old_contents: """ Helpers to download a recent clang release."""
  
  def _get_platform_folder(os_name):
    os_name = os_name.lower()
    if os_name.startswith('windows'):
      return 'Win'
    if os_name.startswith('mac os'):
      return 'Mac'
    if not os_name.startswith('linux'):
      fail('Unknown platform')
    return 'Linux_x64'
  
  def _download_chromium_clang(repo_ctx, platform_folder, package_version, sha256,
                               out_folder):
    cds_url = 'https://commondatastorage.googleapis.com/chromium-browser-clang'
    cds_file = 'clang-%s.tgz' % package_version
    cds_full_url = '{0}/{1}/{2}'.format(cds_url, platform_folder, cds_file)
    repo_ctx.download_and_extract(cds_full_url, output=out_folder, sha256=sha256)
  
  def download_clang(repo_ctx, out_folder):
    """ Download a fresh clang release and put it into out_folder.
  
    Clang itself will be located in 'out_folder/bin/clang'.
    We currently download one of the latest releases of clang by the
    Chromium project (see
    https://chromium.googlesource.com/chromium/src/+/master/docs/clang.md).
  
    Args:
      repo_ctx: An instance of repository_context object.
      out_folder: A folder to extract the compiler into.
    """
    # TODO(ibiryukov): we currently download and extract some extra tools in the
    # clang release (e.g., sanitizers). We should probably remove the ones
    # we don't need and document the ones we want provide in addition to clang.
  
    # Latest CLANG_REVISION and CLANG_SUB_REVISION of the Chromiums's release
    # can be found in https://chromium.googlesource.com/chromium/src/tools/clang/+/master/scripts/update.py
    CLANG_REVISION = '332838'
    CLANG_SUB_REVISION = 1
  
    package_version = '%s-%s' % (CLANG_REVISION, CLANG_SUB_REVISION)
  
    checksums = {
        'Linux_x64':
            'b9ef55de7500778f366039dbe62d1632074a3ef3673022eabf4e59d405730968',
        'Mac':
            '30d808512763c98cecf15f7bb654d845de3e8d065a95f5c5b6b3459254cc98d6',
        'Win':
            '277e799a190b22727c26b09986c0cedbd667a189f425318f421addf6a21ca4bd',
    }
  
    platform_folder = _get_platform_folder(repo_ctx.os.name)
    _download_chromium_clang(repo_ctx, platform_folder, package_version,
                             checksums[platform_folder], out_folder)
  
new_contents: """ Helpers to download a recent clang release."""
  
  def _get_platform_folder(os_name):
    os_name = os_name.lower()
    if os_name.startswith('windows'):
      return 'Win'
    if os_name.startswith('mac os'):
      return 'Mac'
    if not os_name.startswith('linux'):
      fail('Unknown platform')
    return 'Linux_x64'
  
  def _download_chromium_clang(repo_ctx, platform_folder, package_version, sha256,
                               out_folder):
    cds_url = 'https://commondatastorage.googleapis.com/chromium-browser-clang'
    cds_file = 'clang-%s.tgz' % package_version
    cds_full_url = '{0}/{1}/{2}'.format(cds_url, platform_folder, cds_file)
    repo_ctx.download_and_extract(cds_full_url, output=out_folder, sha256=sha256)
  
  def download_clang(repo_ctx, out_folder):
    """ Download a fresh clang release and put it into out_folder.
  
    Clang itself will be located in 'out_folder/bin/clang'.
    We currently download one of the latest releases of clang by the
    Chromium project (see
    https://chromium.googlesource.com/chromium/src/+/master/docs/clang.md).
  
    Args:
      repo_ctx: An instance of repository_context object.
      out_folder: A folder to extract the compiler into.
    """
    # TODO(ibiryukov): we currently download and extract some extra tools in the
    # clang release (e.g., sanitizers). We should probably remove the ones
    # we don't need and document the ones we want provide in addition to clang.
  
    # Latest CLANG_REVISION and CLANG_SUB_REVISION of the Chromiums's release
    # can be found in https://chromium.googlesource.com/chromium/src/tools/clang/+/master/scripts/update.py
    CLANG_REVISION = '334100'
    CLANG_SUB_REVISION = 1
  
    package_version = '%s-%s' % (CLANG_REVISION, CLANG_SUB_REVISION)
  
    checksums = {
        'Linux_x64':
            '3c57420b591601cd14b5babd74b58fcaefa877112938d70cca6f0a1b0b293ab4',
        'Mac':
            '97d313996fb97a6138635f963d7ef4efa9f028a8168bb7917cc428b9eab05ebb',
        'Win':
            '52c1d6d20a0733276597f4ced59d18b545769dbf8beb8c6bdc26a7a862da7fc9',
    }
  
    platform_folder = _get_platform_folder(repo_ctx.os.name)
    _download_chromium_clang(repo_ctx, platform_folder, package_version,
                             checksums[platform_folder], out_folder)
  
subject: Update downloadable clang to r334100.