I’m working with a project where I need to define some preprocessor symbols at build time in CMakeLists.txt. I’ve created a pair of demo projects to isolate the issue:

I created a project using the regular embedded project wizard, opened its CMakeLists.txt, and added the line target_compile_definitions(DefineIssueDemo PRIVATE TEST_DEFINE=1). I then tested for the define in the main source file with
#ifndef TEST_DEFINE
#error "Missing define"
#endif
and the project built as expected.

I repeated the test with a new project created with the STM32CubeMX wizard. Everything builds fine at first. I add the same lines to CMakeLists.txt (only change is that the target is named DefineIssueDemoCube) and to the main source file, and the build errors out with the “Missing define” error message I wrote.

From my main project, I know that some other CMake target-based directives like target_link_libraries and target_link_options work fine. But target_compile_definitions and target_compile_options with -D options don’t work, it seems like the defines just get discarded.

(For added context, the reason I need the defines is to create a bootloader. I’m following the VisualGDB advanced CMake bootloader tutorial, but because of the way the STM32CubeMX BSP works, the BSP’s main.c file is part of the build of both the main program and the bootloader. In order to have the main program move the interrupt vector table on start, I need to have different code execute in main.c depending on which target it’s being built by. Hence the need for target-specific defines.)

Is this a bug, and is there a workaround for getting target-specific preprocessor defines into an STM32CubeMX based project?