[clang] [llvm] [clang][CodeGen][AA] Introduce `!llvm.errno.tbaa` for errno alias disambiguation (PR #125258)

[Nikita Popov via cfe-commits]

https://github.com/nikic commented:

* The metadata should be documented in LangRef.
* We should test linking of two modules with the metadata. Both the case where they match and where they don't (e.g. mixing C and C++). IRLinker::linkNamedMDNodes should be the relevant code. (I do wonder whether we should instead be making this a module flag with AppendUnique behavior. I'm not sure clear on what the tradeoff is between a module flag and separate named metadata.)

https://github.com/llvm/llvm-project/pull/125258