Detect and warn on missing vcvarsall.bat

build/toolchain/win/setup_toolchain.py

 # Copyright (c) 2013 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.
 #
 # Copies the given "win tool" (which the toolchain uses to wrap compiler
 # invocations) and the environment blocks for the 32-bit and 64-bit builds on
 # Windows to the build directory.
 #
 # The arguments are the visual studio install location and the location of the
 # win tool. The script assumes that the root build directory is the current dir
@@ skipping 99 matching lines @@
 
     # Check that the json file contained the same environment as the .cmd file.
     if sys.platform in ('win32', 'cygwin'):
       script = os.path.normpath(os.path.join(sdk_dir, 'Bin/SetEnv.cmd'))
       assert _ExtractImportantEnvironment(variables) == \
              _ExtractImportantEnvironment(_LoadEnvFromBat([script, '/' + cpu]))
   else:
     if 'GYP_MSVS_OVERRIDE_PATH' not in os.environ:
       os.environ['GYP_MSVS_OVERRIDE_PATH'] = _DetectVisualStudioPath()
     # We only support x64-hosted tools.
-    args = [os.path.normpath(os.path.join(os.environ['GYP_MSVS_OVERRIDE_PATH'],
-                                          'VC/vcvarsall.bat')),
-            'amd64_x86' if cpu == 'x86' else 'amd64']
+    script_path = os.path.normpath(os.path.join(
+                                       os.environ['GYP_MSVS_OVERRIDE_PATH'],
+                                       'VC/vcvarsall.bat'))
+    if not os.path.exists(script_path):
+      raise Exception('%s is missing - make sure VC++ tools are installed.' %
+                      script_path)
+    args = [script_path, 'amd64_x86' if cpu == 'x86' else 'amd64']
     variables = _LoadEnvFromBat(args)
   return _ExtractImportantEnvironment(variables)
 
 
 def _FormatAsEnvironmentBlock(envvar_dict):
   """Format as an 'environment block' directly suitable for CreateProcess.
   Briefly this is a list of key=value\0, terminated by an additional \0. See
   CreateProcess documentation for more details."""
   block = ''
   nul = '\0'
@@ skipping 60 matching lines @@
     env_block = _FormatAsEnvironmentBlock(env)
     with open('environment.winrt_' + cpu, 'wb') as f:
         f.write(env_block)
 
   assert vc_bin_dir
   print 'vc_bin_dir = "%s"' % vc_bin_dir
 
 
 if __name__ == '__main__':
   main()