nightly_merge_master.yml

# This job merges every commit to `master` into `nightly-testing`, resolving merge conflicts in favor of `nightly-testing`.

name: Merge master to nightly

on:
  schedule:
    - cron: '30 */3 * * *'  # 8AM CET/11PM PT

jobs:
  merge-to-nightly:
    runs-on: ubuntu-latest
    steps:
      - name: install elan
        run: |
          set -o pipefail
          curl -sSfL https://github.com/leanprover/elan/releases/download/v3.0.0/elan-x86_64-unknown-linux-gnu.tar.gz | tar xz
          ./elan-init -y --default-toolchain none
          echo "$HOME/.elan/bin" >> "${GITHUB_PATH}"

      - name: Checkout repository
        uses: actions/checkout@v4
        with:
          fetch-depth: 0
          token: ${{ secrets.NIGHTLY_TESTING }}

      - name: Configure Git User
        run: |
          git config user.name "leanprover-community-mathlib4-bot"
          git config user.email "leanprover-community-mathlib4-bot@users.noreply.github.com"

      - name: Merge master to nightly favoring nightly changes
        run: |
          git checkout nightly-testing
          # If the merge goes badly, we proceed anyway via '|| true'.
          # CI will report failures on the 'nightly-testing' branch direct to Zulip.
          git merge master --strategy-option ours --no-commit --allow-unrelated-histories || true
          # We aggressively run `lake update`, to avoid having to do this by hand.
          # When Batteries changes break Mathlib, this will likely show up on nightly-testing first.
          lake update
          git add .
          # If there's nothing to do (because there are no new commits from master),
          # that's okay, hence the '|| true'.
          git commit -m "Merge master into nightly-testing" || true
          git push origin nightly-testing