Add a Presubmit to check if a file must be included or imported.

PRESUBMIT.py

Index: PRESUBMIT.py
diff --git a/PRESUBMIT.py b/PRESUBMIT.py
index 686ae511773be4835973f9e2dac4ab7d9776bd2b..a87d017275ec7c8cf0e74943e58c4af2bcb26eed 100644
--- a/PRESUBMIT.py
+++ b/PRESUBMIT.py
@@ -58,6 +58,11 @@ _TEST_ONLY_WARNING = (
     'not perfect.  The commit queue will not block on this warning.')
 
 
+_INCLUDE_IMPORT_WARNING = (
+    'You are including ObjC headers or importing C++ headers. Remember to use '
+    'the right #include/#import directive.')
+
+
 _INCLUDE_ORDER_WARNING = (
     'Your #include order seems to be broken. Remember to use the right '
     'collation (LC_COLLATE=C) and check\nhttps://google.github.io/styleguide/'
@@ -790,6 +795,133 @@ def _CheckNoAuraWindowPropertyHInHeaders(input_api, output_api):
   return results
 
 
+def _CheckHeaderIsObjectiveC(input_api, included_file, included_file_content):
+  """Checks if f is a C++ or an Objective-C header.
+
+  An Objective-C header is a header with a line starting with
+  - #import
+  - @class
+  - @interface
+  - @implementation
+  - @protocol
+  - @end
+
+  or with the two lines
+  #if !defined(__OBJC__)
+  #error ...
+
+  Returns a pair of booleans.
+  - First is true if the determination of Objective-C could be done without
+    error
+  - Second is true if the file has been determined as Objective-C header.
+  """
+  file_path_ios_mac_pattern = input_api.re.compile(
+      r'(?:.*[_./])?(?:ios|mac)[_./].*')
+  if not file_path_ios_mac_pattern.match(included_file):
+    return (False, False)
+  guard_noobjc_pattern = input_api.re.compile(
+      r'\s*#if !defined\(__OBJC__\).*')
+  guard_objc_pattern = input_api.re.compile(
+      r'\s*#if defined\(__OBJC__\).*')
+  error_pattern = input_api.re.compile(
+      r'\s*#error .*')
+  block_pattern = input_api.re.compile(
+      r'\s*typedef.*\(\^.*')
+  objc_pattern = input_api.re.compile(
+      r'\s*(@class|@interface|@end|@implementation|@protocol|#import).*')
+  lines = included_file_content.NewContents()
+  previous_was_noobjc_define = False
+  for included_line in lines:
+    if guard_noobjc_pattern.match(included_line):
+      previous_was_noobjc_define = True
+      continue
+    if previous_was_noobjc_define:
+      # Found No Objc Guard. The next line must be check to see if it is
+      # throwing an error.
+      if error_pattern.match(included_line):
+        # There is an error thrown if the file is compiled without ObjC.
+        # Header is Objective-C.
+        return (True, True)
+      else:
+        # There are ifdefs about Objective-C, file can likely be imported or
+        # included.
+        return (False, False)
+    previous_was_noobjc_define = False
+    if guard_objc_pattern.match(included_line):
+      # Found ObjcGuard. This file can be included or imported.
+      return (False, False)
+    if objc_pattern.match(included_line) or block_pattern.match(included_line):
+      # Found an Objective-C keyword. File is an Objective-C header.
+      return (True, True)
+  # No Objective-C clue, file must be C++.
+  return (True, False)
+
+
+def _CheckIncludeImportInFile(input_api, f):
+  """Checks the include/import coherence in file f."""
+  custom_include_pattern = input_api.re.compile(r'\s*#include "(?P<FILE>.*)"')
+  custom_import_pattern = input_api.re.compile(r'\s*#import "(?P<FILE>.*)"')
+  contents = f.NewContents()
+  warnings = []
+  for (line_num, line) in enumerate(contents):
+    is_imported = False
+    included_file = ""
+    match_cpp = custom_include_pattern.match(line)
+    if match_cpp:
+      match_dict = match_cpp.groupdict()
+      included_file = match_dict['FILE']
+    match_objc = custom_import_pattern.match(line)
+    if match_objc:
+      match_dict = match_objc.groupdict()
+      included_file = match_dict['FILE']
+      is_imported = True
+    if included_file == "":
+      continue
+    included_absolute_path = input_api.os_path.join(
+        input_api.change.RepositoryRoot(), included_file)
+    if not input_api.os_path.isfile(included_absolute_path):
+      # Included file may need a custom -I flag.
+      # Ignore it.
+      continue
+    included_file_content = input_api.ReadFile(included_absolute_path)
+    (detection_ok, has_objc) = \
+        _CheckHeaderIsObjectiveC(input_api,
+                                 included_file,
+                                 included_file_content)
+    if not detection_ok:
+      # There is an Objective-C guard, the file is internded to be included or
+      # imported.
+      continue
+    if is_imported and f.LocalPath().endswith('.cc'):
+      warnings.append('%s:%d %s' % (f.LocalPath(), line_num, line))
+      warnings.append('Header is imported in a C++ file.')
+    if has_objc and not is_imported:
+      warnings.append('%s:%d %s' % (f.LocalPath(), line_num, line))
+      warnings.append('Header is included but has Objective-C instructions.')
+    if not has_objc and is_imported:
+      warnings.append('%s:%d %s' % (f.LocalPath(), line_num, line))
+      warnings.append('Header is imported but has no Objective-C instructions.')
+  return warnings
+
+
+def _CheckIncludeImport(input_api, output_api):
+  """Checks that C++ headers are included, Objective-C headers imported.
+  """
+  def FileFilterIncludeImport(affected_file):
+    black_list = (_EXCLUDED_PATHS + input_api.DEFAULT_BLACK_LIST)
+    return input_api.FilterSourceFile(affected_file, black_list=black_list)
+
+  warnings = []
+  for f in input_api.AffectedFiles(file_filter=FileFilterIncludeImport):
+    warnings.extend(_CheckIncludeImportInFile(input_api, f))
+
+  results = []
+  if warnings:
+    results.append(output_api.PresubmitPromptOrNotify(_INCLUDE_IMPORT_WARNING,
+                                                      warnings))
+  return results
+
+
 def _CheckIncludeOrderForScope(scope, input_api, file_path, changed_linenums):
   """Checks that the lines in scope occur in the right order.
 
@@ -2088,6 +2220,7 @@ def _CommonChecks(input_api, output_api):
   results.extend(_CheckFilePermissions(input_api, output_api))
   results.extend(_CheckTeamTags(input_api, output_api))
   results.extend(_CheckNoAuraWindowPropertyHInHeaders(input_api, output_api))
+  results.extend(_CheckIncludeImport(input_api, output_api))
   results.extend(_CheckIncludeOrder(input_api, output_api))
   results.extend(_CheckForVersionControlConflicts(input_api, output_api))
   results.extend(_CheckPatchFiles(input_api, output_api))