[libcxx-commits] [libcxx] [libc++][math] Add `constexpr` to `copysign`, `copysignf`, `copysignl` (PR #216285)

[Ambrose Leeb via libcxx-commits]

Sirraide wrote:

> > By that you mean Clang should just treat the non-`__builtin` version as `constexpr` even if it wasn’t declared `constexpr`?
> 
> This is what GCC does. I'm totally unsure whether we should follow GCC.
> 
> IIRC we've been waiting on such approach for at least 4 years. It seems to me that we don't need to spend 4 years to implement library workaround for P0533R9 (or even P0533R9 + P1383R2) IF library workaround actually works.

Ok, I feel like something like this might require an RFC, but CC @AaronBallman for opinions.

https://github.com/llvm/llvm-project/pull/216285