Forwarded: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93821
Upstream commit fixing this is https://gcc.gnu.org/git/?p=gcc.git;a=commit;f=libcpp/init.c;h=445430e16bd08ade34637d2346ded40dd49de508
- Bug#1021673: Wrong __cplusplus definition when using -std=c... Marco Trevisan
- Bug#1021673: Acknowledgement (Wrong __cplusplus defini... Marco Trevisan
