https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104065
--- Comment #7 from Gaius Mulley <gaius at gcc dot gnu.org> --- All fixed now (I think), see mailing list entry https://gcc.gnu.org/pipermail/gcc-cvs/2022-January/359679.html In summary $(CC) is only used to compile flex generated source. $(CXX) is used instead. The bootstrap tool has been updated and emits GCC headers system and config inside C++ code blocks and not within extern C blocks.
