From bce7e52d4e70a8d8d824596654bac85545bf9d07 Mon Sep 17 00:00:00 2001
From: Karthik Nayak <karthik.188@gmail.com>
Date: Tue, 23 Jul 2024 10:21:09 +0200
Subject: [PATCH] ci: run style check on GitHub and GitLab

We don't run style checks on our CI, even though we have a
'.clang-format' setup in the repository. Let's add one, the job will
validate only against the new commits added and will only run on merge
requests. Since we're introducing it for the first time, let's allow
this job to fail, so we can validate if this is useful and eventually
enforce it.

For GitHub, we allow the job to pass by adding 'continue-on-error: true'
to the workflow. This means the job would show as passed, even if the
style check failed. To know the status of the job, users have to
manually check the logs.

For GitLab, we allow the job to pass by adding 'allow_failure: true', to
the job. Unlike GitHub, here the job will show as failed with a yellow
warning symbol, but the pipeline would still show as passed.

Also for GitLab, we use the 'CI_MERGE_REQUEST_TARGET_BRANCH_SHA'
variable by default to obtain the base SHA of the merged pipeline (which
is only available for merged pipelines [1]). Otherwise we use the
'CI_MERGE_REQUEST_DIFF_BASE_SHA' variable.

[1]: https://docs.gitlab.com/ee/ci/variables/predefined_variables.html#predefined-variables-for-merge-request-pipelines

Helped-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Karthik Nayak <karthik.188@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 .github/workflows/check-style.yml | 34 +++++++++++++++++++++++++++++++
 .gitlab-ci.yml                    | 18 ++++++++++++++++
 ci/install-dependencies.sh        |  4 ++++
 ci/run-style-check.sh             |  8 ++++++++
 4 files changed, 64 insertions(+)
 create mode 100644 .github/workflows/check-style.yml
 create mode 100755 ci/run-style-check.sh

diff --git a/.github/workflows/check-style.yml b/.github/workflows/check-style.yml
new file mode 100644
index 0000000000..c052a5df23
--- /dev/null
+++ b/.github/workflows/check-style.yml
@@ -0,0 +1,34 @@
+name: check-style
+
+# Get the repository with all commits to ensure that we can analyze
+# all of the commits contributed via the Pull Request.
+
+on:
+  pull_request:
+    types: [opened, synchronize]
+
+# Avoid unnecessary builds. Unlike the main CI jobs, these are not
+# ci-configurable (but could be).
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  check-style:
+    env:
+      CC: clang
+      jobname: ClangFormat
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v4
+      with:
+        fetch-depth: 0
+
+    - run: ci/install-dependencies.sh
+
+    - name: git clang-format
+      continue-on-error: true
+      id: check_out
+      run: |
+        ./ci/run-style-check.sh \
+          "${{github.event.pull_request.base.sha}}"
diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 37b991e080..2886f6e182 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -123,6 +123,24 @@ check-whitespace:
   rules:
     - if: $CI_PIPELINE_SOURCE == 'merge_request_event'
 
+check-style:
+  image: ubuntu:latest
+  allow_failure: true
+  variables:
+    CC: clang
+    jobname: ClangFormat
+  before_script:
+    - ./ci/install-dependencies.sh
+  # Since $CI_MERGE_REQUEST_TARGET_BRANCH_SHA is only defined for merged
+  # pipelines, we fallback to $CI_MERGE_REQUEST_DIFF_BASE_SHA, which should
+  # be defined in all pipelines.
+  script:
+    - |
+      R=${CI_MERGE_REQUEST_TARGET_BRANCH_SHA-${CI_MERGE_REQUEST_DIFF_BASE_SHA:?}} || exit
+      ./ci/run-style-check.sh "$R"
+  rules:
+    - if: $CI_PIPELINE_SOURCE == 'merge_request_event'
+
 documentation:
   image: ubuntu:latest
   variables:
diff --git a/ci/install-dependencies.sh b/ci/install-dependencies.sh
index 6ec0f85972..fb34ced8f0 100755
--- a/ci/install-dependencies.sh
+++ b/ci/install-dependencies.sh
@@ -87,6 +87,10 @@ macos-*)
 esac
 
 case "$jobname" in
+ClangFormat)
+	sudo apt-get -q update
+	sudo apt-get -q -y install clang-format
+	;;
 StaticAnalysis)
 	sudo apt-get -q update
 	sudo apt-get -q -y install coccinelle libcurl4-openssl-dev libssl-dev \
diff --git a/ci/run-style-check.sh b/ci/run-style-check.sh
new file mode 100755
index 0000000000..76dd37d22b
--- /dev/null
+++ b/ci/run-style-check.sh
@@ -0,0 +1,8 @@
+#!/bin/sh
+#
+# Perform style check
+#
+
+baseCommit=$1
+
+git clang-format --style file --diff --extensions c,h "$baseCommit"