[clang] Resolving issue #119101 (PR #119143)

[Richard Smith via cfe-commits]

zygoloid wrote:

Did you mean a different issue than #119101? It's not clear to me what connection this PR has to that issue.

It's not clear to me that there's an issue to be solved here. Under `-pedantic-errors`, clang [already produces an error](https://godbolt.org/z/h6oKarex9) on examples like the ones here, and by default clang produces a warning on such cases, so we are already diagnosing this. And we need to continue to accept things like `static struct A {} a;`, which are valid but would be rejected by this change.

https://github.com/llvm/llvm-project/pull/119143