Add GH action enforcing clang-format (#176)

Author: bigbrett

.github/workflows/clang-format-check.yml

@@ -0,0 +1,65 @@
+name: Clang Format Check
+
+on:
+  pull_request:
+    types: [opened, synchronize, reopened]
+
+jobs:
+  clang-format-check:
+    name: Check PR formatting with clang-format-15
+    runs-on: ubuntu-latest
+
+    steps:
+    - name: Checkout code
+      uses: actions/checkout@v4
+      with:
+        fetch-depth: 0  # Need full history to compare with main branch
+
+    - name: Install clang-format-15
+      run: |
+        sudo apt-get install -y clang-format-15
+
+    - name: Fetch base branch
+      env:
+        BASE_REF: ${{ github.event.pull_request.base.ref }}
+      run: |
+        git fetch origin "$BASE_REF:$BASE_REF"
+
+    - name: Check formatting
+      env:
+        BASE_SHA: ${{ github.event.pull_request.base.sha }}
+        BASE_REF: ${{ github.event.pull_request.base.ref }}
+      run: |
+        echo "Running git-clang-format-15 to check for formatting issues..."
+        echo "Comparing against base branch: $BASE_REF"
+
+        # Create a temporary file for the diff and ensure cleanup
+        DIFF_FILE="$(mktemp)"
+        trap 'rm -f "$DIFF_FILE"' EXIT
+
+        # Run git-clang-format against the PR base commit and capture status safely under set -e
+        if git-clang-format-15 --diff "$BASE_REF" --binary clang-format-15 > "$DIFF_FILE"; then
+          status=0
+        else
+          status=$?
+        fi
+        if [ "$status" -eq 0 ]; then
+          echo "✅ Code is properly formatted!"
+          exit 0
+        elif [ "$status" -eq 1 ]; then
+          echo "❌ Code formatting issues detected!"
+          echo ""
+          echo "The following changes would be made by clang-format-15:"
+          echo "=================================================="
+          cat "$DIFF_FILE"
+          echo "=================================================="
+          echo ""
+          echo "Please run the following command locally on your feature branch and commit the changes:"
+          echo "  git-clang-format-15 --binary clang-format-15 $BASE_REF"
+          exit 1
+        else
+          echo "❌ git-clang-format-15 failed with exit code $status"
+          echo "Output (if any):"
+          cat "$DIFF_FILE"
+          exit 1
+        fi