[Bug c++/90885] GCC should warn about 2^16 and 2^32 and 2^64

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90885

--- Comment #10 from Jonathan Wakely <redi at gcc dot gnu.org> ---
(In reply to Eric Gallager from comment #9)
> * the "not from the expansion of <iso646.h>’s xor macro" criterion I can see
> possibly being a difficulty, due to how many other bugs there are about
> gcc's handling of macros from system headers...

That's not relevant to C++ because xor is a keyword not a macro.