[Bug c++/71537] GCC rejects consetxpr boolean conversions and comparisons on the result of pointer arithmetic.

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71537

--- Comment #9 from Jonathan Wakely <redi at gcc dot gnu.org> ---
I think we need __builtin_memchr et al to be usable in constant expressions,
because replacing them with hand-written loops would be a step backwards. For
uses outside constant expressions we want to go to libc and benefit from the
optimization work put into the libc routines.