__(self) -> int:
+        return int(self.obj)
+
+    def __float__(self) -> float:
+        return float(self.obj)
+
+
+# circular import
+try:
+    from ._speedups import escape as escape
+    from ._speedups import escape_silent as escape_silent
+    from ._speedups import soft_str as soft_str
+    from ._speedups import soft_unicode
+except ImportError:
+    from ._native import escape as escape
+    from ._native import escape_silent as escape_silent  # noqa: F401
+    from ._native import soft_str as soft_str  # noqa: F401
+    from ._native import soft_unicode  # noqa: F401
diff --git a/lib/spack/external/_vendoring/markupsafe/_native.py b/lib/spack/external/_vendoring/markupsafe/_native.py
new file mode 100644
index 0000000000..6f7eb7a8cb
--- /dev/null
+++ b/lib/spack/external/_vendoring/markupsafe/_native.py
@@ -0,0 +1,75 @@
+import typing as t
+
+from . import Markup
+
+
+def escape(s: t.Any) -> Markup:
+    """Replace the characters ``&``, ``<``, ``>``, ``'``, and ``"`` in
+    the string with HTML-safe sequences. Use this if you need to display
+    text that might contain such characters in HTML.
+
+    If the object has an ``__html__`` method, it is called and the
+    return value is assumed to already be safe for HTML.
+
+    :param s: An object to be converted to a string and escaped.
+    :return: A :class:`Markup` string with the escaped text.
+    """
+    if hasattr(s, "__html__"):
+        return Markup(s.__html__())
+
+    return Markup(
+        str(s)
+        .replace("&", "&amp;")
+        .replace(">", "&gt;")
+        .replace("<", "&lt;")
+        .replace("'", "&#39;")
+        .replace('"', "&#34;")
+    )
+
+
+def escape_silent(s: t.Optional[t.Any]) -> Markup:
+    """Like :func:`escape` but treats ``None`` as the empty string.
+    Useful with optional values, as otherwise you get the string
+    ``'None'`` when the value is ``None``.
+
+    >>> escape(None)
+    Markup('None')
+    >>> escape_silent(None)
+    Markup('')
+    """
+    if s is None:
+        return Markup()
+
+    return escape(s)
+
+
+def soft_str(s: t.Any) -> str:
+    """Convert an object to a string if it isn't already. This preserves
+    a :class:`Markup` string rather than converting it back to a basic
+    string, so it will still be marked as safe and won't be escaped
+    again.
+
+    >>> value = escape("<User 1>")
+    >>> value
+    Markup('&lt;User 1&gt;')
+    >>> escape(str(value))
+    Markup('&amp;lt;User 1&amp;gt;')
+    >>> escape(soft_str(value))
+    Markup('&lt;User 1&gt;')
+    """
+    if not isinstance(s, str):
+        return str(s)
+
+    return s
+
+
+def soft_unicode(s: t.Any) -> str:
+    import warnings
+
+    warnings.warn(
+        "'soft_unicode' has been renamed to 'soft_str'. The old name"
+        " will be removed in MarkupSafe 2.1.",
+        DeprecationWarning,
+        stacklevel=2,
+    )
+    return soft_str(s)
diff --git a/lib/spack/external/_vendoring/markupsafe/_speedups.c b/lib/spack/external/_vendoring/markupsafe/_speedups.c
new file mode 100644
index 0000000000..44967b1fdc
--- /dev/null
+++ b/lib/spack/external/_vendoring/markupsafe/_speedups.c
@@ -0,0 +1,339 @@
+#include <Python.h>
+
+static PyObject* markup;
+
+static int
+init_constants(void)
+{
+	PyObject *module;
+
+	/* import markup type so that we can mark the return value */
+	module = PyImport_ImportModule("markupsafe");
+	if (!module)
+		return 0;
+	markup = PyObject_GetAttrString(module, "Markup");
+	Py_DECREF(module);
+
+	return 1;
+}
+
+#define GET_DELTA(inp, inp_end, delta) \
+	while (inp < inp_end) { \
+		switch (*inp++) { \
+		case '"': \
+		case '\'': \
+		case '&': \
+			delta += 4; \
+			break; \
+		case '<': \
+		case '>': \
+			delta += 3; \
+			break; \
+		} \
+	}
+
+#define DO_ESCAPE(inp, inp_end, outp) \
+	{ \
+		Py_ssize_t ncopy = 0; \
+		while (inp < inp_end) { \
+			switch (*inp) { \
+			case '"': \
+				memcpy(outp, inp-ncopy, sizeof(*outp)*ncopy); \
+				outp += ncopy; ncopy = 0; \
+				*outp++ = '&'; \
+				*outp++ = '#'; \
+				*outp++ = '3'; \
+				*outp++ = '4'; \
+				*outp++ = ';'; \
+				break; \
+			case '\'': \
+				memcpy(outp, inp-ncopy, sizeof(*outp)*ncopy); \
+				outp += ncopy; ncopy = 0; \
+				*outp++ = '&'; \
+				*outp++ = '#'; \
+				*outp++ = '3'; \
+				*outp++ = '9'; \
+				*outp++ = ';'; \
+				break; \
+			case '&': \
+				memcpy(outp, inp-ncopy, sizeof(*outp)*ncopy); \
+				outp += ncopy; ncopy = 0; \
+				*outp++ = '&'; \
+				*outp++ = 'a'; \
+				*outp++ = 'm'; \
+				*outp++ = 'p'; \
+				*outp++ = ';'; \
+				break; \
+			case '<': \
+				memcpy(outp, inp-ncopy, sizeof(*outp)*ncopy); \
+				outp += ncopy; ncopy = 0; \
+				*outp++ = '&'; \
+				*outp++ = 'l'; \
+				*outp++ = 't'; \
+				*outp++ = ';'; \
+				break; \
+			case '>': \
+				memcpy(outp, inp-ncopy, sizeof(*outp)*ncopy); \
+				outp += ncopy; ncopy = 0; \
+				*outp++ = '&'; \
+				*outp++ = 'g'; \
+				*outp++ = 't'; \
+				*outp++ = ';'; \
+				break; \
+			default: \
+				ncopy++; \
+			} \
+			inp++; \
+		} \
+		memcpy(outp, inp-ncopy, sizeof(*outp)*ncopy); \
+	}
+
+static PyObject*
+escape_unicode_kind1(PyUnicodeObject *in)
+{
+	Py_UCS1 *inp = PyUnicode_1BYTE_DATA(in);
+	Py_UCS1 *inp_end = inp + PyUnicode_GET_LENGTH(in);
+	Py_UCS1 *outp;
+	PyObject *out;
+	Py_ssize_t delta = 0;
+
+	GET_DELTA(inp, inp_end, delta);
+	if (!delta) {
+		Py_INCREF(in);
+		return (PyObject*)in;
+	}
+
+	out = PyUnicode_New(PyUnicode_GET_LENGTH(in) + delta,
+						PyUnicode_IS_ASCII(in) ? 127 : 255);
+	if (!out)
+		return NULL;
+
+	inp = PyUnicode_1BYTE_DATA(in);
+	outp = PyUnicode_1BYTE_DATA(out);
+	DO_ESCAPE(inp, inp_end, outp);
+	return out;
+}
+
+static PyObject*
+escape_unicode_kind2(PyUnicodeObject *in)
+{
+	Py_UCS2 *inp = PyUnicode_2BYTE_DATA(in);
+	Py_UCS2 *inp_end = inp + PyUnicode_GET_LENGTH(in);
+	Py_UCS2 *outp;
+	PyObject *out;
+	Py_ssize_t delta = 0;
+
+	GET_DELTA(inp, inp_end, delta);
+	if (!delta) {
+		Py_INCREF(in);
+		return (PyObject*)in;
+	}
+
+	out = PyUnicode_New(PyUnicode_GET_LENGTH(in) + delta, 65535);
+	if (!out)
+		return NULL;
+
+	inp = PyUnicode_2BYTE_DATA(in);
+	outp = PyUnicode_2BYTE_DATA(out);
+	DO_ESCAPE(inp, inp_end, outp);
+	return out;
+}
+
+
+static PyObject*
+escape_unicode_kind4(PyUnicodeObject *in)
+{
+	Py_UCS4 *inp = PyUnicode_4BYTE_DATA(in);
+	Py_UCS4 *inp_end = inp + PyUnicode_GET_LENGTH(in);
+	Py_UCS4 *outp;
+	PyObject *out;
+	Py_ssize_t delta = 0;
+
+	GET_DELTA(inp, inp_end, delta);
+	if (!delta) {
+		Py_INCREF(in);
+		return (PyObject*)in;
+	}
+
+	out = PyUnicode_New(PyUnicode_GET_LENGTH(in) + delta, 1114111);
+	if (!out)
+		return NULL;
+
+	inp = PyUnicode_4BYTE_DATA(in);
+	outp = PyUnicode_4BYTE_DATA(out);
+	DO_ESCAPE(inp, inp_end, outp);
+	return out;
+}
+
+static PyObject*
+escape_unicode(PyUnicodeObject *in)
+{
+	if (PyUnicode_READY(in))
+		return NULL;
+
+	switch (PyUnicode_KIND(in)) {
+	case PyUnicode_1BYTE_KIND:
+		return escape_unicode_kind1(in);
+	case PyUnicode_2BYTE_KIND:
+		return escape_unicode_kind2(in);
+	case PyUnicode_4BYTE_KIND:
+		return escape_unicode_kind4(in);
+	}
+	assert(0);  /* shouldn't happen */
+	return NULL;
+}
+
+static PyObject*
+escape(PyObject *self, PyObject *text)
+{
+	static PyObject *id_html;
+	PyObject *s = NULL, *rv = NULL, *html;
+
+	if (id_html == NULL) {
+		id_html = PyUnicode_InternFromString("__html__");
+		if (id_html == NULL) {
+			return NULL;
+		}
+	}
+
+	/* we don't have to escape integers, bools or floats */
+	if (PyLong_CheckExact(text) ||
+		PyFloat_CheckExact(text) || PyBool_Check(text) ||
+		text == Py_None)
+		return PyObject_CallFunctionObjArgs(markup, text, NULL);
+
+	/* if the object has an __html__ method that performs the escaping */
+	html = PyObject_GetAttr(text ,id_html);
+	if (html) {
+		s = PyObject_CallObject(html, NULL);
+		Py_DECREF(html);
+		if (s == NULL) {
+			return NULL;
+		}
+		/* Convert to Markup object */
+		rv = PyObject_CallFunctionObjArgs(markup, (PyObject*)s, NULL);
+		Py_DECREF(s);
+		return rv;
+	}
+
+	/* otherwise make the object unicode if it isn't, then escape */
+	PyErr_Clear();
+	if (!PyUnicode_Check(text)) {
+		PyObject *unicode = PyObject_Str(text);
+		if (!unicode)
+			return NULL;
+		s = escape_unicode((PyUnicodeObject*)unicode);
+		Py_DECREF(unicode);
+	}
+	else
+		s = escape_unicode((PyUnicodeObject*)text);
+
+	/* convert the unicode string into a markup object. */
+	rv = PyObject_CallFunctionObjArgs(markup, (PyObject*)s, NULL);
+	Py_DECREF(s);
+	return rv;
+}
+
+
+static PyObject*
+escape_silent(PyObject *self, PyObject *text)
+{
+	if (text != Py_None)
+		return escape(self, text);
+	return PyObject_CallFunctionObjArgs(markup, NULL);
+}
+
+
+static PyObject*
+soft_str(PyObject *self, PyObject *s)
+{
+	if (!PyUnicode_Check(s))
+		return PyObject_Str(s);
+	Py_INCREF(s);
+	return s;
+}
+
+
+static PyObject*
+soft_unicode(PyObject *self, PyObject *s)
+{
+	PyErr_WarnEx(
+		PyExc_DeprecationWarning,
+		"'soft_unicode' has been renamed to 'soft_str'. The old name"
+		" will be removed in MarkupSafe 2.1.",
+		2
+	);
+	return soft_str(self, s);
+}
+
+
+static PyMethodDef module_methods[] = {
+	{
+		"escape",
+		(PyCFunction)escape,
+		METH_O,
+		"Replace the characters ``&``, ``<``, ``>``, ``'``, and ``\"`` in"
+		" the string with HTML-safe sequences. Use this if you need to display"
+		" text that might contain such characters in HTML.\n\n"
+		"If the object has an ``__html__`` method, it is called and the"
+		" return value is assumed to already be safe for HTML.\n\n"
+		":param s: An object to be converted to a string and escaped.\n"
+		":return: A :class:`Markup` string with the escaped text.\n"
+	},
+	{
+		"escape_silent",
+		(PyCFunction)escape_silent,
+		METH_O,
+		"Like :func:`escape` but treats ``None`` as the empty string."
+		" Useful with optional values, as otherwise you get the string"
+		" ``'None'`` when the value is ``None``.\n\n"
+		">>> escape(None)\n"
+		"Markup('None')\n"
+		">>> escape_silent(None)\n"
+		"Markup('')\n"
+	},
+	{
+		"soft_str",
+		(PyCFunction)soft_str,
+		METH_O,
+		"Convert an object to a string if it isn't already. This preserves"
+		" a :class:`Markup` string rather than converting it back to a basic"
+		" string, so it will still be marked as safe and won't be escaped"
+		" again.\n\n"
+		">>> value = escape(\"<User 1>\")\n"
+		">>> value\n"
+		"Markup('&lt;User 1&gt;')\n"
+		">>> escape(str(value))\n"
+		"Markup('&amp;lt;User 1&amp;gt;')\n"
+		">>> escape(soft_str(value))\n"
+		"Markup('&lt;User 1&gt;')\n"
+	},
+	{
+		"soft_unicode",
+		(PyCFunction)soft_unicode,
+		METH_O,
+		""
+	},
+	{NULL, NULL, 0, NULL}  /* Sentinel */
+};
+
+static struct PyModuleDef module_definition = {
+	PyModuleDef_HEAD_INIT,
+	"markupsafe._speedups",
+	NULL,
+	-1,
+	module_methods,
+	NULL,
+	NULL,
+	NULL,
+	NULL
+};
+
+PyMODINIT_FUNC
+PyInit__speedups(void)
+{
+	if (!init_constants())
+		return NULL;
+
+	return PyModule_Create(&module_definition);
+}
diff --git a/lib/spack/external/_vendoring/markupsafe/_speedups.pyi b/lib/spack/external/_vendoring/markupsafe/_speedups.pyi
new file mode 100644
index 0000000000..f673240f6d
--- /dev/null
+++ b/lib/spack/external/_vendoring/markupsafe/_speedups.pyi
@@ -0,0 +1,9 @@
+from typing import Any
+from typing import Optional
+
+from . import Markup
+
+def escape(s: Any) -> Markup: ...
+def escape_silent(s: Optional[Any]) -> Markup: ...
+def soft_str(s: Any) -> str: ...
+def soft_unicode(s: Any) -> str: ...
diff --git a/lib/spack/external/_vendoring/markupsafe/py.typed b/lib/spack/external/_vendoring/markupsafe/py.typed
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/lib/spack/external/_vendoring/markupsafe/py.typed
diff --git a/lib/spack/external/_vendoring/pyrsistent/LICENSE.mit b/lib/spack/external/_vendoring/pyrsistent/LICENSE.mit
new file mode 100644
index 0000000000..4ceb5123c1
--- /dev/null
+++ b/lib/spack/external/_vendoring/pyrsistent/LICENSE.mit
@@ -0,0 +1,22 @@
+Copyright (c) 2021 Tobias Gustafsson
+
+Permission is hereby granted, free of charge, to any person
+obtaining a copy of this software and associated documentation
+files (the "Software"), to deal in the Software without
+restriction, including without limitation the rights to use,
+copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the
+Software is furnished to do so, subject to the following
+conditions:
+
+The above copyright notice and this permission notice shall be
+included in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+OTHER DEALINGS IN THE SOFTWARE.
\ No newline at end of file
diff --git a/lib/spack/external/_vendoring/pyrsistent/__init__.py b/lib/spack/external/_vendoring/pyrsistent/__init__.py
new file mode 100644
index 0000000000..be299658f3
--- /dev/null
+++ b/lib/spack/external/_vendoring/pyrsistent/__init__.py
@@ -0,0 +1,47 @@
+# -*- coding: utf-8 -*-
+
+from pyrsistent._pmap import pmap, m, PMap
+
+from pyrsistent._pvector import pvector, v, PVector
+
+from pyrsistent._pset import pset, s, PSet
+
+from pyrsistent._pbag import pbag, b, PBag
+
+from pyrsistent._plist import plist, l, PList
+
+from pyrsistent._pdeque import pdeque, dq, PDeque
+
+from pyrsistent._checked_types import (
+    CheckedPMap, CheckedPVector, CheckedPSet, InvariantException, CheckedKeyTypeError,
+    CheckedValueTypeError, CheckedType, optional)
+
+from pyrsistent._field_common import (
+    field, PTypeError, pset_field, pmap_field, pvector_field)
+
+from pyrsistent._precord import PRecord
+
+from pyrsistent._pclass import PClass, PClassMeta
+
+from pyrsistent._immutable import immutable
+
+from pyrsistent._helpers import freeze, thaw, mutant
+
+from pyrsistent._transformations import inc, discard, rex, ny
+
+from pyrsistent._toolz import get_in
+
+
+__all__ = ('pmap', 'm', 'PMap',
+           'pvector', 'v', 'PVector',
+           'pset', 's', 'PSet',
+           'pbag', 'b', 'PBag',
+           'plist', 'l', 'PList',
+           'pdeque', 'dq', 'PDeque',
+           'CheckedPMap', 'CheckedPVector', 'CheckedPSet', 'InvariantException', 'CheckedKeyTypeError', 'CheckedValueTypeError', 'CheckedType', 'optional',
+           'PRecord', 'field', 'pset_field', 'pmap_field', 'pvector_field',
+           'PClass', 'PClassMeta',
+           'immutable',
+           'freeze', 'thaw', 'mutant',
+           'get_in',
+           'inc', 'discard', 'rex', 'ny')
diff --git a/lib/spack/external/_vendoring/pyrsistent/__init__.pyi b/lib/spack/external/_vendoring/pyrsistent/__init__.pyi
new file mode 100644
index 0000000000..5909f7991a
--- /dev/null
+++ b/lib/spack/external/_vendoring/pyrsistent/__init__.pyi
@@ -0,0 +1,213 @@
+# flake8: noqa: E704
+# from https://gist.github.com/WuTheFWasThat/091a17d4b5cab597dfd5d4c2d96faf09
+# Stubs for pyrsistent (Python 3.6)
+
+from typing import Any
+from typing import AnyStr
+from typing import Callable
+from typing import Iterable
+from typing import Iterator
+from typing import List
+from typing import Optional
+from typing import Mapping
+from typing import MutableMapping
+from typing import Sequence
+from typing import Set
+from typing import Union
+from typing import Tuple
+from typing import Type
+from typing import TypeVar
+from typing import overload
+
+# see commit 08519aa for explanation of the re-export
+from pyrsistent.typing import CheckedKeyTypeError as CheckedKeyTypeError
+from pyrsistent.typing import CheckedPMap as CheckedPMap
+from pyrsistent.typing import CheckedPSet as CheckedPSet
+from pyrsistent.typing import CheckedPVector as CheckedPVector
+from pyrsistent.typing import CheckedType as CheckedType
+from pyrsistent.typing import CheckedValueTypeError as CheckedValueTypeError
+from pyrsistent.typing import InvariantException as InvariantException
+from pyrsistent.typing import PClass as PClass
+from pyrsistent.typing import PBag as PBag
+from pyrsistent.typing import PDeque as PDeque
+from pyrsistent.typing import PList as PList
+from pyrsistent.typing import PMap as PMap
+from pyrsistent.typing import PMapEvolver as PMapEvolver
+from pyrsistent.typing import PSet as PSet
+from pyrsistent.typing import PSetEvolver as PSetEvolver
+from pyrsistent.typing import PTypeError as PTypeError
+from pyrsistent.typing import PVector as PVector
+from pyrsistent.typing import PVectorEvolver as PVectorEvolver
+
+T = TypeVar('T')
+KT = TypeVar('KT')
+VT = TypeVar('VT')
+
+def pmap(initial: Union[Mapping[KT, VT], Iterable[Tuple[KT, VT]]] = {}, pre_size: int = 0) -> PMap[KT, VT]: ...
+def m(**kwargs: VT) -> PMap[str, VT]: ...
+
+def pvector(iterable: Iterable[T] = ...) -> PVector[T]: ...
+def v(*iterable: T) -> PVector[T]: ...
+
+def pset(iterable: Iterable[T] = (), pre_size: int = 8) -> PSet[T]: ...
+def s(*iterable: T) -> PSet[T]: ...
+
+# see class_test.py for use cases
+Invariant = Tuple[bool, Optional[Union[str, Callable[[], str]]]]
+
+@overload
+def field(
+    type: Union[Type[T], Sequence[Type[T]]] = ...,
+    invariant: Callable[[Any], Union[Invariant, Iterable[Invariant]]] = lambda _: (True, None),
+    initial: Any = object(),
+    mandatory: bool = False,
+    factory: Callable[[Any], T] = lambda x: x,
+    serializer: Callable[[Any, T], Any] = lambda _, value: value,
+) -> T: ...
+# The actual return value (_PField) is irrelevant after a PRecord has been instantiated,
+# see https://github.com/tobgu/pyrsistent/blob/master/pyrsistent/_precord.py#L10
+@overload
+def field(
+    type: Any = ...,
+    invariant: Callable[[Any], Union[Invariant, Iterable[Invariant]]] = lambda _: (True, None),
+    initial: Any = object(),
+    mandatory: bool = False,
+    factory: Callable[[Any], Any] = lambda x: x,
+    serializer: Callable[[Any, Any], Any] = lambda _, value: value,
+) -> Any: ...
+
+# Use precise types for the simplest use cases, but fall back to Any for
+# everything else. See record_test.py for the wide range of possible types for
+# item_type
+@overload
+def pset_field(
+    item_type: Type[T],
+    optional: bool = False,
+    initial: Iterable[T] = ...,
+) -> PSet[T]: ...
+@overload
+def pset_field(
+    item_type: Any,
+    optional: bool = False,
+    initial: Any = (),
+) -> PSet[Any]: ...
+
+@overload
+def pmap_field(
+    key_type: Type[KT],
+    value_type: Type[VT],
+    optional: bool = False,
+    invariant: Callable[[Any], Tuple[bool, Optional[str]]] = lambda _: (True, None),
+) -> PMap[KT, VT]: ...
+@overload
+def pmap_field(
+    key_type: Any,
+    value_type: Any,
+    optional: bool = False,
+    invariant: Callable[[Any], Tuple[bool, Optional[str]]] = lambda _: (True, None),
+) -> PMap[Any, Any]: ...
+
+@overload
+def pvector_field(
+    item_type: Type[T],
+    optional: bool = False,
+    initial: Iterable[T] = ...,
+) -> PVector[T]: ...
+@overload
+def pvector_field(
+    item_type: Any,
+    optional: bool = False,
+    initial: Any = (),
+) -> PVector[Any]: ...
+
+def pbag(elements: Iterable[T]) -> PBag[T]: ...
+def b(*elements: T) -> PBag[T]: ...
+
+def plist(iterable: Iterable[T] = (), reverse: bool = False) -> PList[T]: ...
+def l(*elements: T) -> PList[T]: ...
+
+def pdeque(iterable: Optional[Iterable[T]] = None, maxlen: Optional[int] = None) -> PDeque[T]: ...
+def dq(*iterable: T) -> PDeque[T]: ...
+
+@overload
+def optional(type: T) -> Tuple[T, Type[None]]: ...
+@overload
+def optional(*typs: Any) -> Tuple[Any, ...]: ...
+
+T_PRecord = TypeVar('T_PRecord', bound='PRecord')
+class PRecord(PMap[AnyStr, Any]):
+    _precord_fields: Mapping
+    _precord_initial_values: Mapping
+
+    def __hash__(self) -> int: ...
+    def __init__(self, **kwargs: Any) -> None: ...
+    def __iter__(self) -> Iterator[Any]: ...
+    def __len__(self) -> int: ...
+    @classmethod
+    def create(
+        cls: Type[T_PRecord],
+        kwargs: Mapping,
+        _factory_fields: Optional[Iterable] = None,
+        ignore_extra: bool = False,
+    ) -> T_PRecord: ...
+    # This is OK because T_PRecord is a concrete type
+    def discard(self: T_PRecord, key: KT) -> T_PRecord: ...
+    def remove(self: T_PRecord, key: KT) -> T_PRecord: ...
+
+    def serialize(self, format: Optional[Any] = ...) -> MutableMapping: ...
+
+    # From pyrsistent documentation:
+    #   This set function differs slightly from that in the PMap
+    #   class. First of all it accepts key-value pairs. Second it accepts multiple key-value
+    #   pairs to perform one, atomic, update of multiple fields.
+    @overload
+    def set(self, key: KT, val: VT) -> Any: ...
+    @overload
+    def set(self, **kwargs: VT) -> Any: ...
+
+def immutable(
+    members: Union[str, Iterable[str]] = '',
+    name: str = 'Immutable',
+    verbose: bool = False,
+) -> Tuple: ...  # actually a namedtuple
+
+# ignore mypy warning "Overloaded function signatures 1 and 5 overlap with
+# incompatible return types"
+@overload
+def freeze(o: Mapping[KT, VT]) -> PMap[KT, VT]: ... # type: ignore
+@overload
+def freeze(o: List[T]) -> PVector[T]: ... # type: ignore
+@overload
+def freeze(o: Tuple[T, ...]) -> Tuple[T, ...]: ...
+@overload
+def freeze(o: Set[T]) -> PSet[T]: ... # type: ignore
+@overload
+def freeze(o: T) -> T: ...
+
+
+@overload
+def thaw(o: PMap[KT, VT]) -> MutableMapping[KT, VT]: ... # type: ignore
+@overload
+def thaw(o: PVector[T]) -> List[T]: ... # type: ignore
+@overload
+def thaw(o: Tuple[T, ...]) -> Tuple[T, ...]: ...
+# collections.abc.MutableSet is kind of garbage:
+# https://stackoverflow.com/questions/24977898/why-does-collections-mutableset-not-bestow-an-update-method
+@overload
+def thaw(o: PSet[T]) -> Set[T]: ... # type: ignore
+@overload
+def thaw(o: T) -> T: ...
+
+def mutant(fn: Callable) -> Callable: ...
+
+def inc(x: int) -> int: ...
+@overload
+def discard(evolver: PMapEvolver[KT, VT], key: KT) -> None: ...
+@overload
+def discard(evolver: PVectorEvolver[T], key: int) -> None: ...
+@overload
+def discard(evolver: PSetEvolver[T], key: T) -> None: ...
+def rex(expr: str) -> Callable[[Any], bool]: ...
+def ny(_: Any) -> bool: ...
+
+def get_in(keys: Iterable, coll: Mapping, default: Optional[Any] = None, no_default: bool = False) -> Any: ...
diff --git a/lib/spack/external/_vendoring/pyrsistent/_checked_types.py b/lib/spack/external/_vendoring/pyrsistent/_checked_types.py
new file mode 100644
index 0000000000..8ab8c2a8cc
--- /dev/null
+++ b/lib/spack/external/_vendoring/pyrsistent/_checked_types.py
@@ -0,0 +1,542 @@
+from enum import Enum
+
+from abc import abstractmethod, ABCMeta
+from collections.abc import Iterable
+
+from pyrsistent._pmap import PMap, pmap
+from pyrsistent._pset import PSet, pset
+from pyrsistent._pvector import PythonPVector, python_pvector
+
+
+class CheckedType(object):
+    """
+    Marker class to enable creation and serialization of checked object graphs.
+    """
+    __slots__ = ()
+
+    @classmethod
+    @abstractmethod
+    def create(cls, source_data, _factory_fields=None):
+        raise NotImplementedError()
+
+    @abstractmethod
+    def serialize(self, format=None):
+        raise NotImplementedError()
+
+
+def _restore_pickle(cls, data):
+    return cls.create(data, _factory_fields=set())
+
+
+class InvariantException(Exception):
+    """
+    Exception raised from a :py:class:`CheckedType` when invariant tests fail or when a mandatory
+    field is missing.
+
+    Contains two fields of interest:
+    invariant_errors, a tuple of error data for the failing invariants
+    missing_fields, a tuple of strings specifying the missing names
+    """
+
+    def __init__(self, error_codes=(), missing_fields=(), *args, **kwargs):
+        self.invariant_errors = tuple(e() if callable(e) else e for e in error_codes)
+        self.missing_fields = missing_fields
+        super(InvariantException, self).__init__(*args, **kwargs)
+
+    def __str__(self):
+        return super(InvariantException, self).__str__() + \
+            ", invariant_errors=[{invariant_errors}], missing_fields=[{missing_fields}]".format(
+            invariant_errors=', '.join(str(e) for e in self.invariant_errors),
+            missing_fields=', '.join(self.missing_fields))
+
+
+_preserved_iterable_types = (
+    Enum,
+)
+"""Some types are themselves iterable, but we want to use the type itself and
+not its members for the type specification. This defines a set of such types
+that we explicitly preserve.
+
+Note that strings are not such types because the string inputs we pass in are
+values, not types.
+"""
+
+
+def maybe_parse_user_type(t):
+    """Try to coerce a user-supplied type directive into a list of types.
+
+    This function should be used in all places where a user specifies a type,
+    for consistency.
+
+    The policy for what defines valid user input should be clear from the implementation.
+    """
+    is_type = isinstance(t, type)
+    is_preserved = isinstance(t, type) and issubclass(t, _preserved_iterable_types)
+    is_string = isinstance(t, str)
+    is_iterable = isinstance(t, Iterable)
+
+    if is_preserved:
+        return [t]
+    elif is_string:
+        return [t]
+    elif is_type and not is_iterable:
+        return [t]
+    elif is_iterable:
+        # Recur to validate contained types as well.
+        ts = t
+        return tuple(e for t in ts for e in maybe_parse_user_type(t))
+    else:
+        # If this raises because `t` cannot be formatted, so be it.
+        raise TypeError(
+            'Type specifications must be types or strings. Input: {}'.format(t)
+        )
+
+
+def maybe_parse_many_user_types(ts):
+    # Just a different name to communicate that you're parsing multiple user
+    # inputs. `maybe_parse_user_type` handles the iterable case anyway.
+    return maybe_parse_user_type(ts)
+
+
+def _store_types(dct, bases, destination_name, source_name):
+    maybe_types = maybe_parse_many_user_types([
+        d[source_name]
+        for d in ([dct] + [b.__dict__ for b in bases]) if source_name in d
+    ])
+
+    dct[destination_name] = maybe_types
+
+
+def _merge_invariant_results(result):
+    verdict = True
+    data = []
+    for verd, dat in result:
+        if not verd:
+            verdict = False
+            data.append(dat)
+
+    return verdict, tuple(data)
+
+
+def wrap_invariant(invariant):
+    # Invariant functions may return the outcome of several tests
+    # In those cases the results have to be merged before being passed
+    # back to the client.
+    def f(*args, **kwargs):
+        result = invariant(*args, **kwargs)
+        if isinstance(result[0], bool):
+            return result
+
+        return _merge_invariant_results(result)
+
+    return f
+
+
+def _all_dicts(bases, seen=None):
+    """
+    Yield each class in ``bases`` and each of their base classes.
+    """
+    if seen is None:
+        seen = set()
+    for cls in bases:
+        if cls in seen:
+            continue
+        seen.add(cls)
+        yield cls.__dict__
+        for b in _all_dicts(cls.__bases__, seen):
+            yield b
+
+
+def store_invariants(dct, bases, destination_name, source_name):
+    # Invariants are inherited
+    invariants = []
+    for ns in [dct] + list(_all_dicts(bases)):
+        try:
+            invariant = ns[source_name]
+        except KeyError:
+            continue
+        invariants.append(invariant)
+
+    if not all(callable(invariant) for invariant in invariants):
+        raise TypeError('Invariants must be callable')
+    dct[destination_name] = tuple(wrap_invariant(inv) for inv in invariants)
+
+
+class _CheckedTypeMeta(ABCMeta):
+    def __new__(mcs, name, bases, dct):
+        _store_types(dct, bases, '_checked_types', '__type__')
+        store_invariants(dct, bases, '_checked_invariants', '__invariant__')
+
+        def default_serializer(self, _, value):
+            if isinstance(value, CheckedType):
+                return value.serialize()
+            return value
+
+        dct.setdefault('__serializer__', default_serializer)
+
+        dct['__slots__'] = ()
+
+        return super(_CheckedTypeMeta, mcs).__new__(mcs, name, bases, dct)
+
+
+class CheckedTypeError(TypeError):
+    def __init__(self, source_class, expected_types, actual_type, actual_value, *args, **kwargs):
+        super(CheckedTypeError, self).__init__(*args, **kwargs)
+        self.source_class = source_class
+        self.expected_types = expected_types
+        self.actual_type = actual_type
+        self.actual_value = actual_value
+
+
+class CheckedKeyTypeError(CheckedTypeError):
+    """
+    Raised when trying to set a value using a key with a type that doesn't match the declared type.
+
+    Attributes:
+    source_class -- The class of the collection
+    expected_types  -- Allowed types
+    actual_type -- The non matching type
+    actual_value -- Value of the variable with the non matching type
+    """
+    pass
+
+
+class CheckedValueTypeError(CheckedTypeError):
+    """
+    Raised when trying to set a value using a key with a type that doesn't match the declared type.
+
+    Attributes:
+    source_class -- The class of the collection
+    expected_types  -- Allowed types
+    actual_type -- The non matching type
+    actual_value -- Value of the variable with the non matching type
+    """
+    pass
+
+
+def _get_class(type_name):
+    module_name, class_name = type_name.rsplit('.', 1)
+    module = __import__(module_name, fromlist=[class_name])
+    return getattr(module, class_name)
+
+
+def get_type(typ):
+    if isinstance(typ, type):
+        return typ
+
+    return _get_class(typ)
+
+
+def get_types(typs):
+    return [get_type(typ) for typ in typs]
+
+
+def _check_types(it, expected_types, source_class, exception_type=CheckedValueTypeError):
+    if expected_types:
+        for e in it:
+            if not any(isinstance(e, get_type(t)) for t in expected_types):
+                actual_type = type(e)
+                msg = "Type {source_class} can only be used with {expected_types}, not {actual_type}".format(
+                    source_class=source_class.__name__,
+                    expected_types=tuple(get_type(et).__name__ for et in expected_types),
+                    actual_type=actual_type.__name__)
+                raise exception_type(source_class, expected_types, actual_type, e, msg)
+
+
+def _invariant_errors(elem, invariants):
+    return [data for valid, data in (invariant(elem) for invariant in invariants) if not valid]
+
+
+def _invariant_errors_iterable(it, invariants):
+    return sum([_invariant_errors(elem, invariants) for elem in it], [])
+
+
+def optional(*typs):
+    """ Convenience function to specify that a value may be of any of the types in type 'typs' or None """
+    return tuple(typs) + (type(None),)
+
+
+def _checked_type_create(cls, source_data, _factory_fields=None, ignore_extra=False):
+    if isinstance(source_data, cls):
+        return source_data
+
+    # Recursively apply create methods of checked types if the types of the supplied data
+    # does not match any of the valid types.
+    types = get_types(cls._checked_types)
+    checked_type = next((t for t in types if issubclass(t, CheckedType)), None)
+    if checked_type:
+        return cls([checked_type.create(data, ignore_extra=ignore_extra)
+                    if not any(isinstance(data, t) for t in types) else data
+                    for data in source_data])
+
+    return cls(source_data)
+
+class CheckedPVector(PythonPVector, CheckedType, metaclass=_CheckedTypeMeta):
+    """
+    A CheckedPVector is a PVector which allows specifying type and invariant checks.
+
+    >>> class Positives(CheckedPVector):
+    ...     __type__ = (int, float)
+    ...     __invariant__ = lambda n: (n >= 0, 'Negative')
+    ...
+    >>> Positives([1, 2, 3])
+    Positives([1, 2, 3])
+    """
+
+    __slots__ = ()
+
+    def __new__(cls, initial=()):
+        if type(initial) == PythonPVector:
+            return super(CheckedPVector, cls).__new__(cls, initial._count, initial._shift, initial._root, initial._tail)
+
+        return CheckedPVector.Evolver(cls, python_pvector()).extend(initial).persistent()
+
+    def set(self, key, value):
+        return self.evolver().set(key, value).persistent()
+
+    def append(self, val):
+        return self.evolver().append(val).persistent()
+
+    def extend(self, it):
+        return self.evolver().extend(it).persistent()
+
+    create = classmethod(_checked_type_create)
+
+    def serialize(self, format=None):
+        serializer = self.__serializer__
+        return list(serializer(format, v) for v in self)
+
+    def __reduce__(self):
+        # Pickling support
+        return _restore_pickle, (self.__class__, list(self),)
+
+    class Evolver(PythonPVector.Evolver):
+        __slots__ = ('_destination_class', '_invariant_errors')
+
+        def __init__(self, destination_class, vector):
+            super(CheckedPVector.Evolver, self).__init__(vector)
+            self._destination_class = destination_class
+            self._invariant_errors = []
+
+        def _check(self, it):
+            _check_types(it, self._destination_class._checked_types, self._destination_class)
+            error_data = _invariant_errors_iterable(it, self._destination_class._checked_invariants)
+            self._invariant_errors.extend(error_data)
+
+        def __setitem__(self, key, value):
+            self._check([value])
+            return super(CheckedPVector.Evolver, self).__setitem__(key, value)
+
+        def append(self, elem):
+            self._check([elem])
+            return super(CheckedPVector.Evolver, self).append(elem)
+
+        def extend(self, it):
+            it = list(it)
+            self._check(it)
+            return super(CheckedPVector.Evolver, self).extend(it)
+
+        def persistent(self):
+            if self._invariant_errors:
+                raise InvariantException(error_codes=self._invariant_errors)
+
+            result = self._orig_pvector
+            if self.is_dirty() or (self._destination_class != type(self._orig_pvector)):
+                pv = super(CheckedPVector.Evolver, self).persistent().extend(self._extra_tail)
+                result = self._destination_class(pv)
+                self._reset(result)
+
+            return result
+
+    def __repr__(self):
+        return self.__class__.__name__ + "({0})".format(self.tolist())
+
+    __str__ = __repr__
+
+    def evolver(self):
+        return CheckedPVector.Evolver(self.__class__, self)
+
+
+class CheckedPSet(PSet, CheckedType, metaclass=_CheckedTypeMeta):
+    """
+    A CheckedPSet is a PSet which allows specifying type and invariant checks.
+
+    >>> class Positives(CheckedPSet):
+    ...     __type__ = (int, float)
+    ...     __invariant__ = lambda n: (n >= 0, 'Negative')
+    ...
+    >>> Positives([1, 2, 3])
+    Positives([1, 2, 3])
+    """
+
+    __slots__ = ()
+
+    def __new__(cls, initial=()):
+        if type(initial) is PMap:
+            return super(CheckedPSet, cls).__new__(cls, initial)
+
+        evolver = CheckedPSet.Evolver(cls, pset())
+        for e in initial:
+            evolver.add(e)
+
+        return evolver.persistent()
+
+    def __repr__(self):
+        return self.__class__.__name__ + super(CheckedPSet, self).__repr__()[4:]
+
+    def __str__(self):
+        return self.__repr__()
+
+    def serialize(self, format=None):
+        serializer = self.__serializer__
+        return set(serializer(format, v) for v in self)
+
+    create = classmethod(_checked_type_create)
+
+    def __reduce__(self):
+        # Pickling support
+        return _restore_pickle, (self.__class__, list(self),)
+
+    def evolver(self):
+        return CheckedPSet.Evolver(self.__class__, self)
+
+    class Evolver(PSet._Evolver):
+        __slots__ = ('_destination_class', '_invariant_errors')
+
+        def __init__(self, destination_class, original_set):
+            super(CheckedPSet.Evolver, self).__init__(original_set)
+            self._destination_class = destination_class
+            self._invariant_errors = []
+
+        def _check(self, it):
+            _check_types(it, self._destination_class._checked_types, self._destination_class)
+            error_data = _invariant_errors_iterable(it, self._destination_class._checked_invariants)
+            self._invariant_errors.extend(error_data)
+
+        def add(self, element):
+            self._check([element])
+            self._pmap_evolver[element] = True
+            return self
+
+        def persistent(self):
+            if self._invariant_errors:
+                raise InvariantException(error_codes=self._invariant_errors)
+
+            if self.is_dirty() or self._destination_class != type(self._original_pset):
+                return self._destination_class(self._pmap_evolver.persistent())
+
+            return self._original_pset
+
+
+class _CheckedMapTypeMeta(type):
+    def __new__(mcs, name, bases, dct):
+        _store_types(dct, bases, '_checked_key_types', '__key_type__')
+        _store_types(dct, bases, '_checked_value_types', '__value_type__')
+        store_invariants(dct, bases, '_checked_invariants', '__invariant__')
+
+        def default_serializer(self, _, key, value):
+            sk = key
+            if isinstance(key, CheckedType):
+                sk = key.serialize()
+
+            sv = value
+            if isinstance(value, CheckedType):
+                sv = value.serialize()
+
+            return sk, sv
+
+        dct.setdefault('__serializer__', default_serializer)
+
+        dct['__slots__'] = ()
+
+        return super(_CheckedMapTypeMeta, mcs).__new__(mcs, name, bases, dct)
+
+# Marker object
+_UNDEFINED_CHECKED_PMAP_SIZE = object()
+
+
+class CheckedPMap(PMap, CheckedType, metaclass=_CheckedMapTypeMeta):
+    """
+    A CheckedPMap is a PMap which allows specifying type and invariant checks.
+
+    >>> class IntToFloatMap(CheckedPMap):
+    ...     __key_type__ = int
+    ...     __value_type__ = float
+    ...     __invariant__ = lambda k, v: (int(v) == k, 'Invalid mapping')
+    ...
+    >>> IntToFloatMap({1: 1.5, 2: 2.25})
+    IntToFloatMap({1: 1.5, 2: 2.25})
+    """
+
+    __slots__ = ()
+
+    def __new__(cls, initial={}, size=_UNDEFINED_CHECKED_PMAP_SIZE):
+        if size is not _UNDEFINED_CHECKED_PMAP_SIZE:
+            return super(CheckedPMap, cls).__new__(cls, size, initial)
+
+        evolver = CheckedPMap.Evolver(cls, pmap())
+        for k, v in initial.items():
+            evolver.set(k, v)
+
+        return evolver.persistent()
+
+    def evolver(self):
+        return CheckedPMap.Evolver(self.__class__, self)
+
+    def __repr__(self):
+        return self.__class__.__name__ + "({0})".format(str(dict(self)))
+
+    __str__ = __repr__
+
+    def serialize(self, format=None):
+        serializer = self.__serializer__
+        return dict(serializer(format, k, v) for k, v in self.items())
+
+    @classmethod
+    def create(cls, source_data, _factory_fields=None):
+        if isinstance(source_data, cls):
+            return source_data
+
+        # Recursively apply create methods of checked types if the types of the supplied data
+        # does not match any of the valid types.
+        key_types = get_types(cls._checked_key_types)
+        checked_key_type = next((t for t in key_types if issubclass(t, CheckedType)), None)
+        value_types = get_types(cls._checked_value_types)
+        checked_value_type = next((t for t in value_types if issubclass(t, CheckedType)), None)
+
+        if checked_key_type or checked_value_type:
+            return cls(dict((checked_key_type.create(key) if checked_key_type and not any(isinstance(key, t) for t in key_types) else key,
+                             checked_value_type.create(value) if checked_value_type and not any(isinstance(value, t) for t in value_types) else value)
+                            for key, value in source_data.items()))
+
+        return cls(source_data)
+
+    def __reduce__(self):
+        # Pickling support
+        return _restore_pickle, (self.__class__, dict(self),)
+
+    class Evolver(PMap._Evolver):
+        __slots__ = ('_destination_class', '_invariant_errors')
+
+        def __init__(self, destination_class, original_map):
+            super(CheckedPMap.Evolver, self).__init__(original_map)
+            self._destination_class = destination_class
+            self._invariant_errors = []
+
+        def set(self, key, value):
+            _check_types([key], self._destination_class._checked_key_types, self._destination_class, CheckedKeyTypeError)
+            _check_types([value], self._destination_class._checked_value_types, self._destination_class)
+            self._invariant_errors.extend(data for valid, data in (invariant(key, value)
+                                                                   for invariant in self._destination_class._checked_invariants)
+                                          if not valid)
+
+            return super(CheckedPMap.Evolver, self).set(key, value)
+
+        def persistent(self):
+            if self._invariant_errors:
+                raise InvariantException(error_codes=self._invariant_errors)
+
+            if self.is_dirty() or type(self._original_pmap) != self._destination_class:
+                return self._destination_class(self._buckets_evolver.persistent(), self._size)
+
+            return self._original_pmap
diff --git a/lib/spack/external/_vendoring/pyrsistent/_field_common.py b/lib/spack/external/_vendoring/pyrsistent/_field_common.py
new file mode 100644
index 0000000000..9ddfe29d2d
--- /dev/null
+++ b/lib/spack/external/_vendoring/pyrsistent/_field_common.py
@@ -0,0 +1,329 @@
+import sys
+
+from pyrsistent._checked_types import (
+    CheckedPMap,
+    CheckedPSet,
+    CheckedPVector,
+    CheckedType,
+    InvariantException,
+    _restore_pickle,
+    get_type,
+    maybe_parse_user_type,
+    maybe_parse_many_user_types,
+)
+from pyrsistent._checked_types import optional as optional_type
+from pyrsistent._checked_types import wrap_invariant
+import inspect
+
+PY2 = sys.version_info[0] < 3
+
+
+def set_fields(dct, bases, name):
+    dct[name] = dict(sum([list(b.__dict__.get(name, {}).items()) for b in bases], []))
+
+    for k, v in list(dct.items()):
+        if isinstance(v, _PField):
+            dct[name][k] = v
+            del dct[k]
+
+
+def check_global_invariants(subject, invariants):
+    error_codes = tuple(error_code for is_ok, error_code in
+                        (invariant(subject) for invariant in invariants) if not is_ok)
+    if error_codes:
+        raise InvariantException(error_codes, (), 'Global invariant failed')
+
+
+def serialize(serializer, format, value):
+    if isinstance(value, CheckedType) and serializer is PFIELD_NO_SERIALIZER:
+        return value.serialize(format)
+
+    return serializer(format, value)
+
+
+def check_type(destination_cls, field, name, value):
+    if field.type and not any(isinstance(value, get_type(t)) for t in field.type):
+        actual_type = type(value)
+        message = "Invalid type for field {0}.{1}, was {2}".format(destination_cls.__name__, name, actual_type.__name__)
+        raise PTypeError(destination_cls, name, field.type, actual_type, message)
+
+
+def is_type_cls(type_cls, field_type):
+    if type(field_type) is set:
+        return True
+    types = tuple(field_type)
+    if len(types) == 0:
+        return False
+    return issubclass(get_type(types[0]), type_cls)
+
+
+def is_field_ignore_extra_complaint(type_cls, field, ignore_extra):
+    # ignore_extra param has default False value, for speed purpose no need to propagate False
+    if not ignore_extra:
+        return False
+
+    if not is_type_cls(type_cls, field.type):
+        return False
+
+    if PY2:
+        return 'ignore_extra' in inspect.getargspec(field.factory).args
+    else:
+        return 'ignore_extra' in inspect.signature(field.factory).parameters
+
+
+
+class _PField(object):
+    __slots__ = ('type', 'invariant', 'initial', 'mandatory', '_factory', 'serializer')
+
+    def __init__(self, type, invariant, initial, mandatory, factory, serializer):
+        self.type = type
+        self.invariant = invariant
+        self.initial = initial
+        self.mandatory = mandatory
+        self._factory = factory
+        self.serializer = serializer
+
+    @property
+    def factory(self):
+        # If no factory is specified and the type is another CheckedType use the factory method of that CheckedType
+        if self._factory is PFIELD_NO_FACTORY and len(self.type) == 1:
+            typ = get_type(tuple(self.type)[0])
+            if issubclass(typ, CheckedType):
+                return typ.create
+
+        return self._factory
+
+PFIELD_NO_TYPE = ()
+PFIELD_NO_INVARIANT = lambda _: (True, None)
+PFIELD_NO_FACTORY = lambda x: x
+PFIELD_NO_INITIAL = object()
+PFIELD_NO_SERIALIZER = lambda _, value: value
+
+
+def field(type=PFIELD_NO_TYPE, invariant=PFIELD_NO_INVARIANT, initial=PFIELD_NO_INITIAL,
+          mandatory=False, factory=PFIELD_NO_FACTORY, serializer=PFIELD_NO_SERIALIZER):
+    """
+    Field specification factory for :py:class:`PRecord`.
+
+    :param type: a type or iterable with types that are allowed for this field
+    :param invariant: a function specifying an invariant that must hold for the field
+    :param initial: value of field if not specified when instantiating the record
+    :param mandatory: boolean specifying if the field is mandatory or not
+    :param factory: function called when field is set.
+    :param serializer: function that returns a serialized version of the field
+    """
+
+    # NB: We have to check this predicate separately from the predicates in
+    # `maybe_parse_user_type` et al. because this one is related to supporting
+    # the argspec for `field`, while those are related to supporting the valid
+    # ways to specify types.
+
+    # Multiple types must be passed in one of the following containers. Note
+    # that a type that is a subclass of one of these containers, like a
+    # `collections.namedtuple`, will work as expected, since we check
+    # `isinstance` and not `issubclass`.
+    if isinstance(type, (list, set, tuple)):
+        types = set(maybe_parse_many_user_types(type))
+    else:
+        types = set(maybe_parse_user_type(type))
+
+    invariant_function = wrap_invariant(invariant) if invariant != PFIELD_NO_INVARIANT and callable(invariant) else invariant
+    field = _PField(type=types, invariant=invariant_function, initial=initial,
+                    mandatory=mandatory, factory=factory, serializer=serializer)
+
+    _check_field_parameters(field)
+
+    return field
+
+
+def _check_field_parameters(field):
+    for t in field.type:
+        if not isinstance(t, type) and not isinstance(t, str):
+            raise TypeError('Type parameter expected, not {0}'.format(type(t)))
+
+    if field.initial is not PFIELD_NO_INITIAL and \
+            not callable(field.initial) and \
+            field.type and not any(isinstance(field.initial, t) for t in field.type):
+        raise TypeError('Initial has invalid type {0}'.format(type(field.initial)))
+
+    if not callable(field.invariant):
+        raise TypeError('Invariant must be callable')
+
+    if not callable(field.factory):
+        raise TypeError('Factory must be callable')
+
+    if not callable(field.serializer):
+        raise TypeError('Serializer must be callable')
+
+
+class PTypeError(TypeError):
+    """
+    Raised when trying to assign a value with a type that doesn't match the declared type.
+
+    Attributes:
+    source_class -- The class of the record
+    field -- Field name
+    expected_types  -- Types allowed for the field
+    actual_type -- The non matching type
+    """
+    def __init__(self, source_class, field, expected_types, actual_type, *args, **kwargs):
+        super(PTypeError, self).__init__(*args, **kwargs)
+        self.source_class = source_class
+        self.field = field
+        self.expected_types = expected_types
+        self.actual_type = actual_type
+
+
+SEQ_FIELD_TYPE_SUFFIXES = {
+    CheckedPVector: "PVector",
+    CheckedPSet: "PSet",
+}
+
+# Global dictionary to hold auto-generated field types: used for unpickling
+_seq_field_types = {}
+
+def _restore_seq_field_pickle(checked_class, item_type, data):
+    """Unpickling function for auto-generated PVec/PSet field types."""
+    type_ = _seq_field_types[checked_class, item_type]
+    return _restore_pickle(type_, data)
+
+def _types_to_names(types):
+    """Convert a tuple of types to a human-readable string."""
+    return "".join(get_type(typ).__name__.capitalize() for typ in types)
+
+def _make_seq_field_type(checked_class, item_type):
+    """Create a subclass of the given checked class with the given item type."""
+    type_ = _seq_field_types.get((checked_class, item_type))
+    if type_ is not None:
+        return type_
+
+    class TheType(checked_class):
+        __type__ = item_type
+
+        def __reduce__(self):
+            return (_restore_seq_field_pickle,
+                    (checked_class, item_type, list(self)))
+
+    suffix = SEQ_FIELD_TYPE_SUFFIXES[checked_class]
+    TheType.__name__ = _types_to_names(TheType._checked_types) + suffix
+    _seq_field_types[checked_class, item_type] = TheType
+    return TheType
+
+def _sequence_field(checked_class, item_type, optional, initial):
+    """
+    Create checked field for either ``PSet`` or ``PVector``.
+
+    :param checked_class: ``CheckedPSet`` or ``CheckedPVector``.
+    :param item_type: The required type for the items in the set.
+    :param optional: If true, ``None`` can be used as a value for
+        this field.
+    :param initial: Initial value to pass to factory.
+
+    :return: A ``field`` containing a checked class.
+    """
+    TheType = _make_seq_field_type(checked_class, item_type)
+
+    if optional:
+        def factory(argument, _factory_fields=None, ignore_extra=False):
+            if argument is None:
+                return None
+            else:
+                return TheType.create(argument, _factory_fields=_factory_fields, ignore_extra=ignore_extra)
+    else:
+        factory = TheType.create
+
+    return field(type=optional_type(TheType) if optional else TheType,
+                 factory=factory, mandatory=True,
+                 initial=factory(initial))
+
+
+def pset_field(item_type, optional=False, initial=()):
+    """
+    Create checked ``PSet`` field.
+
+    :param item_type: The required type for the items in the set.
+    :param optional: If true, ``None`` can be used as a value for
+        this field.
+    :param initial: Initial value to pass to factory if no value is given
+        for the field.
+
+    :return: A ``field`` containing a ``CheckedPSet`` of the given type.
+    """
+    return _sequence_field(CheckedPSet, item_type, optional,
+                           initial)
+
+
+def pvector_field(item_type, optional=False, initial=()):
+    """
+    Create checked ``PVector`` field.
+
+    :param item_type: The required type for the items in the vector.
+    :param optional: If true, ``None`` can be used as a value for
+        this field.
+    :param initial: Initial value to pass to factory if no value is given
+        for the field.
+
+    :return: A ``field`` containing a ``CheckedPVector`` of the given type.
+    """
+    return _sequence_field(CheckedPVector, item_type, optional,
+                           initial)
+
+
+_valid = lambda item: (True, "")
+
+
+# Global dictionary to hold auto-generated field types: used for unpickling
+_pmap_field_types = {}
+
+def _restore_pmap_field_pickle(key_type, value_type, data):
+    """Unpickling function for auto-generated PMap field types."""
+    type_ = _pmap_field_types[key_type, value_type]
+    return _restore_pickle(type_, data)
+
+def _make_pmap_field_type(key_type, value_type):
+    """Create a subclass of CheckedPMap with the given key and value types."""
+    type_ = _pmap_field_types.get((key_type, value_type))
+    if type_ is not None:
+        return type_
+
+    class TheMap(CheckedPMap):
+        __key_type__ = key_type
+        __value_type__ = value_type
+
+        def __reduce__(self):
+            return (_restore_pmap_field_pickle,
+                    (self.__key_type__, self.__value_type__, dict(self)))
+
+    TheMap.__name__ = "{0}To{1}PMap".format(
+        _types_to_names(TheMap._checked_key_types),
+        _types_to_names(TheMap._checked_value_types))
+    _pmap_field_types[key_type, value_type] = TheMap
+    return TheMap
+
+
+def pmap_field(key_type, value_type, optional=False, invariant=PFIELD_NO_INVARIANT):
+    """
+    Create a checked ``PMap`` field.
+
+    :param key: The required type for the keys of the map.
+    :param value: The required type for the values of the map.
+    :param optional: If true, ``None`` can be used as a value for
+        this field.
+    :param invariant: Pass-through to ``field``.
+
+    :return: A ``field`` containing a ``CheckedPMap``.
+    """
+    TheMap = _make_pmap_field_type(key_type, value_type)
+
+    if optional:
+        def factory(argument):
+            if argument is None:
+                return None
+            else:
+                return TheMap.create(argument)
+    else:
+        factory = TheMap.create
+
+    return field(mandatory=True, initial=TheMap(),
+                 type=optional_type(TheMap) if optional else TheMap,
+                 factory=factory, invariant=invariant)
diff --git a/lib/spack/external/_vendoring/pyrsistent/_helpers.py b/lib/spack/external/_vendoring/pyrsistent/_helpers.py
new file mode 100644
index 0000000000..1320e65768
--- /dev/null
+++ b/lib/spack/external/_vendoring/pyrsistent/_helpers.py
@@ -0,0 +1,97 @@
+from functools import wraps
+from pyrsistent._pmap import PMap, pmap
+from pyrsistent._pset import PSet, pset
+from pyrsistent._pvector import PVector, pvector
+
+def freeze(o, strict=True):
+    """
+    Recursively convert simple Python containers into pyrsistent versions
+    of those containers.
+
+    - list is converted to pvector, recursively
+    - dict is converted to pmap, recursively on values (but not keys)
+    - set is converted to pset, but not recursively
+    - tuple is converted to tuple, recursively.
+
+    If strict == True (default):
+
+    - freeze is called on elements of pvectors
+    - freeze is called on values of pmaps
+
+    Sets and dict keys are not recursively frozen because they do not contain
+    mutable data by convention. The main exception to this rule is that
+    dict keys and set elements are often instances of mutable objects that
+    support hash-by-id, which this function can't convert anyway.
+
+    >>> freeze(set([1, 2]))
+    pset([1, 2])
+    >>> freeze([1, {'a': 3}])
+    pvector([1, pmap({'a': 3})])
+    >>> freeze((1, []))
+    (1, pvector([]))
+    """
+    typ = type(o)
+    if typ is dict or (strict and isinstance(o, PMap)):
+        return pmap({k: freeze(v, strict) for k, v in o.items()})
+    if typ is list or (strict and isinstance(o, PVector)):
+        curried_freeze = lambda x: freeze(x, strict)
+        return pvector(map(curried_freeze, o))
+    if typ is tuple:
+        curried_freeze = lambda x: freeze(x, strict)
+        return tuple(map(curried_freeze, o))
+    if typ is set:
+        # impossible to have anything that needs freezing inside a set or pset
+        return pset(o)
+    return o
+
+
+def thaw(o, strict=True):
+    """
+    Recursively convert pyrsistent containers into simple Python containers.
+
+    - pvector is converted to list, recursively
+    - pmap is converted to dict, recursively on values (but not keys)
+    - pset is converted to set, but not recursively
+    - tuple is converted to tuple, recursively.
+
+    If strict == True (the default):
+
+    - thaw is called on elements of lists
+    - thaw is called on values in dicts
+
+    >>> from pyrsistent import s, m, v
+    >>> thaw(s(1, 2))
+    {1, 2}
+    >>> thaw(v(1, m(a=3)))
+    [1, {'a': 3}]
+    >>> thaw((1, v()))
+    (1, [])
+    """
+    typ = type(o)
+    if isinstance(o, PVector) or (strict and typ is list):
+        curried_thaw = lambda x: thaw(x, strict)
+        return list(map(curried_thaw, o))
+    if isinstance(o, PMap) or (strict and typ is dict):
+        return {k: thaw(v, strict) for k, v in o.items()}
+    if typ is tuple:
+        curried_thaw = lambda x: thaw(x, strict)
+        return tuple(map(curried_thaw, o))
+    if isinstance(o, PSet):
+        # impossible to thaw inside psets or sets
+        return set(o)
+    return o
+
+
+def mutant(fn):
+    """
+    Convenience decorator to isolate mutation to within the decorated function (with respect
+    to the input arguments).
+
+    All arguments to the decorated function will be frozen so that they are guaranteed not to change.
+    The return value is also frozen.
+    """
+    @wraps(fn)
+    def inner_f(*args, **kwargs):
+        return freeze(fn(*[freeze(e) for e in args], **dict(freeze(item) for item in kwargs.items())))
+
+    return inner_f
diff --git a/lib/spack/external/_vendoring/pyrsistent/_immutable.py b/lib/spack/external/_vendoring/pyrsistent/_immutable.py
new file mode 100644
index 0000000000..7c75945336
--- /dev/null
+++ b/lib/spack/external/_vendoring/pyrsistent/_immutable.py
@@ -0,0 +1,103 @@
+import sys
+
+
+def immutable(members='', name='Immutable', verbose=False):
+    """
+    Produces a class that either can be used standalone or as a base class for persistent classes.
+
+    This is a thin wrapper around a named tuple.
+
+    Constructing a type and using it to instantiate objects:
+
+    >>> Point = immutable('x, y', name='Point')
+    >>> p = Point(1, 2)
+    >>> p2 = p.set(x=3)
+    >>> p
+    Point(x=1, y=2)
+    >>> p2
+    Point(x=3, y=2)
+
+    Inheriting from a constructed type. In this case no type name needs to be supplied:
+
+    >>> class PositivePoint(immutable('x, y')):
+    ...     __slots__ = tuple()
+    ...     def __new__(cls, x, y):
+    ...         if x > 0 and y > 0:
+    ...             return super(PositivePoint, cls).__new__(cls, x, y)
+    ...         raise Exception('Coordinates must be positive!')
+    ...
+    >>> p = PositivePoint(1, 2)
+    >>> p.set(x=3)
+    PositivePoint(x=3, y=2)
+    >>> p.set(y=-3)
+    Traceback (most recent call last):
+    Exception: Coordinates must be positive!
+
+    The persistent class also supports the notion of frozen members. The value of a frozen member
+    cannot be updated. For example it could be used to implement an ID that should remain the same
+    over time. A frozen member is denoted by a trailing underscore.
+
+    >>> Point = immutable('x, y, id_', name='Point')
+    >>> p = Point(1, 2, id_=17)
+    >>> p.set(x=3)
+    Point(x=3, y=2, id_=17)
+    >>> p.set(id_=18)
+    Traceback (most recent call last):
+    AttributeError: Cannot set frozen members id_
+    """
+
+    if isinstance(members, str):
+        members = members.replace(',', ' ').split()
+
+    def frozen_member_test():
+        frozen_members = ["'%s'" % f for f in members if f.endswith('_')]
+        if frozen_members:
+            return """
+        frozen_fields = fields_to_modify & set([{frozen_members}])
+        if frozen_fields:
+            raise AttributeError('Cannot set frozen members %s' % ', '.join(frozen_fields))
+            """.format(frozen_members=', '.join(frozen_members))
+
+        return ''
+
+    verbose_string = ""
+    if sys.version_info < (3, 7):
+        # Verbose is no longer supported in Python 3.7
+        verbose_string = ", verbose={verbose}".format(verbose=verbose)
+
+    quoted_members = ', '.join("'%s'" % m for m in members)
+    template = """
+class {class_name}(namedtuple('ImmutableBase', [{quoted_members}]{verbose_string})):
+    __slots__ = tuple()
+
+    def __repr__(self):
+        return super({class_name}, self).__repr__().replace('ImmutableBase', self.__class__.__name__)
+
+    def set(self, **kwargs):
+        if not kwargs:
+            return self
+
+        fields_to_modify = set(kwargs.keys())
+        if not fields_to_modify <= {member_set}:
+            raise AttributeError("'%s' is not a member" % ', '.join(fields_to_modify - {member_set}))
+
+        {frozen_member_test}
+
+        return self.__class__.__new__(self.__class__, *map(kwargs.pop, [{quoted_members}], self))
+""".format(quoted_members=quoted_members,
+               member_set="set([%s])" % quoted_members if quoted_members else 'set()',
+               frozen_member_test=frozen_member_test(),
+               verbose_string=verbose_string,
+               class_name=name)
+
+    if verbose:
+        print(template)
+
+    from collections import namedtuple
+    namespace = dict(namedtuple=namedtuple, __name__='pyrsistent_immutable')
+    try:
+        exec(template, namespace)
+    except SyntaxError as e:
+        raise SyntaxError(str(e) + ':\n' + template) from e
+
+    return namespace[name]
diff --git a/lib/spack/external/_vendoring/pyrsistent/_pbag.py b/lib/spack/external/_vendoring/pyrsistent/_pbag.py
new file mode 100644
index 0000000000..9cf5840b72
--- /dev/null
+++ b/lib/spack/external/_vendoring/pyrsistent/_pbag.py
@@ -0,0 +1,267 @@
+from collections.abc import Container, Iterable, Sized, Hashable
+from functools import reduce
+from pyrsistent._pmap import pmap
+
+
+def _add_to_counters(counters, element):
+    return counters.set(element, counters.get(element, 0) + 1)
+
+
+class PBag(object):
+    """
+    A persistent bag/multiset type.
+
+    Requires elements to be hashable, and allows duplicates, but has no
+    ordering. Bags are hashable.
+
+    Do not instantiate directly, instead use the factory functions :py:func:`b`
+    or :py:func:`pbag` to create an instance.
+
+    Some examples:
+
+    >>> s = pbag([1, 2, 3, 1])
+    >>> s2 = s.add(4)
+    >>> s3 = s2.remove(1)
+    >>> s
+    pbag([1, 1, 2, 3])
+    >>> s2
+    pbag([1, 1, 2, 3, 4])
+    >>> s3
+    pbag([1, 2, 3, 4])
+    """
+
+    __slots__ = ('_counts', '__weakref__')
+
+    def __init__(self, counts):
+        self._counts = counts
+
+    def add(self, element):
+        """
+        Add an element to the bag.
+
+        >>> s = pbag([1])
+        >>> s2 = s.add(1)
+        >>> s3 = s.add(2)
+        >>> s2
+        pbag([1, 1])
+        >>> s3
+        pbag([1, 2])
+        """
+        return PBag(_add_to_counters(self._counts, element))
+
+    def update(self, iterable):
+        """
+        Update bag with all elements in iterable.
+
+        >>> s = pbag([1])
+        >>> s.update([1, 2])
+        pbag([1, 1, 2])
+        """
+        if iterable:
+            return PBag(reduce(_add_to_counters, iterable, self._counts))
+
+        return self
+
+    def remove(self, element):
+        """
+        Remove an element from the bag.
+
+        >>> s = pbag([1, 1, 2])
+        >>> s2 = s.remove(1)
+        >>> s3 = s.remove(2)
+        >>> s2
+        pbag([1, 2])
+        >>> s3
+        pbag([1, 1])
+        """
+        if element not in self._counts:
+            raise KeyError(element)
+        elif self._counts[element] == 1:
+            newc = self._counts.remove(element)
+        else:
+            newc = self._counts.set(element, self._counts[element] - 1)
+        return PBag(newc)
+
+    def count(self, element):
+        """
+        Return the number of times an element appears.
+
+
+        >>> pbag([]).count('non-existent')
+        0
+        >>> pbag([1, 1, 2]).count(1)
+        2
+        """
+        return self._counts.get(element, 0)
+
+    def __len__(self):
+        """
+        Return the length including duplicates.
+
+        >>> len(pbag([1, 1, 2]))
+        3
+        """
+        return sum(self._counts.itervalues())
+
+    def __iter__(self):
+        """
+        Return an iterator of all elements, including duplicates.
+
+        >>> list(pbag([1, 1, 2]))
+        [1, 1, 2]
+        >>> list(pbag([1, 2]))
+        [1, 2]
+        """
+        for elt, count in self._counts.iteritems():
+            for i in range(count):
+                yield elt
+
+    def __contains__(self, elt):
+        """
+        Check if an element is in the bag.
+
+        >>> 1 in pbag([1, 1, 2])
+        True
+        >>> 0 in pbag([1, 2])
+        False
+        """
+        return elt in self._counts
+
+    def __repr__(self):
+        return "pbag({0})".format(list(self))
+
+    def __eq__(self, other):
+        """
+        Check if two bags are equivalent, honoring the number of duplicates,
+        and ignoring insertion order.
+
+        >>> pbag([1, 1, 2]) == pbag([1, 2])
+        False
+        >>> pbag([2, 1, 0]) == pbag([0, 1, 2])
+        True
+        """
+        if type(other) is not PBag:
+            raise TypeError("Can only compare PBag with PBags")
+        return self._counts == other._counts
+
+    def __lt__(self, other):
+        raise TypeError('PBags are not orderable')
+
+    __le__ = __lt__
+    __gt__ = __lt__
+    __ge__ = __lt__
+
+    # Multiset-style operations similar to collections.Counter
+
+    def __add__(self, other):
+        """
+        Combine elements from two PBags.
+
+        >>> pbag([1, 2, 2]) + pbag([2, 3, 3])
+        pbag([1, 2, 2, 2, 3, 3])
+        """
+        if not isinstance(other, PBag):
+            return NotImplemented
+        result = self._counts.evolver()
+        for elem, other_count in other._counts.iteritems():
+            result[elem] = self.count(elem) + other_count
+        return PBag(result.persistent())
+
+    def __sub__(self, other):
+        """
+        Remove elements from one PBag that are present in another.
+
+        >>> pbag([1, 2, 2, 2, 3]) - pbag([2, 3, 3, 4])
+        pbag([1, 2, 2])
+        """
+        if not isinstance(other, PBag):
+            return NotImplemented
+        result = self._counts.evolver()
+        for elem, other_count in other._counts.iteritems():
+            newcount = self.count(elem) - other_count
+            if newcount > 0:
+                result[elem] = newcount
+            elif elem in self:
+                result.remove(elem)
+        return PBag(result.persistent())
+
+    def __or__(self, other):
+        """
+        Union: Keep elements that are present in either of two PBags.
+
+        >>> pbag([1, 2, 2, 2]) | pbag([2, 3, 3])
+        pbag([1, 2, 2, 2, 3, 3])
+        """
+        if not isinstance(other, PBag):
+            return NotImplemented
+        result = self._counts.evolver()
+        for elem, other_count in other._counts.iteritems():
+            count = self.count(elem)
+            newcount = max(count, other_count)
+            result[elem] = newcount
+        return PBag(result.persistent())
+
+    def __and__(self, other):
+        """
+        Intersection: Only keep elements that are present in both PBags.
+
+        >>> pbag([1, 2, 2, 2]) & pbag([2, 3, 3])
+        pbag([2])
+        """
+        if not isinstance(other, PBag):
+            return NotImplemented
+        result = pmap().evolver()
+        for elem, count in self._counts.iteritems():
+            newcount = min(count, other.count(elem))
+            if newcount > 0:
+                result[elem] = newcount
+        return PBag(result.persistent())
+
+    def __hash__(self):
+        """
+        Hash based on value of elements.
+
+        >>> m = pmap({pbag([1, 2]): "it's here!"})
+        >>> m[pbag([2, 1])]
+        "it's here!"
+        >>> pbag([1, 1, 2]) in m
+        False
+        """
+        return hash(self._counts)
+
+
+Container.register(PBag)
+Iterable.register(PBag)
+Sized.register(PBag)
+Hashable.register(PBag)
+
+
+def b(*elements):
+    """
+    Construct a persistent bag.
+
+    Takes an arbitrary number of arguments to insert into the new persistent
+    bag.
+
+    >>> b(1, 2, 3, 2)
+    pbag([1, 2, 2, 3])
+    """
+    return pbag(elements)
+
+
+def pbag(elements):
+    """
+    Convert an iterable to a persistent bag.
+
+    Takes an iterable with elements to insert.
+
+    >>> pbag([1, 2, 3, 2])
+    pbag([1, 2, 2, 3])
+    """
+    if not elements:
+        return _EMPTY_PBAG
+    return PBag(reduce(_add_to_counters, elements, pmap()))
+
+
+_EMPTY_PBAG = PBag(pmap())
+
diff --git a/lib/spack/external/_vendoring/pyrsistent/_pclass.py b/lib/spack/external/_vendoring/pyrsistent/_pclass.py
new file mode 100644
index 0000000000..fd31a95d63
--- /dev/null
+++ b/lib/spack/external/_vendoring/pyrsistent/_pclass.py
@@ -0,0 +1,262 @@
+from pyrsistent._checked_types import (InvariantException, CheckedType, _restore_pickle, store_invariants)
+from pyrsistent._field_common import (
+    set_fields, check_type, is_field_ignore_extra_complaint, PFIELD_NO_INITIAL, serialize, check_global_invariants
+)
+from pyrsistent._transformations import transform
+
+
+def _is_pclass(bases):
+    return len(bases) == 1 and bases[0] == CheckedType
+
+
+class PClassMeta(type):
+    def __new__(mcs, name, bases, dct):
+        set_fields(dct, bases, name='_pclass_fields')
+        store_invariants(dct, bases, '_pclass_invariants', '__invariant__')
+        dct['__slots__'] = ('_pclass_frozen',) + tuple(key for key in dct['_pclass_fields'])
+
+        # There must only be one __weakref__ entry in the inheritance hierarchy,
+        # lets put it on the top level class.
+        if _is_pclass(bases):
+            dct['__slots__'] += ('__weakref__',)
+
+        return super(PClassMeta, mcs).__new__(mcs, name, bases, dct)
+
+_MISSING_VALUE = object()
+
+
+def _check_and_set_attr(cls, field, name, value, result, invariant_errors):
+    check_type(cls, field, name, value)
+    is_ok, error_code = field.invariant(value)
+    if not is_ok:
+        invariant_errors.append(error_code)
+    else:
+        setattr(result, name, value)
+
+
+class PClass(CheckedType, metaclass=PClassMeta):
+    """
+    A PClass is a python class with a fixed set of specified fields. PClasses are declared as python classes inheriting
+    from PClass. It is defined the same way that PRecords are and behaves like a PRecord in all aspects except that it
+    is not a PMap and hence not a collection but rather a plain Python object.
+
+
+    More documentation and examples of PClass usage is available at https://github.com/tobgu/pyrsistent
+    """
+    def __new__(cls, **kwargs):    # Support *args?
+        result = super(PClass, cls).__new__(cls)
+        factory_fields = kwargs.pop('_factory_fields', None)
+        ignore_extra = kwargs.pop('ignore_extra', None)
+        missing_fields = []
+        invariant_errors = []
+        for name, field in cls._pclass_fields.items():
+            if name in kwargs:
+                if factory_fields is None or name in factory_fields:
+                    if is_field_ignore_extra_complaint(PClass, field, ignore_extra):
+                        value = field.factory(kwargs[name], ignore_extra=ignore_extra)
+                    else:
+                        value = field.factory(kwargs[name])
+                else:
+                    value = kwargs[name]
+                _check_and_set_attr(cls, field, name, value, result, invariant_errors)
+                del kwargs[name]
+            elif field.initial is not PFIELD_NO_INITIAL:
+                initial = field.initial() if callable(field.initial) else field.initial
+                _check_and_set_attr(
+                    cls, field, name, initial, result, invariant_errors)
+            elif field.mandatory:
+                missing_fields.append('{0}.{1}'.format(cls.__name__, name))
+
+        if invariant_errors or missing_fields:
+            raise InvariantException(tuple(invariant_errors), tuple(missing_fields), 'Field invariant failed')
+
+        if kwargs:
+            raise AttributeError("'{0}' are not among the specified fields for {1}".format(
+                ', '.join(kwargs), cls.__name__))
+
+        check_global_invariants(result, cls._pclass_invariants)
+
+        result._pclass_frozen = True
+        return result
+
+    def set(self, *args, **kwargs):
+        """
+        Set a field in the instance. Returns a new instance with the updated value. The original instance remains
+        unmodified. Accepts key-value pairs or single string representing the field name and a value.
+
+        >>> from pyrsistent import PClass, field
+        >>> class AClass(PClass):
+        ...     x = field()
+        ...
+        >>> a = AClass(x=1)
+        >>> a2 = a.set(x=2)
+        >>> a3 = a.set('x', 3)
+        >>> a
+        AClass(x=1)
+        >>> a2
+        AClass(x=2)
+        >>> a3
+        AClass(x=3)
+        """
+        if args:
+            kwargs[args[0]] = args[1]
+
+        factory_fields = set(kwargs)
+
+        for key in self._pclass_fields:
+            if key not in kwargs:
+                value = getattr(self, key, _MISSING_VALUE)
+                if value is not _MISSING_VALUE:
+                    kwargs[key] = value
+
+        return self.__class__(_factory_fields=factory_fields, **kwargs)
+
+    @classmethod
+    def create(cls, kwargs, _factory_fields=None, ignore_extra=False):
+        """
+        Factory method. Will create a new PClass of the current type and assign the values
+        specified in kwargs.
+
+        :param ignore_extra: A boolean which when set to True will ignore any keys which appear in kwargs that are not
+                             in the set of fields on the PClass.
+        """
+        if isinstance(kwargs, cls):
+            return kwargs
+
+        if ignore_extra:
+            kwargs = {k: kwargs[k] for k in cls._pclass_fields if k in kwargs}
+
+        return cls(_factory_fields=_factory_fields, ignore_extra=ignore_extra, **kwargs)
+
+    def serialize(self, format=None):
+        """
+        Serialize the current PClass using custom serializer functions for fields where
+        such have been supplied.
+        """
+        result = {}
+        for name in self._pclass_fields:
+            value = getattr(self, name, _MISSING_VALUE)
+            if value is not _MISSING_VALUE:
+                result[name] = serialize(self._pclass_fields[name].serializer, format, value)
+
+        return result
+
+    def transform(self, *transformations):
+        """
+        Apply transformations to the currency PClass. For more details on transformations see
+        the documentation for PMap. Transformations on PClasses do not support key matching
+        since the PClass is not a collection. Apart from that the transformations available
+        for other persistent types work as expected.
+        """
+        return transform(self, transformations)
+
+    def __eq__(self, other):
+        if isinstance(other, self.__class__):
+            for name in self._pclass_fields:
+                if getattr(self, name, _MISSING_VALUE) != getattr(other, name, _MISSING_VALUE):
+                    return False
+
+            return True
+
+        return NotImplemented
+
+    def __ne__(self, other):
+        return not self == other
+
+    def __hash__(self):
+        # May want to optimize this by caching the hash somehow
+        return hash(tuple((key, getattr(self, key, _MISSING_VALUE)) for key in self._pclass_fields))
+
+    def __setattr__(self, key, value):
+        if getattr(self, '_pclass_frozen', False):
+            raise AttributeError("Can't set attribute, key={0}, value={1}".format(key, value))
+
+        super(PClass, self).__setattr__(key, value)
+
+    def __delattr__(self, key):
+            raise AttributeError("Can't delete attribute, key={0}, use remove()".format(key))
+
+    def _to_dict(self):
+        result = {}
+        for key in self._pclass_fields:
+            value = getattr(self, key, _MISSING_VALUE)
+            if value is not _MISSING_VALUE:
+                result[key] = value
+
+        return result
+
+    def __repr__(self):
+        return "{0}({1})".format(self.__class__.__name__,
+                                 ', '.join('{0}={1}'.format(k, repr(v)) for k, v in self._to_dict().items()))
+
+    def __reduce__(self):
+        # Pickling support
+        data = dict((key, getattr(self, key)) for key in self._pclass_fields if hasattr(self, key))
+        return _restore_pickle, (self.__class__, data,)
+
+    def evolver(self):
+        """
+        Returns an evolver for this object.
+        """
+        return _PClassEvolver(self, self._to_dict())
+
+    def remove(self, name):
+        """
+        Remove attribute given by name from the current instance. Raises AttributeError if the
+        attribute doesn't exist.
+        """
+        evolver = self.evolver()
+        del evolver[name]
+        return evolver.persistent()
+
+
+class _PClassEvolver(object):
+    __slots__ = ('_pclass_evolver_original', '_pclass_evolver_data', '_pclass_evolver_data_is_dirty', '_factory_fields')
+
+    def __init__(self, original, initial_dict):
+        self._pclass_evolver_original = original
+        self._pclass_evolver_data = initial_dict
+        self._pclass_evolver_data_is_dirty = False
+        self._factory_fields = set()
+
+    def __getitem__(self, item):
+        return self._pclass_evolver_data[item]
+
+    def set(self, key, value):
+        if self._pclass_evolver_data.get(key, _MISSING_VALUE) is not value:
+            self._pclass_evolver_data[key] = value
+            self._factory_fields.add(key)
+            self._pclass_evolver_data_is_dirty = True
+
+        return self
+
+    def __setitem__(self, key, value):
+        self.set(key, value)
+
+    def remove(self, item):
+        if item in self._pclass_evolver_data:
+            del self._pclass_evolver_data[item]
+            self._factory_fields.discard(item)
+            self._pclass_evolver_data_is_dirty = True
+            return self
+
+        raise AttributeError(item)
+
+    def __delitem__(self, item):
+        self.remove(item)
+
+    def persistent(self):
+        if self._pclass_evolver_data_is_dirty:
+            return self._pclass_evolver_original.__class__(_factory_fields=self._factory_fields,
+                                                           **self._pclass_evolver_data)
+
+        return self._pclass_evolver_original
+
+    def __setattr__(self, key, value):
+        if key not in self.__slots__:
+            self.set(key, value)
+        else:
+            super(_PClassEvolver, self).__setattr__(key, value)
+
+    def __getattr__(self, item):
+        return self[item]
diff --git a/lib/spack/external/_vendoring/pyrsistent/_pdeque.py b/lib/spack/external/_vendoring/pyrsistent/_pdeque.py
new file mode 100644
index 0000000000..bd11bfa032
--- /dev/null
+++ b/lib/spack/external/_vendoring/pyrsistent/_pdeque.py
@@ -0,0 +1,376 @@
+from collections.abc import Sequence, Hashable
+from itertools import islice, chain
+from numbers import Integral
+from pyrsistent._plist import plist
+
+
+class PDeque(object):
+    """
+    Persistent double ended queue (deque). Allows quick appends and pops in both ends. Implemented
+    using two persistent lists.
+
+    A maximum length can be specified to create a bounded queue.
+
+    Fully supports the Sequence and Hashable protocols including indexing and slicing but
+    if you need fast random access go for the PVector instead.
+
+    Do not instantiate directly, instead use the factory functions :py:func:`dq` or :py:func:`pdeque` to
+    create an instance.
+
+    Some examples:
+
+    >>> x = pdeque([1, 2, 3])
+    >>> x.left
+    1
+    >>> x.right
+    3
+    >>> x[0] == x.left
+    True
+    >>> x[-1] == x.right
+    True
+    >>> x.pop()
+    pdeque([1, 2])
+    >>> x.pop() == x[:-1]
+    True
+    >>> x.popleft()
+    pdeque([2, 3])
+    >>> x.append(4)
+    pdeque([1, 2, 3, 4])
+    >>> x.appendleft(4)
+    pdeque([4, 1, 2, 3])
+
+    >>> y = pdeque([1, 2, 3], maxlen=3)
+    >>> y.append(4)
+    pdeque([2, 3, 4], maxlen=3)
+    >>> y.appendleft(4)
+    pdeque([4, 1, 2], maxlen=3)
+    """
+    __slots__ = ('_left_list', '_right_list', '_length', '_maxlen', '__weakref__')
+
+    def __new__(cls, left_list, right_list, length, maxlen=None):
+        instance = super(PDeque, cls).__new__(cls)
+        instance._left_list = left_list
+        instance._right_list = right_list
+        instance._length = length
+
+        if maxlen is not None:
+            if not isinstance(maxlen, Integral):
+                raise TypeError('An integer is required as maxlen')
+
+            if maxlen < 0:
+                raise ValueError("maxlen must be non-negative")
+
+        instance._maxlen = maxlen
+        return instance
+
+    @property
+    def right(self):
+        """
+        Rightmost element in dqueue.
+        """
+        return PDeque._tip_from_lists(self._right_list, self._left_list)
+
+    @property
+    def left(self):
+        """
+        Leftmost element in dqueue.
+        """
+        return PDeque._tip_from_lists(self._left_list, self._right_list)
+
+    @staticmethod
+    def _tip_from_lists(primary_list, secondary_list):
+        if primary_list:
+            return primary_list.first
+
+        if secondary_list:
+            return secondary_list[-1]
+
+        raise IndexError('No elements in empty deque')
+
+    def __iter__(self):
+        return chain(self._left_list, self._right_list.reverse())
+
+    def __repr__(self):
+        return "pdeque({0}{1})".format(list(self),
+                                       ', maxlen={0}'.format(self._maxlen) if self._maxlen is not None else '')
+    __str__ = __repr__
+
+    @property
+    def maxlen(self):
+        """
+        Maximum length of the queue.
+        """
+        return self._maxlen
+
+    def pop(self, count=1):
+        """
+        Return new deque with rightmost element removed. Popping the empty queue
+        will return the empty queue. A optional count can be given to indicate the
+        number of elements to pop. Popping with a negative index is the same as
+        popleft. Executes in amortized O(k) where k is the number of elements to pop.
+
+        >>> pdeque([1, 2]).pop()
+        pdeque([1])
+        >>> pdeque([1, 2]).pop(2)
+        pdeque([])
+        >>> pdeque([1, 2]).pop(-1)
+        pdeque([2])
+        """
+        if count < 0:
+            return self.popleft(-count)
+
+        new_right_list, new_left_list = PDeque._pop_lists(self._right_list, self._left_list, count)
+        return PDeque(new_left_list, new_right_list, max(self._length - count, 0), self._maxlen)
+
+    def popleft(self, count=1):
+        """
+        Return new deque with leftmost element removed. Otherwise functionally
+        equivalent to pop().
+
+        >>> pdeque([1, 2]).popleft()
+        pdeque([2])
+        """
+        if count < 0:
+            return self.pop(-count)
+
+        new_left_list, new_right_list = PDeque._pop_lists(self._left_list, self._right_list, count)
+        return PDeque(new_left_list, new_right_list, max(self._length - count, 0), self._maxlen)
+
+    @staticmethod
+    def _pop_lists(primary_list, secondary_list, count):
+        new_primary_list = primary_list
+        new_secondary_list = secondary_list
+
+        while count > 0 and (new_primary_list or new_secondary_list):
+            count -= 1
+            if new_primary_list.rest:
+                new_primary_list = new_primary_list.rest
+            elif new_primary_list:
+                new_primary_list = new_secondary_list.reverse()
+                new_secondary_list = plist()
+            else:
+                new_primary_list = new_secondary_list.reverse().rest
+                new_secondary_list = plist()
+
+        return new_primary_list, new_secondary_list
+
+    def _is_empty(self):
+        return not self._left_list and not self._right_list
+
+    def __lt__(self, other):
+        if not isinstance(other, PDeque):
+            return NotImplemented
+
+        return tuple(self) < tuple(other)
+
+    def __eq__(self, other):
+        if not isinstance(other, PDeque):
+            return NotImplemented
+
+        if tuple(self) == tuple(other):
+            # Sanity check of the length value since it is redundant (there for performance)
+            assert len(self) == len(other)
+            return True
+
+        return False
+
+    def __hash__(self):
+        return  hash(tuple(self))
+
+    def __len__(self):
+        return self._length
+
+    def append(self, elem):
+        """
+        Return new deque with elem as the rightmost element.
+
+        >>> pdeque([1, 2]).append(3)
+        pdeque([1, 2, 3])
+        """
+        new_left_list, new_right_list, new_length = self._append(self._left_list, self._right_list, elem)
+        return PDeque(new_left_list, new_right_list, new_length, self._maxlen)
+
+    def appendleft(self, elem):
+        """
+        Return new deque with elem as the leftmost element.
+
+        >>> pdeque([1, 2]).appendleft(3)
+        pdeque([3, 1, 2])
+        """
+        new_right_list, new_left_list, new_length = self._append(self._right_list, self._left_list, elem)
+        return PDeque(new_left_list, new_right_list, new_length, self._maxlen)
+
+    def _append(self, primary_list, secondary_list, elem):
+        if self._maxlen is not None and self._length == self._maxlen:
+            if self._maxlen == 0:
+                return primary_list, secondary_list, 0
+            new_primary_list, new_secondary_list = PDeque._pop_lists(primary_list, secondary_list, 1)
+            return new_primary_list, new_secondary_list.cons(elem), self._length
+
+        return primary_list, secondary_list.cons(elem), self._length + 1
+
+    @staticmethod
+    def _extend_list(the_list, iterable):
+        count = 0
+        for elem in iterable:
+            the_list = the_list.cons(elem)
+            count += 1
+
+        return the_list, count
+
+    def _extend(self, primary_list, secondary_list, iterable):
+        new_primary_list, extend_count = PDeque._extend_list(primary_list, iterable)
+        new_secondary_list = secondary_list
+        current_len = self._length + extend_count
+        if self._maxlen is not None and current_len > self._maxlen:
+            pop_len = current_len - self._maxlen
+            new_secondary_list, new_primary_list = PDeque._pop_lists(new_secondary_list, new_primary_list, pop_len)
+            extend_count -= pop_len
+
+        return new_primary_list, new_secondary_list, extend_count
+
+    def extend(self, iterable):
+        """
+        Return new deque with all elements of iterable appended to the right.
+
+        >>> pdeque([1, 2]).extend([3, 4])
+        pdeque([1, 2, 3, 4])
+        """
+        new_right_list, new_left_list, extend_count = self._extend(self._right_list, self._left_list, iterable)
+        return PDeque(new_left_list, new_right_list, self._length + extend_count, self._maxlen)
+
+    def extendleft(self, iterable):
+        """
+        Return new deque with all elements of iterable appended to the left.
+
+        NB! The elements will be inserted in reverse order compared to the order in the iterable.
+
+        >>> pdeque([1, 2]).extendleft([3, 4])
+        pdeque([4, 3, 1, 2])
+        """
+        new_left_list, new_right_list, extend_count = self._extend(self._left_list, self._right_list, iterable)
+        return PDeque(new_left_list, new_right_list, self._length + extend_count, self._maxlen)
+
+    def count(self, elem):
+        """
+        Return the number of elements equal to elem present in the queue
+
+        >>> pdeque([1, 2, 1]).count(1)
+        2
+        """
+        return self._left_list.count(elem) + self._right_list.count(elem)
+
+    def remove(self, elem):
+        """
+        Return new deque with first element from left equal to elem removed. If no such element is found
+        a ValueError is raised.
+
+        >>> pdeque([2, 1, 2]).remove(2)
+        pdeque([1, 2])
+        """
+        try:
+            return PDeque(self._left_list.remove(elem), self._right_list, self._length - 1)
+        except ValueError:
+            # Value not found in left list, try the right list
+            try:
+                # This is severely inefficient with a double reverse, should perhaps implement a remove_last()?
+                return PDeque(self._left_list,
+                               self._right_list.reverse().remove(elem).reverse(), self._length - 1)
+            except ValueError as e:
+                raise ValueError('{0} not found in PDeque'.format(elem)) from e
+
+    def reverse(self):
+        """
+        Return reversed deque.
+
+        >>> pdeque([1, 2, 3]).reverse()
+        pdeque([3, 2, 1])
+
+        Also supports the standard python reverse function.
+
+        >>> reversed(pdeque([1, 2, 3]))
+        pdeque([3, 2, 1])
+        """
+        return PDeque(self._right_list, self._left_list, self._length)
+    __reversed__ = reverse
+
+    def rotate(self, steps):
+        """
+        Return deque with elements rotated steps steps.
+
+        >>> x = pdeque([1, 2, 3])
+        >>> x.rotate(1)
+        pdeque([3, 1, 2])
+        >>> x.rotate(-2)
+        pdeque([3, 1, 2])
+        """
+        popped_deque = self.pop(steps)
+        if steps >= 0:
+            return popped_deque.extendleft(islice(self.reverse(), steps))
+
+        return popped_deque.extend(islice(self, -steps))
+
+    def __reduce__(self):
+        # Pickling support
+        return pdeque, (list(self), self._maxlen)
+
+    def __getitem__(self, index):
+        if isinstance(index, slice):
+            if index.step is not None and index.step != 1:
+                # Too difficult, no structural sharing possible
+                return pdeque(tuple(self)[index], maxlen=self._maxlen)
+
+            result = self
+            if index.start is not None:
+                result = result.popleft(index.start % self._length)
+            if index.stop is not None:
+                result = result.pop(self._length - (index.stop % self._length))
+
+            return result
+
+        if not isinstance(index, Integral):
+            raise TypeError("'%s' object cannot be interpreted as an index" % type(index).__name__)
+
+        if index >= 0:
+            return self.popleft(index).left
+
+        shifted = len(self) + index
+        if shifted < 0:
+            raise IndexError(
+                "pdeque index {0} out of range {1}".format(index, len(self)),
+            )
+        return self.popleft(shifted).left
+
+    index = Sequence.index
+
+Sequence.register(PDeque)
+Hashable.register(PDeque)
+
+
+def pdeque(iterable=(), maxlen=None):
+    """
+    Return deque containing the elements of iterable. If maxlen is specified then
+    len(iterable) - maxlen elements are discarded from the left to if len(iterable) > maxlen.
+
+    >>> pdeque([1, 2, 3])
+    pdeque([1, 2, 3])
+    >>> pdeque([1, 2, 3, 4], maxlen=2)
+    pdeque([3, 4], maxlen=2)
+    """
+    t = tuple(iterable)
+    if maxlen is not None:
+        t = t[-maxlen:]
+    length = len(t)
+    pivot = int(length / 2)
+    left = plist(t[:pivot])
+    right = plist(t[pivot:], reverse=True)
+    return PDeque(left, right, length, maxlen)
+
+def dq(*elements):
+    """
+    Return deque containing all arguments.
+
+    >>> dq(1, 2, 3)
+    pdeque([1, 2, 3])
+    """
+    return pdeque(elements)
diff --git a/lib/spack/external/_vendoring/pyrsistent/_plist.py b/lib/spack/external/_vendoring/pyrsistent/_plist.py
new file mode 100644
index 0000000000..bea7f5ecfe
--- /dev/null
+++ b/lib/spack/external/_vendoring/pyrsistent/_plist.py
@@ -0,0 +1,313 @@
+from collections.abc import Sequence, Hashable
+from numbers import Integral
+from functools import reduce
+
+
+class _PListBuilder(object):
+    """
+    Helper class to allow construction of a list without
+    having to reverse it in the end.
+    """
+    __slots__ = ('_head', '_tail')
+
+    def __init__(self):
+        self._head = _EMPTY_PLIST
+        self._tail = _EMPTY_PLIST
+
+    def _append(self, elem, constructor):
+        if not self._tail:
+            self._head = constructor(elem)
+            self._tail = self._head
+        else:
+            self._tail.rest = constructor(elem)
+            self._tail = self._tail.rest
+
+        return self._head
+
+    def append_elem(self, elem):
+        return self._append(elem, lambda e: PList(e, _EMPTY_PLIST))
+
+    def append_plist(self, pl):
+        return self._append(pl, lambda l: l)
+
+    def build(self):
+        return self._head
+
+
+class _PListBase(object):
+    __slots__ = ('__weakref__',)
+
+    # Selected implementations can be taken straight from the Sequence
+    # class, other are less suitable. Especially those that work with
+    # index lookups.
+    count = Sequence.count
+    index = Sequence.index
+
+    def __reduce__(self):
+        # Pickling support
+        return plist, (list(self),)
+
+    def __len__(self):
+        """
+        Return the length of the list, computed by traversing it.
+
+        This is obviously O(n) but with the current implementation
+        where a list is also a node the overhead of storing the length
+        in every node would be quite significant.
+        """
+        return sum(1 for _ in self)
+
+    def __repr__(self):
+        return "plist({0})".format(list(self))
+    __str__ = __repr__
+
+    def cons(self, elem):
+        """
+        Return a new list with elem inserted as new head.
+
+        >>> plist([1, 2]).cons(3)
+        plist([3, 1, 2])
+        """
+        return PList(elem, self)
+
+    def mcons(self, iterable):
+        """
+        Return a new list with all elements of iterable repeatedly cons:ed to the current list.
+        NB! The elements will be inserted in the reverse order of the iterable.
+        Runs in O(len(iterable)).
+
+        >>> plist([1, 2]).mcons([3, 4])
+        plist([4, 3, 1, 2])
+        """
+        head = self
+        for elem in iterable:
+            head = head.cons(elem)
+
+        return head
+
+    def reverse(self):
+        """
+        Return a reversed version of list. Runs in O(n) where n is the length of the list.
+
+        >>> plist([1, 2, 3]).reverse()
+        plist([3, 2, 1])
+
+        Also supports the standard reversed function.
+
+        >>> reversed(plist([1, 2, 3]))
+        plist([3, 2, 1])
+        """
+        result = plist()
+        head = self
+        while head:
+            result = result.cons(head.first)
+            head = head.rest
+
+        return result
+    __reversed__ = reverse
+
+    def split(self, index):
+        """
+        Spilt the list at position specified by index. Returns a tuple containing the
+        list up until index and the list after the index. Runs in O(index).
+
+        >>> plist([1, 2, 3, 4]).split(2)
+        (plist([1, 2]), plist([3, 4]))
+        """
+        lb = _PListBuilder()
+        right_list = self
+        i = 0
+        while right_list and i < index:
+            lb.append_elem(right_list.first)
+            right_list = right_list.rest
+            i += 1
+
+        if not right_list:
+            # Just a small optimization in the cases where no split occurred
+            return self, _EMPTY_PLIST
+
+        return lb.build(), right_list
+
+    def __iter__(self):
+        li = self
+        while li:
+            yield li.first
+            li = li.rest
+
+    def __lt__(self, other):
+        if not isinstance(other, _PListBase):
+            return NotImplemented
+
+        return tuple(self) < tuple(other)
+
+    def __eq__(self, other):
+        """
+        Traverses the lists, checking equality of elements.
+
+        This is an O(n) operation, but preserves the standard semantics of list equality.
+        """
+        if not isinstance(other, _PListBase):
+            return NotImplemented
+
+        self_head = self
+        other_head = other
+        while self_head and other_head:
+            if not self_head.first == other_head.first:
+                return False
+            self_head = self_head.rest
+            other_head = other_head.rest
+
+        return not self_head and not other_head
+
+    def __getitem__(self, index):
+        # Don't use this this data structure if you plan to do a lot of indexing, it is
+        # very inefficient! Use a PVector instead!
+
+        if isinstance(index, slice):
+            if index.start is not None and index.stop is None and (index.step is None or index.step == 1):
+                return self._drop(index.start)
+
+            # Take the easy way out for all other slicing cases, not much structural reuse possible anyway
+            return plist(tuple(self)[index])
+
+        if not isinstance(index, Integral):
+            raise TypeError("'%s' object cannot be interpreted as an index" % type(index).__name__)
+
+        if index < 0:
+            # NB: O(n)!
+            index += len(self)
+
+        try:
+            return self._drop(index).first
+        except AttributeError as e:
+            raise IndexError("PList index out of range") from e
+
+    def _drop(self, count):
+        if count < 0:
+            raise IndexError("PList index out of range")
+
+        head = self
+        while count > 0:
+            head = head.rest
+            count -= 1
+
+        return head
+
+    def __hash__(self):
+        return hash(tuple(self))
+
+    def remove(self, elem):
+        """
+        Return new list with first element equal to elem removed. O(k) where k is the position
+        of the element that is removed.
+
+        Raises ValueError if no matching element is found.
+
+        >>> plist([1, 2, 1]).remove(1)
+        plist([2, 1])
+        """
+
+        builder = _PListBuilder()
+        head = self
+        while head:
+            if head.first == elem:
+                return builder.append_plist(head.rest)
+
+            builder.append_elem(head.first)
+            head = head.rest
+
+        raise ValueError('{0} not found in PList'.format(elem))
+
+
+class PList(_PListBase):
+    """
+    Classical Lisp style singly linked list. Adding elements to the head using cons is O(1).
+    Element access is O(k) where k is the position of the element in the list. Taking the
+    length of the list is O(n).
+
+    Fully supports the Sequence and Hashable protocols including indexing and slicing but
+    if you need fast random access go for the PVector instead.
+
+    Do not instantiate directly, instead use the factory functions :py:func:`l` or :py:func:`plist` to
+    create an instance.
+
+    Some examples:
+
+    >>> x = plist([1, 2])
+    >>> y = x.cons(3)
+    >>> x
+    plist([1, 2])
+    >>> y
+    plist([3, 1, 2])
+    >>> y.first
+    3
+    >>> y.rest == x
+    True
+    >>> y[:2]
+    plist([3, 1])
+    """
+    __slots__ = ('first', 'rest')
+
+    def __new__(cls, first, rest):
+        instance = super(PList, cls).__new__(cls)
+        instance.first = first
+        instance.rest = rest
+        return instance
+
+    def __bool__(self):
+        return True
+    __nonzero__ = __bool__
+
+
+Sequence.register(PList)
+Hashable.register(PList)
+
+
+class _EmptyPList(_PListBase):
+    __slots__ = ()
+
+    def __bool__(self):
+        return False
+    __nonzero__ = __bool__
+
+    @property
+    def first(self):
+        raise AttributeError("Empty PList has no first")
+
+    @property
+    def rest(self):
+        return self
+
+
+Sequence.register(_EmptyPList)
+Hashable.register(_EmptyPList)
+
+_EMPTY_PLIST = _EmptyPList()
+
+
+def plist(iterable=(), reverse=False):
+    """
+    Creates a new persistent list containing all elements of iterable.
+    Optional parameter reverse specifies if the elements should be inserted in
+    reverse order or not.
+
+    >>> plist([1, 2, 3])
+    plist([1, 2, 3])
+    >>> plist([1, 2, 3], reverse=True)
+    plist([3, 2, 1])
+    """
+    if not reverse:
+        iterable = list(iterable)
+        iterable.reverse()
+
+    return reduce(lambda pl, elem: pl.cons(elem), iterable, _EMPTY_PLIST)
+
+
+def l(*elements):
+    """
+    Creates a new persistent list containing all arguments.
+
+    >>> l(1, 2, 3)
+    plist([1, 2, 3])
+    """
+    return plist(elements)
diff --git a/lib/spack/external/_vendoring/pyrsistent/_pmap.py b/lib/spack/external/_vendoring/pyrsistent/_pmap.py
new file mode 100644
index 0000000000..81d99c076f
--- /dev/null
+++ b/lib/spack/external/_vendoring/pyrsistent/_pmap.py
@@ -0,0 +1,461 @@
+from collections.abc import Mapping, Hashable
+from itertools import chain
+from pyrsistent._pvector import pvector
+from pyrsistent._transformations import transform
+
+
+class PMap(object):
+    """
+    Persistent map/dict. Tries to follow the same naming conventions as the built in dict where feasible.
+
+    Do not instantiate directly, instead use the factory functions :py:func:`m` or :py:func:`pmap` to
+    create an instance.
+
+    Was originally written as a very close copy of the Clojure equivalent but was later rewritten to closer
+    re-assemble the python dict. This means that a sparse vector (a PVector) of buckets is used. The keys are
+    hashed and the elements inserted at position hash % len(bucket_vector). Whenever the map size exceeds 2/3 of
+    the containing vectors size the map is reallocated to a vector of double the size. This is done to avoid
+    excessive hash collisions.
+
+    This structure corresponds most closely to the built in dict type and is intended as a replacement. Where the
+    semantics are the same (more or less) the same function names have been used but for some cases it is not possible,
+    for example assignments and deletion of values.
+
+    PMap implements the Mapping protocol and is Hashable. It also supports dot-notation for
+    element access.
+
+    Random access and insert is log32(n) where n is the size of the map.
+
+    The following are examples of some common operations on persistent maps
+
+    >>> m1 = m(a=1, b=3)
+    >>> m2 = m1.set('c', 3)
+    >>> m3 = m2.remove('a')
+    >>> m1
+    pmap({'b': 3, 'a': 1})
+    >>> m2
+    pmap({'c': 3, 'b': 3, 'a': 1})
+    >>> m3
+    pmap({'c': 3, 'b': 3})
+    >>> m3['c']
+    3
+    >>> m3.c
+    3
+    """
+    __slots__ = ('_size', '_buckets', '__weakref__', '_cached_hash')
+
+    def __new__(cls, size, buckets):
+        self = super(PMap, cls).__new__(cls)
+        self._size = size
+        self._buckets = buckets
+        return self
+
+    @staticmethod
+    def _get_bucket(buckets, key):
+        index = hash(key) % len(buckets)
+        bucket = buckets[index]
+        return index, bucket
+
+    @staticmethod
+    def _getitem(buckets, key):
+        _, bucket = PMap._get_bucket(buckets, key)
+        if bucket:
+            for k, v in bucket:
+                if k == key:
+                    return v
+
+        raise KeyError(key)
+
+    def __getitem__(self, key):
+        return PMap._getitem(self._buckets, key)
+
+    @staticmethod
+    def _contains(buckets, key):
+        _, bucket = PMap._get_bucket(buckets, key)
+        if bucket:
+            for k, _ in bucket:
+                if k == key:
+                    return True
+
+            return False
+
+        return False
+
+    def __contains__(self, key):
+        return self._contains(self._buckets, key)
+
+    get = Mapping.get
+
+    def __iter__(self):
+        return self.iterkeys()
+
+    def __getattr__(self, key):
+        try:
+            return self[key]
+        except KeyError as e:
+            raise AttributeError(
+                "{0} has no attribute '{1}'".format(type(self).__name__, key)
+            ) from e
+
+    def iterkeys(self):
+        for k, _ in self.iteritems():
+            yield k
+
+    # These are more efficient implementations compared to the original
+    # methods that are based on the keys iterator and then calls the
+    # accessor functions to access the value for the corresponding key
+    def itervalues(self):
+        for _, v in self.iteritems():
+            yield v
+
+    def iteritems(self):
+        for bucket in self._buckets:
+            if bucket:
+                for k, v in bucket:
+                    yield k, v
+
+    def values(self):
+        return pvector(self.itervalues())
+
+    def keys(self):
+        return pvector(self.iterkeys())
+
+    def items(self):
+        return pvector(self.iteritems())
+
+    def __len__(self):
+        return self._size
+
+    def __repr__(self):
+        return 'pmap({0})'.format(str(dict(self)))
+
+    def __eq__(self, other):
+        if self is other:
+            return True
+        if not isinstance(other, Mapping):
+            return NotImplemented
+        if len(self) != len(other):
+            return False
+        if isinstance(other, PMap):
+            if (hasattr(self, '_cached_hash') and hasattr(other, '_cached_hash')
+                    and self._cached_hash != other._cached_hash):
+                return False
+            if self._buckets == other._buckets:
+                return True
+            return dict(self.iteritems()) == dict(other.iteritems())
+        elif isinstance(other, dict):
+            return dict(self.iteritems()) == other
+        return dict(self.iteritems()) == dict(other.items())
+
+    __ne__ = Mapping.__ne__
+
+    def __lt__(self, other):
+        raise TypeError('PMaps are not orderable')
+
+    __le__ = __lt__
+    __gt__ = __lt__
+    __ge__ = __lt__
+
+    def __str__(self):
+        return self.__repr__()
+
+    def __hash__(self):
+        if not hasattr(self, '_cached_hash'):
+            self._cached_hash = hash(frozenset(self.iteritems()))
+        return self._cached_hash
+
+    def set(self, key, val):
+        """
+        Return a new PMap with key and val inserted.
+
+        >>> m1 = m(a=1, b=2)
+        >>> m2 = m1.set('a', 3)
+        >>> m3 = m1.set('c' ,4)
+        >>> m1
+        pmap({'b': 2, 'a': 1})
+        >>> m2
+        pmap({'b': 2, 'a': 3})
+        >>> m3
+        pmap({'c': 4, 'b': 2, 'a': 1})
+        """
+        return self.evolver().set(key, val).persistent()
+
+    def remove(self, key):
+        """
+        Return a new PMap without the element specified by key. Raises KeyError if the element
+        is not present.
+
+        >>> m1 = m(a=1, b=2)
+        >>> m1.remove('a')
+        pmap({'b': 2})
+        """
+        return self.evolver().remove(key).persistent()
+
+    def discard(self, key):
+        """
+        Return a new PMap without the element specified by key. Returns reference to itself
+        if element is not present.
+
+        >>> m1 = m(a=1, b=2)
+        >>> m1.discard('a')
+        pmap({'b': 2})
+        >>> m1 is m1.discard('c')
+        True
+        """
+        try:
+            return self.remove(key)
+        except KeyError:
+            return self
+
+    def update(self, *maps):
+        """
+        Return a new PMap with the items in Mappings inserted. If the same key is present in multiple
+        maps the rightmost (last) value is inserted.
+
+        >>> m1 = m(a=1, b=2)
+        >>> m1.update(m(a=2, c=3), {'a': 17, 'd': 35})
+        pmap({'c': 3, 'b': 2, 'a': 17, 'd': 35})
+        """
+        return self.update_with(lambda l, r: r, *maps)
+
+    def update_with(self, update_fn, *maps):
+        """
+        Return a new PMap with the items in Mappings maps inserted. If the same key is present in multiple
+        maps the values will be merged using merge_fn going from left to right.
+
+        >>> from operator import add
+        >>> m1 = m(a=1, b=2)
+        >>> m1.update_with(add, m(a=2))
+        pmap({'b': 2, 'a': 3})
+
+        The reverse behaviour of the regular merge. Keep the leftmost element instead of the rightmost.
+
+        >>> m1 = m(a=1)
+        >>> m1.update_with(lambda l, r: l, m(a=2), {'a':3})
+        pmap({'a': 1})
+        """
+        evolver = self.evolver()
+        for map in maps:
+            for key, value in map.items():
+                evolver.set(key, update_fn(evolver[key], value) if key in evolver else value)
+
+        return evolver.persistent()
+
+    def __add__(self, other):
+        return self.update(other)
+
+    __or__ = __add__
+
+    def __reduce__(self):
+        # Pickling support
+        return pmap, (dict(self),)
+
+    def transform(self, *transformations):
+        """
+        Transform arbitrarily complex combinations of PVectors and PMaps. A transformation
+        consists of two parts. One match expression that specifies which elements to transform
+        and one transformation function that performs the actual transformation.
+
+        >>> from pyrsistent import freeze, ny
+        >>> news_paper = freeze({'articles': [{'author': 'Sara', 'content': 'A short article'},
+        ...                                   {'author': 'Steve', 'content': 'A slightly longer article'}],
+        ...                      'weather': {'temperature': '11C', 'wind': '5m/s'}})
+        >>> short_news = news_paper.transform(['articles', ny, 'content'], lambda c: c[:25] + '...' if len(c) > 25 else c)
+        >>> very_short_news = news_paper.transform(['articles', ny, 'content'], lambda c: c[:15] + '...' if len(c) > 15 else c)
+        >>> very_short_news.articles[0].content
+        'A short article'
+        >>> very_short_news.articles[1].content
+        'A slightly long...'
+
+        When nothing has been transformed the original data structure is kept
+
+        >>> short_news is news_paper
+        True
+        >>> very_short_news is news_paper
+        False
+        >>> very_short_news.articles[0] is news_paper.articles[0]
+        True
+        """
+        return transform(self, transformations)
+
+    def copy(self):
+        return self
+
+    class _Evolver(object):
+        __slots__ = ('_buckets_evolver', '_size', '_original_pmap')
+
+        def __init__(self, original_pmap):
+            self._original_pmap = original_pmap
+            self._buckets_evolver = original_pmap._buckets.evolver()
+            self._size = original_pmap._size
+
+        def __getitem__(self, key):
+            return PMap._getitem(self._buckets_evolver, key)
+
+        def __setitem__(self, key, val):
+            self.set(key, val)
+
+        def set(self, key, val):
+            if len(self._buckets_evolver) < 0.67 * self._size:
+                self._reallocate(2 * len(self._buckets_evolver))
+
+            kv = (key, val)
+            index, bucket = PMap._get_bucket(self._buckets_evolver, key)
+            if bucket:
+                for k, v in bucket:
+                    if k == key:
+                        if v is not val:
+                            new_bucket = [(k2, v2) if k2 != k else (k2, val) for k2, v2 in bucket]
+                            self._buckets_evolver[index] = new_bucket
+
+                        return self
+
+                new_bucket = [kv]
+                new_bucket.extend(bucket)
+                self._buckets_evolver[index] = new_bucket
+                self._size += 1
+            else:
+                self._buckets_evolver[index] = [kv]
+                self._size += 1
+
+            return self
+
+        def _reallocate(self, new_size):
+            new_list = new_size * [None]
+            buckets = self._buckets_evolver.persistent()
+            for k, v in chain.from_iterable(x for x in buckets if x):
+                index = hash(k) % new_size
+                if new_list[index]:
+                    new_list[index].append((k, v))
+                else:
+                    new_list[index] = [(k, v)]
+
+            # A reallocation should always result in a dirty buckets evolver to avoid
+            # possible loss of elements when doing the reallocation.
+            self._buckets_evolver = pvector().evolver()
+            self._buckets_evolver.extend(new_list)
+
+        def is_dirty(self):
+            return self._buckets_evolver.is_dirty()
+
+        def persistent(self):
+            if self.is_dirty():
+                self._original_pmap = PMap(self._size, self._buckets_evolver.persistent())
+
+            return self._original_pmap
+
+        def __len__(self):
+            return self._size
+
+        def __contains__(self, key):
+            return PMap._contains(self._buckets_evolver, key)
+
+        def __delitem__(self, key):
+            self.remove(key)
+
+        def remove(self, key):
+            index, bucket = PMap._get_bucket(self._buckets_evolver, key)
+
+            if bucket:
+                new_bucket = [(k, v) for (k, v) in bucket if k != key]
+                if len(bucket) > len(new_bucket):
+                    self._buckets_evolver[index] = new_bucket if new_bucket else None
+                    self._size -= 1
+                    return self
+
+            raise KeyError('{0}'.format(key))
+
+    def evolver(self):
+        """
+        Create a new evolver for this pmap. For a discussion on evolvers in general see the
+        documentation for the pvector evolver.
+
+        Create the evolver and perform various mutating updates to it:
+
+        >>> m1 = m(a=1, b=2)
+        >>> e = m1.evolver()
+        >>> e['c'] = 3
+        >>> len(e)
+        3
+        >>> del e['a']
+
+        The underlying pmap remains the same:
+
+        >>> m1
+        pmap({'b': 2, 'a': 1})
+
+        The changes are kept in the evolver. An updated pmap can be created using the
+        persistent() function on the evolver.
+
+        >>> m2 = e.persistent()
+        >>> m2
+        pmap({'c': 3, 'b': 2})
+
+        The new pmap will share data with the original pmap in the same way that would have
+        been done if only using operations on the pmap.
+        """
+        return self._Evolver(self)
+
+Mapping.register(PMap)
+Hashable.register(PMap)
+
+
+def _turbo_mapping(initial, pre_size):
+    if pre_size:
+        size = pre_size
+    else:
+        try:
+            size = 2 * len(initial) or 8
+        except Exception:
+            # Guess we can't figure out the length. Give up on length hinting,
+            # we can always reallocate later.
+            size = 8
+
+    buckets = size * [None]
+
+    if not isinstance(initial, Mapping):
+        # Make a dictionary of the initial data if it isn't already,
+        # that will save us some job further down since we can assume no
+        # key collisions
+        initial = dict(initial)
+
+    for k, v in initial.items():
+        h = hash(k)
+        index = h % size
+        bucket = buckets[index]
+
+        if bucket:
+            bucket.append((k, v))
+        else:
+            buckets[index] = [(k, v)]
+
+    return PMap(len(initial), pvector().extend(buckets))
+
+
+_EMPTY_PMAP = _turbo_mapping({}, 0)
+
+
+def pmap(initial={}, pre_size=0):
+    """
+    Create new persistent map, inserts all elements in initial into the newly created map.
+    The optional argument pre_size may be used to specify an initial size of the underlying bucket vector. This
+    may have a positive performance impact in the cases where you know beforehand that a large number of elements
+    will be inserted into the map eventually since it will reduce the number of reallocations required.
+
+    >>> pmap({'a': 13, 'b': 14})
+    pmap({'b': 14, 'a': 13})
+    """
+    if not initial and pre_size == 0:
+        return _EMPTY_PMAP
+
+    return _turbo_mapping(initial, pre_size)
+
+
+def m(**kwargs):
+    """
+    Creates a new persistent map. Inserts all key value arguments into the newly created map.
+
+    >>> m(a=13, b=14)
+    pmap({'b': 14, 'a': 13})
+    """
+    return pmap(kwargs)
diff --git a/lib/spack/external/_vendoring/pyrsistent/_precord.py b/lib/spack/external/_vendoring/pyrsistent/_precord.py
new file mode 100644
index 0000000000..1ee8198a1a
--- /dev/null
+++ b/lib/spack/external/_vendoring/pyrsistent/_precord.py
@@ -0,0 +1,167 @@
+from pyrsistent._checked_types import CheckedType, _restore_pickle, InvariantException, store_invariants
+from pyrsistent._field_common import (
+    set_fields, check_type, is_field_ignore_extra_complaint, PFIELD_NO_INITIAL, serialize, check_global_invariants
+)
+from pyrsistent._pmap import PMap, pmap
+
+
+class _PRecordMeta(type):
+    def __new__(mcs, name, bases, dct):
+        set_fields(dct, bases, name='_precord_fields')
+        store_invariants(dct, bases, '_precord_invariants', '__invariant__')
+
+        dct['_precord_mandatory_fields'] = \
+            set(name for name, field in dct['_precord_fields'].items() if field.mandatory)
+
+        dct['_precord_initial_values'] = \
+            dict((k, field.initial) for k, field in dct['_precord_fields'].items() if field.initial is not PFIELD_NO_INITIAL)
+
+
+        dct['__slots__'] = ()
+
+        return super(_PRecordMeta, mcs).__new__(mcs, name, bases, dct)
+
+
+class PRecord(PMap, CheckedType, metaclass=_PRecordMeta):
+    """
+    A PRecord is a PMap with a fixed set of specified fields. Records are declared as python classes inheriting
+    from PRecord. Because it is a PMap it has full support for all Mapping methods such as iteration and element
+    access using subscript notation.
+
+    More documentation and examples of PRecord usage is available at https://github.com/tobgu/pyrsistent
+    """
+    def __new__(cls, **kwargs):
+        # Hack total! If these two special attributes exist that means we can create
+        # ourselves. Otherwise we need to go through the Evolver to create the structures
+        # for us.
+        if '_precord_size' in kwargs and '_precord_buckets' in kwargs:
+            return super(PRecord, cls).__new__(cls, kwargs['_precord_size'], kwargs['_precord_buckets'])
+
+        factory_fields = kwargs.pop('_factory_fields', None)
+        ignore_extra = kwargs.pop('_ignore_extra', False)
+
+        initial_values = kwargs
+        if cls._precord_initial_values:
+            initial_values = dict((k, v() if callable(v) else v)
+                                  for k, v in cls._precord_initial_values.items())
+            initial_values.update(kwargs)
+
+        e = _PRecordEvolver(cls, pmap(pre_size=len(cls._precord_fields)), _factory_fields=factory_fields, _ignore_extra=ignore_extra)
+        for k, v in initial_values.items():
+            e[k] = v
+
+        return e.persistent()
+
+    def set(self, *args, **kwargs):
+        """
+        Set a field in the record. This set function differs slightly from that in the PMap
+        class. First of all it accepts key-value pairs. Second it accepts multiple key-value
+        pairs to perform one, atomic, update of multiple fields.
+        """
+
+        # The PRecord set() can accept kwargs since all fields that have been declared are
+        # valid python identifiers. Also allow multiple fields to be set in one operation.
+        if args:
+            return super(PRecord, self).set(args[0], args[1])
+
+        return self.update(kwargs)
+
+    def evolver(self):
+        """
+        Returns an evolver of this object.
+        """
+        return _PRecordEvolver(self.__class__, self)
+
+    def __repr__(self):
+        return "{0}({1})".format(self.__class__.__name__,
+                                 ', '.join('{0}={1}'.format(k, repr(v)) for k, v in self.items()))
+
+    @classmethod
+    def create(cls, kwargs, _factory_fields=None, ignore_extra=False):
+        """
+        Factory method. Will create a new PRecord of the current type and assign the values
+        specified in kwargs.
+
+        :param ignore_extra: A boolean which when set to True will ignore any keys which appear in kwargs that are not
+                             in the set of fields on the PRecord.
+        """
+        if isinstance(kwargs, cls):
+            return kwargs
+
+        if ignore_extra:
+            kwargs = {k: kwargs[k] for k in cls._precord_fields if k in kwargs}
+
+        return cls(_factory_fields=_factory_fields, _ignore_extra=ignore_extra, **kwargs)
+
+    def __reduce__(self):
+        # Pickling support
+        return _restore_pickle, (self.__class__, dict(self),)
+
+    def serialize(self, format=None):
+        """
+        Serialize the current PRecord using custom serializer functions for fields where
+        such have been supplied.
+        """
+        return dict((k, serialize(self._precord_fields[k].serializer, format, v)) for k, v in self.items())
+
+
+class _PRecordEvolver(PMap._Evolver):
+    __slots__ = ('_destination_cls', '_invariant_error_codes', '_missing_fields', '_factory_fields', '_ignore_extra')
+
+    def __init__(self, cls, original_pmap, _factory_fields=None, _ignore_extra=False):
+        super(_PRecordEvolver, self).__init__(original_pmap)
+        self._destination_cls = cls
+        self._invariant_error_codes = []
+        self._missing_fields = []
+        self._factory_fields = _factory_fields
+        self._ignore_extra = _ignore_extra
+
+    def __setitem__(self, key, original_value):
+        self.set(key, original_value)
+
+    def set(self, key, original_value):
+        field = self._destination_cls._precord_fields.get(key)
+        if field:
+            if self._factory_fields is None or field in self._factory_fields:
+                try:
+                    if is_field_ignore_extra_complaint(PRecord, field, self._ignore_extra):
+                        value = field.factory(original_value, ignore_extra=self._ignore_extra)
+                    else:
+                        value = field.factory(original_value)
+                except InvariantException as e:
+                    self._invariant_error_codes += e.invariant_errors
+                    self._missing_fields += e.missing_fields
+                    return self
+            else:
+                value = original_value
+
+            check_type(self._destination_cls, field, key, value)
+
+            is_ok, error_code = field.invariant(value)
+            if not is_ok:
+                self._invariant_error_codes.append(error_code)
+
+            return super(_PRecordEvolver, self).set(key, value)
+        else:
+            raise AttributeError("'{0}' is not among the specified fields for {1}".format(key, self._destination_cls.__name__))
+
+    def persistent(self):
+        cls = self._destination_cls
+        is_dirty = self.is_dirty()
+        pm = super(_PRecordEvolver, self).persistent()
+        if is_dirty or not isinstance(pm, cls):
+            result = cls(_precord_buckets=pm._buckets, _precord_size=pm._size)
+        else:
+            result = pm
+
+        if cls._precord_mandatory_fields:
+            self._missing_fields += tuple('{0}.{1}'.format(cls.__name__, f) for f
+                                          in (cls._precord_mandatory_fields - set(result.keys())))
+
+        if self._invariant_error_codes or self._missing_fields:
+            raise InvariantException(tuple(self._invariant_error_codes), tuple(self._missing_fields),
+                                     'Field invariant failed')
+
+        check_global_invariants(result, cls._precord_invariants)
+
+        return result
diff --git a/lib/spack/external/_vendoring/pyrsistent/_pset.py b/lib/spack/external/_vendoring/pyrsistent/_pset.py
new file mode 100644
index 0000000000..4fae8278f0
--- /dev/null
+++ b/lib/spack/external/_vendoring/pyrsistent/_pset.py
@@ -0,0 +1,227 @@
+from collections.abc import Set, Hashable
+import sys
+from pyrsistent._pmap import pmap
+
+
+class PSet(object):
+    """
+    Persistent set implementation. Built on top of the persistent map. The set supports all operations
+    in the Set protocol and is Hashable.
+
+    Do not instantiate directly, instead use the factory functions :py:func:`s` or :py:func:`pset`
+    to create an instance.
+
+    Random access and insert is log32(n) where n is the size of the set.
+
+    Some examples:
+
+    >>> s = pset([1, 2, 3, 1])
+    >>> s2 = s.add(4)
+    >>> s3 = s2.remove(2)
+    >>> s
+    pset([1, 2, 3])
+    >>> s2
+    pset([1, 2, 3, 4])
+    >>> s3
+    pset([1, 3, 4])
+    """
+    __slots__ = ('_map', '__weakref__')
+
+    def __new__(cls, m):
+        self = super(PSet, cls).__new__(cls)
+        self._map = m
+        return self
+
+    def __contains__(self, element):
+        return element in self._map
+
+    def __iter__(self):
+        return iter(self._map)
+
+    def __len__(self):
+        return len(self._map)
+
+    def __repr__(self):
+        if not self:
+            return 'p' + str(set(self))
+
+        return 'pset([{0}])'.format(str(set(self))[1:-1])
+
+    def __str__(self):
+        return self.__repr__()
+
+    def __hash__(self):
+        return hash(self._map)
+
+    def __reduce__(self):
+        # Pickling support
+        return pset, (list(self),)
+
+    @classmethod
+    def _from_iterable(cls, it, pre_size=8):
+        return PSet(pmap(dict((k, True) for k in it), pre_size=pre_size))
+
+    def add(self, element):
+        """
+        Return a new PSet with element added
+
+        >>> s1 = s(1, 2)
+        >>> s1.add(3)
+        pset([1, 2, 3])
+        """
+        return self.evolver().add(element).persistent()
+
+    def update(self, iterable):
+        """
+        Return a new PSet with elements in iterable added
+
+        >>> s1 = s(1, 2)
+        >>> s1.update([3, 4, 4])
+        pset([1, 2, 3, 4])
+        """
+        e = self.evolver()
+        for element in iterable:
+            e.add(element)
+
+        return e.persistent()
+
+    def remove(self, element):
+        """
+        Return a new PSet with element removed. Raises KeyError if element is not present.
+
+        >>> s1 = s(1, 2)
+        >>> s1.remove(2)
+        pset([1])
+        """
+        if element in self._map:
+            return self.evolver().remove(element).persistent()
+
+        raise KeyError("Element '%s' not present in PSet" % repr(element))
+
+    def discard(self, element):
+        """
+        Return a new PSet with element removed. Returns itself if element is not present.
+        """
+        if element in self._map:
+            return self.evolver().remove(element).persistent()
+
+        return self
+
+    class _Evolver(object):
+        __slots__ = ('_original_pset', '_pmap_evolver')
+
+        def __init__(self, original_pset):
+            self._original_pset = original_pset
+            self._pmap_evolver = original_pset._map.evolver()
+
+        def add(self, element):
+            self._pmap_evolver[element] = True
+            return self
+
+        def remove(self, element):
+            del self._pmap_evolver[element]
+            return self
+
+        def is_dirty(self):
+            return self._pmap_evolver.is_dirty()
+
+        def persistent(self):
+            if not self.is_dirty():
+                return  self._original_pset
+
+            return PSet(self._pmap_evolver.persistent())
+
+        def __len__(self):
+            return len(self._pmap_evolver)
+
+    def copy(self):
+        return self
+
+    def evolver(self):
+        """
+        Create a new evolver for this pset. For a discussion on evolvers in general see the
+        documentation for the pvector evolver.
+
+        Create the evolver and perform various mutating updates to it:
+
+        >>> s1 = s(1, 2, 3)
+        >>> e = s1.evolver()
+        >>> _ = e.add(4)
+        >>> len(e)
+        4
+        >>> _ = e.remove(1)
+
+        The underlying pset remains the same:
+
+        >>> s1
+        pset([1, 2, 3])
+
+        The changes are kept in the evolver. An updated pmap can be created using the
+        persistent() function on the evolver.
+
+        >>> s2 = e.persistent()
+        >>> s2
+        pset([2, 3, 4])
+
+        The new pset will share data with the original pset in the same way that would have
+        been done if only using operations on the pset.
+        """
+        return PSet._Evolver(self)
+
+    # All the operations and comparisons you would expect on a set.
+    #
+    # This is not very beautiful. If we avoid inheriting from PSet we can use the
+    # __slots__ concepts (which requires a new style class) and hopefully save some memory.
+    __le__ = Set.__le__
+    __lt__ = Set.__lt__
+    __gt__ = Set.__gt__
+    __ge__ = Set.__ge__
+    __eq__ = Set.__eq__
+    __ne__ = Set.__ne__
+
+    __and__ = Set.__and__
+    __or__ = Set.__or__
+    __sub__ = Set.__sub__
+    __xor__ = Set.__xor__
+
+    issubset = __le__
+    issuperset = __ge__
+    union = __or__
+    intersection = __and__
+    difference = __sub__
+    symmetric_difference = __xor__
+
+    isdisjoint = Set.isdisjoint
+
+Set.register(PSet)
+Hashable.register(PSet)
+
+_EMPTY_PSET = PSet(pmap())
+
+
+def pset(iterable=(), pre_size=8):
+    """
+    Creates a persistent set from iterable. Optionally takes a sizing parameter equivalent to that
+    used for :py:func:`pmap`.
+
+    >>> s1 = pset([1, 2, 3, 2])
+    >>> s1
+    pset([1, 2, 3])
+    """
+    if not iterable:
+        return _EMPTY_PSET
+
+    return PSet._from_iterable(iterable, pre_size=pre_size)
+
+
+def s(*elements):
+    """
+    Create a persistent set.
+
+    Takes an arbitrary number of arguments to insert into the new set.
+
+    >>> s1 = s(1, 2, 3, 2)
+    >>> s1
+    pset([1, 2, 3])
+    """
+    return pset(elements)
diff --git a/lib/spack/external/_vendoring/pyrsistent/_pvector.py b/lib/spack/external/_vendoring/pyrsistent/_pvector.py
new file mode 100644
index 0000000000..2aff0e8b42
--- /dev/null
+++ b/lib/spack/external/_vendoring/pyrsistent/_pvector.py
@@ -0,0 +1,711 @@
+from abc import abstractmethod, ABCMeta
+from collections.abc import Sequence, Hashable
+from numbers import Integral
+import operator
+from pyrsistent._transformations import transform
+
+
+def _bitcount(val):
+    return bin(val).count("1")
+
+BRANCH_FACTOR = 32
+BIT_MASK = BRANCH_FACTOR - 1
+SHIFT = _bitcount(BIT_MASK)
+
+
+def compare_pvector(v, other, operator):
+    return operator(v.tolist(), other.tolist() if isinstance(other, PVector) else other)
+
+
+def _index_or_slice(index, stop):
+    if stop is None:
+        return index
+
+    return slice(index, stop)
+
+
+class PythonPVector(object):
+    """
+    Support structure for PVector that implements structural sharing for vectors using a trie.
+    """
+    __slots__ = ('_count', '_shift', '_root', '_tail', '_tail_offset', '__weakref__')
+
+    def __new__(cls, count, shift, root, tail):
+        self = super(PythonPVector, cls).__new__(cls)
+        self._count = count
+        self._shift = shift
+        self._root = root
+        self._tail = tail
+
+        # Derived attribute stored for performance
+        self._tail_offset = self._count - len(self._tail)
+        return self
+
+    def __len__(self):
+        return self._count
+
+    def __getitem__(self, index):
+        if isinstance(index, slice):
+            # There are more conditions than the below where it would be OK to
+            # return ourselves, implement those...
+            if index.start is None and index.stop is None and index.step is None:
+                return self
+
+            # This is a bit nasty realizing the whole structure as a list before
+            # slicing it but it is the fastest way I've found to date, and it's easy :-)
+            return _EMPTY_PVECTOR.extend(self.tolist()[index])
+
+        if index < 0:
+            index += self._count
+
+        return PythonPVector._node_for(self, index)[index & BIT_MASK]
+
+    def __add__(self, other):
+        return self.extend(other)
+
+    def __repr__(self):
+        return 'pvector({0})'.format(str(self.tolist()))
+
+    def __str__(self):
+        return self.__repr__()
+
+    def __iter__(self):
+        # This is kind of lazy and will produce some memory overhead but it is the fasted method
+        # by far of those tried since it uses the speed of the built in python list directly.
+        return iter(self.tolist())
+
+    def __ne__(self, other):
+        return not self.__eq__(other)
+
+    def __eq__(self, other):
+        return self is other or (hasattr(other, '__len__') and self._count == len(other)) and compare_pvector(self, other, operator.eq)
+
+    def __gt__(self, other):
+        return compare_pvector(self, other, operator.gt)
+
+    def __lt__(self, other):
+        return compare_pvector(self, other, operator.lt)
+
+    def __ge__(self, other):
+        return compare_pvector(self, other, operator.ge)
+
+    def __le__(self, other):
+        return compare_pvector(self, other, operator.le)
+
+    def __mul__(self, times):
+        if times <= 0 or self is _EMPTY_PVECTOR:
+            return _EMPTY_PVECTOR
+
+        if times == 1:
+            return self
+
+        return _EMPTY_PVECTOR.extend(times * self.tolist())
+
+    __rmul__ = __mul__
+
+    def _fill_list(self, node, shift, the_list):
+        if shift:
+            shift -= SHIFT
+            for n in node:
+                self._fill_list(n, shift, the_list)
+        else:
+            the_list.extend(node)
+
+    def tolist(self):
+        """
+        The fastest way to convert the vector into a python list.
+        """
+        the_list = []
+        self._fill_list(self._root, self._shift, the_list)
+        the_list.extend(self._tail)
+        return the_list
+
+    def _totuple(self):
+        """
+        Returns the content as a python tuple.
+        """
+        return tuple(self.tolist())
+
+    def __hash__(self):
+        # Taking the easy way out again...
+        return hash(self._totuple())
+
+    def transform(self, *transformations):
+        return transform(self, transformations)
+
+    def __reduce__(self):
+        # Pickling support
+        return pvector, (self.tolist(),)
+
+    def mset(self, *args):
+        if len(args) % 2:
+            raise TypeError("mset expected an even number of arguments")
+
+        evolver = self.evolver()
+        for i in range(0, len(args), 2):
+            evolver[args[i]] = args[i+1]
+
+        return evolver.persistent()
+
+    class Evolver(object):
+        __slots__ = ('_count', '_shift', '_root', '_tail', '_tail_offset', '_dirty_nodes',
+                     '_extra_tail', '_cached_leafs', '_orig_pvector')
+
+        def __init__(self, v):
+            self._reset(v)
+
+        def __getitem__(self, index):
+            if not isinstance(index, Integral):
+                raise TypeError("'%s' object cannot be interpreted as an index" % type(index).__name__)
+
+            if index < 0:
+                index += self._count + len(self._extra_tail)
+
+            if self._count <= index < self._count + len(self._extra_tail):
+                return self._extra_tail[index - self._count]
+
+            return PythonPVector._node_for(self, index)[index & BIT_MASK]
+
+        def _reset(self, v):
+            self._count = v._count
+            self._shift = v._shift
+            self._root = v._root
+            self._tail = v._tail
+            self._tail_offset = v._tail_offset
+            self._dirty_nodes = {}
+            self._cached_leafs = {}
+            self._extra_tail = []
+            self._orig_pvector = v
+
+        def append(self, element):
+            self._extra_tail.append(element)
+            return self
+
+        def extend(self, iterable):
+            self._extra_tail.extend(iterable)
+            return self
+
+        def set(self, index, val):
+            self[index] = val
+            return self
+
+        def __setitem__(self, index, val):
+            if not isinstance(index, Integral):
+                raise TypeError("'%s' object cannot be interpreted as an index" % type(index).__name__)
+
+            if index < 0:
+                index += self._count + len(self._extra_tail)
+
+            if 0 <= index < self._count:
+                node = self._cached_leafs.get(index >> SHIFT)
+                if node:
+                    node[index & BIT_MASK] = val
+                elif index >= self._tail_offset:
+                    if id(self._tail) not in self._dirty_nodes:
+                        self._tail = list(self._tail)
+                        self._dirty_nodes[id(self._tail)] = True
+                        self._cached_leafs[index >> SHIFT] = self._tail
+                    self._tail[index & BIT_MASK] = val
+                else:
+                    self._root = self._do_set(self._shift, self._root, index, val)
+            elif self._count <= index < self._count + len(self._extra_tail):
+                self._extra_tail[index - self._count] = val
+            elif index == self._count + len(self._extra_tail):
+                self._extra_tail.append(val)
+            else:
+                raise IndexError("Index out of range: %s" % (index,))
+
+        def _do_set(self, level, node, i, val):
+            if id(node) in self._dirty_nodes:
+                ret = node
+            else:
+                ret = list(node)
+                self._dirty_nodes[id(ret)] = True
+
+            if level == 0:
+                ret[i & BIT_MASK] = val
+                self._cached_leafs[i >> SHIFT] = ret
+            else:
+                sub_index = (i >> level) & BIT_MASK  # >>>
+                ret[sub_index] = self._do_set(level - SHIFT, node[sub_index], i, val)
+
+            return ret
+
+        def delete(self, index):
+            del self[index]
+            return self
+
+        def __delitem__(self, key):
+            if self._orig_pvector:
+                # All structural sharing bets are off, base evolver on _extra_tail only
+                l = PythonPVector(self._count, self._shift, self._root, self._tail).tolist()
+                l.extend(self._extra_tail)
+                self._reset(_EMPTY_PVECTOR)
+                self._extra_tail = l
+
+            del self._extra_tail[key]
+
+        def persistent(self):
+            result = self._orig_pvector
+            if self.is_dirty():
+                result = PythonPVector(self._count, self._shift, self._root, self._tail).extend(self._extra_tail)
+                self._reset(result)
+
+            return result
+
+        def __len__(self):
+            return self._count + len(self._extra_tail)
+
+        def is_dirty(self):
+            return bool(self._dirty_nodes or self._extra_tail)
+
+    def evolver(self):
+        return PythonPVector.Evolver(self)
+
+    def set(self, i, val):
+        # This method could be implemented by a call to mset() but doing so would cause
+        # a ~5 X performance penalty on PyPy (considered the primary platform for this implementation
+        #  of PVector) so we're keeping this implementation for now.
+
+        if not isinstance(i, Integral):
+            raise TypeError("'%s' object cannot be interpreted as an index" % type(i).__name__)
+
+        if i < 0:
+            i += self._count
+
+        if 0 <= i < self._count:
+            if i >= self._tail_offset:
+                new_tail = list(self._tail)
+                new_tail[i & BIT_MASK] = val
+                return PythonPVector(self._count, self._shift, self._root, new_tail)
+
+            return PythonPVector(self._count, self._shift, self._do_set(self._shift, self._root, i, val), self._tail)
+
+        if i == self._count:
+            return self.append(val)
+
+        raise IndexError("Index out of range: %s" % (i,))
+
+    def _do_set(self, level, node, i, val):
+        ret = list(node)
+        if level == 0:
+            ret[i & BIT_MASK] = val
+        else:
+            sub_index = (i >> level) & BIT_MASK  # >>>
+            ret[sub_index] = self._do_set(level - SHIFT, node[sub_index], i, val)
+
+        return ret
+
+    @staticmethod
+    def _node_for(pvector_like, i):
+        if 0 <= i < pvector_like._count:
+            if i >= pvector_like._tail_offset:
+                return pvector_like._tail
+
+            node = pvector_like._root
+            for level in range(pvector_like._shift, 0, -SHIFT):
+                node = node[(i >> level) & BIT_MASK]  # >>>
+
+            return node
+
+        raise IndexError("Index out of range: %s" % (i,))
+
+    def _create_new_root(self):
+        new_shift = self._shift
+
+        # Overflow root?
+        if (self._count >> SHIFT) > (1 << self._shift): # >>>
+            new_root = [self._root, self._new_path(self._shift, self._tail)]
+            new_shift += SHIFT
+        else:
+            new_root = self._push_tail(self._shift, self._root, self._tail)
+
+        return new_root, new_shift
+
+    def append(self, val):
+        if len(self._tail) < BRANCH_FACTOR:
+            new_tail = list(self._tail)
+            new_tail.append(val)
+            return PythonPVector(self._count + 1, self._shift, self._root, new_tail)
+
+        # Full tail, push into tree
+        new_root, new_shift = self._create_new_root()
+        return PythonPVector(self._count + 1, new_shift, new_root, [val])
+
+    def _new_path(self, level, node):
+        if level == 0:
+            return node
+
+        return [self._new_path(level - SHIFT, node)]
+
+    def _mutating_insert_tail(self):
+        self._root, self._shift = self._create_new_root()
+        self._tail = []
+
+    def _mutating_fill_tail(self, offset, sequence):
+        max_delta_len = BRANCH_FACTOR - len(self._tail)
+        delta = sequence[offset:offset + max_delta_len]
+        self._tail.extend(delta)
+        delta_len = len(delta)
+        self._count += delta_len
+        return offset + delta_len
+
+    def _mutating_extend(self, sequence):
+        offset = 0
+        sequence_len = len(sequence)
+        while offset < sequence_len:
+            offset = self._mutating_fill_tail(offset, sequence)
+            if len(self._tail) == BRANCH_FACTOR:
+                self._mutating_insert_tail()
+
+        self._tail_offset = self._count - len(self._tail)
+
+    def extend(self, obj):
+        # Mutates the new vector directly for efficiency but that's only an
+        # implementation detail, once it is returned it should be considered immutable
+        l = obj.tolist() if isinstance(obj, PythonPVector) else list(obj)
+        if l:
+            new_vector = self.append(l[0])
+            new_vector._mutating_extend(l[1:])
+            return new_vector
+
+        return self
+
+    def _push_tail(self, level, parent, tail_node):
+        """
+        if parent is leaf, insert node,
+        else does it map to an existing child? ->
+             node_to_insert = push node one more level
+        else alloc new path
+
+        return  node_to_insert placed in copy of parent
+        """
+        ret = list(parent)
+
+        if level == SHIFT:
+            ret.append(tail_node)
+            return ret
+
+        sub_index = ((self._count - 1) >> level) & BIT_MASK  # >>>
+        if len(parent) > sub_index:
+            ret[sub_index] = self._push_tail(level - SHIFT, parent[sub_index], tail_node)
+            return ret
+
+        ret.append(self._new_path(level - SHIFT, tail_node))
+        return ret
+
+    def index(self, value, *args, **kwargs):
+        return self.tolist().index(value, *args, **kwargs)
+
+    def count(self, value):
+        return self.tolist().count(value)
+
+    def delete(self, index, stop=None):
+        l = self.tolist()
+        del l[_index_or_slice(index, stop)]
+        return _EMPTY_PVECTOR.extend(l)
+
+    def remove(self, value):
+        l = self.tolist()
+        l.remove(value)
+        return _EMPTY_PVECTOR.extend(l)
+
+class PVector(metaclass=ABCMeta):
+    """
+    Persistent vector implementation. Meant as a replacement for the cases where you would normally
+    use a Python list.
+
+    Do not instantiate directly, instead use the factory functions :py:func:`v` and :py:func:`pvector` to
+    create an instance.
+
+    Heavily influenced by the persistent vector available in Clojure. Initially this was more or
+    less just a port of the Java code for the Clojure vector. It has since been modified and to
+    some extent optimized for usage in Python.
+
+    The vector is organized as a trie, any mutating method will return a new vector that contains the changes. No
+    updates are done to the original vector. Structural sharing between vectors are applied where possible to save
+    space and to avoid making complete copies.
+
+    This structure corresponds most closely to the built in list type and is intended as a replacement. Where the
+    semantics are the same (more or less) the same function names have been used but for some cases it is not possible,
+    for example assignments.
+
+    The PVector implements the Sequence protocol and is Hashable.
+
+    Inserts are amortized O(1). Random access is log32(n) where n is the size of the vector.
+
+    The following are examples of some common operations on persistent vectors:
+
+    >>> p = v(1, 2, 3)
+    >>> p2 = p.append(4)
+    >>> p3 = p2.extend([5, 6, 7])
+    >>> p
+    pvector([1, 2, 3])
+    >>> p2
+    pvector([1, 2, 3, 4])
+    >>> p3
+    pvector([1, 2, 3, 4, 5, 6, 7])
+    >>> p3[5]
+    6
+    >>> p.set(1, 99)
+    pvector([1, 99, 3])
+    >>>
+    """
+
+    @abstractmethod
+    def __len__(self):
+        """
+        >>> len(v(1, 2, 3))
+        3
+        """
+
+    @abstractmethod
+    def __getitem__(self, index):
+        """
+        Get value at index. Full slicing support.
+
+        >>> v1 = v(5, 6, 7, 8)
+        >>> v1[2]
+        7
+        >>> v1[1:3]
+        pvector([6, 7])
+        """
+
+    @abstractmethod
+    def __add__(self, other):
+        """
+        >>> v1 = v(1, 2)
+        >>> v2 = v(3, 4)
+        >>> v1 + v2
+        pvector([1, 2, 3, 4])
+        """
+
+    @abstractmethod
+    def __mul__(self, times):
+        """
+        >>> v1 = v(1, 2)
+        >>> 3 * v1
+        pvector([1, 2, 1, 2, 1, 2])
+        """
+
+    @abstractmethod
+    def __hash__(self):
+        """
+        >>> v1 = v(1, 2, 3)
+        >>> v2 = v(1, 2, 3)
+        >>> hash(v1) == hash(v2)
+        True
+        """
+
+    @abstractmethod
+    def evolver(self):
+        """
+        Create a new evolver for this pvector. The evolver acts as a mutable view of the vector
+        with "transaction like" semantics. No part of the underlying vector i updated, it is still
+        fully immutable. Furthermore multiple evolvers created from the same pvector do not
+        interfere with each other.
+
+        You may want to use an evolver instead of working directly with the pvector in the
+        following cases:
+
+        * Multiple updates are done to the same vector and the intermediate results are of no
+          interest. In this case using an evolver may be a more efficient and easier to work with.
+        * You need to pass a vector into a legacy function or a function that you have no control
+          over which performs in place mutations of lists. In this case pass an evolver instance
+          instead and then create a new pvector from the evolver once the function returns.
+
+        The following example illustrates a typical workflow when working with evolvers. It also
+        displays most of the API (which i kept small by design, you should not be tempted to
+        use evolvers in excess ;-)).
+
+        Create the evolver and perform various mutating updates to it:
+
+        >>> v1 = v(1, 2, 3, 4, 5)
+        >>> e = v1.evolver()
+        >>> e[1] = 22
+        >>> _ = e.append(6)
+        >>> _ = e.extend([7, 8, 9])
+        >>> e[8] += 1
+        >>> len(e)
+        9
+
+        The underlying pvector remains the same:
+
+        >>> v1
+        pvector([1, 2, 3, 4, 5])
+
+        The changes are kept in the evolver. An updated pvector can be created using the
+        persistent() function on the evolver.
+
+        >>> v2 = e.persistent()
+        >>> v2
+        pvector([1, 22, 3, 4, 5, 6, 7, 8, 10])
+
+        The new pvector will share data with the original pvector in the same way that would have
+        been done if only using operations on the pvector.
+        """
+
+    @abstractmethod
+    def mset(self, *args):
+        """
+        Return a new vector with elements in specified positions replaced by values (multi set).
+
+        Elements on even positions in the argument list are interpreted as indexes while
+        elements on odd positions are considered values.
+
+        >>> v1 = v(1, 2, 3)
+        >>> v1.mset(0, 11, 2, 33)
+        pvector([11, 2, 33])
+        """
+
+    @abstractmethod
+    def set(self, i, val):
+        """
+        Return a new vector with element at position i replaced with val. The original vector remains unchanged.
+
+        Setting a value one step beyond the end of the vector is equal to appending. Setting beyond that will
+        result in an IndexError.
+
+        >>> v1 = v(1, 2, 3)
+        >>> v1.set(1, 4)
+        pvector([1, 4, 3])
+        >>> v1.set(3, 4)
+        pvector([1, 2, 3, 4])
+        >>> v1.set(-1, 4)
+        pvector([1, 2, 4])
+        """
+
+    @abstractmethod
+    def append(self, val):
+        """
+        Return a new vector with val appended.
+
+        >>> v1 = v(1, 2)
+        >>> v1.append(3)
+        pvector([1, 2, 3])
+        """
+
+    @abstractmethod
+    def extend(self, obj):
+        """
+        Return a new vector with all values in obj appended to it. Obj may be another
+        PVector or any other Iterable.
+
+        >>> v1 = v(1, 2, 3)
+        >>> v1.extend([4, 5])
+        pvector([1, 2, 3, 4, 5])
+        """
+
+    @abstractmethod
+    def index(self, value, *args, **kwargs):
+        """
+        Return first index of value. Additional indexes may be supplied to limit the search to a
+        sub range of the vector.
+
+        >>> v1 = v(1, 2, 3, 4, 3)
+        >>> v1.index(3)
+        2
+        >>> v1.index(3, 3, 5)
+        4
+        """
+
+    @abstractmethod
+    def count(self, value):
+        """
+        Return the number of times that value appears in the vector.
+
+        >>> v1 = v(1, 4, 3, 4)
+        >>> v1.count(4)
+        2
+        """
+
+    @abstractmethod
+    def transform(self, *transformations):
+        """
+        Transform arbitrarily complex combinations of PVectors and PMaps. A transformation
+        consists of two parts. One match expression that specifies which elements to transform
+        and one transformation function that performs the actual transformation.
+
+        >>> from pyrsistent import freeze, ny
+        >>> news_paper = freeze({'articles': [{'author': 'Sara', 'content': 'A short article'},
+        ...                                   {'author': 'Steve', 'content': 'A slightly longer article'}],
+        ...                      'weather': {'temperature': '11C', 'wind': '5m/s'}})
+        >>> short_news = news_paper.transform(['articles', ny, 'content'], lambda c: c[:25] + '...' if len(c) > 25 else c)
+        >>> very_short_news = news_paper.transform(['articles', ny, 'content'], lambda c: c[:15] + '...' if len(c) > 15 else c)
+        >>> very_short_news.articles[0].content
+        'A short article'
+        >>> very_short_news.articles[1].content
+        'A slightly long...'
+
+        When nothing has been transformed the original data structure is kept
+
+        >>> short_news is news_paper
+        True
+        >>> very_short_news is news_paper
+        False
+        >>> very_short_news.articles[0] is news_paper.articles[0]
+        True
+        """
+
+    @abstractmethod
+    def delete(self, index, stop=None):
+        """
+        Delete a portion of the vector by index or range.
+
+        >>> v1 = v(1, 2, 3, 4, 5)
+        >>> v1.delete(1)
+        pvector([1, 3, 4, 5])
+        >>> v1.delete(1, 3)
+        pvector([1, 4, 5])
+        """
+
+    @abstractmethod
+    def remove(self, value):
+        """
+        Remove the first occurrence of a value from the vector.
+
+        >>> v1 = v(1, 2, 3, 2, 1)
+        >>> v2 = v1.remove(1)
+        >>> v2
+        pvector([2, 3, 2, 1])
+        >>> v2.remove(1)
+        pvector([2, 3, 2])
+        """
+
+
+_EMPTY_PVECTOR = PythonPVector(0, SHIFT, [], [])
+PVector.register(PythonPVector)
+Sequence.register(PVector)
+Hashable.register(PVector)
+
+def python_pvector(iterable=()):
+    """
+    Create a new persistent vector containing the elements in iterable.
+
+    >>> v1 = pvector([1, 2, 3])
+    >>> v1
+    pvector([1, 2, 3])
+    """
+    return _EMPTY_PVECTOR.extend(iterable)
+
+try:
+    # Use the C extension as underlying trie implementation if it is available
+    import os
+    if os.environ.get('PYRSISTENT_NO_C_EXTENSION'):
+        pvector = python_pvector
+    else:
+        from pvectorc import pvector
+        PVector.register(type(pvector()))
+except ImportError:
+    pvector = python_pvector
+
+
+def v(*elements):
+    """
+    Create a new persistent vector containing all parameters to this function.
+
+    >>> v1 = v(1, 2, 3)
+    >>> v1
+    pvector([1, 2, 3])
+    """
+    return pvector(elements)
diff --git a/lib/spack/external/_vendoring/pyrsistent/_toolz.py b/lib/spack/external/_vendoring/pyrsistent/_toolz.py
new file mode 100644
index 0000000000..a7faed1653
--- /dev/null
+++ b/lib/spack/external/_vendoring/pyrsistent/_toolz.py
@@ -0,0 +1,83 @@
+"""
+Functionality copied from the toolz package to avoid having
+to add toolz as a dependency.
+
+See https://github.com/pytoolz/toolz/.
+
+toolz is relased under BSD licence. Below is the licence text
+from toolz as it appeared when copying the code.
+
+--------------------------------------------------------------
+
+Copyright (c) 2013 Matthew Rocklin
+
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+  a. Redistributions of source code must retain the above copyright notice,
+     this list of conditions and the following disclaimer.
+  b. Redistributions in binary form must reproduce the above copyright
+     notice, this list of conditions and the following disclaimer in the
+     documentation and/or other materials provided with the distribution.
+  c. Neither the name of toolz nor the names of its contributors
+     may be used to endorse or promote products derived from this software
+     without specific prior written permission.
+
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE FOR
+ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
+DAMAGE.
+"""
+import operator
+from functools import reduce
+
+
+def get_in(keys, coll, default=None, no_default=False):
+    """
+    NB: This is a straight copy of the get_in implementation found in
+        the toolz library (https://github.com/pytoolz/toolz/). It works
+        with persistent data structures as well as the corresponding
+        datastructures from the stdlib.
+
+    Returns coll[i0][i1]...[iX] where [i0, i1, ..., iX]==keys.
+
+    If coll[i0][i1]...[iX] cannot be found, returns ``default``, unless
+    ``no_default`` is specified, then it raises KeyError or IndexError.
+
+    ``get_in`` is a generalization of ``operator.getitem`` for nested data
+    structures such as dictionaries and lists.
+    >>> from pyrsistent import freeze
+    >>> transaction = freeze({'name': 'Alice',
+    ...                       'purchase': {'items': ['Apple', 'Orange'],
+    ...                                    'costs': [0.50, 1.25]},
+    ...                       'credit card': '5555-1234-1234-1234'})
+    >>> get_in(['purchase', 'items', 0], transaction)
+    'Apple'
+    >>> get_in(['name'], transaction)
+    'Alice'
+    >>> get_in(['purchase', 'total'], transaction)
+    >>> get_in(['purchase', 'items', 'apple'], transaction)
+    >>> get_in(['purchase', 'items', 10], transaction)
+    >>> get_in(['purchase', 'total'], transaction, 0)
+    0
+    >>> get_in(['y'], {}, no_default=True)
+    Traceback (most recent call last):
+        ...
+    KeyError: 'y'
+    """
+    try:
+        return reduce(operator.getitem, keys, coll)
+    except (KeyError, IndexError, TypeError):
+        if no_default:
+            raise
+        return default
diff --git a/lib/spack/external/_vendoring/pyrsistent/_transformations.py b/lib/spack/external/_vendoring/pyrsistent/_transformations.py
new file mode 100644
index 0000000000..7544843aca
--- /dev/null
+++ b/lib/spack/external/_vendoring/pyrsistent/_transformations.py
@@ -0,0 +1,139 @@
+import re
+try:
+    from inspect import Parameter, signature
+except ImportError:
+    signature = None
+    from inspect import getfullargspec
+
+
+_EMPTY_SENTINEL = object()
+
+
+def inc(x):
+    """ Add one to the current value """
+    return x + 1
+
+
+def dec(x):
+    """ Subtract one from the current value """
+    return x - 1
+
+
+def discard(evolver, key):
+    """ Discard the element and returns a structure without the discarded elements """
+    try:
+        del evolver[key]
+    except KeyError:
+        pass
+
+
+# Matchers
+def rex(expr):
+    """ Regular expression matcher to use together with transform functions """
+    r = re.compile(expr)
+    return lambda key: isinstance(key, str) and r.match(key)
+
+
+def ny(_):
+    """ Matcher that matches any value """
+    return True
+
+
+# Support functions
+def _chunks(l, n):
+    for i in range(0, len(l), n):
+        yield l[i:i + n]
+
+
+def transform(structure, transformations):
+    r = structure
+    for path, command in _chunks(transformations, 2):
+        r = _do_to_path(r, path, command)
+    return r
+
+
+def _do_to_path(structure, path, command):
+    if not path:
+        return command(structure) if callable(command) else command
+
+    kvs = _get_keys_and_values(structure, path[0])
+    return _update_structure(structure, kvs, path[1:], command)
+
+
+def _items(structure):
+    try:
+        return structure.items()
+    except AttributeError:
+        # Support wider range of structures by adding a transform_items() or similar?
+        return list(enumerate(structure))
+
+
+def _get(structure, key, default):
+    try:
+        if hasattr(structure, '__getitem__'):
+            return structure[key]
+
+        return getattr(structure, key)
+
+    except (IndexError, KeyError):
+        return default
+
+
+def _get_keys_and_values(structure, key_spec):
+    if callable(key_spec):
+        # Support predicates as callable objects in the path
+        arity = _get_arity(key_spec)
+        if arity == 1:
+            # Unary predicates are called with the "key" of the path
+            # - eg a key in a mapping, an index in a sequence.
+            return [(k, v) for k, v in _items(structure) if key_spec(k)]
+        elif arity == 2:
+            # Binary predicates are called with the key and the corresponding
+            # value.
+            return [(k, v) for k, v in _items(structure) if key_spec(k, v)]
+        else:
+            # Other arities are an error.
+            raise ValueError(
+                "callable in transform path must take 1 or 2 arguments"
+            )
+
+    # Non-callables are used as-is as a key.
+    return [(key_spec, _get(structure, key_spec, _EMPTY_SENTINEL))]
+
+
+if signature is None:
+    def _get_arity(f):
+        argspec = getfullargspec(f)
+        return len(argspec.args) - len(argspec.defaults or ())
+else:
+    def _get_arity(f):
+        return sum(
+            1
+            for p
+            in signature(f).parameters.values()
+            if p.default is Parameter.empty
+            and p.kind in (Parameter.POSITIONAL_ONLY, Parameter.POSITIONAL_OR_KEYWORD)
+        )
+
+
+def _update_structure(structure, kvs, path, command):
+    from pyrsistent._pmap import pmap
+    e = structure.evolver()
+    if not path and command is discard:
+        # Do this in reverse to avoid index problems with vectors. See #92.
+        for k, v in reversed(kvs):
+            discard(e, k)
+    else:
+        for k, v in kvs:
+            is_empty = False
+            if v is _EMPTY_SENTINEL:
+                # Allow expansion of structure but make sure to cover the case
+                # when an empty pmap is added as leaf node. See #154.
+                is_empty = True
+                v = pmap()
+
+            result = _do_to_path(v, path, command)
+            if result is not v or is_empty:
+                e[k] = result
+
+    return e.persistent()
diff --git a/lib/spack/external/_vendoring/pyrsistent/py.typed b/lib/spack/external/_vendoring/pyrsistent/py.typed
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/lib/spack/external/_vendoring/pyrsistent/py.typed
diff --git a/lib/spack/external/_vendoring/pyrsistent/typing.py b/lib/spack/external/_vendoring/pyrsistent/typing.py
new file mode 100644
index 0000000000..6a86c831ba
--- /dev/null
+++ b/lib/spack/external/_vendoring/pyrsistent/typing.py
@@ -0,0 +1,80 @@
+"""Helpers for use with type annotation.
+
+Use the empty classes in this module when annotating the types of Pyrsistent
+objects, instead of using the actual collection class.
+
+For example,
+
+    from pyrsistent import pvector
+    from pyrsistent.typing import PVector
+
+    myvector: PVector[str] = pvector(['a', 'b', 'c'])
+
+"""
+from __future__ import absolute_import
+
+try:
+    from typing import Container
+    from typing import Hashable
+    from typing import Generic
+    from typing import Iterable
+    from typing import Mapping
+    from typing import Sequence
+    from typing import Sized
+    from typing import TypeVar
+
+    __all__ = [
+        'CheckedPMap',
+        'CheckedPSet',
+        'CheckedPVector',
+        'PBag',
+        'PDeque',
+        'PList',
+        'PMap',
+        'PSet',
+        'PVector',
+    ]
+
+    T = TypeVar('T')
+    KT = TypeVar('KT')
+    VT = TypeVar('VT')
+
+    class CheckedPMap(Mapping[KT, VT], Hashable):
+        pass
+
+    # PSet.add and PSet.discard have different type signatures than that of Set.
+    class CheckedPSet(Generic[T], Hashable):
+        pass
+
+    class CheckedPVector(Sequence[T], Hashable):
+        pass
+
+    class PBag(Container[T], Iterable[T], Sized, Hashable):
+        pass
+
+    class PDeque(Sequence[T], Hashable):
+        pass
+
+    class PList(Sequence[T], Hashable):
+        pass
+
+    class PMap(Mapping[KT, VT], Hashable):
+        pass
+
+    # PSet.add and PSet.discard have different type signatures than that of Set.
+    class PSet(Generic[T], Hashable):
+        pass
+
+    class PVector(Sequence[T], Hashable):
+        pass
+
+    class PVectorEvolver(Generic[T]):
+        pass
+
+    class PMapEvolver(Generic[KT, VT]):
+        pass
+
+    class PSetEvolver(Generic[T]):
+        pass
+except ImportError:
+    pass
diff --git a/lib/spack/external/_vendoring/pyrsistent/typing.pyi b/lib/spack/external/_vendoring/pyrsistent/typing.pyi
new file mode 100644
index 0000000000..0221c48cc9
--- /dev/null
+++ b/lib/spack/external/_vendoring/pyrsistent/typing.pyi
@@ -0,0 +1,292 @@
+# flake8: noqa: E704
+# from https://gist.github.com/WuTheFWasThat/091a17d4b5cab597dfd5d4c2d96faf09
+# Stubs for pyrsistent (Python 3.6)
+#
+from typing import Any
+from typing import Callable
+from typing import Dict
+from typing import Generic
+from typing import Hashable
+from typing import Iterator
+from typing import Iterable
+from typing import List
+from typing import Mapping
+from typing import Optional
+from typing import Sequence
+from typing import AbstractSet
+from typing import Sized
+from typing import Set
+from typing import Tuple
+from typing import TypeVar
+from typing import Type
+from typing import Union
+from typing import overload
+
+T = TypeVar('T')
+KT = TypeVar('KT')
+VT = TypeVar('VT')
+
+
+class PMap(Mapping[KT, VT], Hashable):
+    def __add__(self, other: PMap[KT, VT]) -> PMap[KT, VT]: ...
+    def __getitem__(self, key: KT) -> VT: ...
+    def __getattr__(self, key: str) -> VT: ...
+    def __hash__(self) -> int: ...
+    def __iter__(self) -> Iterator[KT]: ...
+    def __len__(self) -> int: ...
+    def copy(self) -> PMap[KT, VT]: ...
+    def discard(self, key: KT) -> PMap[KT, VT]: ...
+    def evolver(self) -> PMapEvolver[KT, VT]: ...
+    def iteritems(self) -> Iterable[Tuple[KT, VT]]: ...
+    def iterkeys(self) -> Iterable[KT]: ...
+    def itervalues(self) -> Iterable[VT]: ...
+    def remove(self, key: KT) -> PMap[KT, VT]: ...
+    def set(self, key: KT, val: VT) -> PMap[KT, VT]: ...
+    def transform(self, *transformations: Any) -> PMap[KT, VT]: ...
+    def update(self, *args: Mapping): ...
+    def update_with(self, update_fn: Callable[[VT, VT], VT], *args: Mapping) -> Any: ...
+
+
+class PMapEvolver(Generic[KT, VT]):
+    def __delitem__(self, key: KT) -> None: ...
+    def __getitem__(self, key: KT) -> VT: ...
+    def __len__(self) -> int: ...
+    def __setitem__(self, key: KT, val: VT) -> None: ...
+    def is_dirty(self) -> bool: ...
+    def persistent(self) -> PMap[KT, VT]: ...
+    def remove(self, key: KT) -> PMapEvolver[KT, VT]: ...
+    def set(self, key: KT, val: VT) -> PMapEvolver[KT, VT]: ...
+
+
+class PVector(Sequence[T], Hashable):
+    def __add__(self, other: PVector[T]) -> PVector[T]: ...
+    @overload
+    def __getitem__(self, index: int) -> T: ...
+    @overload
+    def __getitem__(self, index: slice) -> PVector[T]: ...
+    def __hash__(self) -> int: ...
+    def __len__(self) -> int: ...
+    def __mul__(self, other: PVector[T]) -> PVector[T]: ...
+    def append(self, val: T) -> PVector[T]: ...
+    def delete(self, index: int, stop: Optional[int]) -> PVector[T]: ...
+    def evolver(self) -> PVectorEvolver[T]: ...
+    def extend(self, obj: Iterable[T]) -> PVector[T]: ...
+    def tolist(self) -> List[T]: ...
+    def mset(self, *args: Iterable[Union[T, int]]) -> PVector[T]: ...
+    def remove(self, value: T) -> PVector[T]: ...
+    # Not compatible with MutableSequence
+    def set(self, i: int, val: T) -> PVector[T]: ...
+    def transform(self, *transformations: Any) -> PVector[T]: ...
+
+
+class PVectorEvolver(Sequence[T], Sized):
+    def __delitem__(self, i: Union[int, slice]) -> None: ...
+    @overload
+    def __getitem__(self, index: int) -> T: ...
+    # Not actually supported
+    @overload
+    def __getitem__(self, index: slice) -> PVectorEvolver[T]: ...
+    def __len__(self) -> int: ...
+    def __setitem__(self, index: int, val: T) -> None: ...
+    def append(self, val: T) -> PVectorEvolver[T]: ...
+    def delete(self, value: T) -> PVectorEvolver[T]: ...
+    def extend(self, obj: Iterable[T]) -> PVectorEvolver[T]: ...
+    def is_dirty(self) -> bool: ...
+    def persistent(self) -> PVector[T]: ...
+    def set(self, i: int, val: T) -> PVectorEvolver[T]: ...
+
+
+class PSet(AbstractSet[T], Hashable):
+    def __contains__(self, element: object) -> bool: ...
+    def __hash__(self) -> int: ...
+    def __iter__(self) -> Iterator[T]: ...
+    def __len__(self) -> int: ...
+    def add(self, element: T) -> PSet[T]: ...
+    def copy(self) -> PSet[T]: ...
+    def difference(self, iterable: Iterable) -> PSet[T]: ...
+    def discard(self, element: T) -> PSet[T]: ...
+    def evolver(self) -> PSetEvolver[T]: ...
+    def intersection(self, iterable: Iterable) -> PSet[T]: ...
+    def issubset(self, iterable: Iterable) -> bool: ...
+    def issuperset(self, iterable: Iterable) -> bool: ...
+    def remove(self, element: T) -> PSet[T]: ...
+    def symmetric_difference(self, iterable: Iterable[T]) -> PSet[T]: ...
+    def union(self, iterable: Iterable[T]) -> PSet[T]: ...
+    def update(self, iterable: Iterable[T]) -> PSet[T]: ...
+
+
+class PSetEvolver(Generic[T], Sized):
+    def __len__(self) -> int: ...
+    def add(self, element: T) -> PSetEvolver[T]: ...
+    def is_dirty(self) -> bool: ...
+    def persistent(self) -> PSet[T]: ...
+    def remove(self, element: T) -> PSetEvolver[T]: ...
+
+
+class PBag(Generic[T], Sized, Hashable):
+    def __add__(self, other: PBag[T]) -> PBag[T]: ...
+    def __and__(self, other: PBag[T]) -> PBag[T]: ...
+    def __contains__(self, elem: object) -> bool: ...
+    def __hash__(self) -> int: ...
+    def __iter__(self) -> Iterator[T]: ...
+    def __len__(self) -> int: ...
+    def __or__(self, other: PBag[T]) -> PBag[T]: ...
+    def __sub__(self, other: PBag[T]) -> PBag[T]: ...
+    def add(self, elem: T) -> PBag[T]: ...
+    def count(self, elem: T) -> int: ...
+    def remove(self, elem: T) -> PBag[T]: ...
+    def update(self, iterable: Iterable[T]) -> PBag[T]: ...
+
+
+class PDeque(Sequence[T], Hashable):
+    @overload
+    def __getitem__(self, index: int) -> T: ...
+    @overload
+    def __getitem__(self, index: slice) -> PDeque[T]: ...
+    def __hash__(self) -> int: ...
+    def __len__(self) -> int: ...
+    def __lt__(self, other: PDeque[T]) -> bool: ...
+    def append(self, elem: T) -> PDeque[T]: ...
+    def appendleft(self, elem: T) -> PDeque[T]: ...
+    def extend(self, iterable: Iterable[T]) -> PDeque[T]: ...
+    def extendleft(self, iterable: Iterable[T]) -> PDeque[T]: ...
+    @property
+    def left(self) -> T: ...
+    # The real return type is Integral according to what pyrsistent
+    # checks at runtime but mypy doesn't deal in numeric.*:
+    # https://github.com/python/mypy/issues/2636
+    @property
+    def maxlen(self) -> int: ...
+    def pop(self, count: int = 1) -> PDeque[T]: ...
+    def popleft(self, count: int = 1) -> PDeque[T]: ...
+    def remove(self, elem: T) -> PDeque[T]: ...
+    def reverse(self) -> PDeque[T]: ...
+    @property
+    def right(self) -> T: ...
+    def rotate(self, steps: int) -> PDeque[T]: ...
+
+
+class PList(Sequence[T], Hashable):
+    @overload
+    def __getitem__(self, index: int) -> T: ...
+    @overload
+    def __getitem__(self, index: slice) -> PList[T]: ...
+    def __hash__(self) -> int: ...
+    def __len__(self) -> int: ...
+    def __lt__(self, other: PList[T]) -> bool: ...
+    def __gt__(self, other: PList[T]) -> bool: ...
+    def cons(self, elem: T) -> PList[T]: ...
+    @property
+    def first(self) -> T: ...
+    def mcons(self, iterable: Iterable[T]) -> PList[T]: ...
+    def remove(self, elem: T) -> PList[T]: ...
+    @property
+    def rest(self) -> PList[T]: ...
+    def reverse(self) -> PList[T]: ...
+    def split(self, index: int) -> Tuple[PList[T], PList[T]]: ...
+
+T_PClass = TypeVar('T_PClass', bound='PClass')
+
+class PClass(Hashable):
+    def __new__(cls, **kwargs: Any): ...
+    def set(self: T_PClass, *args: Any, **kwargs: Any) -> T_PClass: ...
+    @classmethod
+    def create(
+        cls: Type[T_PClass],
+        kwargs: Any,
+        _factory_fields: Optional[Any] = ...,
+        ignore_extra: bool = ...,
+    ) -> T_PClass: ...
+    def serialize(self, format: Optional[Any] = ...): ...
+    def transform(self, *transformations: Any): ...
+    def __eq__(self, other: object): ...
+    def __ne__(self, other: object): ...
+    def __hash__(self): ...
+    def __reduce__(self): ...
+    def evolver(self) -> PClassEvolver: ...
+    def remove(self: T_PClass, name: Any) -> T_PClass: ...
+
+class PClassEvolver:
+    def __init__(self, original: Any, initial_dict: Any) -> None: ...
+    def __getitem__(self, item: Any): ...
+    def set(self, key: Any, value: Any): ...
+    def __setitem__(self, key: Any, value: Any) -> None: ...
+    def remove(self, item: Any): ...
+    def __delitem__(self, item: Any) -> None: ...
+    def persistent(self) -> PClass: ...
+    def __getattr__(self, item: Any): ...
+
+
+
+class CheckedPMap(PMap[KT, VT]):
+    __key_type__: Type[KT]
+    __value_type__: Type[VT]
+    def __new__(cls, source: Mapping[KT, VT] = ..., size: int = ...) -> CheckedPMap: ...
+    @classmethod
+    def create(cls, source_data: Mapping[KT, VT], _factory_fields: Any = ...) -> CheckedPMap[KT, VT]: ...
+    def serialize(self, format: Optional[Any] = ...) -> Dict[KT, VT]: ...
+
+
+class CheckedPVector(PVector[T]):
+    __type__: Type[T]
+    def __new__(self, initial: Iterable[T] = ...) -> CheckedPVector: ...
+    @classmethod
+    def create(cls, source_data: Iterable[T], _factory_fields: Any = ...) -> CheckedPVector[T]: ...
+    def serialize(self, format: Optional[Any] = ...) -> List[T]: ...
+
+
+class CheckedPSet(PSet[T]):
+    __type__: Type[T]
+    def __new__(cls, initial: Iterable[T] = ...) -> CheckedPSet: ...
+    @classmethod
+    def create(cls, source_data: Iterable[T], _factory_fields: Any = ...) -> CheckedPSet[T]: ...
+    def serialize(self, format: Optional[Any] = ...) -> Set[T]: ...
+
+
+class InvariantException(Exception):
+    invariant_errors: Tuple[Any, ...] = ...  # possibly nested tuple
+    missing_fields: Tuple[str, ...] = ...
+    def __init__(
+        self,
+        error_codes: Any = ...,
+        missing_fields: Any = ...,
+        *args: Any,
+        **kwargs: Any
+    ) -> None: ...
+
+
+class CheckedTypeError(TypeError):
+    source_class: Type[Any]
+    expected_types: Tuple[Any, ...]
+    actual_type: Type[Any]
+    actual_value: Any
+    def __init__(
+        self,
+        source_class: Any,
+        expected_types: Any,
+        actual_type: Any,
+        actual_value: Any,
+        *args: Any,
+        **kwargs: Any
+    ) -> None: ...
+
+
+class CheckedKeyTypeError(CheckedTypeError): ...
+class CheckedValueTypeError(CheckedTypeError): ...
+class CheckedType: ...
+
+
+class PTypeError(TypeError):
+    source_class: Type[Any] = ...
+    field: str = ...
+    expected_types: Tuple[Any, ...] = ...
+    actual_type: Type[Any] = ...
+    def __init__(
+        self,
+        source_class: Any,
+        field: Any,
+        expected_types: Any,
+        actual_type: Any,
+        *args: Any,
+        **kwargs: Any
+    ) -> None: ...
diff --git a/lib/spack/external/_vendoring/six.LICENSE b/lib/spack/external/_vendoring/six.LICENSE
new file mode 100644
index 0000000000..de6633112c
--- /dev/null
+++ b/lib/spack/external/_vendoring/six.LICENSE
@@ -0,0 +1,18 @@
+Copyright (c) 2010-2020 Benjamin Peterson
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of
+this software and associated documentation files (the "Software"), to deal in
+the Software without restriction, including without limitation the rights to
+use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
+the Software, and to permit persons to whom the Software is furnished to do so,
+subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
+IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
diff --git a/lib/spack/external/_vendoring/six.py b/lib/spack/external/_vendoring/six.py
new file mode 100644
index 0000000000..4e15675d8b
--- /dev/null
+++ b/lib/spack/external/_vendoring/six.py
@@ -0,0 +1,998 @@
+# Copyright (c) 2010-2020 Benjamin Peterson
+#
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files (the "Software"), to deal
+# in the Software without restriction, including without limitation the rights
+# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+# copies of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be included in all
+# copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+# SOFTWARE.
+
+"""Utilities for writing code that runs on Python 2 and 3"""
+
+from __future__ import absolute_import
+
+import functools
+import itertools
+import operator
+import sys
+import types
+
+__author__ = "Benjamin Peterson <benjamin@python.org>"
+__version__ = "1.16.0"
+
+
+# Useful for very coarse version differentiation.
+PY2 = sys.version_info[0] == 2
+PY3 = sys.version_info[0] == 3
+PY34 = sys.version_info[0:2] >= (3, 4)
+
+if PY3:
+    string_types = str,
+    integer_types = int,
+    class_types = type,
+    text_type = str
+    binary_type = bytes
+
+    MAXSIZE = sys.maxsize
+else:
+    string_types = basestring,
+    integer_types = (int, long)
+    class_types = (type, types.ClassType)
+    text_type = unicode
+    binary_type = str
+
+    if sys.platform.startswith("java"):
+        # Jython always uses 32 bits.
+        MAXSIZE = int((1 << 31) - 1)
+    else:
+        # It's possible to have sizeof(long) != sizeof(Py_ssize_t).
+        class X(object):
+
+            def __len__(self):
+                return 1 << 31
+        try:
+            len(X())
+        except OverflowError:
+            # 32-bit
+            MAXSIZE = int((1 << 31) - 1)
+        else:
+            # 64-bit
+            MAXSIZE = int((1 << 63) - 1)
+        del X
+
+if PY34:
+    from importlib.util import spec_from_loader
+else:
+    spec_from_loader = None
+
+
+def _add_doc(func, doc):
+    """Add documentation to a function."""
+    func.__doc__ = doc
+
+
+def _import_module(name):
+    """Import module, returning the module after the last dot."""
+    __import__(name)
+    return sys.modules[name]
+
+
+class _LazyDescr(object):
+
+    def __init__(self, name):
+        self.name = name
+
+    def __get__(self, obj, tp):
+        result = self._resolve()
+        setattr(obj, self.name, result)  # Invokes __set__.
+        try:
+            # This is a bit ugly, but it avoids running this again by
+            # removing this descriptor.
+            delattr(obj.__class__, self.name)
+        except AttributeError:
+            pass
+        return result
+
+
+class MovedModule(_LazyDescr):
+
+    def __init__(self, name, old, new=None):
+        super(MovedModule, self).__init__(name)
+        if PY3:
+            if new is None:
+                new = name
+            self.mod = new
+        else:
+            self.mod = old
+
+    def _resolve(self):
+        return _import_module(self.mod)
+
+    def __getattr__(self, attr):
+        _module = self._resolve()
+        value = getattr(_module, attr)
+        setattr(self, attr, value)
+        return value
+
+
+class _LazyModule(types.ModuleType):
+
+    def __init__(self, name):
+        super(_LazyModule, self).__init__(name)
+        self.__doc__ = self.__class__.__doc__
+
+    def __dir__(self):
+        attrs = ["__doc__", "__name__"]
+        attrs += [attr.name for attr in self._moved_attributes]
+        return attrs
+
+    # Subclasses should override this
+    _moved_attributes = []
+
+
+class MovedAttribute(_LazyDescr):
+
+    def __init__(self, name, old_mod, new_mod, old_attr=None, new_attr=None):
+        super(MovedAttribute, self).__init__(name)
+        if PY3:
+            if new_mod is None:
+                new_mod = name
+            self.mod = new_mod
+            if new_attr is None:
+                if old_attr is None:
+                    new_attr = name
+                else:
+                    new_attr = old_attr
+            self.attr = new_attr
+        else:
+            self.mod = old_mod
+            if old_attr is None:
+                old_attr = name
+            self.attr = old_attr
+
+    def _resolve(self):
+        module = _import_module(self.mod)
+        return getattr(module, self.attr)
+
+
+class _SixMetaPathImporter(object):
+
+    """
+    A meta path importer to import six.moves and its submodules.
+
+    This class implements a PEP302 finder and loader. It should be compatible
+    with Python 2.5 and all existing versions of Python3
+    """
+
+    def __init__(self, six_module_name):
+        self.name = six_module_name
+        self.known_modules = {}
+
+    def _add_module(self, mod, *fullnames):
+        for fullname in fullnames:
+            self.known_modules[self.name + "." + fullname] = mod
+
+    def _get_module(self, fullname):
+        return self.known_modules[self.name + "." + fullname]
+
+    def find_module(self, fullname, path=None):
+        if fullname in self.known_modules:
+            return self
+        return None
+
+    def find_spec(self, fullname, path, target=None):
+        if fullname in self.known_modules:
+            return spec_from_loader(fullname, self)
+        return None
+
+    def __get_module(self, fullname):
+        try:
+            return self.known_modules[fullname]
+        except KeyError:
+            raise ImportError("This loader does not know module " + fullname)
+
+    def load_module(self, fullname):
+        try:
+            # in case of a reload
+            return sys.modules[fullname]
+        except KeyError:
+            pass
+        mod = self.__get_module(fullname)
+        if isinstance(mod, MovedModule):
+            mod = mod._resolve()
+        else:
+            mod.__loader__ = self
+        sys.modules[fullname] = mod
+        return mod
+
+    def is_package(self, fullname):
+        """
+        Return true, if the named module is a package.
+
+        We need this method to get correct spec objects with
+        Python 3.4 (see PEP451)
+        """
+        return hasattr(self.__get_module(fullname), "__path__")
+
+    def get_code(self, fullname):
+        """Return None
+
+        Required, if is_package is implemented"""
+        self.__get_module(fullname)  # eventually raises ImportError
+        return None
+    get_source = get_code  # same as get_code
+
+    def create_module(self, spec):
+        return self.load_module(spec.name)
+
+    def exec_module(self, module):
+        pass
+
+_importer = _SixMetaPathImporter(__name__)
+
+
+class _MovedItems(_LazyModule):
+
+    """Lazy loading of moved objects"""
+    __path__ = []  # mark as package
+
+
+_moved_attributes = [
+    MovedAttribute("cStringIO", "cStringIO", "io", "StringIO"),
+    MovedAttribute("filter", "itertools", "builtins", "ifilter", "filter"),
+    MovedAttribute("filterfalse", "itertools", "itertools", "ifilterfalse", "filterfalse"),
+    MovedAttribute("input", "__builtin__", "builtins", "raw_input", "input"),
+    MovedAttribute("intern", "__builtin__", "sys"),
+    MovedAttribute("map", "itertools", "builtins", "imap", "map"),
+    MovedAttribute("getcwd", "os", "os", "getcwdu", "getcwd"),
+    MovedAttribute("getcwdb", "os", "os", "getcwd", "getcwdb"),
+    MovedAttribute("getoutput", "commands", "subprocess"),
+    MovedAttribute("range", "__builtin__", "builtins", "xrange", "range"),
+    MovedAttribute("reload_module", "__builtin__", "importlib" if PY34 else "imp", "reload"),
+    MovedAttribute("reduce", "__builtin__", "functools"),
+    MovedAttribute("shlex_quote", "pipes", "shlex", "quote"),
+    MovedAttribute("StringIO", "StringIO", "io"),
+    MovedAttribute("UserDict", "UserDict", "collections"),
+    MovedAttribute("UserList", "UserList", "collections"),
+    MovedAttribute("UserString", "UserString", "collections"),
+    MovedAttribute("xrange", "__builtin__", "builtins", "xrange", "range"),
+    MovedAttribute("zip", "itertools", "builtins", "izip", "zip"),
+    MovedAttribute("zip_longest", "itertools", "itertools", "izip_longest", "zip_longest"),
+    MovedModule("builtins", "__builtin__"),
+    MovedModule("configparser", "ConfigParser"),
+    MovedModule("collections_abc", "collections", "collections.abc" if sys.version_info >= (3, 3) else "collections"),
+    MovedModule("copyreg", "copy_reg"),
+    MovedModule("dbm_gnu", "gdbm", "dbm.gnu"),
+    MovedModule("dbm_ndbm", "dbm", "dbm.ndbm"),
+    MovedModule("_dummy_thread", "dummy_thread", "_dummy_thread" if sys.version_info < (3, 9) else "_thread"),
+    MovedModule("http_cookiejar", "cookielib", "http.cookiejar"),
+    MovedModule("http_cookies", "Cookie", "http.cookies"),
+    MovedModule("html_entities", "htmlentitydefs", "html.entities"),
+    MovedModule("html_parser", "HTMLParser", "html.parser"),
+    MovedModule("http_client", "httplib", "http.client"),
+    MovedModule("email_mime_base", "email.MIMEBase", "email.mime.base"),
+    MovedModule("email_mime_image", "email.MIMEImage", "email.mime.image"),
+    MovedModule("email_mime_multipart", "email.MIMEMultipart", "email.mime.multipart"),
+    MovedModule("email_mime_nonmultipart", "email.MIMENonMultipart", "email.mime.nonmultipart"),
+    MovedModule("email_mime_text", "email.MIMEText", "email.mime.text"),
+    MovedModule("BaseHTTPServer", "BaseHTTPServer", "http.server"),
+    MovedModule("CGIHTTPServer", "CGIHTTPServer", "http.server"),
+    MovedModule("SimpleHTTPServer", "SimpleHTTPServer", "http.server"),
+    MovedModule("cPickle", "cPickle", "pickle"),
+    MovedModule("queue", "Queue"),
+    MovedModule("reprlib", "repr"),
+    MovedModule("socketserver", "SocketServer"),
+    MovedModule("_thread", "thread", "_thread"),
+    MovedModule("tkinter", "Tkinter"),
+    MovedModule("tkinter_dialog", "Dialog", "tkinter.dialog"),
+    MovedModule("tkinter_filedialog", "FileDialog", "tkinter.filedialog"),
+    MovedModule("tkinter_scrolledtext", "ScrolledText", "tkinter.scrolledtext"),
+    MovedModule("tkinter_simpledialog", "SimpleDialog", "tkinter.simpledialog"),
+    MovedModule("tkinter_tix", "Tix", "tkinter.tix"),
+    MovedModule("tkinter_ttk", "ttk", "tkinter.ttk"),
+    MovedModule("tkinter_constants", "Tkconstants", "tkinter.constants"),
+    MovedModule("tkinter_dnd", "Tkdnd", "tkinter.dnd"),
+    MovedModule("tkinter_colorchooser", "tkColorChooser",
+                "tkinter.colorchooser"),
+    MovedModule("tkinter_commondialog", "tkCommonDialog",
+                "tkinter.commondialog"),
+    MovedModule("tkinter_tkfiledialog", "tkFileDialog", "tkinter.filedialog"),
+    MovedModule("tkinter_font", "tkFont", "tkinter.font"),
+    MovedModule("tkinter_messagebox", "tkMessageBox", "tkinter.messagebox"),
+    MovedModule("tkinter_tksimpledialog", "tkSimpleDialog",
+                "tkinter.simpledialog"),
+    MovedModule("urllib_parse", __name__ + ".moves.urllib_parse", "urllib.parse"),
+    MovedModule("urllib_error", __name__ + ".moves.urllib_error", "urllib.error"),
+    MovedModule("urllib", __name__ + ".moves.urllib", __name__ + ".moves.urllib"),
+    MovedModule("urllib_robotparser", "robotparser", "urllib.robotparser"),
+    MovedModule("xmlrpc_client", "xmlrpclib", "xmlrpc.client"),
+    MovedModule("xmlrpc_server", "SimpleXMLRPCServer", "xmlrpc.server"),
+]
+# Add windows specific modules.
+if sys.platform == "win32":
+    _moved_attributes += [
+        MovedModule("winreg", "_winreg"),
+    ]
+
+for attr in _moved_attributes:
+    setattr(_MovedItems, attr.name, attr)
+    if isinstance(attr, MovedModule):
+        _importer._add_module(attr, "moves." + attr.name)
+del attr
+
+_MovedItems._moved_attributes = _moved_attributes
+
+moves = _MovedItems(__name__ + ".moves")
+_importer._add_module(moves, "moves")
+
+
+class Module_six_moves_urllib_parse(_LazyModule):
+
+    """Lazy loading of moved objects in six.moves.urllib_parse"""
+
+
+_urllib_parse_moved_attributes = [
+    MovedAttribute("ParseResult", "urlparse", "urllib.parse"),
+    MovedAttribute("SplitResult", "urlparse", "urllib.parse"),
+    MovedAttribute("parse_qs", "urlparse", "urllib.parse"),
+    MovedAttribute("parse_qsl", "urlparse", "urllib.parse"),
+    MovedAttribute("urldefrag", "urlparse", "urllib.parse"),
+    MovedAttribute("urljoin", "urlparse", "urllib.parse"),
+    MovedAttribute("urlparse", "urlparse", "urllib.parse"),
+    MovedAttribute("urlsplit", "urlparse", "urllib.parse"),
+    MovedAttribute("urlunparse", "urlparse", "urllib.parse"),
+    MovedAttribute("urlunsplit", "urlparse", "urllib.parse"),
+    MovedAttribute("quote", "urllib", "urllib.parse"),
+    MovedAttribute("quote_plus", "urllib", "urllib.parse"),
+    MovedAttribute("unquote", "urllib", "urllib.parse"),
+    MovedAttribute("unquote_plus", "urllib", "urllib.parse"),
+    MovedAttribute("unquote_to_bytes", "urllib", "urllib.parse", "unquote", "unquote_to_bytes"),
+    MovedAttribute("urlencode", "urllib", "urllib.parse"),
+    MovedAttribute("splitquery", "urllib", "urllib.parse"),
+    MovedAttribute("splittag", "urllib", "urllib.parse"),
+    MovedAttribute("splituser", "urllib", "urllib.parse"),
+    MovedAttribute("splitvalue", "urllib", "urllib.parse"),
+    MovedAttribute("uses_fragment", "urlparse", "urllib.parse"),
+    MovedAttribute("uses_netloc", "urlparse", "urllib.parse"),
+    MovedAttribute("uses_params", "urlparse", "urllib.parse"),
+    MovedAttribute("uses_query", "urlparse", "urllib.parse"),
+    MovedAttribute("uses_relative", "urlparse", "urllib.parse"),
+]
+for attr in _urllib_parse_moved_attributes:
+    setattr(Module_six_moves_urllib_parse, attr.name, attr)
+del attr
+
+Module_six_moves_urllib_parse._moved_attributes = _urllib_parse_moved_attributes
+
+_importer._add_module(Module_six_moves_urllib_parse(__name__ + ".moves.urllib_parse"),
+                      "moves.urllib_parse", "moves.urllib.parse")
+
+
+class Module_six_moves_urllib_error(_LazyModule):
+
+    """Lazy loading of moved objects in six.moves.urllib_error"""
+
+
+_urllib_error_moved_attributes = [
+    MovedAttribute("URLError", "urllib2", "urllib.error"),
+    MovedAttribute("HTTPError", "urllib2", "urllib.error"),
+    MovedAttribute("ContentTooShortError", "urllib", "urllib.error"),
+]
+for attr in _urllib_error_moved_attributes:
+    setattr(Module_six_moves_urllib_error, attr.name, attr)
+del attr
+
+Module_six_moves_urllib_error._moved_attributes = _urllib_error_moved_attributes
+
+_importer._add_module(Module_six_moves_urllib_error(__name__ + ".moves.urllib.error"),
+                      "moves.urllib_error", "moves.urllib.error")
+
+
+class Module_six_moves_urllib_request(_LazyModule):
+
+    """Lazy loading of moved objects in six.moves.urllib_request"""
+
+
+_urllib_request_moved_attributes = [
+    MovedAttribute("urlopen", "urllib2", "urllib.request"),
+    MovedAttribute("install_opener", "urllib2", "urllib.request"),
+    MovedAttribute("build_opener", "urllib2", "urllib.request"),
+    MovedAttribute("pathname2url", "urllib", "urllib.request"),
+    MovedAttribute("url2pathname", "urllib", "urllib.request"),
+    MovedAttribute("getproxies", "urllib", "urllib.request"),
+    MovedAttribute("Request", "urllib2", "urllib.request"),
+    MovedAttribute("OpenerDirector", "urllib2", "urllib.request"),
+    MovedAttribute("HTTPDefaultErrorHandler", "urllib2", "urllib.request"),
+    MovedAttribute("HTTPRedirectHandler", "urllib2", "urllib.request"),
+    MovedAttribute("HTTPCookieProcessor", "urllib2", "urllib.request"),
+    MovedAttribute("ProxyHandler", "urllib2", "urllib.request"),
+    MovedAttribute("BaseHandler", "urllib2", "urllib.request"),
+    MovedAttribute("HTTPPasswordMgr", "urllib2", "urllib.request"),
+    MovedAttribute("HTTPPasswordMgrWithDefaultRealm", "urllib2", "urllib.request"),
+    MovedAttribute("AbstractBasicAuthHandler", "urllib2", "urllib.request"),
+    MovedAttribute("HTTPBasicAuthHandler", "urllib2", "urllib.request"),
+    MovedAttribute("ProxyBasicAuthHandler", "urllib2", "urllib.request"),
+    MovedAttribute("AbstractDigestAuthHandler", "urllib2", "urllib.request"),
+    MovedAttribute("HTTPDigestAuthHandler", "urllib2", "urllib.request"),
+    MovedAttribute("ProxyDigestAuthHandler", "urllib2", "urllib.request"),
+    MovedAttribute("HTTPHandler", "urllib2", "urllib.request"),
+    MovedAttribute("HTTPSHandler", "urllib2", "urllib.request"),
+    MovedAttribute("FileHandler", "urllib2", "urllib.request"),
+    MovedAttribute("FTPHandler", "urllib2", "urllib.request"),
+    MovedAttribute("CacheFTPHandler", "urllib2", "urllib.request"),
+    MovedAttribute("UnknownHandler", "urllib2", "urllib.request"),
+    MovedAttribute("HTTPErrorProcessor", "urllib2", "urllib.request"),
+    MovedAttribute("urlretrieve", "urllib", "urllib.request"),
+    MovedAttribute("urlcleanup", "urllib", "urllib.request"),
+    MovedAttribute("URLopener", "urllib", "urllib.request"),
+    MovedAttribute("FancyURLopener", "urllib", "urllib.request"),
+    MovedAttribute("proxy_bypass", "urllib", "urllib.request"),
+    MovedAttribute("parse_http_list", "urllib2", "urllib.request"),
+    MovedAttribute("parse_keqv_list", "urllib2", "urllib.request"),
+]
+for attr in _urllib_request_moved_attributes:
+    setattr(Module_six_moves_urllib_request, attr.name, attr)
+del attr
+
+Module_six_moves_urllib_request._moved_attributes = _urllib_request_moved_attributes
+
+_importer._add_module(Module_six_moves_urllib_request(__name__ + ".moves.urllib.request"),
+                      "moves.urllib_request", "moves.urllib.request")
+
+
+class Module_six_moves_urllib_response(_LazyModule):
+
+    """Lazy loading of moved objects in six.moves.urllib_response"""
+
+
+_urllib_response_moved_attributes = [
+    MovedAttribute("addbase", "urllib", "urllib.response"),
+    MovedAttribute("addclosehook", "urllib", "urllib.response"),
+    MovedAttribute("addinfo", "urllib", "urllib.response"),
+    MovedAttribute("addinfourl", "urllib", "urllib.response"),
+]
+for attr in _urllib_response_moved_attributes:
+    setattr(Module_six_moves_urllib_response, attr.name, attr)
+del attr
+
+Module_six_moves_urllib_response._moved_attributes = _urllib_response_moved_attributes
+
+_importer._add_module(Module_six_moves_urllib_response(__name__ + ".moves.urllib.response"),
+                      "moves.urllib_response", "moves.urllib.response")
+
+
+class Module_six_moves_urllib_robotparser(_LazyModule):
+
+    """Lazy loading of moved objects in six.moves.urllib_robotparser"""
+
+
+_urllib_robotparser_moved_attributes = [
+    MovedAttribute("RobotFileParser", "robotparser", "urllib.robotparser"),
+]
+for attr in _urllib_robotparser_moved_attributes:
+    setattr(Module_six_moves_urllib_robotparser, attr.name, attr)
+del attr
+
+Module_six_moves_urllib_robotparser._moved_attributes = _urllib_robotparser_moved_attributes
+
+_importer._add_module(Module_six_moves_urllib_robotparser(__name__ + ".moves.urllib.robotparser"),
+                      "moves.urllib_robotparser", "moves.urllib.robotparser")
+
+
+class Module_six_moves_urllib(types.ModuleType):
+
+    """Create a six.moves.urllib namespace that resembles the Python 3 namespace"""
+    __path__ = []  # mark as package
+    parse = _importer._get_module("moves.urllib_parse")
+    error = _importer._get_module("moves.urllib_error")
+    request = _importer._get_module("moves.urllib_request")
+    response = _importer._get_module("moves.urllib_response")
+    robotparser = _importer._get_module("moves.urllib_robotparser")
+
+    def __dir__(self):
+        return ['parse', 'error', 'request', 'response', 'robotparser']
+
+_importer._add_module(Module_six_moves_urllib(__name__ + ".moves.urllib"),
+                      "moves.urllib")
+
+
+def add_move(move):
+    """Add an item to six.moves."""
+    setattr(_MovedItems, move.name, move)
+
+
+def remove_move(name):
+    """Remove item from six.moves."""
+    try:
+        delattr(_MovedItems, name)
+    except AttributeError:
+        try:
+            del moves.__dict__[name]
+        except KeyError:
+            raise AttributeError("no such move, %r" % (name,))
+
+
+if PY3:
+    _meth_func = "__func__"
+    _meth_self = "__self__"
+
+    _func_closure = "__closure__"
+    _func_code = "__code__"
+    _func_defaults = "__defaults__"
+    _func_globals = "__globals__"
+else:
+    _meth_func = "im_func"
+    _meth_self = "im_self"
+
+    _func_closure = "func_closure"
+    _func_code = "func_code"
+    _func_defaults = "func_defaults"
+    _func_globals = "func_globals"
+
+
+try:
+    advance_iterator = next
+except NameError:
+    def advance_iterator(it):
+        return it.next()
+next = advance_iterator
+
+
+try:
+    callable = callable
+except NameError:
+    def callable(obj):
+        return any("__call__" in klass.__dict__ for klass in type(obj).__mro__)
+
+
+if PY3:
+    def get_unbound_function(unbound):
+        return unbound
+
+    create_bound_method = types.MethodType
+
+    def create_unbound_method(func, cls):
+        return func
+
+    Iterator = object
+else:
+    def get_unbound_function(unbound):
+        return unbound.im_func
+
+    def create_bound_method(func, obj):
+        return types.MethodType(func, obj, obj.__class__)
+
+    def create_unbound_method(func, cls):
+        return types.MethodType(func, None, cls)
+
+    class Iterator(object):
+
+        def next(self):
+            return type(self).__next__(self)
+
+    callable = callable
+_add_doc(get_unbound_function,
+         """Get the function out of a possibly unbound function""")
+
+
+get_method_function = operator.attrgetter(_meth_func)
+get_method_self = operator.attrgetter(_meth_self)
+get_function_closure = operator.attrgetter(_func_closure)
+get_function_code = operator.attrgetter(_func_code)
+get_function_defaults = operator.attrgetter(_func_defaults)
+get_function_globals = operator.attrgetter(_func_globals)
+
+
+if PY3:
+    def iterkeys(d, **kw):
+        return iter(d.keys(**kw))
+
+    def itervalues(d, **kw):
+        return iter(d.values(**kw))
+
+    def iteritems(d, **kw):
+        return iter(d.items(**kw))
+
+    def iterlists(d, **kw):
+        return iter(d.lists(**kw))
+
+    viewkeys = operator.methodcaller("keys")
+
+    viewvalues = operator.methodcaller("values")
+
+    viewitems = operator.methodcaller("items")
+else:
+    def iterkeys(d, **kw):
+        return d.iterkeys(**kw)
+
+    def itervalues(d, **kw):
+        return d.itervalues(**kw)
+
+    def iteritems(d, **kw):
+        return d.iteritems(**kw)
+
+    def iterlists(d, **kw):
+        return d.iterlists(**kw)
+
+    viewkeys = operator.methodcaller("viewkeys")
+
+    viewvalues = operator.methodcaller("viewvalues")
+
+    viewitems = operator.methodcaller("viewitems")
+
+_add_doc(iterkeys, "Return an iterator over the keys of a dictionary.")
+_add_doc(itervalues, "Return an iterator over the values of a dictionary.")
+_add_doc(iteritems,
+         "Return an iterator over the (key, value) pairs of a dictionary.")
+_add_doc(iterlists,
+         "Return an iterator over the (key, [values]) pairs of a dictionary.")
+
+
+if PY3:
+    def b(s):
+        return s.encode("latin-1")
+
+    def u(s):
+        return s
+    unichr = chr
+    import struct
+    int2byte = struct.Struct(">B").pack
+    del struct
+    byte2int = operator.itemgetter(0)
+    indexbytes = operator.getitem
+    iterbytes = iter
+    import io
+    StringIO = io.StringIO
+    BytesIO = io.BytesIO
+    del io
+    _assertCountEqual = "assertCountEqual"
+    if sys.version_info[1] <= 1:
+        _assertRaisesRegex = "assertRaisesRegexp"
+        _assertRegex = "assertRegexpMatches"
+        _assertNotRegex = "assertNotRegexpMatches"
+    else:
+        _assertRaisesRegex = "assertRaisesRegex"
+        _assertRegex = "assertRegex"
+        _assertNotRegex = "assertNotRegex"
+else:
+    def b(s):
+        return s
+    # Workaround for standalone backslash
+
+    def u(s):
+        return unicode(s.replace(r'\\', r'\\\\'), "unicode_escape")
+    unichr = unichr
+    int2byte = chr
+
+    def byte2int(bs):
+        return ord(bs[0])
+
+    def indexbytes(buf, i):
+        return ord(buf[i])
+    iterbytes = functools.partial(itertools.imap, ord)
+    import StringIO
+    StringIO = BytesIO = StringIO.StringIO
+    _assertCountEqual = "assertItemsEqual"
+    _assertRaisesRegex = "assertRaisesRegexp"
+    _assertRegex = "assertRegexpMatches"
+    _assertNotRegex = "assertNotRegexpMatches"
+_add_doc(b, """Byte literal""")
+_add_doc(u, """Text literal""")
+
+
+def assertCountEqual(self, *args, **kwargs):
+    return getattr(self, _assertCountEqual)(*args, **kwargs)
+
+
+def assertRaisesRegex(self, *args, **kwargs):
+    return getattr(self, _assertRaisesRegex)(*args, **kwargs)
+
+
+def assertRegex(self, *args, **kwargs):
+    return getattr(self, _assertRegex)(*args, **kwargs)
+
+
+def assertNotRegex(self, *args, **kwargs):
+    return getattr(self, _assertNotRegex)(*args, **kwargs)
+
+
+if PY3:
+    exec_ = getattr(moves.builtins, "exec")
+
+    def reraise(tp, value, tb=None):
+        try:
+            if value is None:
+                value = tp()
+            if value.__traceback__ is not tb:
+                raise value.with_traceback(tb)
+            raise value
+        finally:
+            value = None
+            tb = None
+
+else:
+    def exec_(_code_, _globs_=None, _locs_=None):
+        """Execute code in a namespace."""
+        if _globs_ is None:
+            frame = sys._getframe(1)
+            _globs_ = frame.f_globals
+            if _locs_ is None:
+                _locs_ = frame.f_locals
+            del frame
+        elif _locs_ is None:
+            _locs_ = _globs_
+        exec("""exec _code_ in _globs_, _locs_""")
+
+    exec_("""def reraise(tp, value, tb=None):
+    try:
+        raise tp, value, tb
+    finally:
+        tb = None
+""")
+
+
+if sys.version_info[:2] > (3,):
+    exec_("""def raise_from(value, from_value):
+    try:
+        raise value from from_value
+    finally:
+        value = None
+""")
+else:
+    def raise_from(value, from_value):
+        raise value
+
+
+print_ = getattr(moves.builtins, "print", None)
+if print_ is None:
+    def print_(*args, **kwargs):
+        """The new-style print function for Python 2.4 and 2.5."""
+        fp = kwargs.pop("file", sys.stdout)
+        if fp is None:
+            return
+
+        def write(data):
+            if not isinstance(data, basestring):
+                data = str(data)
+            # If the file has an encoding, encode unicode with it.
+            if (isinstance(fp, file) and
+                    isinstance(data, unicode) and
+                    fp.encoding is not None):
+                errors = getattr(fp, "errors", None)
+                if errors is None:
+                    errors = "strict"
+                data = data.encode(fp.encoding, errors)
+            fp.write(data)
+        want_unicode = False
+        sep = kwargs.pop("sep", None)
+        if sep is not None:
+            if isinstance(sep, unicode):
+                want_unicode = True
+            elif not isinstance(sep, str):
+                raise TypeError("sep must be None or a string")
+        end = kwargs.pop("end", None)
+        if end is not None:
+            if isinstance(end, unicode):
+                want_unicode = True
+            elif not isinstance(end, str):
+                raise TypeError("end must be None or a string")
+        if kwargs:
+            raise TypeError("invalid keyword arguments to print()")
+        if not want_unicode:
+            for arg in args:
+                if isinstance(arg, unicode):
+                    want_unicode = True
+                    break
+        if want_unicode:
+            newline = unicode("\n")
+            space = unicode(" ")
+        else:
+            newline = "\n"
+            space = " "
+        if sep is None:
+            sep = space
+        if end is None:
+            end = newline
+        for i, arg in enumerate(args):
+            if i:
+                write(sep)
+            write(arg)
+        write(end)
+if sys.version_info[:2] < (3, 3):
+    _print = print_
+
+    def print_(*args, **kwargs):
+        fp = kwargs.get("file", sys.stdout)
+        flush = kwargs.pop("flush", False)
+        _print(*args, **kwargs)
+        if flush and fp is not None:
+            fp.flush()
+
+_add_doc(reraise, """Reraise an exception.""")
+
+if sys.version_info[0:2] < (3, 4):
+    # This does exactly the same what the :func:`py3:functools.update_wrapper`
+    # function does on Python versions after 3.2. It sets the ``__wrapped__``
+    # attribute on ``wrapper`` object and it doesn't raise an error if any of
+    # the attributes mentioned in ``assigned`` and ``updated`` are missing on
+    # ``wrapped`` object.
+    def _update_wrapper(wrapper, wrapped,
+                        assigned=functools.WRAPPER_ASSIGNMENTS,
+                        updated=functools.WRAPPER_UPDATES):
+        for attr in assigned:
+            try:
+                value = getattr(wrapped, attr)
+            except AttributeError:
+                continue
+            else:
+                setattr(wrapper, attr, value)
+        for attr in updated:
+            getattr(wrapper, attr).update(getattr(wrapped, attr, {}))
+        wrapper.__wrapped__ = wrapped
+        return wrapper
+    _update_wrapper.__doc__ = functools.update_wrapper.__doc__
+
+    def wraps(wrapped, assigned=functools.WRAPPER_ASSIGNMENTS,
+              updated=functools.WRAPPER_UPDATES):
+        return functools.partial(_update_wrapper, wrapped=wrapped,
+                                 assigned=assigned, updated=updated)
+    wraps.__doc__ = functools.wraps.__doc__
+
+else:
+    wraps = functools.wraps
+
+
+def with_metaclass(meta, *bases):
+    """Create a base class with a metaclass."""
+    # This requires a bit of explanation: the basic idea is to make a dummy
+    # metaclass for one level of class instantiation that replaces itself with
+    # the actual metaclass.
+    class metaclass(type):
+
+        def __new__(cls, name, this_bases, d):
+            if sys.version_info[:2] >= (3, 7):
+                # This version introduced PEP 560 that requires a bit
+                # of extra care (we mimic what is done by __build_class__).
+                resolved_bases = types.resolve_bases(bases)
+                if resolved_bases is not bases:
+                    d['__orig_bases__'] = bases
+            else:
+                resolved_bases = bases
+            return meta(name, resolved_bases, d)
+
+        @classmethod
+        def __prepare__(cls, name, this_bases):
+            return meta.__prepare__(name, bases)
+    return type.__new__(metaclass, 'temporary_class', (), {})
+
+
+def add_metaclass(metaclass):
+    """Class decorator for creating a class with a metaclass."""
+    def wrapper(cls):
+        orig_vars = cls.__dict__.copy()
+        slots = orig_vars.get('__slots__')
+        if slots is not None:
+            if isinstance(slots, str):
+                slots = [slots]
+            for slots_var in slots:
+                orig_vars.pop(slots_var)
+        orig_vars.pop('__dict__', None)
+        orig_vars.pop('__weakref__', None)
+        if hasattr(cls, '__qualname__'):
+            orig_vars['__qualname__'] = cls.__qualname__
+        return metaclass(cls.__name__, cls.__bases__, orig_vars)
+    return wrapper
+
+
+def ensure_binary(s, encoding='utf-8', errors='strict'):
+    """Coerce **s** to six.binary_type.
+
+    For Python 2:
+      - `unicode` -> encoded to `str`
+      - `str` -> `str`
+
+    For Python 3:
+      - `str` -> encoded to `bytes`
+      - `bytes` -> `bytes`
+    """
+    if isinstance(s, binary_type):
+        return s
+    if isinstance(s, text_type):
+        return s.encode(encoding, errors)
+    raise TypeError("not expecting type '%s'" % type(s))
+
+
+def ensure_str(s, encoding='utf-8', errors='strict'):
+    """Coerce *s* to `str`.
+
+    For Python 2:
+      - `unicode` -> encoded to `str`
+      - `str` -> `str`
+
+    For Python 3:
+      - `str` -> `str`
+      - `bytes` -> decoded to `str`
+    """
+    # Optimization: Fast return for the common case.
+    if type(s) is str:
+        return s
+    if PY2 and isinstance(s, text_type):
+        return s.encode(encoding, errors)
+    elif PY3 and isinstance(s, binary_type):
+        return s.decode(encoding, errors)
+    elif not isinstance(s, (text_type, binary_type)):
+        raise TypeError("not expecting type '%s'" % type(s))
+    return s
+
+
+def ensure_text(s, encoding='utf-8', errors='strict'):
+    """Coerce *s* to six.text_type.
+
+    For Python 2:
+      - `unicode` -> `unicode`
+      - `str` -> `unicode`
+
+    For Python 3:
+      - `str` -> `str`
+      - `bytes` -> decoded to `str`
+    """
+    if isinstance(s, binary_type):
+        return s.decode(encoding, errors)
+    elif isinstance(s, text_type):
+        return s
+    else:
+        raise TypeError("not expecting type '%s'" % type(s))
+
+
+def python_2_unicode_compatible(klass):
+    """
+    A class decorator that defines __unicode__ and __str__ methods under Python 2.
+    Under Python 3 it does nothing.
+
+    To support Python 2 and 3 with a single code base, define a __str__ method
+    returning text and apply this decorator to the class.
+    """
+    if PY2:
+        if '__str__' not in klass.__dict__:
+            raise ValueError("@python_2_unicode_compatible cannot be applied "
+                             "to %s because it doesn't define __str__()." %
+                             klass.__name__)
+        klass.__unicode__ = klass.__str__
+        klass.__str__ = lambda self: self.__unicode__().encode('utf-8')
+    return klass
+
+
+# Complete the moves implementation.
+# This code is at the end of this module to speed up module loading.
+# Turn this module into a package.
+__path__ = []  # required for PEP 302 and PEP 451
+__package__ = __name__  # see PEP 366 @ReservedAssignment
+if globals().get("__spec__") is not None:
+    __spec__.submodule_search_locations = []  # PEP 451 @UndefinedVariable
+# Remove other six meta path importers, since they cause problems. This can
+# happen if six is removed from sys.modules and then reloaded. (Setuptools does
+# this for some reason.)
+if sys.meta_path:
+    for i, importer in enumerate(sys.meta_path):
+        # Here's some real nastiness: Another "instance" of the six module might
+        # be floating around. Therefore, we can't use isinstance() to check for
+        # the six meta path importer, since the other six instance will have
+        # inserted an importer with different class.
+        if (type(importer).__name__ == "_SixMetaPathImporter" and
+                importer.name == __name__):
+            del sys.meta_path[i]
+            break
+    del i, importer
+# Finally, add the importer to the meta path import hook.
+sys.meta_path.append(_importer)
diff --git a/lib/spack/external/_vendoring/six/__init__.pyi b/lib/spack/external/_vendoring/six/__init__.pyi
new file mode 100644
index 0000000000..e5c0e24227
--- /dev/null
+++ b/lib/spack/external/_vendoring/six/__init__.pyi
@@ -0,0 +1 @@
+from six import *
\ No newline at end of file
diff --git a/lib/spack/external/_vendoring/six/moves/__init__.pyi b/lib/spack/external/_vendoring/six/moves/__init__.pyi
new file mode 100644
index 0000000000..7a82f79db6
--- /dev/null
+++ b/lib/spack/external/_vendoring/six/moves/__init__.pyi
@@ -0,0 +1 @@
+from six.moves import *
\ No newline at end of file
diff --git a/lib/spack/external/_vendoring/six/moves/configparser.pyi b/lib/spack/external/_vendoring/six/moves/configparser.pyi
new file mode 100644
index 0000000000..f77b3f4105
--- /dev/null
+++ b/lib/spack/external/_vendoring/six/moves/configparser.pyi
@@ -0,0 +1 @@
+from six.moves.configparser import *
\ No newline at end of file