Fix sync-upstream workflow to squash all fork-specific files into single commit

[Copilot]

The current workflow only preserves .github/workflows/ files and uses a merge-base diff approach that doesn't consistently squash fork changes. This causes the fork history to diverge with multiple commits instead of maintaining upstream commits + 1 fork commit.

Changes

Core Logic Replacement

• Replaced merge-base diff with git reset --hard upstream/master + selective restore pattern
• Expanded file detection from .github/workflows/ to all files in repository
• Uses git cat-file -e upstream/master:"$file" to identify fork-specific files (files absent in upstream)

Implementation

# Backup all fork-specific files
for file in $FILES_TO_CHECK; do
  if ! git cat-file -e upstream/master:"$file" 2>/dev/null; then
    cp "$file" "/tmp/fork-specific/$file"
  fi
done

# Reset to upstream, restore fork files, commit as single squashed commit
git reset --hard upstream/master
cp -r /tmp/fork-specific/* ./
git add . && git commit -m "Fork-specific customizations"

Additional Improvements

• Added proper await to all GitHub API calls (reactions, comments)
• Removed redundant git fetch operations
• Added || true to git remote add for workflow re-runs
• Updated to actions/github-script@v8
• Simplified manual sync job condition (removed redundant event type check)

Result

Fork master will maintain clean history: all upstream commits followed by exactly one squashed commit containing all customizations. Works for scheduled (daily 3am UTC) and manual (/sync-upstream comment) triggers.

Original prompt

Problem

Der aktuelle sync-upstream.yml Workflow in diesem Repository squasht nicht korrekt alle Fork-Änderungen auf einen einzelnen Commit. Im Vergleich dazu funktioniert der Workflow in carstenartur/eclipse.jdt.ui wie gewünscht:

• Gewünschtes Verhalten (jdt.ui): Jede Nacht werden ALLE Fork-spezifischen Änderungen gegenüber upstream auf einen einzigen Commit gesquasht
• Aktuelles Verhalten (jdt.debug): Nur .github/workflows/ Dateien werden berücksichtigt

Lösung

Ersetze den aktuellen .github/workflows/sync-upstream.yml durch die Version aus eclipse.jdt.ui, angepasst für eclipse.jdt.debug:

Wichtige Änderungen:

1. Upstream-URL anpassen:

   • Von: https://github.com/eclipse-jdt/eclipse.jdt.ui.git
   • Zu: https://github.com/eclipse-jdt/eclipse.jdt.debug.git

2. Commit-Messages und Kommentare anpassen:

   • Alle Referenzen zu eclipse.jdt.ui durch eclipse.jdt.debug ersetzen

3. Logik übernehmen:

   • git reset --hard upstream/master Ansatz verwenden
   • Alle fork-spezifischen Dateien (nicht nur .github/workflows/) sichern und wiederherstellen
   • Fork-spezifische Dateien = Dateien die im Fork existieren aber nicht in upstream

Neuer Workflow (aus jdt.ui adaptiert):

name: Sync Fork with Upstream

on:
  schedule:
    - cron: '0 3 * * *'  # Daily at 3:00 AM UTC
  workflow_dispatch:
  issue_comment:
    types: [created]

jobs:
  sync-scheduled:
    name: Sync Fork (Scheduled)
    if: github.event_name == 'schedule' || github.event_name == 'workflow_dispatch'
    runs-on: ubuntu-latest
    permissions:
      contents: write
    steps:
      - name: Checkout fork master
        uses: actions/checkout@v4
        with:
          ref: master
          fetch-depth: 0
          token: ${{ secrets.GITHUB_TOKEN }}

      - name: Configure Git
        run: |
          git config user.name "github-actions[bot]"
          git config user.email "github-actions[bot]@users.noreply.github.com"

      - name: Add upstream remote
        run: |
          git remote add upstream https://github.com/eclipse-jdt/eclipse.jdt.debug.git
          git fetch upstream master

      - name: Identify and backup fork-specific files
        id: backup
        run: |
          # Create temporary directory for fork-specific files
          mkdir -p /tmp/fork-specific
          
          # Identify fork-specific workflow files (files that don't exist in upstream)
          git fetch upstream master
          
          # Get list of workflow files in fork
          FORK_WORKFLOWS=$(git ls-tree -r HEAD --name-only .github/workflows/ 2>/dev/null || echo "")
          
          # For each workflow file in fork, check if it exists in upstream
          for file in $FORK_WORKFLOWS; do
            if ! git cat-file -e upstream/master:"$file" 2>/dev/null; then
              echo "Fork-specific file: $file"
              # Create directory structure and copy file
              mkdir -p "/tmp/fork-specific/$(dirname "$file")"
              cp "$file" "/tmp/fork-specific/$file"
            fi
          done
          
          # Check if any fork-specific files were found
          if [ -d "/tmp/fork-specific/.github" ]; then
            echo "has_fork_files=true" >> $GITHUB_OUTPUT
            echo "Found fork-specific files:"
            find /tmp/fork-specific -type f
          else
            echo "has_fork_files=false" >> $GITHUB_OUTPUT
            echo "No fork-specific files found"
          fi

      - name: Reset to upstream master
        run: |
          # Reset fork master to upstream master
          git reset --hard upstream/master

      - name: Restore fork-specific files
        if: steps.backup.outputs.has_fork_files == 'true'
        run: |
          # Copy fork-specific files back
          if [ -d "/tmp/fork-specific" ]; then
            cp -r /tmp/fork-specific/.github ./ 2>/dev/null || true
          fi
          
          # Add all fork-specific changes
          git add .github/

      - name: Commit fork-specific changes
        if: steps.backup.outputs.has_fork_files == 'true'
        run: |
          # Check if there are changes to commit
          if ! git diff --cached --quiet; then
            git commit -m "Fork-specific CI and workflow configurations"
            echo "✅ Fork-specific changes committed"
          else
            echo "ℹ️  No fork-specific changes to commit"
          fi

      - name: Push to fork master
        run: |
          git push --force origin master
          echo "✅ Successfully synced with upstream"

  sync-manual:
    name: Sync Fork (Manual)
    if: |
      github.event_name == 'issue_comment' &&
      contains(github.event.comment.body, '/sync-upstream')
    runs-on: ubuntu-latest
    permissions:
      contents: write
      issues: write
    steps:
      - name: Check user permission
        id: check
        uses: actions/github-script@v8
        with:
          result-encoding: string
          script: |
        ...

</details>



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