[Bug c/118375] Fixits for feature test macros (FTMs)

[sjames at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=118375

--- Comment #1 from Sam James <sjames at gcc dot gnu.org> ---
I find this comes up most with people using -std=c99/c11/whatever instead of
-std=gnu* and not realising the implications of that.