https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94745
--- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> --- This is by design. It means that makefiles written for different versions of GCC do not trigger spurious diagnostics. If somebody says "I don't want warnings about cat noises" and their version of GCC doesn't support -Wmeow then their request is granted. Warning about it would cause valid compilations to fail. If other diagnostics are being emitted anyway, then adding one to point out the unrecognized option isn't going to make a build go from passing to failing.
