How to enable/disable addons when using CMake FetchContent?

[xgalaxy]

Hello, is there a way to inject the flecs_config.h or add target compile definitions when using CMake FetchContent? Here is what I've tried:

FetchContent_Declare(
        flecs
        GIT_REPOSITORY https://github.com/SanderMertens/flecs
        GIT_TAG v4.0.3
        GIT_SHALLOW TRUE
        GIT_PROGRESS TRUE
)

message(STATUS "Checking flecs")
FetchContent_MakeAvailable(flecs)

target_compile_definitions(
    flecs_static
        PUBLIC
            FLECS_CUSTOM_BUILD
            FLECS_CPP
            FLECS_SYSTEM
            FLECS_PIPELINE
            FLECS_TIMER
            $<$<CONFIG:Debug>:FLECS_JOURNAL>
            $<$<CONFIG:Debug>:FLECS_LOG>
            $<$<CONFIG:Debug>:FLECS_METRICS>
            $<$<CONFIG:Debug>:FLECS_STATS>
)

But this isn't working. Maybe there is a way to do this that I'm not aware of. If not, maybe we could update flecs CMake script to provide an option to point it at a flecs_config.h?

[xgalaxy]

If I do add_compile_definitions() before doing FetchContent then I can set the definitions that way but I'd prefer not to use that because it sets the definitions for all targets not just flecs.