can't use git merge-base with checkout

[xiqingongzi]

my ci script use git merge-base to find the common commit.

but I always get fatal: Not a valid object name master

although I use full clone

      - uses: actions/checkout@v2
        with:
          fetch-depth: 0

[solarmosaic-kflorence]

@xiqingongzi I got this to work using origin/master instead of master

[jamacku]

I have encountered the same issue when using commit SHA.

git merge-base "${{ github.event.before }}" "${{ github.event.after }}"

I wasn't able to resolve the issue so far. I have noticed that when the triggering event is pull_request, then git merge-base works as expected. But when the triggering event is push it fails.

[socketbox]

This is still a problem, even with actions/checkout@v3 and prepending origin to the reference didn't help:

Determining the checkout info
  /usr/bin/git branch --list --remote origin/origin/thebranchname
  /usr/bin/git tag --list origin/thebranchname
  Error: A branch or tag with the name 'origin/thebranchname' could not be found

Note how on the second line above the action uses origin/origin/thebranchname as an argument.

[ohyesboy]

Jan 2024, git merge-base still doesn't work in this action

[porter-stripe]

Not working in May 2024

[zcao]

Found this solution: (use fetch-depth: 0 for full checkout)

steps:
  - uses: actions/checkout@v3
    with:
      fetch-depth: 0

Later this works for me. " git merge-base" is sub-command
git diff --name-status $(git merge-base origin/${{github.event.pull_request.base.ref}} HEAD) > changes.txt

[rbellido-ut]

It only took me 18 commits to confirm that this is in fact not working in June 2024.

@zcao's solution works tho

[brtbrt]

+1 I'm experiencing the same issue. Interestingly though, it used to work nicely until last week. Now master is an unknown object

[yasn77]

Hi,

This is how I got around this problem:

    - name: Get Affected
      id: get-affected
      shell: bash
      run: |
        set -x
        GIT_BASE=${GITHUB_BASE_REF:-master}
        HEAD_REF=$(echo ${{ github.ref }} | sed -e 's#/merge#/head#')
        git fetch origin +${GIT_BASE}:${GIT_BASE}
        git fetch origin +${HEAD_REF}:${HEAD_REF}
        NX_HEAD=$(git rev-parse ${HEAD_REF})
        NX_BASE=$(git merge-base origin/${GIT_BASE} ${HEAD_REF})
        AFFECTED_JSON=$(npx nx show projects --affected --base "${NX_BASE}" --head "${NX_HEAD}" --verbose | jq -rc -nR '[inputs | select(length>0)] as $projects | { "projects": $projects, "count": ($projects | length)}')
        AFFECTED_COUNT=$(echo $AFFECTED_JSON | jq -rc '.count')
        AFFECTED_PROJECTS=$(echo $AFFECTED_JSON | jq -rc '.projects')
        echo "affected-json=${AFFECTED_JSON}" >> "$GITHUB_OUTPUT"
        echo "affected-projects=${AFFECTED_PROJECTS}" >> "$GITHUB_OUTPUT"
        echo "affected-count=${AFFECTED_COUNT}" >> "$GITHUB_OUTPUT"

The main thing was to fetch branch/PR reference and master. Then we can correctly use git merge-base. It definitely would be nice not to have to do such a thing and have references available via actions/checkout

Hopefully that helps someone :)