It is possible to redundantly implement an auto trait for a trait-object type

[arielb1]

STR

#![feature(optin_builtin_traits)]

trait Xyz {}
auto trait Abc {}

impl Abc for dyn Xyz + Abc {
    
}

Expected Result

Code gives the same error as impl Xyz for dyn Xyz + Abc, giving error[E0371]: the object type (dyn Xyz + Abc + 'static)automatically implements the traitXyz`

Actual Result

Code passes coherence, but wfcheck fails because of the confusion:

error[E0283]: type annotations required: cannot resolve `(dyn Xyz + Abc + 'static): Abc`
 --> src/lib.rs:6:6
  |
6 | impl Abc for dyn Xyz + Abc {
  |      ^^^

error: aborting due to previous error