This action checks if the source code matches the .clang-format file.

Where the source files are located.
Default: '.' (current folder)
Example: './src' or 'src test examples' for multiple.

What folder should be excluded from format checking.
Default: 'none'
Example: './third_party' or 'third_party exclude' for multiple.

Multiple exclude rules can also be put in a .clang-format-ignore file, which also supports comments.
Example:

# ignore third_party code from clang-format checks
src/third_party/*
src/ignored/*

What filename extensions should be used for format checking.
Default: 'c,h,C,H,cpp,hpp,cc,hh,c++,h++,cxx,hxx'
Example: 'cpp,h'

What clang-format version should be used.
Available version are from 5 to 11.
Default: 9
Example: 11

Style to use.
Results in the appropriate --style parameter.
Default: file
Example: chromium

Whether to change the files on the disk instead of writing to disk.
This is the same as clang-format -i
Default: False\

You probably want to pair this with a GitHub action (such as EndBug/add-and-commit) to commit the changed files. For example:

name: Run clang-format Linter

on: [push]

jobs:
  build:
    runs-on: ubuntu-latest

    steps:
    - uses: actions/checkout@v2
    - uses: DoozyX/[email protected]
      with:
        source: '.'
        exclude: './lib'
        extensions: 'h,cpp,c'
        clangFormatVersion: 11
        inplace: True
    - uses: EndBug/add-and-commit@v4
      with:
        author_name: Clang Robot
        author_email: [email protected]
        message: 'Committing clang-format changes'
      env:
        GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}

name: test-clang-format

on: [push]

jobs:
  build:
    runs-on: ubuntu-latest

    steps:
    - uses: actions/checkout@v2
    - uses: DoozyX/[email protected]
      with:
        source: '.'
        exclude: './third_party ./external'
        extensions: 'h,cpp'
        clangFormatVersion: 11
        style: chromium

Install Docker and then run:

docker build -t clang-format-lint github.com/DoozyX/clang-format-lint-action

When the image is built, run the linting:

docker run -it --rm --workdir /src -v $(pwd):/src clang-format-lint \
    --clang-format-executable /clang-format/clang-format9 -r --exclude .git .