[llvm] [LLVM] Create `lf_alias` nodes for `typedef` and `using` (PR #153936)

[Michael Buch via llvm-commits]

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Michael137 wrote:

Yea that's fair. Though off the top I don't see a good reason why it was done this way for the other tests. Perhaps the test infrastructure wasn't mature enough? @rnk will probably know

I'm not a PDB/CodeView expert, so I might be misunderstanding what's required to test these changes. But does Clang generate PDBs when you specify `-gcodeview`? If so, we have tests (e.g., search `llvm/test/DebugInfo/COFF` for `-gcodeview`) that generate and then inspect CodeView. Would that be sufficient to test your changes?

https://github.com/llvm/llvm-project/pull/153936