ci: generate the style patch artifact

.gitlab-ci.yml

@@ -68,9 +68,33 @@ Check licenses:
   interruptible: true
 
 Check style:
-  extends: .common_pre_commit
+  extends:
+    - .colorized
+    - .common_pre_commit
+  variables:
+    STYLE_PATCH: style.patch
   script:
-    - pre-commit run --show-diff-on-failure --color=always --all-files
+    - |
+      # pre-commit run --all-files
+      pre-commit run --color=always --all-files || {
+        printf "${RED}The source code does not meet the style requirements:\n
+        ${CI_PROJECT_URL}/-/blob/${CI_DEFAULT_BRANCH}/CONTRIBUTING.md#coding-style.\n${DEFAULT}"
+        git diff --ignore-submodules --patch-with-raw > "${STYLE_PATCH}"
+        test -s "${STYLE_PATCH}" && {
+          printf "${RED}At least some of the issues can be resolved with the patch (see artifacts):\n
+        ${CI_JOB_URL}/artifacts/raw/${STYLE_PATCH}.\n${DEFAULT}"
+        } || {
+          printf "${RED}The issues cannot be resolved with a patch.\n${DEFAULT}"
+          rm -rf "${STYLE_PATCH}"
+        }
+        exit 1
+      }
+  artifacts:
+    paths:
+      - ${STYLE_PATCH}
+    expose_as: 'Style Patch'
+    when: on_failure
+
   rules:
     - if: $CI_PIPELINE_SOURCE == "web"
       when: manual

CONTRIBUTING.md

-# Formatting and linting
+# Coding style
 We use [`pre-commit`](https://pre-commit.com) hooks to maintain a set of
 formatting and linting rules. Although there is a CI job that runs for each
 merge request and checks whether the contribution does not break the rules, we