https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61532
--- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> --- Targets that define wchar_t as unsigned int are not conforming to the C++ standard, which requires wchar_t to be a distinct type, not a typedef. I can look into a hack to detect non-conforming targets, but probably not until next week.