Hello Attila,
lately I've been trying to make arm-none-eabi toolchain with gcc 12.3, since the older ones cannot be used with QMK. I also stumbled accross this issue. The issue is actually caused by wrong order of paths in "CROSS_CPLUS_INCLUDE_PATH". The C include path has to come after the C++ path. So as a workaround, remove the /include from beginning of this, and append it instead as last. Apart from that you will probably have an issue with linking against the libstdc++, since it's inside of "lib" folder instead or "arm-none-eabi/lib" that is in CROSS_LIBRARY_PATH. As a workaround, just add "$GUIX_ENVIRONMENT/lib" to "CROSS_LIBRARY_PATH". I will try to submit the 12.3 patch soon. In the mean time I have it inside of my own channel https://github.com/Rutherther/guix-exprs/blob/main/ruther/packages/embedded.scm Redards, Rutherther
