[libcxx-commits] [libcxx] [libc++] Avoid -Wzero-as-null-pointer-constant in operator<=> (PR #79465)

[Barry Revzin via libcxx-commits]

brevzin wrote:

As far as I can tell @horenmar, @cor3ntin's `enable_if` implementation will work in Catch2 just fine with no changes. It basically does [this](https://godbolt.org/z/vfccfx7nz).

Catch2 could then do the same thing on clang itself, which makes the implementation simpler and allows rejecting `== 1` at compile time. But given that gcc doesn't have `enable_if`, it doesn't actually make the implementation simpler, so... probably not worth doing. 

https://github.com/llvm/llvm-project/pull/79465