[ci] adds clang-format action (#833)

This patch adds an action that runs clang-format on pushes to main and
when opening pull requests. The action runs `clang-format` with version
`18.1.8` on the `src/` and `test/` folders. If the pushed code contains
ill-formatted code, the actions displays the diff.

Also adds the required steps in order to install clang-format-18 in the
Dockerfile.

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

@@ -0,0 +1,20 @@
+name: check-clang-format
+
+on:
+  push:
+    branches:
+      - main
+  pull_request:
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: actions/checkout@v2
+    - uses: DoozyX/[email protected]
+      with:
+        source: 'src test'
+        exclude: './third_party ./external'
+        extensions: 'h,cpp'
+        clangFormatVersion: 18.1.3

containers/daphne-dev.Dockerfile

@@ -33,8 +33,9 @@ RUN apt-get -qq -y update && apt-get -y upgrade && apt-get -y --no-install-recom
     build-essential clang gfortran lld llvm llvm-18-tools ninja-build openjdk-11-jdk-headless pkg-config python3-numpy python3-pandas \
     vim nano rsync sudo iputils-ping virtualenv openssh-server iproute2 git htop gdb lldb lld gpg-agent net-tools \
     software-properties-common ca-certificates file unzip wget tar zstd \
-    ccache python3-pip python3-networkx python3-dev graphviz-dev \
+    ccache python3-pip python3-networkx python3-dev graphviz-dev clang-format \
     && apt-get clean && rm -rf /var/lib/apt/lists/*
+
 COPY --from=daphneeu/daphne-deps /usr/local/bin/ /usr/local/bin/
 COPY --from=daphneeu/daphne-deps /usr/local/include/ /usr/local/include/
 COPY --from=daphneeu/daphne-deps /usr/local/lib/ /usr/local/lib/