[clang] [Clang][Sema] Fix malformed AST for anonymous class access in template. (PR #90842)

[Richard Smith via cfe-commits]

https://github.com/zygoloid commented:

Another possibility to consider: when [transforming a member access](https://github.com/llvm/llvm-project/blob/ff210b94d449de8ebe1f32cf0d7763ba63b27b39/clang/lib/Sema/TreeTransform.h#L11950), strip off any implicit member accesses from the base expression before transforming the base. That way, we'll rebuild the implicit member access from scratch, which might be a little more work, but should get details like this one right. (We can then probably also remove the logic to deal with an absent `DeclName` in `RebuildMemberExpr` since that shouldn't happen any more.)

https://github.com/llvm/llvm-project/pull/90842