[libcxx-commits] [libcxx] [libc++][NFC] Simplify pair a bit (PR #96165)

[James Y Knight via libcxx-commits]

jyknight wrote:

I believe this change is broken. This following code now fails to compile, under `clang -std=c++20 -stdlib=libc++`, and I think it ought not to.

```
#include <utility>
#include <vector>

struct Test {
  std::vector<std::pair<int, Test>> v;
};

std::pair<int, Test> p;
```

https://github.com/llvm/llvm-project/pull/96165