Revert "Adding PRESUBMIT check to avoid mixing C, C++ and Objc-C/Obj-C++."

This reverts commit 0c15c5332fea2bbf5fe29dd806f9f4e606eeb9b8.

Reason for revert: This causes problems in this moment. I have to fix a target in rtc_base before landing this presubmit check.

Original change's description:
> Adding PRESUBMIT check to avoid mixing C, C++ and Objc-C/Obj-C++.
> 
> The error message will be something like:
> 
> GN targets cannot mix .c (or .cc) and .m (or .mm) source files.
> Please create a separate target for each collection of sources.
> Mixed sources:
> {
>   BUILD_GN_PATH: [
>     [
>       TARGET_NAME,
>       [
>         SOURCES
>       ]
>     ],
>     ...
>   ],
>   ...
> }
> 
> Bug: webrtc:7743
> Change-Id: I45dd2c621b830e5aeb081fa8d17c9497a49c2554
> Reviewed-on: https://webrtc-review.googlesource.com/1980
> Commit-Queue: Mirko Bonadei <mbonadei@webrtc.org>
> Reviewed-by: Henrik Kjellander <kjellander@webrtc.org>
> Cr-Commit-Position: refs/heads/master@{#19897}

TBR=kjellander@webrtc.org,mbonadei@webrtc.org

Change-Id: I73ff609b0140719473afd36ead1632e5cc3b41f6
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: webrtc:7743
Reviewed-on: https://webrtc-review.googlesource.com/2180
Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org>
Commit-Queue: Mirko Bonadei <mbonadei@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#19898}
diff --git a/PRESUBMIT.py b/PRESUBMIT.py
index aebadb5..37047d4 100755
--- a/PRESUBMIT.py
+++ b/PRESUBMIT.py
@@ -11,7 +11,6 @@
 import re
 import subprocess
 import sys
-from collections import defaultdict
 
 
 # Files and directories that are *skipped* by cpplint in the presubmit script.
@@ -68,7 +67,6 @@
   'modules/audio_device/include',
   'pc',
 )
-
 # These directories should not be used but are maintained only to avoid breaking
 # some legacy downstream code.
 LEGACY_API_DIRS = (
@@ -92,22 +90,8 @@
   'system_wrappers/include',
   'voice_engine/include',
 )
-
 API_DIRS = NATIVE_API_DIRS[:] + LEGACY_API_DIRS[:]
 
-# TARGET_RE matches a GN target, and extracts the target name and the contents.
-TARGET_RE = re.compile(r'(?P<indent>\s*)\w+\("(?P<target_name>\w+)"\) {'
-                       r'(?P<target_contents>.*?)'
-                       r'(?P=indent)}',
-                       re.MULTILINE | re.DOTALL)
-
-# SOURCES_RE matches a block of sources inside a GN target.
-SOURCES_RE = re.compile(r'sources \+?= \[(?P<sources>.*?)\]',
-                        re.MULTILINE | re.DOTALL)
-
-# FILE_PATH_RE matchies a file path.
-FILE_PATH_RE = re.compile(r'"(?P<file_path>(\w|\/)+)(?P<extension>\.\w+)"')
-
 
 def _RunCommand(command, cwd):
   """Runs a command and returns the output from that command."""
@@ -313,48 +297,33 @@
         items=violating_gn_files)]
   return []
 
-def CheckNoMixingSources(input_api, gn_files, output_api):
-  """Disallow mixing C, C++ and Obj-C/Obj-C++ in the same target.
-
-  See bugs.webrtc.org/7743 for more context.
-  """
-  def _MoreThanOneSourceUsed(*sources_lists):
-    sources_used = 0
-    for source_list in sources_lists:
-      if len(source_list):
-        sources_used += 1
-    return sources_used > 1
-
-  errors = defaultdict(lambda: [])
+def CheckNoMixingCAndCCSources(input_api, gn_files, output_api):
+  # Disallow mixing .c and .cc source files in the same target.
+  source_pattern = input_api.re.compile(r' +sources \+?= \[(.*?)\]',
+                                        re.MULTILINE | re.DOTALL)
+  file_pattern = input_api.re.compile(r'"(.*)"')
+  violating_gn_files = dict()
   for gn_file in gn_files:
-    gn_file_content = input_api.ReadFile(gn_file)
-    for target_match in TARGET_RE.finditer(gn_file_content):
+    contents = input_api.ReadFile(gn_file)
+    for source_block_match in source_pattern.finditer(contents):
       c_files = []
       cc_files = []
-      objc_files = []
-      target_name = target_match.group('target_name')
-      target_contents = target_match.group('target_contents')
-      for sources_match in SOURCES_RE.finditer(target_contents):
-        for file_match in FILE_PATH_RE.finditer(sources_match.group(1)):
-          file_path = file_match.group('file_path')
-          extension = file_match.group('extension')
-          if extension == '.c':
-            c_files.append(file_path + extension)
-          if extension == '.cc':
-            cc_files.append(file_path + extension)
-          if extension in ['.m', '.mm']:
-            objc_files.append(file_path + extension)
-      if _MoreThanOneSourceUsed(c_files, cc_files, objc_files):
-        all_sources = sorted(c_files + cc_files + objc_files)
-        errors[gn_file.LocalPath()].append((target_name, all_sources))
-  if errors:
+      for file_list_match in file_pattern.finditer(source_block_match.group(1)):
+        source_file = file_list_match.group(1)
+        if source_file.endswith('.c'):
+          c_files.append(source_file)
+        if source_file.endswith('.cc'):
+          cc_files.append(source_file)
+      if c_files and cc_files:
+        violating_gn_files[gn_file.LocalPath()] = sorted(c_files + cc_files)
+  if violating_gn_files:
     return [output_api.PresubmitError(
-        'GN targets cannot mix .c, .cc and .m (or .mm) source files.\n'
-        'Please create a separate target for each collection of sources.\n'
+        'GN targets cannot mix .cc and .c source files. Please create a '
+        'separate target for each collection of sources.\n'
         'Mixed sources: \n'
         '%s\n'
-        'Violating GN files:\n%s\n' % (json.dumps(errors, indent=2),
-                                       '\n'.join(errors.keys())))]
+        'Violating GN files:' % json.dumps(violating_gn_files, indent=2),
+        items=violating_gn_files.keys())]
   return []
 
 def CheckNoPackageBoundaryViolations(input_api, gn_files, output_api):
@@ -381,9 +350,9 @@
   result = []
   if gn_files:
     result.extend(CheckNoSourcesAbove(input_api, gn_files, output_api))
-    result.extend(CheckNoMixingSources(input_api, gn_files, output_api))
-    result.extend(CheckNoPackageBoundaryViolations(input_api, gn_files,
-                                                   output_api))
+    result.extend(CheckNoMixingCAndCCSources(input_api, gn_files, output_api))
+    result.extend(CheckNoPackageBoundaryViolations(
+        input_api, gn_files, output_api))
   return result
 
 def CheckUnwantedDependencies(input_api, output_api):
diff --git a/presubmit_test.py b/presubmit_test.py
index 5e342ba..f17a20f 100755
--- a/presubmit_test.py
+++ b/presubmit_test.py
@@ -60,7 +60,7 @@
     shutil.rmtree(self.tmp_dir, ignore_errors=True)
 
   def testErrorIfProtoFileDoesNotEndWithNewline(self):
-    self._GenerateProtoWithoutNewlineAtTheEnd()
+    self.__GenerateProtoWithoutNewlineAtTheEnd()
     self.input_api.files = [MockFile(self.proto_file_path)]
     errors = PRESUBMIT.CheckNewlineAtTheEndOfProtoFiles(self.input_api,
                                                         self.output_api)
@@ -70,13 +70,13 @@
         str(errors[0]))
 
   def testNoErrorIfProtoFileEndsWithNewline(self):
-    self._GenerateProtoWithNewlineAtTheEnd()
+    self.__GenerateProtoWithNewlineAtTheEnd()
     self.input_api.files = [MockFile(self.proto_file_path)]
     errors = PRESUBMIT.CheckNewlineAtTheEndOfProtoFiles(self.input_api,
                                                         self.output_api)
     self.assertEqual(0, len(errors))
 
-  def _GenerateProtoWithNewlineAtTheEnd(self):
+  def __GenerateProtoWithNewlineAtTheEnd(self):
     with open(self.proto_file_path, 'w') as f:
       f.write(textwrap.dedent("""
         syntax = "proto2";
@@ -84,7 +84,7 @@
         package webrtc.audioproc;
       """))
 
-  def _GenerateProtoWithoutNewlineAtTheEnd(self):
+  def __GenerateProtoWithoutNewlineAtTheEnd(self):
     with open(self.proto_file_path, 'w') as f:
       f.write(textwrap.dedent("""
         syntax = "proto2";
@@ -92,72 +92,5 @@
         package webrtc.audioproc;"""))
 
 
-class CheckNoMixingSourcesTest(unittest.TestCase):
-
-  def setUp(self):
-    self.tmp_dir = tempfile.mkdtemp()
-    self.file_path = os.path.join(self.tmp_dir, 'BUILD.gn')
-    self.input_api = MockInputApi()
-    self.output_api = MockOutputApi()
-
-  def tearDown(self):
-    shutil.rmtree(self.tmp_dir, ignore_errors=True)
-
-  def testErrorIfCAndCppAreMixed(self):
-    self._AssertNumberOfErrorsWithSources(1, ['foo.c', 'bar.cc', 'bar.h'])
-
-  def testErrorIfCAndObjCAreMixed(self):
-    self._AssertNumberOfErrorsWithSources(1, ['foo.c', 'bar.m', 'bar.h'])
-
-  def testErrorIfCAndObjCppAreMixed(self):
-    self._AssertNumberOfErrorsWithSources(1, ['foo.c', 'bar.mm', 'bar.h'])
-
-  def testErrorIfCppAndObjCAreMixed(self):
-    self._AssertNumberOfErrorsWithSources(1, ['foo.cc', 'bar.m', 'bar.h'])
-
-  def testErrorIfCppAndObjCppAreMixed(self):
-    self._AssertNumberOfErrorsWithSources(1, ['foo.cc', 'bar.mm', 'bar.h'])
-
-  def testNoErrorIfOnlyC(self):
-    self._AssertNumberOfErrorsWithSources(0, ['foo.c', 'bar.c', 'bar.h'])
-
-  def testNoErrorIfOnlyCpp(self):
-    self._AssertNumberOfErrorsWithSources(0, ['foo.cc', 'bar.cc', 'bar.h'])
-
-  def testNoErrorIfOnlyObjC(self):
-    self._AssertNumberOfErrorsWithSources(0, ['foo.m', 'bar.m', 'bar.h'])
-
-  def testNoErrorIfOnlyObjCpp(self):
-    self._AssertNumberOfErrorsWithSources(0, ['foo.mm', 'bar.mm', 'bar.h'])
-
-  def testNoErrorIfObjCAndObjCppAreMixed(self):
-    self._AssertNumberOfErrorsWithSources(0, ['foo.m', 'bar.mm', 'bar.h'])
-
-  def _AssertNumberOfErrorsWithSources(self, number_of_errors, sources):
-    assert 3 == len(sources), 'This function accepts a list of 3 source files'
-    self._GenerateBuildFile(textwrap.dedent("""
-      rtc_source_set("foo_bar") {
-        sources = [
-          "%s",
-          "%s",
-          "%s",
-        ],
-      }
-    """ % tuple(sources)))
-    self.input_api.files = [MockFile(self.file_path)]
-    errors = PRESUBMIT.CheckNoMixingSources(self.input_api,
-                                            [MockFile(self.file_path)],
-                                            self.output_api)
-    self.assertEqual(number_of_errors, len(errors))
-    if number_of_errors == 1:
-      for source in sources:
-        if not source.endswith('.h'):
-          self.assertTrue(source in str(errors[0]))
-
-  def _GenerateBuildFile(self, content):
-    with open(self.file_path, 'w') as f:
-      f.write(content)
-
-
 if __name__ == '__main__':
   unittest.main()
diff --git a/presubmit_test_mocks.py b/presubmit_test_mocks.py
index cbfc4f5..f7ead25 100644
--- a/presubmit_test_mocks.py
+++ b/presubmit_test_mocks.py
@@ -25,15 +25,6 @@
     # pylint: disable=unused-argument
     return self.files
 
-  def ReadFile(self, affected_file, mode='rU'):
-    filename = affected_file.AbsoluteLocalPath()
-    for f in self.files:
-      if f.LocalPath() == filename:
-        with open(filename, mode) as f:
-          return f.read()
-    # Otherwise, file is not in our mock API.
-    raise IOError, "No such file or directory: '%s'" % filename
-
 
 class MockOutputApi(object):
   """Mock class for the OutputApi class.
@@ -80,6 +71,3 @@
 
   def LocalPath(self):
     return self._local_path
-
-  def AbsoluteLocalPath(self):
-    return self._local_path