Refactor setting compiler warnings

Author: DownerCase

CMakeLists.txt

@@ -202,6 +202,13 @@ option(ECAL_INSTALL_SAMPLE_SOURCES                  "Install the sources of eCAL
 option(ECAL_USE_NPCAP                               "Enable the eCAL Npcap Receiver (i.e. the Win10 performance fix)"  OFF)
 option(ECAL_USE_CLOCKLOCK_MUTEX                     "Use native mutex with monotonic clock (requires glibc >= 2.30)"   OFF)
 
+set(ECAL_EXTRA_COMPILER_ARGS "" CACHE STRING "; separated list of additional compiler arguments to use for eCAL code")
+include(./cmake/helper_functions/ecal_compiler_warnings.cmake)
+ecal_get_default_compiler_warnings(ecal_default_warnings)
+list(APPEND ecal_default_warnings ${ECAL_EXTRA_COMPILER_ARGS})
+set(ECAL_COMPILER_WARNINGS "${ecal_default_warnings}" CACHE STRING "Warning flags used for eCAL code")
+mark_as_advanced(FORCE ECAL_COMPILER_WARNINGS)
+
 # --------------------------------------------------------
 # ecal core configuration
 # --------------------------------------------------------
@@ -583,7 +590,6 @@ install(FILES ${eCAL_config} ${eCAL_config_version}
 
 install(FILES
   cmake/helper_functions/ecal_add_functions.cmake
-  cmake/helper_functions/ecal_compiler_warnings.cmake
   cmake/helper_functions/ecal_helper_functions.cmake
   cmake/helper_functions/ecal_install_functions.cmake
   DESTINATION ${${PROJECT_NAME}_install_cmake_dir}/helper_functions

cmake/helper_functions/ecal_add_functions.cmake

@@ -18,7 +18,17 @@
 
 include_guard(GLOBAL)
 
-include("${CMAKE_CURRENT_LIST_DIR}/ecal_compiler_warnings.cmake")
+# ECAL_COMPILER_WARNINGS is set by the root CMakeLists and may be user customized
+add_library(_ecal_warnings INTERFACE)
+target_compile_options(_ecal_warnings INTERFACE
+  "$<$<COMPILE_LANGUAGE:C,CXX>:${ECAL_COMPILER_WARNINGS}>"
+)
+
+function(ecal_add_compiler_warnings TARGET_NAME)
+  target_link_libraries("${TARGET_NAME}" PRIVATE
+    "$<BUILD_INTERFACE:_ecal_warnings>"
+  )
+endfunction()
 
 # This function will set the output names of the target according to eCAL conventions.
 function(ecal_add_app_console TARGET_NAME)

cmake/helper_functions/ecal_compiler_warnings.cmake

@@ -1,27 +1,17 @@
 include_guard(GLOBAL)
 
-add_library(_ecal_warnings INTERFACE)
+function(ecal_get_default_compiler_warnings cxx_out_var)
+  set(cxx_compiler_flags "")
 
-set(cxx_compiler_flags "")
+  if("${CMAKE_CXX_COMPILER_ID}" MATCHES "MSVC")
+    message(STATUS "MSVC detected - Adding flags")
+    set(cxx_compiler_flags "/MP" "/W4")
+  elseif("${CMAKE_CXX_COMPILER_ID}" MATCHES "GNU|Clang")
+    message(STATUS "Setting GNU/Clang flags")
+    set(cxx_compiler_flags "-Wall" "-Wextra")
+  else()
+    message(WARNING "Unknown compiler, will not set warning flags")
+  endif()
 
-if("${CMAKE_CXX_COMPILER_ID}" MATCHES "MSVC")
-  message(STATUS "MSVC detected - Adding flags")
-  set(cxx_compiler_flags "/MP" "/W4")
-elseif("${CMAKE_CXX_COMPILER_ID}" MATCHES "GNU|Clang")
-  message(STATUS "Setting GNU/Clang flags")
-  set(cxx_compiler_flags "-Wall" "-Wextra")
-else()
-  message(WARNING "Unknown compiler, will not set warning flags")
-endif()
-
-target_compile_options(_ecal_warnings INTERFACE
-  "$<$<COMPILE_LANGUAGE:C,CXX>:${cxx_compiler_flags}>"
-)
-
-unset(cxx_compiler_flags)
-
-function(ecal_add_compiler_warnings TARGET_NAME)
-  target_link_libraries("${TARGET_NAME}" PRIVATE
-    "$<BUILD_INTERFACE:_ecal_warnings>"
-  )
+  set("${cxx_out_var}" "${cxx_compiler_flags}" PARENT_SCOPE)
 endfunction()

ecal/service/CMakeLists.txt

@@ -19,26 +19,23 @@
 cmake_minimum_required(VERSION 3.16)
 project(ecal_service)
 
-# Root CMakeLists sets CMAKE_MODULE_PATH to include the correct path
-# If the module cannot be found warnings basic warnings will be applied instead
-include(helper_functions/ecal_compiler_warnings OPTIONAL RESULT_VARIABLE _ecal_warnings_found)
-if("${_ecal_warnings_found}" STREQUAL "NOTFOUND")
-  message(AUTHOR_WARNING
-    "  helper_functions/ecal_compiler_warnings.cmake not found.\n"
-    "  Add the path to CMAKE_MODULE_PATH to use warnings specified by the main eCAL repo."
-  )
-  add_library(_ecal_service_warnings INTERFACE)
-  set(cxx_compiler_flags "")
+if(TARGET _ecal_warnings)
+  # _ecal_warnings is the internal eCAL target containing the warning flags
+  # and will be absent if this is being built standalone
+  add_library(_ecal_service_warnings ALIAS _ecal_warnings)
+else()
+  # Otherwise, use a fallback implementation
   if("${CMAKE_CXX_COMPILER_ID}" MATCHES "MSVC")
-      set(cxx_compiler_flags "/MP" "/W4")
+    set(cxx_compiler_flags "/MP" "/W4")
   elseif("${CMAKE_CXX_COMPILER_ID}" MATCHES "GNU|Clang")
-      set(cxx_compiler_flags "-Wall" "-Wextra")
+    set(cxx_compiler_flags "-Wall" "-Wextra")
   else()
-      message(WARNING "Unknown compiler, will not set warning flags")
+    message(WARNING "Unknown compiler, will not set warning flags")
   endif()
-  target_compile_options(_ecal_service_warnings INTERFACE "${cxx_compiler_flags}")
-else()
-  add_library(_ecal_service_warnings ALIAS _ecal_warnings)
+
+  set(ECAL_SERVICE_COMPILER_WARNINGS "${cxx_compiler_flags}" CACHE STRING "Warning flags used for eCAL service code")
+  add_library(_ecal_service_warnings INTERFACE)
+  target_compile_options(_ecal_service_warnings INTERFACE "${ECAL_SERVICE_COMPILER_WARNINGS}")
 endif()
 
 # Main library