VM: Enforce correctly formatted C++ code

runtime/PRESUBMIT.py

Index: runtime/PRESUBMIT.py
diff --git a/runtime/PRESUBMIT.py b/runtime/PRESUBMIT.py
index 0170f2f98d67efb2b22f06ea1775c7b328b525f8..e2396f4d3169929e2819f886c2490fa054c264fa 100644
--- a/runtime/PRESUBMIT.py
+++ b/runtime/PRESUBMIT.py
@@ -5,6 +5,7 @@
 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
@@ -49,7 +50,18 @@ def CheckGn(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):