check_clang_tidy.py now passes `-format-style=none` to clang_tidy

[gribozavr]

Summary

If the test does not specify a formatting style, force "none"; otherwise
autodetection logic can discover a ".clang-tidy" file that is not
related to the test.

[alexfh]

LG, thanks!

clang-tools-extra/trunk/test/clang-tidy/check_clang_tidy.py

def main():
 
   file_name_with_extension = assume_file_name or input_file_name
   _, extension = os.path.splitext(file_name_with_extension)
   if extension not in ['.c', '.hpp', '.m', '.mm']:
     extension = '.cpp'
   temp_file_name = temp_file_name + extension
 
   clang_tidy_extra_args = extra_args
-  if len(clang_tidy_extra_args) == 0:
-    clang_tidy_extra_args = ['--']
+  clang_extra_args = []
+  if '--' in extra_args:
+    i = clang_tidy_extra_args.index('--')
+    clang_extra_args = clang_tidy_extra_args[i + 1:]
+    clang_tidy_extra_args = clang_tidy_extra_args[:i]
+
+  # If the test does not specify a formatting style, force "none"; otherwise
+  # autodetection logic can discover a ".clang-tidy" file that is not related to
+  # the test.
+  if not any(
+      [arg.startswith('-format-style=') for arg in clang_tidy_extra_args]):
+    clang_tidy_extra_args.append('-format-style=none')
+
+  if len(clang_extra_args) == 0:
     if extension in ['.cpp', '.hpp', '.mm']:
-      clang_tidy_extra_args.append('--std=c++11')
+      clang_extra_args.append('--std=c++11')
     if extension in ['.m', '.mm']:
-      clang_tidy_extra_args.extend(
+      clang_extra_args.extend(
           ['-fobjc-abi-version=2', '-fobjc-arc'])
 
   # Tests should not rely on STL being available, and instead provide mock
   # implementations of relevant APIs.
-  clang_tidy_extra_args.append('-nostdinc++')
+  clang_extra_args.append('-nostdinc++')
 
   if resource_dir is not None:
-    clang_tidy_extra_args.append('-resource-dir=%s' % resource_dir)
+    clang_extra_args.append('-resource-dir=%s' % resource_dir)
 
   with open(input_file_name, 'r') as input_file:
     input_text = input_file.read()
 
   check_fixes_prefixes = []
   check_messages_prefixes = []
   check_notes_prefixes = []
 
def main():
   cleaned_test = re.sub('// *CHECK-[A-Z0-9\-]*:[^\r\n]*', '//', input_text)
 
   write_file(temp_file_name, cleaned_test)
 
   original_file_name = temp_file_name + ".orig"
   write_file(original_file_name, cleaned_test)
 
   args = ['clang-tidy', temp_file_name, '-fix', '--checks=-*,' + check_name] + \
-        clang_tidy_extra_args
+      clang_tidy_extra_args + ['--'] + clang_extra_args
   if expect_clang_tidy_error:
     args.insert(0, 'not')
   print('Running ' + repr(args) + '...')
   try:
     clang_tidy_output = \
         subprocess.check_output(args, stderr=subprocess.STDOUT).decode()
   except subprocess.CalledProcessError as e:
     print('clang-tidy failed:\n' + e.output.decode())