VM: Enforce correctly formatted C++ code

runtime/PRESUBMIT.py

 # Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
 # for details. All rights reserved. Use of this source code is governed by a
 # BSD-style license that can be found in the LICENSE file.
 
 import os
 import cpplint
 import re
+import StringIO
 
 # memcpy does not handle overlapping memory regions. Even though this
 # is well documented it seems to be used in error quite often. To avoid
 # problems we disallow the direct use of memcpy.  The exceptions are in
 # third-party code and in platform/globals.h which uses it to implement
 # bit_cast and bit_copy.
 def CheckMemcpy(filename):
   if filename.endswith(os.path.join('platform', 'globals.h')) or \
      filename.find('third_party') != -1:
     return 0
@@ skipping 24 matching lines @@
   if cpplint._cpplint_state.error_count > 0 or memcpy_match_count > 0:
     result = [output_api.PresubmitError('Failed cpplint check.')]
   return result
 
 
 def CheckGn(input_api, output_api):
   return input_api.canned_checks.CheckGNFormatted(input_api, output_api)
 
 
 def CheckFormatted(input_api, output_api):
-  return input_api.canned_checks.CheckPatchFormatted(input_api, output_api)
+  def convert_warning_to_error(presubmit_result):
+    if not presubmit_result.fatal:
+      # Convert this warning to an error.
+      stream = StringIO.StringIO()
+      presubmit_result.handle(stream)
+      message = stream.getvalue()
+      return output_api.PresubmitError(message)
+    return presubmit_result
+
+  results = input_api.canned_checks.CheckPatchFormatted(input_api, output_api)
+  return [convert_warning_to_error(r) for r in results]
 
 
 def CheckChangeOnUpload(input_api, output_api):
   return (RunLint(input_api, output_api) +
           CheckGn(input_api, output_api) +
           CheckFormatted(input_api, output_api))
 
 
 def CheckChangeOnCommit(input_api, output_api):
   return (RunLint(input_api, output_api) +
           CheckGn(input_api, output_api) +
           CheckFormatted(input_api, output_api))