error[E0282]: type annotations needed
  --> $DIR/concrete-impl.rs:14:5
   |
LL |     <Struct as Ambiguous<_>>::method();
   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ cannot infer type of the type parameter `A` declared on the trait `Ambiguous`

error[E0283]: type annotations needed
  --> $DIR/concrete-impl.rs:14:5
   |
LL |     <Struct as Ambiguous<_>>::method();
   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ cannot infer type of the type parameter `A` declared on the trait `Ambiguous`
   |
note: multiple `impl`s satisfying `Struct: Ambiguous<_>` found
  --> $DIR/concrete-impl.rs:9:1
   |
LL | impl Ambiguous<One> for Struct {}
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
LL |
LL | impl Ambiguous<Two> for Struct {}
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

error: aborting due to 2 previous errors

Some errors have detailed explanations: E0282, E0283.
For more information about an error, try `rustc --explain E0282`.