Use C++ (not C) warning flags for GTK client (#4395)

Use the opportunity to reduce duplication.

CMakeLists.txt

@@ -603,6 +603,12 @@ else()
     unset(CMAKE_REQUIRED_FLAGS)
 endif()
 
+string(REPLACE ";" "$<SEMICOLON>" C_WARNING_FLAGS_GENEX "${C_WARNING_FLAGS}")
+string(REPLACE ";" "$<SEMICOLON>" CXX_WARNING_FLAGS_GENEX "${CXX_WARNING_FLAGS}")
+add_compile_options(
+    $<$<COMPILE_LANGUAGE:C>:${C_WARNING_FLAGS_GENEX}>
+    $<$<COMPILE_LANGUAGE:CXX>:${CXX_WARNING_FLAGS_GENEX}>)
+
 ###
 
 include(LargeFileSupport)

cli/CMakeLists.txt

@@ -1,7 +1,5 @@
 project(trcli)
 
-add_compile_options(${CXX_WARNING_FLAGS})
-
 include_directories(${CMAKE_SOURCE_DIR})
 
 tr_win32_app_info(${PROJECT_NAME}_WIN32_RC_FILE

daemon/CMakeLists.txt

@@ -4,8 +4,6 @@ if(WITH_SYSTEMD)
     add_definitions(-DUSE_SYSTEMD)
 endif()
 
-add_compile_options(${CXX_WARNING_FLAGS})
-
 include_directories(
     ${CMAKE_SOURCE_DIR}
 )

gtk/CMakeLists.txt

@@ -1,6 +1,5 @@
 project(trgtk)
 
-add_compile_options(${C_WARNING_FLAGS})
 if(ENABLE_WERROR)
     add_compile_options($<IF:$<CXX_COMPILER_ID:MSVC>,/WX,-Werror>)
 endif()

libtransmission/CMakeLists.txt

@@ -89,11 +89,6 @@ set(PROJECT_FILES
   webseed.cc
 )
 
-string(REPLACE ";" " " CXX_WARNING_FLAGS_STR "${CXX_WARNING_FLAGS}")
-foreach(FILE ${PROJECT_FILES})
-  set_source_files_properties(${FILE} PROPERTIES COMPILE_FLAGS "${CXX_WARNING_FLAGS_STR}")
-endforeach()
-
 set(THIRD_PARTY_FILES
   jsonsl.c
   wildmat.c

qt/CMakeLists.txt

@@ -57,11 +57,6 @@ set(${PROJECT_NAME}_SOURCES
     WatchDir.cc
 )
 
-string(REPLACE ";" " " CXX_WARNING_FLAGS_STR "${CXX_WARNING_FLAGS}")
-foreach(FILE ${${PROJECT_NAME}_SOURCES})
-    set_source_files_properties(${FILE} PROPERTIES COMPILE_FLAGS "${CXX_WARNING_FLAGS_STR}")
-endforeach()
-
 if (NOT ENABLE_QT_COM_INTEROP)
     set_source_files_properties(ComInteropHelper.cc PROPERTIES HEADER_FILE_ONLY ON)
 endif()

tests/libtransmission/CMakeLists.txt

@@ -73,7 +73,6 @@ target_include_directories(libtransmission-test SYSTEM
 
 target_compile_options(libtransmission-test
     PRIVATE
-        ${CXX_WARNING_FLAGS}
         $<$<OR:$<CXX_COMPILER_ID:GNU>,$<CXX_COMPILER_ID:Clang>>:-Wno-sign-compare>) # patches welcomed
 
 target_link_libraries(libtransmission-test

utils/CMakeLists.txt

@@ -1,7 +1,5 @@
 project(trutils)
 
-add_compile_options(${CXX_WARNING_FLAGS})
-
 include_directories(
     ${CMAKE_SOURCE_DIR}
 )