[clang] [Inliner] Improve attribute propagation to callsites when inlining. (PR #66036)

[Nikita Popov via cfe-commits]

nikic wrote:

It occurs to me that the current return attribute propagation is currently buggy for poison-generating attributes: https://llvm.godbolt.org/z/x8n18q9Mj

In this case the argument to use() will now be poison as well, while before inlining only the return value was poison.

This code needs to distinguish poison and UB generating attributes.

https://github.com/llvm/llvm-project/pull/66036