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

[via llvm-commits]

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Walnut356 wrote:

I'm not super familiar with LLVM's test structure, but I more or less copied the surrounding tests. All of the native pdb tests use pre-compiled PDB files and they seem to all be testing "can LLVM's native reader read the node", not "can LLVM generate the node". They're compiled with `cl.exe`, but afaict they're not outputting anything that `cl.exe` can't. The only reason this one is compiled with clang instead of cl is because I can't coerce cl to output the proper node, but that's largely incidental to "can LLVM native reader read this node?"

Do the tests for LLVM's node generation live somewhere else, and would that test be more appropriately placed there?

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