Comment on syntax errors (#656)

.github/workflows/lint_c.yml

@@ -43,7 +43,19 @@ jobs:
         uses: ./.github/actions/docker
 
       - name: 'Check syntax'
+        id: syntax_check
         uses: ./.github/actions/docker
-        continue-on-error: false
         with:
-          run: /syntax_check.sh
+          run: SET_GH_OUTPUT=1 /syntax_check.sh
+
+      - name: Report syntax errors
+        if: failure() && steps.syntax_check.outputs.errors && github.event.pull_request
+        uses: peter-evans/create-or-update-comment@v1
+        with:
+          issue-number: ${{ github.event.pull_request.number }}
+          body: |
+            Please fix following syntax errors:
+            ```
+            ${{ steps.syntax_check.outputs.errors }}
+            ```
+            You might want to run `docker compose exec dev /syntax_check.sh` for an auto-fix.

docker/syntax_check.sh

@@ -3,7 +3,6 @@
 # set -e
 
 CLANG_FORMAT_BIN="/usr/bin/clang-format-12"
-PATH="$HOME/.cargo/bin:${PATH}"
 
 PROJECT_DIR=$(pwd)
 
@@ -19,14 +18,20 @@ C_FILES=$(find . \
 
 ulimit -s 65536
 $CLANG_FORMAT_BIN --version
-$CLANG_FORMAT_BIN --verbose -style=file -n --Werror --ferror-limit=0 $C_FILES
-c_syntax_rc=$?
+errors=$($CLANG_FORMAT_BIN --verbose -style=file -n --Werror --ferror-limit=0 $C_FILES |& tee /dev/stderr | sed '/^Formatting/d')
 
-if [[ $c_syntax_rc -eq 0 ]]; then
+if [[ -z "$errors" ]]; then
     echo "Code looks fine for me!"
     exit 0
 fi
 
+if [[ -n "${SET_GH_OUTPUT}" ]]; then
+    errors="${errors//'%'/'%25'}"
+    errors="${errors//$'\n'/'%0A'}"
+    errors="${errors//$'\r'/'%0D'}"
+    echo "::set-output name=errors::$errors"
+fi
+
 read -p "Do you want fix syntax? (y/n): " confirm && [[ $confirm == [yY] || $confirm == [yY][eE][sS] ]] || exit 1
 
 cd $PROJECT_DIR