Add lint ci job

Author: kateinoigakukun

.github/workflows/build.yml

@@ -16,6 +16,13 @@ on:
         required: true
 
 jobs:
+  lint:
+    runs-on: ubuntu-20.04
+    steps:
+      - uses: actions/checkout@v2
+      - run: sudo apt-get install clang-format
+      - run: ./scripts/clang-format-diff.sh
+
   build-builder-image:
     strategy:
       fail-fast: false

scripts/clang-format-diff.sh

@@ -0,0 +1,18 @@
+#!/bin/bash
+
+set -eo pipefail
+
+if [ -n "$1" ]; then
+  BASE_BRANCH="$1"
+elif [ -n "$GITHUB_EVENT_BEFORE" ] && [ "push" = "$GITHUB_EVENT_NAME" ]; then
+  BASE_BRANCH="$GITHUB_EVENT_BEFORE"
+elif [ -n "$GITHUB_BASE_REF" ]; then
+  BASE_BRANCH="origin/$GITHUB_BASE_REF"
+else
+  BASE_BRANCH="@{upstream}"
+fi
+
+MERGE_BASE=$(git merge-base $BASE_BRANCH HEAD)
+
+git diff -U0 --no-color $MERGE_BASE -- '*.c' '*.h' | clang-format-diff -i -p1
+exit $?