This makes the intention of inherent vs. trait impls somewhat more
clear and also fixes (?) an issue where trait impls with an unresolved
trait were added as inherent impls instead (hence the test changes).
We might as well handle them internally, via queries.
I am not sure, but it looks like the current LibraryData setup might
even predate salsa? It's not really needed and creates a bunch of
complexity.
4689: Implement return position impl trait / opaque type support r=matklad a=flodiebold
This is working, but I'm not that happy with how the lowering works. We might need an additional representation between `TypeRef` and `Ty` where names are resolved and `impl Trait` bounds are separated out, but things like inference variables don't exist and `impl Trait` is always represented the same way.
Also note that this doesn't implement correct handling of RPIT *inside* the function (which involves turning the `impl Trait`s into variables and creating obligations for them). That intermediate representation might help there as well.
Co-authored-by: Florian Diebold <flodiebold@gmail.com>
Co-authored-by: Florian Diebold <florian.diebold@freiheit.com>
