Description

With #9243 merged, I can not build anything for Cortex-M anymore, as apparently the NEWLIB_INCLUDE_DIR is not set properly for my environment:

cc1: error: /newlib-nano: No such file or directory [-Werror=missing-include-dirs]
cc1: all warnings being treated as errors

I might have a more or less custom setup (though not too fancy I would guess):

• toolchain at custom location
• custom folder containing symbolic links to binaries added to global PATH var

Now the definition of the NEWLIB_INCLUDE_DIR variable in makefiles/libc/newlib.mk does not cover this case, and thus leading to my setup not be able to build anything with the newly enabled warnings set.

Quick solution is for me to export the NEWLIB_INCLUDE_DIR variable manually for my environment, but this seems quite hacky to me. So any suggestion on how to fix this in a more nice way?

This is one of the extremely annoying things, forcing me to debug our make system for things that break from one day to the other...