[clang] Reland: [clang] Diagnose dangling issues for the "Container<GSLPointer>" case. #107213 (PR #108344)

[Utkarsh Saxena via cfe-commits]

https://github.com/usx95 commented:

We seem to be good at detecting new false positives but this is natural due to the visible compiler diagnositc. Unfortunately, same is not true for new false-negatives. More tests in our test-suite is the only way to detect those and we should be extensively adding more tests. This is something I feel particularly missing for lifetime analysis given the complexity of the code. This is obviously not actionable and non-blocking and is more of a meta comment.

See my comment for ideas for more tests.

I also found a recently introduced false-negative. This is not particularly introduced by this PR but is very related:
https://github.com/llvm/llvm-project/issues/108463

https://github.com/llvm/llvm-project/pull/108344