test: fork-PR comment recipe (do not merge)

.github/workflows/fork-pr-comment-recipe.yml

@@ -0,0 +1,102 @@
+name: fork-PR comment recipe test
+on:
+  pull_request:
+    paths: ['**.c', '**.cpp', '**.h', '**.hpp', '**.cxx', '**.hxx', '**.cc', '**.hh', '**CMakeLists.txt', 'meson.build', '**.cmake']
+
+permissions: {}
+
+jobs:
+  cpp-linter:
+    runs-on: ubuntu-latest
+    permissions:
+      contents: read
+      pull-requests: read
+    steps:
+      - uses: actions/checkout@v7
+        with:
+          persist-credentials: false
+
+      # ... optionally setup build env to create a compilation database
+
+      - uses: cpp-linter/cpp-linter-action@v2
+        id: linter
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        with:
+          style: 'file'  # Use .clang-format config file.
+          tidy-checks: '' # Use .clang-tidy config file.
+          # No thread-comments here: this job's token is read-only.
+          summary-output-file: ${{ runner.temp }}/cpp-linter-comment/comment.md
+
+      - name: Save the pull request number
+        env:
+          PR_NUMBER: ${{ github.event.pull_request.number }}
+        run: |
+          mkdir -p "$RUNNER_TEMP/cpp-linter-comment"
+          echo "$PR_NUMBER" > "$RUNNER_TEMP/cpp-linter-comment/pr-number.txt"
+
+      - uses: actions/upload-artifact@v7
+        with:
+          name: cpp-linter-comment
+          path: ${{ runner.temp }}/cpp-linter-comment/
+          retention-days: 1
+
+      - name: Fail fast?!
+        if: steps.linter.outputs.checks-failed > 0
+        run: exit 1
+
+  # Stand-in for the workflow_run workflow, which GitHub only runs from the default branch.
+  comment:
+    needs: cpp-linter
+    if: ${{ !cancelled() }}
+    runs-on: ubuntu-latest
+    permissions:
+      actions: read
+      pull-requests: write
+    steps:
+      - uses: actions/download-artifact@v8
+        id: download
+        continue-on-error: true
+        with:
+          name: cpp-linter-comment
+          path: ${{ runner.temp }}/cpp-linter-comment
+          run-id: ${{ github.run_id }}
+          github-token: ${{ github.token }}
+
+      - name: Post or update the comment
+        if: steps.download.outcome == 'success'
+        env:
+          GH_TOKEN: ${{ github.token }}
+          GH_REPO: ${{ github.repository }}
+          HEAD_SHA: ${{ github.event.pull_request.head.sha }}
+          RUN_URL: ${{ github.server_url }}/${{ github.repository }}/actions/runs/${{ github.run_id }}
+        run: |
+          dir="$RUNNER_TEMP/cpp-linter-comment"
+          # The artifact was made while linting the pull request: use it only as data.
+          pr="$(tr -cd '0-9' < "$dir/pr-number.txt" | head -c 10)"
+          if [ -z "$pr" ] || [ ! -f "$dir/comment.md" ]; then
+            echo "::warning::The artifact has no pull request number or no comment"
+            exit 0
+          fi
+          # Only comment on the pull request whose head the lint run checked. (4)
+          if [ "$(gh api "repos/$GH_REPO/pulls/$pr" --jq .head.sha)" != "$HEAD_SHA" ]; then
+            echo "::notice::Pull request #$pr has new commits since this run; not commenting"
+            exit 0
+          fi
+          marker='<!-- cpp-linter-action workflow_run comment -->'
+          body="$RUNNER_TEMP/body.md"
+          if [ "$(wc -c < "$dir/comment.md")" -gt 60000 ]; then
+            # A comment holds at most 65536 characters.
+            printf '%s\nToo many findings to show here. See the [workflow run](%s).\n' "$marker" "$RUN_URL" > "$body"
+          else
+            { echo "$marker"; cat "$dir/comment.md"; } > "$body"
+          fi
+          # Update the comment from an earlier run instead of adding another one.
+          id="$(gh api --paginate "repos/$GH_REPO/issues/$pr/comments" \
+            --jq ".[] | select(.user.login == \"github-actions[bot]\" and (.body | startswith(\"$marker\"))) | .id" \
+            | head -n 1)"
+          if [ -n "$id" ]; then
+            gh api -X PATCH "repos/$GH_REPO/issues/comments/$id" -F "body=@$body" > /dev/null
+          else
+            gh api "repos/$GH_REPO/issues/$pr/comments" -F "body=@$body" > /dev/null
+          fi

src/demo.cpp

@@ -1,17 +1,20 @@
 /** This is a very ugly test code (doomed to fail linting) */
 #include "demo.hpp"
 #include <cstdio>
 #include <cstddef>
 
 // using size_t from cstddef
 size_t dummyFunc(size_t i) { return i; }
 
 int main()
 {
     for (;;)
         break;
 
     printf("Hello world!\n");
 
     return 0;
 }
+// fork-PR comment recipe test
+// second run: the comment should be updated, not duplicated
+int thirdRun(int x) { return x; }