.github: add iwyu workflow

iwyu is short for "include what you use". this workflow is added to
identify missing "#include" and extraneous "#include" in C++ source
files.

This workflow is triggered when a pull request is created targetting
the "master" branch. It uses the clang-include-cleaner tool provided
by clang-tools package to analyze all the ".cc" and ".hh" source files.

Signed-off-by: Kefu Chai <[email protected]>

.github/workflows/iwyu.yaml

@@ -0,0 +1,77 @@
+name: iwyu
+
+on:
+  push:
+    branches:
+      - master
+  pull_request:
+    branches:
+      - master
+
+env:
+  CLANG_VERSION: 19
+  BUILD_TYPE: RelWithDebInfo
+  BUILD_DIR: build
+  CLEANER_OUTPUT_PATH: build/clang-include-cleaner.log
+
+permissions: {}
+
+jobs:
+  clang-include-cleaner:
+    name: "Analyze #includes in source files"
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          submodules: true
+      - name: Add scylla-ppa repo
+        env:
+          scylla_ppa_key: 6B2BFD3660EF3F5B
+        # "add-apt-repository ppa:scylladb/ppa" does not work, as jammy is not built in this ppa repo,
+        # so, let's use xenial instead. it is the latest version provided by ppa:scylladb/ppa
+        run: |
+          gpg_home=$(mktemp -d)
+          gpg --homedir $gpg_home --no-default-keyring --keyring ppa.key --keyserver keyserver.ubuntu.com --recv-key $scylla_ppa_key
+          sudo gpg --homedir $gpg_home --keyring ppa.key --export --output /etc/apt/trusted.gpg.d/ubuntu-scylladb-ppa.gpg $scylla_ppa_key
+          echo "deb http://ppa.launchpadcontent.net/scylladb/ppa/ubuntu xenial main" | sudo tee -a /etc/apt/sources.list.d/scylla-ppa.list
+      - name: Install clang-tools
+        run: |
+          sudo apt-get install -y curl
+          curl -fsSL https://apt.llvm.org/llvm-snapshot.gpg.key | sudo tee /etc/apt/trusted.gpg.d/apt.llvm.org.asc >/dev/null
+          echo "deb http://apt.llvm.org/jammy/ llvm-toolchain-jammy main" | sudo tee -a /etc/apt/sources.list.d/llvm.list
+          sudo apt-get update
+          sudo apt-get install -y clang-tools-$CLANG_VERSION
+      - name: Install more build dependencies
+        run: |
+          # - do not install java dependencies, which is not only not necessary,
+          #   and they include "python", which is not EOL and not available.
+          # - replace "scylla-libthrift010" with "libthrift-dev". because
+          #   scylla-libthrift010 : Depends: libssl1.0.0 (>= 1.0.1) but it is not installable
+          # - we don't perform tests, so minio is not necessary.
+          sed -i.orig \
+            -e '/tools\/.*\/install-dependencies.sh/d' \
+            -e 's/scylla-libthrift010-dev/libthrift-dev/' \
+            -e 's/(minio_download_jobs)/(true)/' \
+            ./install-dependencies.sh
+          sudo ./install-dependencies.sh
+          mv ./install-dependencies.sh{.orig,}
+      - name: Generate compilation database
+        run: |
+          cmake                                 \
+            -DCMAKE_BUILD_TYPE=$BUILD_TYPE      \
+            -DCMAKE_C_COMPILER=clang            \
+            -DCMAKE_CXX_COMPILER=clang++        \
+            -DCMAKE_EXPORT_COMPILE_COMMANDS=ON  \
+            -G Ninja                            \
+            -B $BUILD_DIR                       \
+            -S .
+      - name: clang-include-cleaner
+        run: |
+          # TODO: run multi-threaded
+          find $PWD -name "*.cc" -o -name ".hh" | \
+            xargs -t -n 1 \
+            clang-include-cleaner-$CLANG_VERSION --print=changes -p $BUILD_DIR > $CLEANER_OUTPUT_PATH 2>&1
+      - uses: actions/upload-artifact@v4
+        with:
+          name: Logs (clang-include-cleaner)
+          path: "./${{ env.CLEANER_OUTPUT_PATH }}"