old_contents: #!/usr/bin/env python2.7
  # Copyright 2017 gRPC authors.
  #
  # Licensed under the Apache License, Version 2.0 (the "License");
  # you may not use this file except in compliance with the License.
  # You may obtain a copy of the License at
  #
  #     http://www.apache.org/licenses/LICENSE-2.0
  #
  # Unless required by applicable law or agreed to in writing, software
  # distributed under the License is distributed on an "AS IS" BASIS,
  # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  # See the License for the specific language governing permissions and
  # limitations under the License.
  
  import sys
  import os
  import subprocess
  import argparse
  import multiprocessing
  
  sys.path.append(
      os.path.join(
          os.path.dirname(sys.argv[0]), '..', 'run_tests', 'python_utils'))
  import jobset
  
  GRPC_CHECKS = [
      'modernize-use-nullptr',
  ]
  
  extra_args = [
      '-x',
      'c++',
      '-std=c++11',
  ]
  with open('.clang_complete') as f:
      for line in f:
          line = line.strip()
          if line.startswith('-I'):
              extra_args.append(line)
  
  clang_tidy = os.environ.get('CLANG_TIDY', 'clang-tidy')
  
  argp = argparse.ArgumentParser(description='Run clang-tidy against core')
  argp.add_argument('files', nargs='+', help='Files to tidy')
  argp.add_argument('--fix', dest='fix', action='store_true')
  argp.add_argument(
      '-j',
      '--jobs',
      type=int,
      default=multiprocessing.cpu_count(),
      help='Number of CPUs to use')
  argp.set_defaults(fix=False)
  args = argp.parse_args()
  
  cmdline = [
      clang_tidy,
      '--checks=-*,%s' % ','.join(GRPC_CHECKS),
      '--warnings-as-errors=%s' % ','.join(GRPC_CHECKS)
  ] + ['--extra-arg-before=%s' % arg for arg in extra_args]
  
  if args.fix:
      cmdline.append('--fix')
  
  jobs = []
  for filename in args.files:
      jobs.append(jobset.JobSpec(
          cmdline + [filename],
          shortname=filename,
      ))  #verbose_success=True))
  
  num_fails, res_set = jobset.run(jobs, maxjobs=args.jobs)
  sys.exit(num_fails)
  
new_contents: #!/usr/bin/env python2.7
  # Copyright 2017 gRPC authors.
  #
  # Licensed under the Apache License, Version 2.0 (the "License");
  # you may not use this file except in compliance with the License.
  # You may obtain a copy of the License at
  #
  #     http://www.apache.org/licenses/LICENSE-2.0
  #
  # Unless required by applicable law or agreed to in writing, software
  # distributed under the License is distributed on an "AS IS" BASIS,
  # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  # See the License for the specific language governing permissions and
  # limitations under the License.
  
  import sys
  import os
  import subprocess
  import argparse
  import multiprocessing
  
  sys.path.append(
      os.path.join(
          os.path.dirname(sys.argv[0]), '..', 'run_tests', 'python_utils'))
  import jobset
  
  GRPC_CHECKS = [
      'modernize-use-nullptr',
      'google-build-namespaces',
      'google-build-explicit-make-pair',
      'google-readability-namespace-comments',
  ]
  
  extra_args = [
      '-x',
      'c++',
      '-std=c++11',
  ]
  with open('.clang_complete') as f:
      for line in f:
          line = line.strip()
          if line.startswith('-I'):
              extra_args.append(line)
  
  clang_tidy = os.environ.get('CLANG_TIDY', 'clang-tidy')
  
  argp = argparse.ArgumentParser(description='Run clang-tidy against core')
  argp.add_argument('files', nargs='+', help='Files to tidy')
  argp.add_argument('--fix', dest='fix', action='store_true')
  argp.add_argument(
      '-j',
      '--jobs',
      type=int,
      default=multiprocessing.cpu_count(),
      help='Number of CPUs to use')
  argp.set_defaults(fix=False)
  args = argp.parse_args()
  
  cmdline = [
      clang_tidy,
      '--checks=-*,%s' % ','.join(GRPC_CHECKS),
      '--warnings-as-errors=%s' % ','.join(GRPC_CHECKS)
  ] + ['--extra-arg-before=%s' % arg for arg in extra_args]
  
  if args.fix:
      cmdline.append('--fix')
  
  jobs = []
  for filename in args.files:
      jobs.append(jobset.JobSpec(
          cmdline + [filename],
          shortname=filename,
      ))  #verbose_success=True))
  
  num_fails, res_set = jobset.run(jobs, maxjobs=args.jobs)
  sys.exit(num_fails)
  
subject: Add google clang-tidy check for free