Limit clang-format CI to changed files

Author: allnes

.github/workflows/ci.yml

@@ -12,9 +12,15 @@ jobs:
     runs-on: ubuntu-latest
     steps:
     - uses: actions/checkout@v4
-    - uses: DoozyX/clang-format-lint-action@v0.15
       with:
-        source: './app ./include ./src ./test'
+        fetch-depth: 0
+    - name: Install clang-format
+      run: sudo apt-get update && sudo apt-get install -y clang-format-18
+    - name: Run clang-format
+      env:
+        BASE_SHA: ${{ github.event_name == 'pull_request' && github.event.pull_request.base.sha || github.event.before }}
+        HEAD_SHA: ${{ github.event_name == 'pull_request' && github.event.pull_request.head.sha || github.sha }}
+      run: ./scripts/ci/clang-format-check.sh "${BASE_SHA}" "${HEAD_SHA}"
   build-linux:
     strategy:
       matrix:

scripts/ci/clang-format-check.sh

@@ -0,0 +1,24 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+base_ref="${1:-}"
+head_ref="${2:-HEAD}"
+
+if [[ -z "${base_ref}" || "${base_ref}" =~ ^0+$ ]]; then
+  base_ref="$(git rev-parse "${head_ref}^")"
+fi
+
+mapfile -t files < <(
+  git diff --name-only --diff-filter=ACMR "${base_ref}" "${head_ref}" -- app include src test \
+    | grep -E '\.(c|h|C|H|cpp|hpp|cc|hh|c\+\+|h\+\+|cxx|hxx)$' \
+    || true
+)
+
+if [[ "${#files[@]}" -eq 0 ]]; then
+  echo "No source files changed."
+  exit 0
+fi
+
+clang_format_bin="${CLANG_FORMAT_BIN:-clang-format-18}"
+
+"${clang_format_bin}" --dry-run -Werror "${files[@]}"