[clang] [clang] Fix a use-after-free in expression evaluation (PR #118480)

[Aaron Ballman via cfe-commits]

AaronBallman wrote:

> hi @AaronBallman, no unfortunately we didn't make any progress here, and I just verified that reproducer from [#118480 (comment)](https://github.com/llvm/llvm-project/pull/118480#issuecomment-2538988006) is still triggering the issue (with -std=c++20).

Internal validation testing at Intel is hitting this same problem, so we can also reproduce the issue. Any chance we can get this PR across the finish line?

https://github.com/llvm/llvm-project/pull/118480