[llvm] [Github] Fetch through merge base in code formatting action (PR #72020)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-github-workflow

Author: Aiden Grossman (boomanaiden154)

<details>
<summary>Changes</summary>

This commit adds another step to the Github workflow that runs the code formatting check to fetch through the merge base. This ensures that the necessary history is present to find the changed files and also to run clang-format over. This change massively increases the speed of the action (~10 minutes down to ~2 minutes in most cases from my testing) and also increases the reliability significantly.

---
Full diff: https://github.com/llvm/llvm-project/pull/72020.diff


1 Files Affected:

- (modified) .github/workflows/pr-code-format.yml (+24-5) 


``````````diff
diff --git a/.github/workflows/pr-code-format.yml b/.github/workflows/pr-code-format.yml
index 4fa5c42bca22b02..b7673009aa4f6a9 100644
--- a/.github/workflows/pr-code-format.yml
+++ b/.github/workflows/pr-code-format.yml
@@ -11,14 +11,33 @@ jobs:
       - name: Fetch LLVM sources
         uses: actions/checkout at v4
         with:
-          fetch-depth: 2 # Fetches only the last 2 commits
+          ref: ${{ github.event.pull_request.head.ref }}
+
+      - name: Checkout through merge base
+        uses: rmacklin/fetch-through-merge-base at v0
+        with:
+          base_ref: ${{ github.event.pull_request.base.ref }}
+          head_ref: ${{ github.event.pull_request.head.ref }}
+          deepen_length: 500
 
       - name: Get changed files
         id: changed-files
         uses: tj-actions/changed-files at v39
         with:
           separator: ","
-          fetch_depth: 2000 # Fetches only the last 2000 commits
+          skip_initial_fetch: true
+
+      # We need to make sure that we aren't executing/using any code from the
+      # PR for security reasons as we're using pull_request_target. Checkout
+      # the target branch with the necessary files.
+      - name: Fetch code formatting utils
+        uses: actions/checkout at v4
+        with:
+          sparse-checkout: |
+            llvm/utils/git/requirements_formatting.txt
+            llvm/utils/git/code-format-helper.py
+          sparse-checkout-cone-mode: false
+          path: code-format-tools
 
       - name: "Listed files"
         run: |
@@ -35,10 +54,10 @@ jobs:
         with:
           python-version: '3.11'
           cache: 'pip'
-          cache-dependency-path: 'llvm/utils/git/requirements_formatting.txt'
+          cache-dependency-path: 'code-format-tools/llvm/utils/git/requirements_formatting.txt'
 
       - name: Install python dependencies
-        run: pip install -r llvm/utils/git/requirements_formatting.txt
+        run: pip install -r code-format-tools/llvm/utils/git/requirements_formatting.txt
 
       - name: Run code formatter
         env:
@@ -47,7 +66,7 @@ jobs:
           END_REV: ${{ github.event.pull_request.head.sha }}
           CHANGED_FILES: ${{ steps.changed-files.outputs.all_changed_files }}
         run: |
-          python llvm/utils/git/code-format-helper.py \
+          python ./code-format-tools/llvm/utils/git/code-format-helper.py \
             --token ${{ secrets.GITHUB_TOKEN }} \
             --issue-number $GITHUB_PR_NUMBER \
             --start-rev $START_REV \

``````````

</details>


https://github.com/llvm/llvm-project/pull/72020