[clang] clang: improve diagnostic for 'auto' used in disallowed local class contexts (PR #167164)

[Younan Zhang via cfe-commits]

https://github.com/zyn0217 requested changes to this pull request.

Can you please revert unrelated changes? That makes review very hard.

Also, the entire patch looks like AI-generated. If that's the case, please clarify what part you are fixing with an AI and why you are considering the fix is correct, before you ask someone to review the patch.


https://github.com/llvm/llvm-project/pull/167164