[llvm] [LLVM][DebugInfo] Allow ExtraData field to be a node reference (PR #165023)

[Laxman Sole via llvm-commits]

laxmansole wrote:

 
> That said, this area does seem poorly specified. The langref only briefly mentions the extraData field and the verifier doesn't complain. I think in an ideal world the verifier would have complained about the tuple extraData, rather than hitting an assert later.

Verifier didn't complain about the tuple extraData because that is a valid IR if the `tag` in `!DIDerivedType` is `DW_TAG_ptr_to_member_type` and is handled correctly in the backend. 
https://github.com/llvm/llvm-project/blob/3d42b48d5df80b89b630d0602b1c5d1e3d4b4683/llvm/test/DebugInfo/Generic/debug-info-qualifiers.ll#L86-L93



https://github.com/llvm/llvm-project/pull/165023