alias-bounds for normalizable alias + deeply normalize ~> MIR typeck ICE

[lcnr]

trait Trait {
    type Assoc: Clone;
}

fn is_clone<T: Clone>(_: *mut T) {}

fn foo<T: Trait<Assoc = U>, U>(x: *mut <T as Trait>::Assoc) {
    is_clone(x);
}

https://rust.godbolt.org/z/4WojT7KTW

This currently results in an ICE:

• in HIR typeck <T as Trait>::Assoc: Clone holds due to the alias bound candidate
• during writeback we deeply normalize, replacing <T as Trait>::Assoc with U
• MIR typeck checks U: Clone which does not hold, resulting in an ICE

[lcnr]

the easiest fix is to change assemble_candidates_after_normalizing_self_ty to only assemble candidates for a fully normalized type by switching it to use try_normalize_ty 🤔 this matches the behavior of the old solver and should avoid deeply normalizing from erasing relevant info

[compiler-errors]

the easiest fix is to change assemble_candidates_after_normalizing_self_ty to only assemble candidates for a fully normalized type by switching it to use try_normalize_ty

:( incompleteness