[Bug c/96284] Outdated C features should be made errors with newer standards

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96284

--- Comment #2 from Jonathan Wakely <redi at gcc dot gnu.org> ---
But they're not enabled by default, meaning that the unsafe, ill-formed code is
still accepted by default.