https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77817
--- Comment #6 from Jakub Jelinek <jakub at gcc dot gnu.org> --- (In reply to Marek Polacek from comment #5) > Yeah, I think this one's WONTFIX. Well, in theory we could for the comments that satisfy fallthrough_comment_p create CPP_COMMENT token and insert it, even without -C or -CC (perhaps only if -Wimplicit-fallthrough). But, when without those options, we'd have to cope with the behavior changes where it makes a difference. E.g. I believe /* FALLTHROUGH */ #ifdef SOMETHING etc. would change behavior. As a workaround, with the patches I've posted -Wimplicit-fallthrough -C (or -CC) would work in this case.