error[E0271]: type mismatch resolving `<<T as Trait>::A as MultiDispatch<i32>>::O == T`
  --> $DIR/issue-24204.rs:14:1
   |
LL | trait Trait: Sized {
   | ------------------ required by `Trait`
...
LL | fn test<T: Trait<B=i32>>(b: i32) -> T where T::A: MultiDispatch<i32> { T::new(b) }
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected type parameter `T`, found associated type
   |
   = note: expected type `T`
              found type `<<T as Trait>::A as MultiDispatch<i32>>::O`
   = note: you might be missing a type parameter or trait bound

error: aborting due to previous error

For more information about this error, try `rustc --explain E0271`.