feat: add CI to detect references

.github/workflows/check-reference.yml

@@ -0,0 +1,39 @@
+name: Check patch references
+
+on:
+ push:
+ branches-ignore:
+ - dependabot/**
+ schedule:
+ # Once every day at midnight UTC
+ - cron: "0 0 * * *"
+
+jobs:
+ stale:
+ runs-on: ubuntu-latest
+ steps:
+ - name: Checkout patches
+ uses: actions/checkout@v4
+
+ - name: Checkout core
+ uses: actions/checkout@v4
+ with:
+ repository: 'homebrew/homebrew-core'
+ path: homebrew-core
+
+ - name: Detect references
+ run: |
+ #!/bin/bash
+
+ core_patches=$(git -C homebrew-core grep -h "Homebrew/formula-patches" | awk -F/ '{print $NF}' | tr -d '"')
+ all_patches=$(git ls-files | grep -v "LICENSE" | grep -v "README.md" | grep -v ".github/workflows/triage-issues.yml" | grep -v ".github/workflows/check-reference.yml")
+ status=0
+
+ for patch in $all_patches; do
+ if ! grep -q "$core_patches" <<< "$patch"; then
+ echo "Unused patch: $patch."
+ # TODO: Delete the patch and commit the deletion.
+ status=1
+ fi
+ done
+ exit $status