CI: run clang-format to make sure the coding style is correct

Part-of: <https://gitlab.freedesktop.org/libinput/libei/-/merge_requests/390>

.gitlab-ci.yml

@@ -40,7 +40,7 @@ variables:
   # See the documentation here:                                                 #
   # https://wayland.freedesktop.org/libinput/doc/latest/building_libinput.html  #
   ###############################################################################
-  FEDORA_PACKAGES: 'git diffutils gcc gcc-c++ pkgconf-pkg-config systemd-devel libxkbcommon-devel libxml2 doxygen python3-pytest python3-dbusmock python3-jinja2 python3-pip python3-pyyaml golang libabigail '
+  FEDORA_PACKAGES: 'git diffutils gcc gcc-c++ pkgconf-pkg-config systemd-devel libxkbcommon-devel libxml2 doxygen python3-pytest python3-dbusmock python3-jinja2 python3-pip python3-pyyaml golang libabigail clang-tools-extra '
   FEDORA_PIP_PACKAGES: 'meson ninja structlog strenum '
   DEBIAN_PACKAGES: 'git gcc g++ pkg-config libsystemd-dev libxkbcommon-dev libxml2 doxygen python3-pytest python3-dbusmock python3-jinja2 python3-pip python3-yaml '
   DEBIAN_PIP_PACKAGES: 'meson ninja structlog strenum '
@@ -50,8 +50,8 @@ variables:
   # changing these will force rebuilding the associated image
   # Note: these tags have no meaning and are not tied to a particular
   # libinput version
-  FEDORA_TAG:  '2025-05-19.1'
-  DEBIAN_TAG:  '2025-05-19.1'
+  FEDORA_TAG:  '2026-05-13.0'
+  DEBIAN_TAG:  '2026-05-13.0'
 
   FDO_UPSTREAM_REPO: libinput/libei
 
@@ -200,6 +200,21 @@ debian:bullseye@container-prep:
       junit: $MESON_BUILDDIR/meson-logs/.junit.xml
   dependencies: []
 
+# Format C source files with clang-format
+#
+clang-format@fedora:43:
+  extends:
+    - .fdo.distribution-image@fedora
+    - .policy
+  stage: build
+  variables:
+    FDO_DISTRIBUTION_VERSION: '43'
+    FDO_DISTRIBUTION_TAG: $FEDORA_TAG
+  needs:
+    - "fedora:43@container-prep"
+  script:
+    - clang-format --dry-run --Werror src/*.[ch] test/*.[ch] tools/*.[ch]
+
 #
 # Fedora
 #

.gitlab-ci/ci.template

@@ -198,6 +198,24 @@ python-ruff:
       junit: $MESON_BUILDDIR/meson-logs/.junit.xml
   dependencies: []
 
+# Format C source files with clang-format
+#
+{% for distro in distributions if distro.use_for_custom_build_tests %}
+{% set version = "{}".format(distro.versions|last()) %}
+clang-format@{{distro.name}}:{{version}}:
+  extends:
+    - .fdo.distribution-image@{{distro.name}}
+    - .policy
+  stage: build
+  variables:
+    FDO_DISTRIBUTION_VERSION: '{{version}}'
+    FDO_DISTRIBUTION_TAG: ${{distro.name.upper()}}_TAG
+  needs:
+    - "{{distro.name}}:{{version}}@container-prep"
+  script:
+    - clang-format --dry-run --Werror src/*.[ch] test/*.[ch] tools/*.[ch]
+{% endfor %}
+
 #
 # Fedora
 #

.gitlab-ci/config.yml

@@ -3,7 +3,7 @@
 #
 
 # We're happy to rebuild all containers when one changes.
-.default_tag: &default_tag '2025-05-19.1'
+.default_tag: &default_tag '2026-05-13.0'
 
 last_abi_break: abe85e051e7029bfd2e7913ab980a9e0042b6d0d
 minimum_meson_version: 0.57.0
@@ -31,6 +31,7 @@ distributions:
       - python3-pyyaml
       - golang   # for documentation only
       - libabigail  # for abidiff only
+      - clang-tools-extra  # for clang-format
     pips:
       - meson
       - ninja