[clang] [clang] emit an error when the same identifier appears with both internal and external linkage in a translation unit (PR #78064)

[Mariya Podchishchaeva via cfe-commits]

Fznamznon wrote:

> @Fznamznon So should I update the test files manually?

Yes, AFAIK there is no script to update the tests. Make sure the new errors seen in the tests are expected outcome of the patch though.

https://github.com/llvm/llvm-project/pull/78064