[llvm-branch-commits] [libcxx] [libc++] Implement std::move_only_function (P0288R9) (PR #94670)

[A. Jiang via llvm-branch-commits]

frederick-vs-ja wrote:

FYI [P2548R2](https://wg21.link/p2548r2) added relaxing wording to [[func.wrap.general]](https://eel.is/c++draft/func.wrap.general) to allow unwrapping in construction. I think we should implement the allowance for `move_only_function` in C++23 as a DR.
We can't unwrap in `function` construction though, IIUC, because its target object is observable. But we can unwrap `function` when constructing a `move_only_function`.

https://github.com/llvm/llvm-project/pull/94670