def _VerifySourcesExist(sources, root_dir):
  """Verifies that all source files exist on disk.

  Checks that all regular source files, i.e. not created at run time,
  exist on disk.  Missing files cause needless recompilation but no otherwise
  visible errors.

  Arguments:
    sources: A recursive list of Filter/file names.
    root_dir: The root directory for the relative path names.
  Returns:
    A list of source files that cannot be found on disk.
  """
  missing_sources = []
  for source in sources:
    if isinstance(source, MSVSProject.Filter):
      missing_sources.extend(_VerifySourcesExist(source.contents, root_dir))
    else:
      if source not in '$':
        full_path = os.path.join(root_dir, source)
        if not os.path.exists(full_path):
          missing_sources.append(full_path)
  return missing_sources
dataset/ETHPy150Open adblockplus/gyp/pylib/gyp/generator/msvs.py/_VerifySourcesExist/swapped operands of `not in`