Inspired by CMake's format checking, this action (or container) runs git-clang-format on every commit in a PR individually and highlights format errors per commit.

This enforces users to rebase their branches and amend the bad commits, rather than adding format fixup commits that will result in bad git blame results in the future.

By default, the most recent clang-format version is used, which is subject to being updated at some point after a new LLVM release. A fixed version can be selected with the clang-version argument (with the set-clang-version script in GitLab CI scripts). No checkout before running this action is required.

Uses static clang-format binaries from muttleyxd/clang-tools-static-binaries.

The container can also be used locally via the clang-format-checker script.

jobs:
  check-format:
    runs-on: ubuntu-latest
    steps:
      - uses: wolletd/clang-format-checker@v1
        with:
          target-ref: main      # required, merge target
          clang-version: 10     # optional, default: latest (in image)
          fetch-depth: 80       # optional, rarely needed, default: 50
          source-ref: develop   # optional, almost never needed, default: HEAD if
                                # a repository exists, $GITHUB_REF_NAME otherwise

Download the clang-format-checker script (or clone the repository if you want to build the container yourself) and execute it with arguments [-v VER] <target> [source].

• the user has to be a member of the docker group
• no fetches are performed
• run clang-format-checker --build to build the image locally (repository required)
• run clang-format-checker --pull to update the image from hub.docker.com