tools/clang-format.py

#!/usr/bin/env python3
# Copyright 2016 The Android Open Source Project
#
# 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.

"""Wrapper to run git-clang-format and parse its output."""

import argparse
import os
import sys

_path = os.path.realpath(__file__ + "/../..")
if sys.path[0] != _path:
    sys.path.insert(0, _path)
del _path

# We have to import our local modules after the sys.path tweak.  We can't use
# relative imports because this is an executable program, not a module.
# pylint: disable=wrong-import-position,import-error
import rh.shell
import rh.utils


# Since we're asking git-clang-format to print a diff, all modified filenames
# that have formatting errors are printed with this prefix.
DIFF_MARKER_PREFIX = "+++ b/"


def get_parser():
    """Return a command line parser."""
    parser = argparse.ArgumentParser(description=__doc__)
    parser.add_argument(
        "--clang-format",
        default="clang-format",
        help="The path of the clang-format executable.",
    )
    parser.add_argument(
        "--git-clang-format",
        default="git-clang-format",
        help="The path of the git-clang-format executable.",
    )
    parser.add_argument(
        "--style",
        metavar="STYLE",
        type=str,
        help="The style that clang-format will use.",
    )
    parser.add_argument(
        "--extensions",
        metavar="EXTENSIONS",
        type=str,
        help="Comma-separated list of file extensions to format.",
    )
    parser.add_argument(
        "--fix",
        action="store_true",
        help="Fix any formatting errors automatically.",
    )

    scope = parser.add_mutually_exclusive_group(required=True)
    scope.add_argument(
        "--commit",
        type=str,
        default="HEAD",
        help="Specify the commit to validate.",
    )
    scope.add_argument(
        "--working-tree",
        action="store_true",
        help="Validates the files that have changed from "
        "HEAD in the working directory.",
    )

    parser.add_argument(
        "files",
        type=str,
        nargs="*",
        help="If specified, only consider differences in these files.",
    )
    return parser


def main(argv):
    """The main entry."""
    parser = get_parser()
    opts = parser.parse_args(argv)

    cmd = [opts.git_clang_format, "--binary", opts.clang_format, "--diff"]
    if opts.style:
        cmd.extend(["--style", opts.style])
    if opts.extensions:
        cmd.extend(["--extensions", opts.extensions])
    if not opts.working_tree:
        cmd.extend([f"{opts.commit}^", opts.commit])
    cmd.extend(["--"] + opts.files)

    # Fail gracefully if clang-format itself aborts/fails.
    result = rh.utils.run(cmd, capture_output=True, check=False)
    # Newer versions of git-clang-format will exit 1 when it worked.  Assume a
    # real failure is any exit code above 1, or any time stderr is used, or if
    # it exited 1 and produce useful format diffs to stdout.  If it exited 0,
    # then assume all is well and we'll attempt to parse its output below.
    ret_code = None
    if (
        result.returncode > 1
        or result.stderr
        or (result.stdout and result.returncode)
    ):
        # Apply fix if the flag is set and clang-format shows it is fixible.
        if opts.fix and result.stdout and result.returncode:
            result = rh.utils.run(
                ["git", "apply"], input=result.stdout, check=False
            )
            ret_code = result.returncode
            if ret_code:
                print(
                    "Error: Unable to automatically fix things.\n"
                    "  Make sure your checkout is clean first.\n"
                    "  If you have multiple commits, you might have to "
                    "manually rebase your tree first.",
                    file=sys.stderr,
                )

        else:  # Regular clang-format aborts/fails.
            print(
                f"clang-format failed:\ncmd: {result.cmdstr}\n"
                f"stdout:\n{result.stdout}\n",
                file=sys.stderr,
            )
            if result.returncode > 1 or result.stderr:
                print(
                    "\nPlease report this to the clang team.\n",
                    f"stderr:\n{result.stderr}",
                    file=sys.stderr,
                )
            ret_code = 1

        return ret_code

    stdout = result.stdout
    if stdout.rstrip("\n") == "no modified files to format":
        # This is always printed when only files that clang-format does not
        # understand were modified.
        return 0

    diff_filenames = []
    for line in stdout.splitlines():
        if line.startswith(DIFF_MARKER_PREFIX):
            diff_filenames.append(line[len(DIFF_MARKER_PREFIX) :].rstrip())

    if diff_filenames:
        if opts.fix:
            result = rh.utils.run(["git", "apply"], input=stdout, check=False)
            if result.returncode:
                print(
                    "Error: Unable to automatically fix things.\n"
                    "  Make sure your checkout is clean first.\n"
                    "  If you have multiple commits, you might have to "
                    "manually rebase your tree first.",
                    file=sys.stderr,
                )
                return result.returncode
        else:
            print("The following files have formatting errors:")
            for filename in diff_filenames:
                print(f"\t{filename}")
            print(
                "You can try to fix this by running:\n"
                f"{sys.argv[0]} --fix {rh.shell.cmd_to_str(argv)}"
            )
            return 1

    return 0


if __name__ == "__main__":
    sys.exit(main(sys.argv[1:]))