[cmake] Introduce run-clang-tidy target.

As suggested in Prof. CMake, Craig Scott.

.clang-tidy

 ---
-Checks: '-*,clang-diagnostic-*,clang-analyzer-*,cppcoreguidelines-pro-type-member-init, *explicit-conversions*, google-explicit-constructor, google-readability-braces-around-statements, modernize-loop-convert, modernize-use-default-member-init, modernize-use-emplace, modernize-use-using, readability-braces-around-statements, readability-else-after-return, readability-named-parameter, *readability-namespace-comments, *readability-inconsistent-*, readability-redundant-member-init, readability-simplify-boolean-expr, readability-string-compare'
+Checks: >
+  -*
+  ,clang-diagnostic-*,
+  clang-analyzer-*,
+  cppcoreguidelines-pro-type-member-init,
+  *explicit-conversions*,
+  google-explicit-constructor,
+  google-readability-braces-around-statements,
+  modernize-loop-convert,
+  modernize-use-default-member-init,
+  modernize-use-emplace,
+  modernize-use-using,
+  readability-braces-around-statements,
+  readability-else-after-return,
+  readability-named-parameter,
+  *readability-namespace-comments,
+  *readability-inconsistent-*,
+  readability-redundant-member-init,
+  readability-simplify-boolean-expr,
+  readability-string-compare
 
-WarningsAsErrors: ''
-HeaderFilterRegex: '.*'
+WarningsAsErrors: ""
+HeaderFilterRegex: ".*"
 AnalyzeTemporaryDtors: false
-FormatStyle:     file
+FormatStyle: file
 CheckOptions:
-  - key:             google-readability-braces-around-statements.ShortStatementLines
-    value:           '1'
-  - key:             hicpp-braces-around-statements.ShortStatementLines
-    value:           '1'
-  - key:             readability-braces-around-statements.ShortStatementLines
-    value:           '1'
+  - key: google-readability-braces-around-statements.ShortStatementLines
+    value: "1"
+  - key: hicpp-braces-around-statements.ShortStatementLines
+    value: "1"
+  - key: readability-braces-around-statements.ShortStatementLines
+    value: "1"

CMakeLists.txt

@@ -85,6 +85,7 @@ include(DocumentationSetup)
 include(test/Test)
 include(Coverage)
 include(CppCheck)
+include(ClangTidy)
 
 # ---- More Options ----
 

scripts/ci/jobs/clang-tidy.yml

@@ -6,18 +6,12 @@ clang tidy:
   needs: []
   variables:
     BUILD_DIR: "./build-tidy"
-    CMAKE_ARGS: "-DBUILD_SHARED_LIBS=ON -DBUILD_TESTING=OFF -DCMAKE_CXX_CLANG_TIDY=clang-tidy;--extra-arg=-Wno-error=unknown-warning-option"
   script:
     - rm -rf $BUILD_DIR
     - mkdir -p $BUILD_DIR
     - cd $BUILD_DIR
     - >
       cmake .. -G Ninja
-      $CMAKE_ARGS
+      -DBUILD_SHARED_LIBS=ON -DBUILD_TESTING=OFF
       -DCMAKE_BUILD_TYPE=$BUILD_TYPE
-    - cmake --build . > >(tee make.txt)
-  artifacts:
-    # No report yet: https://gitlab.com/gitlab-org/gitlab/-/issues/3985
-    paths:
-      - $BUILD_DIR/make.txt
-    expire_in: 1 week
+    - cmake --build . --target run-clang-tidy

scripts/cmake/ClangTidy.cmake

+if(NOT PROJECT_IS_TOP_LEVEL)
+    return()
+endif()
+
+find_program(CLANG_TIDY_EXECUTABLE clang-tidy)
+find_program(RUN_CLANG_TIDY_EXECUTABLE run-clang-tidy)
+if(CLANG_TIDY_EXECUTABLE AND RUN_CLANG_TIDY_EXECUTABLE)
+    set(CMAKE_EXPORT_COMPILE_COMMANDS TRUE)
+    add_custom_target(
+        run-clang-tidy
+        COMMAND ${RUN_CLANG_TIDY_EXECUTABLE} -clang-tidy-binary
+                ${CLANG_TIDY_EXECUTABLE} -p ${CMAKE_BINARY_DIR}
+        WORKING_DIRECTORY ${PROJECT_SOURCE_DIR}
+        USES_TERMINAL
+    )
+    # Disable clang-tidy in cpm build dirs, hack: Disable all checks, but one
+    # check has to be enabled.
+    file(WRITE ${PROJECT_BINARY_DIR}/_deps/.clang-tidy
+         "Checks: '-*,boost-use-to-string'"
+    )
+endif()