win ninja: build fix for msvs_pre/postbuild error test

pylib/gyp/msvs_emulation.py

 # Copyright (c) 2012 Google Inc. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 """
 This module helps emulate Visual Studio 2008 behavior on top of other
 build systems, primarily ninja.
 """
 
 import os
@@ skipping 149 matching lines @@
       setattr(self, field, {})
       for configname, config in configs.iteritems():
         getattr(self, field)[configname] = config.get(field, default())
 
     self.msvs_cygwin_dirs = spec.get('msvs_cygwin_dirs', ['.'])
 
     unsupported_fields = [
         'msvs_prebuild',
         'msvs_postbuild',
     ]
+    unsupported = []
     for field in unsupported_fields:
       for config in configs.values():
         if field in config:
-          print "Warning: %s not supported, dropping. (target %s)" \
-                % (field, spec['target_name'])
-          break
+          unsupported += ["%s not supported (target %s)." %
+                          (field, spec['target_name'])]
+    if unsupported:
+      raise Exception('\n'.join(unsupported))
 
   def GetVSMacroEnv(self, base_to_build=None, config=None):
     """Get a dict of variables mapping internal VS macro names to their gyp
     equivalents."""
     target_platform = 'Win32' if self.GetArch(config) == 'x86' else 'x64'
     target_name = self.spec.get('product_prefix', '') + \
         self.spec.get('product_name', self.spec['target_name'])
     target_dir = base_to_build + '\\' if base_to_build else ''
     replacements = {
         '$(OutDir)\\': target_dir,
@@ skipping 775 matching lines @@
 
   # To determine processor word size on Windows, in addition to checking
   # PROCESSOR_ARCHITECTURE (which reflects the word size of the current
   # process), it is also necessary to check PROCESSOR_ARCHITEW6432 (which
   # contains the actual word size of the system when running thru WOW64).
   if ('64' in os.environ.get('PROCESSOR_ARCHITECTURE', '') or
       '64' in os.environ.get('PROCESSOR_ARCHITEW6432', '')):
     default_variables['MSVS_OS_BITS'] = 64
   else:
     default_variables['MSVS_OS_BITS'] = 32