[clang] [clang] visit constraint of NTTP (PR #91842)

[Erich Keane via cfe-commits]

erichkeane wrote:

> > Yeah, that seems incredibly reasonable and a much lower touch here with fewer concerns about the side-effects that we got here.
> 
> Should I open a PR then?

Yep, I think you should.  

Sorry @jcsxky : We're going to close this one, it seems that @sdkrystian has a 'more correct' patch here, so we'll go with his.  I hope/encourage you to help review it!

https://github.com/llvm/llvm-project/pull/91842