[Bug c/77817] -Wimplicit-fallthrough: cpp directive renders FALLTHRU comment ineffective

[jakub at gcc dot gnu.org]

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.