github actions: Add an include-what-you-need check

Probably lots of issues right now, so let's fix it step by step
by only checking modified files - new PRs should fix their
modified files.

Signed-off-by: Bernd Schubert <bernd@bsbernd.com>

diff --git a/.github/workflows/iwyi-check.yml b/.github/workflows/iwyi-check.yml
new file mode 100644 (file)
index 0000000..3751f35
--- /dev/null
+++ b/.github/workflows/iwyi-check.yml
@@ -0,0 +1,51 @@
+# check for uneeded header includes of modified files
+# False positives can be avoided with
+# #include "some_include.h"  // IWYU pragma: keep
+
+name: IWYU Check
+
+on:
+  pull_request:
+    branches: [ main ]
+    paths:
+      - '**.cpp'
+      - '**.hpp'
+      - '**.c'
+      - '**.h'
+
+jobs:
+  iwyu-check:
+    name: Include What You Use Check
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
+        with:
+          fetch-depth: 0
+
+      - name: Install IWYU
+        run: |
+          sudo apt-get update
+          sudo apt-get install -y iwyu
+
+      - name: Get changed files
+        id: changed-files
+        run: |
+          git fetch origin ${{ github.base_ref }}
+          base_commit=$(git merge-base FETCH_HEAD ${{ github.event.pull_request.head.sha }})
+          changed_files=$(git diff --name-only $base_commit HEAD | grep -E '\.(cpp|hpp|c|h)$' || true)
+          echo "files=$changed_files" >> $GITHUB_OUTPUT
+
+      - name: Run IWYU checks on changed files
+        if: steps.changed-files.outputs.files != ''
+        run: |
+          echo "${{ steps.changed-files.outputs.files }}" | while read -r file; do
+            if [ -f "$file" ]; then
+              echo "Checking $file..."
+              iwyu -Xiwyu --mapping_file=iwyu.imp "$file" 2>&1 || true
+            fi
+          done | tee iwyu_output.txt
+          if grep -q "should add these lines:" iwyu_output.txt || \
+             grep -q "should remove these lines:" iwyu_output.txt; then
+            echo "IWYU checks failed. Please fix the includes in the affected files."
+            exit 1
+          fi