[clang] [clang][analyzer][NFC] Add test for a limitation of alpha.unix.Bloc… (PR #93799)

[Donát Nagy via cfe-commits]

https://github.com/NagyDonat approved this pull request.

It's good to document this, the commit LGTM. Are you planning to fix this soon?

https://github.com/llvm/llvm-project/pull/93799