使用GitHub Actions执行git clang-format时遇git rev-parse main错误

问题背景 #

配置GitHub Actions实现向main分支提交PR时自动检查代码格式规范的Workflow时，执行git rev-parse main命令持续报错。本地Windows环境下该命令可正常运行，但Actions中返回错误：

fatal: ambiguous argument 'main': unknown revision or path not in the working tree.
Use '--' to separate paths from revisions, like this:
'git <command> [<revision>...] -- [<file>...]'

错误原因 #

actions/checkout@v2默认仅拉取当前PR的HEAD提交，不会拉取仓库完整历史或其他分支的引用，因此在Actions环境中git无法识别main分支名。

修复方案 #

方案1：拉取完整仓库历史 #

修改checkout步骤，添加fetch-depth: 0参数拉取仓库所有分支与完整历史：

- name: Checkout repository
  uses: actions/checkout@v2
  with:
    fetch-depth: 0  # 拉取完整仓库数据，包含所有分支和历史

方案2：单独拉取main分支 #

若无需完整历史，可在checkout后单独拉取main分支：

- name: Checkout repository
  uses: actions/checkout@v2
  
- name: Fetch main branch
  run: git fetch origin main:main

方案3：使用PR的base分支环境变量（推荐） #

利用GitHub Actions提供的GITHUB_BASE_REF环境变量直接获取PR目标分支引用，该方式更通用，后续目标分支名称变更无需修改Workflow：

- name: Get commit ID of base branch
  run: |
    BASE_COMMIT=$(git rev-parse origin/${{ github.base_ref }})
    echo "Commit ID of base branch: $BASE_COMMIT"
    
- name: Check code formatting
  run: |
    git clang-format --style=firmware/.clang-format --diff $BASE_COMMIT..HEAD '*.cpp' '*.h'

完整修复后的Workflow配置 #

基于完整历史拉取的版本 #

on:
  pull_request:
    branches:
      - main

jobs:
  clang_format_check:
    name: Check Clang Format
    runs-on: ubuntu-latest
    
    steps:
      - name: Checkout repository
        uses: actions/checkout@v2
        with:
          fetch-depth: 0
          
      - name: Set up clang-format
        run: sudo apt-get install clang-format
        
      - name: Get commit ID of main branch
        run: |
          MAIN_COMMIT=$(git rev-parse main)
          echo "Commit ID of main branch: $MAIN_COMMIT"
          
      - name: Check code formatting
        run: |
          git clang-format --style=firmware/.clang-format --diff $MAIN_COMMIT..HEAD '*.cpp' '*.h'
          
      - name: Check for changes
        id: check_changes
        run: |
          git diff --exit-code || (echo "Code is not formatted properly. Please run clang-format and commit the changes." && exit 1)
          
      - name: Complete
        if: steps.check_changes.outcome == 'success'
        run: echo "Code is properly formatted." 

基于环境变量的推荐版本 #

on:
  pull_request:
    branches:
      - main

jobs:
  clang_format_check:
    name: Check Clang Format
    runs-on: ubuntu-latest
    
    steps:
      - name: Checkout repository
        uses: actions/checkout@v2
        
      - name: Set up clang-format
        run: sudo apt-get install clang-format
        
      - name: Get commit ID of base branch
        run: |
          BASE_COMMIT=$(git rev-parse origin/${{ github.base_ref }})
          echo "Commit ID of base branch: $BASE_COMMIT"
          
      - name: Check code formatting
        run: |
          git clang-format --style=firmware/.clang-format --diff $BASE_COMMIT..HEAD '*.cpp' '*.h'
          
      - name: Check for changes
        id: check_changes
        run: |
          git diff --exit-code || (echo "Code is not formatted properly. Please run clang-format and commit the changes." && exit 1)
          
      - name: Complete
        if: steps.check_changes.outcome == 'success'
        run: echo "Code is properly formatted." 

内容的提问来源于stack exchange，提问作者Micnasr