[libcxx-commits] [libcxx] [libc++][functional] Implement `not_fn<NTTP>` (PR #86133)

[Louis Dionne via libcxx-commits]

https://github.com/ldionne requested changes to this pull request.

Thanks for the patch and sorry for this falling under the radar. I have a few comments but this looks mostly good. The tests are really comprehensive, thanks for that!

https://github.com/llvm/llvm-project/pull/86133