[Bug preprocessor/109994] Issue a diagnostic when a C++ file defines a macro that hides a keyword

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109994

--- Comment #2 from Jonathan Wakely <redi at gcc dot gnu.org> ---
(In reply to Andrew Pinski from comment #1)
> There are definitly testcases in GCC's testsuite which does this all the
> time.
> #define int ...

Yeah, it shouldn't be in -Wall, and it's not a required diagnostic for
conformance. But it might be nice. Not a priority though.