[llvm] [Inline][WinEH] Fix try scopes leaking to caller on inline (PR #164170)

[Reid Kleckner via llvm-commits]

rnk wrote:

I spent a minute looking at this issue and the code, but I didn't get very far before I had to move on.

It seems that the core of the issue is that the /EHa state numbering algorithm isn't resilient to unreachable block removal eliminating the scope end/close operation, which is a problem, since Clang/LLVM like to do that whenever they can. I'm not sure fixing this in the frontend is the right move. It will probably require significant careful time and though to revisit the EHa numbering algorithm.

https://github.com/llvm/llvm-project/pull/164170