Add cppcheck to CI

Suppress some things we are okay with

.gitlab-ci.yml

@@ -8,6 +8,7 @@ include:
       - /gitlab-templates/linux-qt6-next.yml
       - /gitlab-templates/linux-qt6-static.yml
       - /gitlab-templates/android-qt6.yml
+      - /gitlab-templates/cppcheck.yml
       - /gitlab-templates/windows-qt6.yml
       - /gitlab-templates/freebsd-qt6.yml
       - /gitlab-templates/alpine-qt6.yml

.kde-ci.yml

@@ -9,4 +9,7 @@ Options:
  require-passing-tests-on: ['Linux', 'FreeBSD', 'Windows']
  cmake-options: -DBUILD_EXAMPLES=ON
  cppcheck-ignore-files: ['templates/']
+ cppcheck-arguments:
+  - '--enable=warning,style,performance'
+  - '--suppress-xml=cppcheck-suppressions.xml'
  run-qmllint: true

cppcheck-suppressions.xml

@@ -0,0 +1,14 @@
+<?xml version="1.0"?>
+<suppressions>
+<suppress>
+<id>returnByReference</id>
+</suppress>
+<suppress>
+<id>constParameterPointer</id>
+</suppress>
+<!-- generic -->
+<suppress>
+<id>useStlAlgorithm</id>
+</suppress>
+<!-- embedded 3rdparty -->
+</suppressions>