https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86471
--- Comment #23 from Matt Bentley <mattreecebentley at gmail dot com> --- > Actually, don't quote me on that - I may be thinking of the > 'reinterpret_cast<_Tp>(0)' - one of the two. Just to confirm, "reinterpret_cast<void *>(__first)" not required in this context, either "reinterpret_cast<_Tp>(0)" or "static_cast<_Tp>(0)" *are* required to avoid warnings in clang when _Tp is a pointer. Either works fine. I understand that reinterpret_cast isn't allowed inside constexpr, but not why, and can't find any resources explicitly stating the reasoning. But __builtin_constant_p allows it, so it's use is a matter of programmer choice, at least in this context.
