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)
+      messages = stream.getvalue().split('\n')

[zra, 2016/11/27 04:04:55]

I don't remember exactly how the messages look, but this looks a little fragile.
If the goal here is to avoid printing the "Continue (y/N)" line, then maybe chop
off that line instead of taking only the first line.

[kustermann, 2016/11/30 21:40:32]

The goal is not to prevent the "Continue (y/N)" line. The goal was to just
extract the message itself (I cannot access the protected members
`presubmit_result._message`.

The code comes from here
(https://github.com/coreos/depot_tools/blob/master/presubmit_support.py#L132):

  def handle(self, output):
    output.write(self._message)
    output.write('\n')
    for index, item in enumerate(self._items):
      output.write('  ')
      # Write separately in case it's unicode.
      output.write(str(item))
      if index < len(self._items) - 1:
        output.write(' \\')
      output.write('\n')
    if self._long_text:
      output.write('\n***************\n')
      # Write separately in case it's unicode.
      output.write(self._long_text)
      output.write('\n***************\n')
    if self.fatal:
      output.fail()

Done - I'll just use the entire message.

+      message = messages[0] if messages else 'Unknown formatting error.'

[zra, 2016/11/27 04:04:55]

Did you see this happen? Instead of printing 'Unknown formatting error.' which
indicates a problem with the source code in the CL, I think this should fail
some other way to indicate that this bit of code isn't getting what it expects.
Maybe leave the check out, and let it throw the exception.

[kustermann, 2016/11/30 21:40:32]

Done - It was just a precaution, I'll let it throw then.

+      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))