[CMake] Custom Configurations and CMAKE_<LANG>_FLAGS_<CONFIG>_INIT

[Marek Vojtko (Firaxis)]

Hi,

Do CMAKE_<LANG>_FLAGS_<CONFIG>_INIT variables not automatically populate CMAKE_<LANG>_FLAGS_<CONFIG> variables for *custom* configurations? 

When I use the _INIT variables for one of the default configuration names, e.g. CMAKE_C_FLAGS_DEBUG_INIT or CMAKE_C_FLAGS_RELEASE_INIT, they correctly populate their "usage" counterparts, i.e. CMAKE_C_FLAGS_DEBUG and CMAKE_C_FLAGS_RELEASE respectively.

But when I set the _INIT variables for a custom configuration name (created through CMAKE_CONFIGURATION_TYPES), e.g. CMAKE_C_FLAGS_LALALAND_INIT, CMake fails the compiler tests, because CMAKE_C_FLAGS_LALALAND does not exist.

My setup:

*CMakeLists.txt*
set( CMAKE_USER_MAKE_RULES_OVERRIDE "${CMAKE_CURRENT_LIST_DIR}/CompilerOptions.cmake" )
project( Test )
add_executable( "${CMAKE_CURRENT_LIST_DIR}/main.c" )

*CompilerOptions.cmake*
set( CMAKE_CONFIGURATION_TYPES "Debug" "Release" "Lalaland" )

set( CMAKE_C_FLAGS_DEBUG_INIT "/Od" )
set( CMAKE_C_FLAGS_RELEASE_INIT "/Ox" )
set( CMAKE_C_FLAGS_LALALAND_INIT "/Ob2" )

set( CMAKE_EXE_LINKER_FLAGS_DEBUG_INIT "/machine:x64" )
set( CMAKE_EXE_LINKER_FLAGS_RELEASE_INIT "/machine:x64" )
set( CMAKE_EXE_LINKER_FLAGS_LALALAND_INIT "/machine:x64" )

The error I get is:

> CMake Error: Error required internal CMake variable not set, cmake may not be built correctly.
> Missing variable is:
> CMAKE_C_FLAGS_LALALAND

> CMake Error: Error required internal CMake variable not set, cmake may not be built correctly.
> Missing variable is:
> CMAKE_EXE_LINKER_FLAGS_LALALAND

> CMake Error at C:/Program Files/CMake/share/cmake-3.10/Modules/CMakeTestCCompiler.cmake:37 (try_compile):
> Failed to generate test project build system.

This is just a simplified example, in my actual usecase I have two custom configurations and both fail to populate their CMAKE_<LANG>_FLAGS_<CONFIG> variables from their CMAKE_<LANG>_FLAGS_<CONFIG>_INIT variables.

Do I have to set the CMAKE_<LANG>_FLAGS_<CONFIG>_INIT variables for the default CMake configuration names, but set the actual CMAKE_<LANG>_FLAGS_<CONFIG> variables for any custom configurations?
 
I am using CMake 3.10.3 and Visual Studio 11/14 Win64 generator.

Thanks,
Marek