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

[jakub at gcc dot gnu.org]

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

--- Comment #8 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
(In reply to Martin Sebor from comment #7)
> Unfortunately, __builtin_memchr is not usable in constexpr contexts.  Hardly
> any of these builtins are.

Can you explain why?  Most of the builtins that can fold on GENERIC should be
usable in constexpr contexts.  The constexpr folder invokes the middle-end
builtin folder.