Use Spec.constrain to construct spec lists for stacks (#28783)

* stacks: add regression tests for matrix expansion

* Use constrain semantics to construct spec lists for stacks

* Fix semantics for constraining an anonymous spec. Add tests

4 files changed, 62 insertions, 40 deletions

diff --git a/lib/spack/spack/spec.py b/lib/spack/spack/spec.py
index 9e2a2ec929..619b0a93d8 100644
--- a/lib/spack/spack/spec.py
+++ b/lib/spack/spack/spec.py
@@ -3159,6 +3159,15 @@ class Spec(object):
                     raise UnsatisfiableArchitectureSpecError(sarch, oarch)
 
         changed = False
+
+        if not self.name and other.name:
+            self.name = other.name
+            changed = True
+
+        if not self.namespace and other.namespace:
+            self.namespace = other.namespace
+            changed = True
+
         if self.compiler is not None and other.compiler is not None:
             changed |= self.compiler.constrain(other.compiler)
         elif self.compiler is None:
diff --git a/lib/spack/spack/spec_list.py b/lib/spack/spack/spec_list.py
index e7b12e0996..7dee561d69 100644
--- a/lib/spack/spack/spec_list.py
+++ b/lib/spack/spack/spec_list.py
@@ -11,19 +11,6 @@ from spack.error import SpackError
 from spack.spec import Spec
 
 
-def spec_ordering_key(s):
-    if s.startswith('^'):
-        return 5
-    elif s.startswith('/'):
-        return 4
-    elif s.startswith('%'):
-        return 3
-    elif any(s.startswith(c) for c in '~-+@') or '=' in s:
-        return 2
-    else:
-        return 1
-
-
 class SpecList(object):
 
     def __init__(self, name='specs', yaml_list=None, reference=None):
@@ -177,30 +164,36 @@ class SpecList(object):
         return self.specs[key]
 
 
-def _expand_matrix_constraints(object, specify=True):
-    # recurse so we can handle nexted matrices
+def _expand_matrix_constraints(matrix_config):
+    # recurse so we can handle nested matrices
     expanded_rows = []
-    for row in object['matrix']:
+    for row in matrix_config['matrix']:
         new_row = []
         for r in row:
             if isinstance(r, dict):
+                # Flatten the nested matrix into a single row of constraints
                 new_row.extend(
-                    [[' '.join(c)]
-                     for c in _expand_matrix_constraints(r, specify=False)])
+                    [[' '.join([str(c) for c in expanded_constraint_list])]
+                     for expanded_constraint_list in _expand_matrix_constraints(r)]
+                )
             else:
                 new_row.append([r])
         expanded_rows.append(new_row)
 
-    excludes = object.get('exclude', [])  # only compute once
-    sigil = object.get('sigil', '')
+    excludes = matrix_config.get('exclude', [])  # only compute once
+    sigil = matrix_config.get('sigil', '')
 
     results = []
     for combo in itertools.product(*expanded_rows):
         # Construct a combined spec to test against excludes
-        flat_combo = [constraint for list in combo for constraint in list]
-        ordered_combo = sorted(flat_combo, key=spec_ordering_key)
+        flat_combo = [constraint for constraint_list in combo
+                      for constraint in constraint_list]
+        flat_combo = [Spec(x) for x in flat_combo]
+
+        test_spec = flat_combo[0].copy()
+        for constraint in flat_combo[1:]:
+            test_spec.constrain(constraint)
 
-        test_spec = Spec(' '.join(ordered_combo))
         # Abstract variants don't have normal satisfaction semantics
         # Convert all variants to concrete types.
         # This method is best effort, so all existing variants will be
@@ -214,14 +207,12 @@ def _expand_matrix_constraints(object, specify=True):
         if any(test_spec.satisfies(x) for x in excludes):
             continue
 
-        if sigil:  # add sigil if necessary
-            ordered_combo[0] = sigil + ordered_combo[0]
+        if sigil:
+            flat_combo[0] = Spec(sigil + str(flat_combo[0]))
 
         # Add to list of constraints
-        if specify:
-            results.append([Spec(x) for x in ordered_combo])
-        else:
-            results.append(ordered_combo)
+        results.append(flat_combo)
+
     return results
 
 
diff --git a/lib/spack/spack/test/spec_list.py b/lib/spack/spack/test/spec_list.py
index d6461b00d5..ab82627f5f 100644
--- a/lib/spack/spack/test/spec_list.py
+++ b/lib/spack/spack/test/spec_list.py
@@ -45,24 +45,34 @@ class TestSpecList(object):
         assert speclist.specs_as_constraints == self.default_constraints
         assert speclist.specs == self.default_specs
 
-    def test_spec_list_constraint_ordering(self):
-        specs = [{'matrix': [
+    @pytest.mark.regression('28749')
+    @pytest.mark.parametrize('specs,expected', [
+        # Constraints are ordered randomly
+        ([{'matrix': [
             ['^zmpi'],
             ['%gcc@4.5.0'],
             ['hypre', 'libelf'],
             ['~shared'],
             ['cflags=-O3', 'cflags="-g -O0"'],
             ['^foo']
-        ]}]
-
+        ]}], [
+            'hypre cflags=-O3 ~shared %gcc@4.5.0 ^foo ^zmpi',
+            'hypre cflags="-g -O0" ~shared %gcc@4.5.0 ^foo ^zmpi',
+            'libelf cflags=-O3 ~shared %gcc@4.5.0 ^foo ^zmpi',
+            'libelf cflags="-g -O0" ~shared %gcc@4.5.0 ^foo ^zmpi',
+        ]),
+        # A constraint affects both the root and a dependency
+        ([{'matrix': [
+            ['gromacs'],
+            ['%gcc'],
+            ['+plumed ^plumed%gcc']
+        ]}], [
+            'gromacs+plumed%gcc ^plumed%gcc'
+        ])
+    ])
+    def test_spec_list_constraint_ordering(self, specs, expected):
         speclist = SpecList('specs', specs)
-
-        expected_specs = [
-            Spec('hypre cflags=-O3 ~shared %gcc@4.5.0 ^foo ^zmpi'),
-            Spec('hypre cflags="-g -O0" ~shared %gcc@4.5.0 ^foo ^zmpi'),
-            Spec('libelf cflags=-O3 ~shared %gcc@4.5.0 ^foo ^zmpi'),
-            Spec('libelf cflags="-g -O0" ~shared %gcc@4.5.0 ^foo ^zmpi'),
-        ]
+        expected_specs = [Spec(x) for x in expected]
         assert speclist.specs == expected_specs
 
     def test_spec_list_add(self):
diff --git a/lib/spack/spack/test/spec_semantics.py b/lib/spack/spack/test/spec_semantics.py
index a3952397cf..7083ef6339 100644
--- a/lib/spack/spack/test/spec_semantics.py
+++ b/lib/spack/spack/test/spec_semantics.py
@@ -1228,3 +1228,15 @@ def test_merge_abstract_anonymous_specs(specs, expected):
     specs = [Spec(x) for x in specs]
     result = spack.spec.merge_abstract_anonymous_specs(*specs)
     assert result == Spec(expected)
+
+
+@pytest.mark.parametrize('anonymous,named,expected', [
+    ('+plumed', 'gromacs', 'gromacs+plumed'),
+    ('+plumed ^plumed%gcc', 'gromacs', 'gromacs+plumed ^plumed%gcc'),
+    ('+plumed', 'builtin.gromacs', 'builtin.gromacs+plumed')
+])
+def test_merge_anonymous_spec_with_named_spec(anonymous, named, expected):
+    s = Spec(anonymous)
+    changed = s.constrain(named)
+    assert changed
+    assert s == Spec(expected)