Import clang-tidy-diff.py

diff --git a/.github/scripts/clang-tidy-diff.py b/.github/scripts/clang-tidy-diff.py
new file mode 100755 (executable)
index 0000000..396a201
--- /dev/null
+++ b/.github/scripts/clang-tidy-diff.py
@@ -0,0 +1,279 @@
+#!/usr/bin/env python3
+#
+#===- clang-tidy-diff.py - ClangTidy Diff Checker -----------*- python -*--===#
+#
+# Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+# See https://llvm.org/LICENSE.txt for license information.
+# SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+#
+#===-----------------------------------------------------------------------===#
+
+r"""
+ClangTidy Diff Checker
+======================
+
+This script reads input from a unified diff, runs clang-tidy on all changed
+files and outputs clang-tidy warnings in changed lines only. This is useful to
+detect clang-tidy regressions in the lines touched by a specific patch.
+Example usage for git/svn users:
+
+  git diff -U0 HEAD^ | clang-tidy-diff.py -p1
+  svn diff --diff-cmd=diff -x-U0 | \
+      clang-tidy-diff.py -fix -checks=-*,modernize-use-override
+
+"""
+
+import argparse
+import glob
+import json
+import multiprocessing
+import os
+import re
+import shutil
+import subprocess
+import sys
+import tempfile
+import threading
+import traceback
+
+try:
+  import yaml
+except ImportError:
+  yaml = None
+
+is_py2 = sys.version[0] == '2'
+
+if is_py2:
+    import Queue as queue
+else:
+    import queue as queue
+
+
+def run_tidy(task_queue, lock, timeout):
+  watchdog = None
+  while True:
+    command = task_queue.get()
+    try:
+      proc = subprocess.Popen(command,
+                              stdout=subprocess.PIPE,
+                              stderr=subprocess.PIPE)
+
+      if timeout is not None:
+        watchdog = threading.Timer(timeout, proc.kill)
+        watchdog.start()
+
+      stdout, stderr = proc.communicate()
+
+      with lock:
+        sys.stdout.write(stdout.decode('utf-8') + '\n')
+        sys.stdout.flush()
+        if stderr:
+          sys.stderr.write(stderr.decode('utf-8') + '\n')
+          sys.stderr.flush()
+    except Exception as e:
+      with lock:
+        sys.stderr.write('Failed: ' + str(e) + ': '.join(command) + '\n')
+    finally:
+      with lock:
+        if not (timeout is None or watchdog is None):
+          if not watchdog.is_alive():
+              sys.stderr.write('Terminated by timeout: ' +
+                               ' '.join(command) + '\n')
+          watchdog.cancel()
+      task_queue.task_done()
+
+
+def start_workers(max_tasks, tidy_caller, task_queue, lock, timeout):
+  for _ in range(max_tasks):
+    t = threading.Thread(target=tidy_caller, args=(task_queue, lock, timeout))
+    t.daemon = True
+    t.start()
+
+
+def merge_replacement_files(tmpdir, mergefile):
+  """Merge all replacement files in a directory into a single file"""
+  # The fixes suggested by clang-tidy >= 4.0.0 are given under
+  # the top level key 'Diagnostics' in the output yaml files
+  mergekey = "Diagnostics"
+  merged = []
+  for replacefile in glob.iglob(os.path.join(tmpdir, '*.yaml')):
+    content = yaml.safe_load(open(replacefile, 'r'))
+    if not content:
+      continue # Skip empty files.
+    merged.extend(content.get(mergekey, []))
+
+  if merged:
+    # MainSourceFile: The key is required by the definition inside
+    # include/clang/Tooling/ReplacementsYaml.h, but the value
+    # is actually never used inside clang-apply-replacements,
+    # so we set it to '' here.
+    output = {'MainSourceFile': '', mergekey: merged}
+    with open(mergefile, 'w') as out:
+      yaml.safe_dump(output, out)
+  else:
+    # Empty the file:
+    open(mergefile, 'w').close()
+
+
+def main():
+  parser = argparse.ArgumentParser(description=
+                                   'Run clang-tidy against changed files, and '
+                                   'output diagnostics only for modified '
+                                   'lines.')
+  parser.add_argument('-clang-tidy-binary', metavar='PATH',
+                      default='clang-tidy',
+                      help='path to clang-tidy binary')
+  parser.add_argument('-p', metavar='NUM', default=0,
+                      help='strip the smallest prefix containing P slashes')
+  parser.add_argument('-regex', metavar='PATTERN', default=None,
+                      help='custom pattern selecting file paths to check '
+                      '(case sensitive, overrides -iregex)')
+  parser.add_argument('-iregex', metavar='PATTERN', default=
+                      r'.*\.(cpp|cc|c\+\+|cxx|c|cl|h|hpp|m|mm|inc)',
+                      help='custom pattern selecting file paths to check '
+                      '(case insensitive, overridden by -regex)')
+  parser.add_argument('-j', type=int, default=1,
+                      help='number of tidy instances to be run in parallel.')
+  parser.add_argument('-timeout', type=int, default=None,
+                      help='timeout per each file in seconds.')
+  parser.add_argument('-fix', action='store_true', default=False,
+                      help='apply suggested fixes')
+  parser.add_argument('-checks',
+                      help='checks filter, when not specified, use clang-tidy '
+                      'default',
+                      default='')
+  parser.add_argument('-use-color', action='store_true',
+                      help='Use colors in output')
+  parser.add_argument('-path', dest='build_path',
+                      help='Path used to read a compile command database.')
+  if yaml:
+    parser.add_argument('-export-fixes', metavar='FILE', dest='export_fixes',
+                        help='Create a yaml file to store suggested fixes in, '
+                        'which can be applied with clang-apply-replacements.')
+  parser.add_argument('-extra-arg', dest='extra_arg',
+                      action='append', default=[],
+                      help='Additional argument to append to the compiler '
+                      'command line.')
+  parser.add_argument('-extra-arg-before', dest='extra_arg_before',
+                      action='append', default=[],
+                      help='Additional argument to prepend to the compiler '
+                      'command line.')
+  parser.add_argument('-quiet', action='store_true', default=False,
+                      help='Run clang-tidy in quiet mode')
+  parser.add_argument('-load', dest='plugins',
+                      action='append', default=[],
+                      help='Load the specified plugin in clang-tidy.')
+
+  clang_tidy_args = []
+  argv = sys.argv[1:]
+  if '--' in argv:
+    clang_tidy_args.extend(argv[argv.index('--'):])
+    argv = argv[:argv.index('--')]
+
+  args = parser.parse_args(argv)
+
+  # Extract changed lines for each file.
+  filename = None
+  lines_by_file = {}
+  for line in sys.stdin:
+    match = re.search('^\+\+\+\ \"?(.*?/){%s}([^ \t\n\"]*)' % args.p, line)
+    if match:
+      filename = match.group(2)
+    if filename is None:
+      continue
+
+    if args.regex is not None:
+      if not re.match('^%s$' % args.regex, filename):
+        continue
+    else:
+      if not re.match('^%s$' % args.iregex, filename, re.IGNORECASE):
+        continue
+
+    match = re.search('^@@.*\+(\d+)(,(\d+))?', line)
+    if match:
+      start_line = int(match.group(1))
+      line_count = 1
+      if match.group(3):
+        line_count = int(match.group(3))
+      if line_count == 0:
+        continue
+      end_line = start_line + line_count - 1
+      lines_by_file.setdefault(filename, []).append([start_line, end_line])
+
+  if not any(lines_by_file):
+    print("No relevant changes found.")
+    sys.exit(0)
+
+  max_task_count = args.j
+  if max_task_count == 0:
+      max_task_count = multiprocessing.cpu_count()
+  max_task_count = min(len(lines_by_file), max_task_count)
+
+  tmpdir = None
+  if yaml and args.export_fixes:
+    tmpdir = tempfile.mkdtemp()
+
+  # Tasks for clang-tidy.
+  task_queue = queue.Queue(max_task_count)
+  # A lock for console output.
+  lock = threading.Lock()
+
+  # Run a pool of clang-tidy workers.
+  start_workers(max_task_count, run_tidy, task_queue, lock, args.timeout)
+
+  # Form the common args list.
+  common_clang_tidy_args = []
+  if args.fix:
+    common_clang_tidy_args.append('-fix')
+  if args.checks != '':
+    common_clang_tidy_args.append('-checks=' + args.checks)
+  if args.quiet:
+    common_clang_tidy_args.append('-quiet')
+  if args.build_path is not None:
+    common_clang_tidy_args.append('-p=%s' % args.build_path)
+  if args.use_color:
+    common_clang_tidy_args.append('--use-color')
+  for arg in args.extra_arg:
+    common_clang_tidy_args.append('-extra-arg=%s' % arg)
+  for arg in args.extra_arg_before:
+    common_clang_tidy_args.append('-extra-arg-before=%s' % arg)
+  for plugin in args.plugins:
+    common_clang_tidy_args.append('-load=%s' % plugin)
+
+  for name in lines_by_file:
+    line_filter_json = json.dumps(
+      [{"name": name, "lines": lines_by_file[name]}],
+      separators=(',', ':'))
+
+    # Run clang-tidy on files containing changes.
+    command = [args.clang_tidy_binary]
+    command.append('-line-filter=' + line_filter_json)
+    if yaml and args.export_fixes:
+      # Get a temporary file. We immediately close the handle so clang-tidy can
+      # overwrite it.
+      (handle, tmp_name) = tempfile.mkstemp(suffix='.yaml', dir=tmpdir)
+      os.close(handle)
+      command.append('-export-fixes=' + tmp_name)
+    command.extend(common_clang_tidy_args)
+    command.append(name)
+    command.extend(clang_tidy_args)
+
+    task_queue.put(command)
+
+  # Wait for all threads to be done.
+  task_queue.join()
+
+  if yaml and args.export_fixes:
+    print('Writing fixes to ' + args.export_fixes + ' ...')
+    try:
+      merge_replacement_files(tmpdir, args.export_fixes)
+    except:
+      sys.stderr.write('Error exporting fixes.\n')
+      traceback.print_exc()
+
+  if tmpdir:
+    shutil.rmtree(tmpdir)
+
+
+if __name__ == '__main__':
+  main()