Add Python 3 aliases to our argparse backport.

1 files changed, 17 insertions, 5 deletions

diff --git a/lib/spack/external/argparse.py b/lib/spack/external/argparse.py
index 394e5da152..ec9a9ee738 100644
--- a/lib/spack/external/argparse.py
+++ b/lib/spack/external/argparse.py
@@ -1067,9 +1067,13 @@ class _SubParsersAction(Action):
 
     class _ChoicesPseudoAction(Action):
 
-        def __init__(self, name, help):
+        def __init__(self, name, aliases, help):
+            metavar = dest = name
+            if aliases:
+                metavar += ' (%s)' % ', '.join(aliases)
             sup = super(_SubParsersAction._ChoicesPseudoAction, self)
-            sup.__init__(option_strings=[], dest=name, help=help)
+            sup.__init__(option_strings=[], dest=dest, help=help,
+                         metavar=metavar)
 
     def __init__(self,
                  option_strings,
@@ -1097,15 +1101,22 @@ class _SubParsersAction(Action):
         if kwargs.get('prog') is None:
             kwargs['prog'] = '%s %s' % (self._prog_prefix, name)
 
+        aliases = kwargs.pop('aliases', ())
+
         # create a pseudo-action to hold the choice help
         if 'help' in kwargs:
             help = kwargs.pop('help')
-            choice_action = self._ChoicesPseudoAction(name, help)
+            choice_action = self._ChoicesPseudoAction(name, aliases, help)
             self._choices_actions.append(choice_action)
 
         # create the parser and add it to the map
         parser = self._parser_class(**kwargs)
         self._name_parser_map[name] = parser
+
+        # make parser available under aliases also
+        for alias in aliases:
+            self._name_parser_map[alias] = parser
+
         return parser
 
     def _get_subactions(self):
@@ -1123,8 +1134,9 @@ class _SubParsersAction(Action):
         try:
             parser = self._name_parser_map[parser_name]
         except KeyError:
-            tup = parser_name, ', '.join(self._name_parser_map)
-            msg = _('unknown parser %r (choices: %s)' % tup)
+            args = {'parser_name': parser_name,
+                    'choices': ', '.join(self._name_parser_map)}
+            msg = _('unknown parser %(parser_name)r (choices: %(choices)s)') % args
             raise ArgumentError(self, msg)
 
         # parse all the remaining options into the namespace