[clang] [clang] Implement CTAD for type alias template. (PR #77890)

[Haojian Wu via cfe-commits]

hokein wrote:

> > Thank you for all the reviews, I will wait 1 or 2 days before merging it in case anyone has more comments.
> 
> Sure! Do you plan to keep working on completing this feature?

Yeah, I plan to complete this feature before the next clang release. If anyone is willing to help, that would be even greater.

BTW, should we close https://github.com/llvm/llvm-project/issues/54051 with this PR? or should we keep it open until the feature is fully implemented? The `is_deducible` part is a major missing piece, I think we can close #54051 and open a separate issue to track the missing piece, WDYT?


https://github.com/llvm/llvm-project/pull/77890