Enable clang-tidy at target level (#1844)

Follow up
#1824 (comment)

Signed-off-by: Balakrishna Avulapati <[email protected]>
Signed-off-by: Juan Cruz Viotti <[email protected]>
Co-authored-by: Juan Cruz Viotti <[email protected]>

Author: bavulapati

CMakeLists.txt

@@ -32,7 +32,6 @@ include(Sourcemeta)
 # Don't force downstream consumers on this
 if(PROJECT_IS_TOP_LEVEL)
   sourcemeta_enable_simd()
-  sourcemeta_clang_tidy_attempt_enable()
 endif()
 
 # TODO: Turn this into a re-usable utility CMake function
@@ -124,7 +123,6 @@ endif()
 if(PROJECT_IS_TOP_LEVEL)
   # TODO: Try once more to enable this per target,
   # so, we don't need to manually disable it here
-  sourcemeta_clang_tidy_attempt_disable()
   sourcemeta_target_clang_format(SOURCES
     src/*.h src/*.cc
     benchmark/*.h benchmark/*.cc

cmake/common/clang-tidy.cmake

@@ -77,48 +77,40 @@ function(sourcemeta_clang_tidy_attempt_install)
 endfunction()
 
 function(sourcemeta_clang_tidy_attempt_enable)
-  cmake_parse_arguments(SOURCEMETA_TARGET_CLANG_TIDY "REQUIRED" "" "" ${ARGN})
-
-  if(SOURCEMETA_COMPILER_LLVM)
-    message(STATUS "Enabling ClangTidy alongside compilation")
-  else()
-    message(STATUS "Ignoring ClangTidy setup on a compiler other than LLVM")
-    return()
+  cmake_parse_arguments(SOURCEMETA_TARGET_CLANG_TIDY_ATTEMPT_ENABLE "" "TARGET" "" ${ARGN})
+  if(NOT SOURCEMETA_TARGET_CLANG_TIDY_ATTEMPT_ENABLE_TARGET)
+    message(FATAL_ERROR "You must pass the target name using the TARGET option")
   endif()
 
-  sourcemeta_clang_tidy_attempt_install(OUTPUT_DIRECTORY "${CMAKE_CURRENT_BINARY_DIR}/bin")
-
-  if(SOURCEMETA_TARGET_CLANG_TIDY_REQUIRED)
-    find_program(CLANG_TIDY_BIN NAMES clang-tidy NO_DEFAULT_PATH
-      PATHS "${CMAKE_CURRENT_BINARY_DIR}/bin")
-    if(NOT CLANG_TIDY_BIN)
-      find_program(CLANG_TIDY_BIN NAMES clang-tidy REQUIRED)
-    endif()
+  # TODO: Support other platforms too, like Linux
+  if(APPLE AND SOURCEMETA_COMPILER_LLVM)
+    message(STATUS "Enabling ClangTidy alongside compilation for target ${SOURCEMETA_TARGET_CLANG_TIDY_ATTEMPT_ENABLE_TARGET}")
   else()
-    find_program(CLANG_TIDY_BIN NAMES clang-tidy NO_DEFAULT_PATH
-      PATHS "${CMAKE_CURRENT_BINARY_DIR}/bin")
-    if(NOT CLANG_TIDY_BIN)
-      find_program(CLANG_TIDY_BIN NAMES clang-tidy)
-    endif()
+    return()
   endif()
 
-  set(CLANG_TIDY_CONFIG "${CMAKE_CURRENT_FUNCTION_LIST_DIR}/clang-tidy.config")
-
-  # TODO: Support other platforms too, like Linux
-  if(APPLE)
+  # We rely on this cache variable to not pre-compute the ClangTidy
+  # setup over and over again for every single target
+  if(NOT SOURCEMETA_CXX_CLANG_TIDY)
+    sourcemeta_clang_tidy_attempt_install(
+      OUTPUT_DIRECTORY "${PROJECT_BINARY_DIR}/bin")
+    find_program(CLANG_TIDY_BIN NAMES clang-tidy
+        NO_DEFAULT_PATH
+        PATHS "${PROJECT_BINARY_DIR}/bin"
+        REQUIRED)
+    set(CLANG_TIDY_CONFIG "${CMAKE_CURRENT_FUNCTION_LIST_DIR}/clang-tidy.config")
     execute_process(COMMAND xcrun --show-sdk-path
-      OUTPUT_VARIABLE MACOSX_SDK_PATH OUTPUT_STRIP_TRAILING_WHITESPACE)
+        OUTPUT_VARIABLE MACOSX_SDK_PATH OUTPUT_STRIP_TRAILING_WHITESPACE)
     execute_process(COMMAND "${CMAKE_CXX_COMPILER}" -print-resource-dir
-      OUTPUT_VARIABLE MACOSX_RESOURCE_PATH OUTPUT_STRIP_TRAILING_WHITESPACE)
-    set(CMAKE_CXX_CLANG_TIDY
-      "${CLANG_TIDY_BIN};--config-file=${CLANG_TIDY_CONFIG};-header-filter=${PROJECT_SOURCE_DIR}/src/*"
-      "--extra-arg=-isysroot"
-      "--extra-arg=${MACOSX_SDK_PATH}"
-      "--extra-arg=-resource-dir=${MACOSX_RESOURCE_PATH}"
-      PARENT_SCOPE)
+        OUTPUT_VARIABLE MACOSX_RESOURCE_PATH OUTPUT_STRIP_TRAILING_WHITESPACE)
+    set(SOURCEMETA_CXX_CLANG_TIDY
+        "${CLANG_TIDY_BIN};--config-file=${CLANG_TIDY_CONFIG};-header-filter=${PROJECT_SOURCE_DIR}/src/*"
+        "--extra-arg=-isysroot"
+        "--extra-arg=${MACOSX_SDK_PATH}"
+        "--extra-arg=-resource-dir=${MACOSX_RESOURCE_PATH}"
+        CACHE STRING "CXX_CLANG_TIDY")
   endif()
-endfunction()
 
-function(sourcemeta_clang_tidy_attempt_disable)
-  unset(CMAKE_CXX_CLANG_TIDY PARENT_SCOPE)
+  set_target_properties("${SOURCEMETA_TARGET_CLANG_TIDY_ATTEMPT_ENABLE_TARGET}"
+    PROPERTIES CXX_CLANG_TIDY "${SOURCEMETA_CXX_CLANG_TIDY}")
 endfunction()

cmake/common/targets/library.cmake

@@ -115,6 +115,8 @@ function(sourcemeta_library)
     target_include_directories(${TARGET_NAME}
       PUBLIC "$<BUILD_INTERFACE:${CMAKE_CURRENT_BINARY_DIR}/include>")
   endif()
+
+  sourcemeta_clang_tidy_attempt_enable(TARGET "${TARGET_NAME}")
 endfunction()
 
 function(sourcemeta_library_install)