Handle conflicting os deps better in gclient.

gclient.py

 #!/usr/bin/env python
 # Copyright (c) 2012 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 """Meta checkout manager supporting both Subversion and GIT."""
 # Files
 #   .gclient      : Current client configuration, written by 'config' command.
 #                   Format is a Python script defining 'solutions', a list whose
 #                   entries each are maps binding the strings "name" and "url"
@@ skipping 472 matching lines @@
       self.recursion_override = local_scope.get('recursion')
       logging.warning(
           'Setting %s recursion to %d.', self.name, self.recursion_limit)
     # If present, save 'target_os' in the local_target_os property.
     if 'target_os' in local_scope:
       self.local_target_os = local_scope['target_os']
     # load os specific dependencies if defined.  these dependencies may
     # override or extend the values defined by the 'deps' member.
     target_os_deps = {}
     if 'deps_os' in local_scope:
-      for deps_os_key in self.target_os:
-        os_deps = local_scope['deps_os'].get(deps_os_key, {})
-        if len(self.target_os) > 1:
-          # Ignore any conflict when including deps for more than one
-          # platform, so we collect the broadest set of dependencies
-          # available. We may end up with the wrong revision of something for
-          # our platform, but this is the best we can do.
-          target_os_deps.update(
-              [x for x in os_deps.items() if not x[0] in target_os_deps])
-        else:
-          target_os_deps.update(os_deps)
+      if len(self.target_os) > 0:

[iannucci, 2013/09/16 22:54:40]

what values can target_os have? can it be None?

Would it work to just do `if 'deps_os' in local_scope and self.target_os:`?

+        the_first_os = self.target_os[0]
+        # |set_by_os| tracks what deps are overridden and by whom.
+        set_by_os = dict.fromkeys(deps.keys(), the_first_os)
+        for os_dep_key in deps.keys():
+          set_by_os[os_dep_key] = the_first_os

[iannucci, 2013/09/16 22:54:40]

Hm... Isn't this loop doing exactly the same thing as fromkeys?

+
+        os_deps = local_scope['deps_os'].get(the_first_os, {})
+        for os_dep_key, os_dep_value in os_deps.iteritems():
+          target_os_deps[os_dep_key] = os_dep_value
+          set_by_os[os_dep_key] = the_first_os
+
+        for the_target_os in self.target_os[1:]:
+          # Ignore (but warn) for any conflict when including deps for
+          # more than one platform, so we collect the broadest set of
+          # dependencies available. We may end up with the wrong
+          # revision of something for our platform, but this is the
+          # best we can do.
+          os_deps = local_scope['deps_os'].get(the_target_os, {})
+          for os_dep_key, os_dep_value in os_deps.iteritems():
+            prev_value = target_os_deps.get(os_dep_key, deps.get(os_dep_key))
+            if os_dep_key in set_by_os and prev_value is not None:
+              # Some platforms override with None just to create a
+              # smaller checkout. No reason to warn about that.
+              if os_dep_value is not None and os_dep_value != prev_value:
+                print('Conflicting dependencies for %s. %s wants %s '

[iannucci, 2013/09/16 22:54:40]

this should be logging.warning, probably

+                      'while %s wants %s. '
+                      '%s will be used since %s was listed before %s.' %
+                      (os_dep_key, the_target_os, os_dep_value,
+                       set_by_os[os_dep_key], prev_value,
+                       prev_value, set_by_os[os_dep_key], the_target_os))
+            else:
+              target_os_deps[os_dep_key] = os_dep_value
+              set_by_os[os_dep_key] = the_target_os
 
     # deps_os overrides paths from deps
     deps.update(target_os_deps)
 
     # If a line is in custom_deps, but not in the solution, we want to append
     # this line to the solution.
     for d in self.custom_deps:
       if d not in deps:
         deps[d] = self.custom_deps[d]
 
@@ skipping 1283 matching lines @@
     raise
   except (gclient_utils.Error, subprocess2.CalledProcessError), e:
     print >> sys.stderr, 'Error: %s' % str(e)
     return 1
 
 
 if '__main__' == __name__:
   sys.exit(Main(sys.argv[1:]))
 
 # vim: ts=2:sw=2:tw=80:et: