CMAKE: Fix the C/CXX flag passing

CMakeLists.txt

@@ -52,6 +52,10 @@ set(RelWithDebInfo_GNU_C_FLAGS   -Wno-switch)
 set(Release_GNU_C_FLAGS            -Wno-switch)
 set(RelWithDebInfo_Clang_C_FLAGS   -Wno-switch-enum)
 set(Release_Clang_C_FLAGS          -Wno-switch-enum)
+set(RelWithDebInfo_GNU_CXX_FLAGS   $<$<COMPILE_LANGUAGE:CXX>:-Wno-switch)
+set(Release_GNU_CXX_FLAGS          $<$<COMPILE_LANGUAGE:CXX>:-Wno-switch)
+set(RelWithDebInfo_Clang_CXX_FLAGS $<$<COMPILE_LANGUAGE:CXX>:-Wno-switch-enum)
+set(Release_Clang_CXX_FLAGS        $<$<COMPILE_LANGUAGE:CXX>:-Wno-switch-enum)
 
 # Common flags, also per compiler
 set(COMMON_C_FLAGS
@@ -314,13 +318,15 @@ target_compile_options(lektord PRIVATE
     ${COMMON_C_FLAGS}
     ${${CMAKE_C_COMPILER_ID}_C_FLAGS}
     ${${CMAKE_CXX_COMPILER_ID}_CXX_FLAGS}
-    ${${CMAKE_C_COMPILER_ID}_${CMAKE_C_COMPILER_ID}_C_FLAGS}
+    ${${CMAKE_BUILD_TYPE}_${CMAKE_C_COMPILER_ID}_C_FLAGS}
+    ${${CMAKE_BUILD_TYPE}_${CMAKE_CXX_COMPILER_ID}_C_FLAGS}
 )
 target_compile_options(lkt PRIVATE
     ${COMMON_C_FLAGS}
     ${${CMAKE_C_COMPILER_ID}_C_FLAGS}
     ${${CMAKE_CXX_COMPILER_ID}_CXX_FLAGS}
-    ${${CMAKE_C_COMPILER_ID}_${CMAKE_C_COMPILER_ID}_C_FLAGS}
+    ${${CMAKE_BUILD_TYPE}_${CMAKE_C_COMPILER_ID}_C_FLAGS}
+    ${${CMAKE_BUILD_TYPE}_${CMAKE_CXX_COMPILER_ID}_C_FLAGS}
 )
 
 set_directory_properties(PROPERTIES EP_PREFIX ${CMAKE_BINARY_DIR}/Rust)