[llvm] [WIP] [Coroutines] fix coroutines + std::unique_ptr with async exceptions validation errors (PR #149691)

[Weibo He via llvm-commits]

https://github.com/NewSigma commented:

Just some comments on styles. Could you please explain the problem and your solution in the pr description?

https://github.com/llvm/llvm-project/pull/149691