[libcxx-commits] [libcxx] [libc++] Add __detected_or_t and use it to implement some of the allocator traits aliases (PR #115654)

[Louis Dionne via libcxx-commits]

https://github.com/ldionne approved this pull request.

I like this a lot, nice simplification.

https://github.com/llvm/llvm-project/pull/115654