[clang] [Clang] Allow all address spaces to be converted to the default (PR #112248)

[Matt Arsenault via cfe-commits]

arsenm wrote:

> I'm thinking we could have a language option like `-fimplicit-default-addrspace-cast` that allows all conversions to default. Then if we want users to be aware that this even exists we could suggest it in the error message if it would fix it.
> 
> I do understand that there's some weird semantics here, and it does change some surprisingly unrelated tests so I don't think the patch as-is will be sound. Hiding it behind an option makes sense so I can do that.

I think we should avoid modality / language dependence. I thought the problem you were dealing with was the cuda_ attributes not behaving consistently in C++ mode? 


https://github.com/llvm/llvm-project/pull/112248