[clang] [RFC] Initial implementation of P2719 (PR #113510)

[Oliver Hunt via cfe-commits]

ojhunt wrote:

This has been tentatively approved C++26 - CWG didn't have time to look at it this week but EWG and SG23 have approved it. I did spend some time discussing semantics with a couple of folk in EWG and CWG and the feedback was fairly strongly on the side of "the operator delete used for cleanup when a constructor throws must have the same typed awaredness" (e.g. the existing exact placement new parameters match requirement). But this implementation currently allows fallback to a non-type aware delete, so I'm changing that and adding test cases to ensure correctness according to those semantics.

https://github.com/llvm/llvm-project/pull/113510