Introduce workflow_run workflow

Author: madebr

.editorconfig

@@ -13,4 +13,7 @@ insert_final_newline = true
 trim_trailing_whitespace = true
 
 [{CMakeLists.txt,*.cmake,*.yml}]
+indent_style = space
 indent_size = 2
+insert_final_newline = true
+trim_trailing_whitespace = true

.github/workflows/build.yml

@@ -158,6 +158,9 @@ jobs:
       env:
         GH_TOKEN: ${{ github.token }}
       run: |
+        python -c 'txt=open("LEGORACERS-diff.txt").read().strip(); open("LEGORACERS-diff.txt","w").write(txt);'
+        python -c 'txt=open("GOLDP-diff.txt").read().strip(); open("GOLDP-diff.txt","w").write(txt);'
+
         cat <<EOF >reccmp-pr-message.txt
         # reccmp report
         ## LEGORACERS (LEGORacers.exe)
@@ -170,11 +173,9 @@ jobs:
         \`\`\`
         EOF
 
-        gh pr comment ${{ github.event.number }} \
-          --repo "${{ github.repository }}" \
-          --create-if-none \
-          --edit-last \
-          --body-file "reccmp-pr-message.txt"
+        echo "${{ github.event.number }}" >pr-number.txt
+
+        cat reccmp-pr-message.txt
 
     - name: Upload Artifact
       uses: actions/upload-artifact@main
@@ -184,6 +185,15 @@ jobs:
           LEGORACERSPROGRESS*
           GOLDPPROGRESS*
 
+    - name: Upload PR comment payload
+      if: ${{ github.event_name == 'pull_request' && always() }}
+      uses: actions/upload-artifact@main
+      with:
+        name: reccmp-pr-comment
+        path: |
+          reccmp-pr-message.txt
+          pr-number.txt
+
   upload:
     name: Upload artifacts
     needs: [verify]

.github/workflows/pr-comment.yml

@@ -0,0 +1,39 @@
+name: Post reccmp output as PR comment
+
+# Runs after the Build workflow finishes. Triggered via workflow_run so it
+# executes in the base-repo context with a writable token, which lets it comment
+# on pull requests opened from forks (those builds only get a read-only token).
+on:
+  workflow_run:
+    workflows: [Build]
+    types: [completed]
+
+jobs:
+  comment:
+    name: Comment reccmp report
+    runs-on: ubuntu-latest
+    if: ${{ github.event.workflow_run.event == 'pull_request' }}
+    permissions:
+      actions: read
+      issues: write
+      pull-requests: write
+    steps:
+      - name: Download PR comment payload
+        id: download
+        continue-on-error: true
+        uses: actions/download-artifact@v8
+        with:
+          name: reccmp-pr-comment
+          run-id: ${{ github.event.workflow_run.id }}
+          github-token: ${{ github.token }}
+
+      - name: Post comment
+        if: ${{ steps.download.outcome == 'success' }}
+        env:
+          GH_TOKEN: ${{ github.token }}
+        run: |
+          gh pr comment "$(cat pr-number.txt)" \
+            --repo "${{ github.repository }}" \
+            --create-if-none \
+            --edit-last \
+            --body-file reccmp-pr-message.txt