error[E0782]: expected a type, found a trait
  --> $DIR/ice-return-unsized-can-impl-2.rs:12:20
   |
LL |     fn concrete(b: B) -> B;
   |                    ^
   |
   = note: `B` is dyn-incompatible, otherwise a trait object could be used
help: use a new generic type parameter, constrained by `B`
   |
LL -     fn concrete(b: B) -> B;
LL +     fn concrete<T: B>(b: T) -> B;
   |
help: you can also use an opaque type, but users won't be able to specify the type parameter when calling the `fn`, having to rely exclusively on type inference
   |
LL |     fn concrete(b: impl B) -> B;
   |                    ++++

error[E0782]: expected a type, found a trait
  --> $DIR/ice-return-unsized-can-impl-2.rs:12:26
   |
LL |     fn concrete(b: B) -> B;
   |                          ^
   |
help: `B` is dyn-incompatible, use `impl B` to return an opaque type, as long as you return a single underlying type
   |
LL |     fn concrete(b: B) -> impl B;
   |                          ++++

error[E0782]: expected a type, found a trait
  --> $DIR/ice-return-unsized-can-impl-2.rs:6:13
   |
LL |     fn f(a: A) -> A;
   |             ^
   |
   = note: `A` is dyn-incompatible, otherwise a trait object could be used
help: use a new generic type parameter, constrained by `A`
   |
LL -     fn f(a: A) -> A;
LL +     fn f<T: A>(a: T) -> A;
   |
help: you can also use an opaque type, but users won't be able to specify the type parameter when calling the `fn`, having to rely exclusively on type inference
   |
LL |     fn f(a: impl A) -> A;
   |             ++++

error[E0782]: expected a type, found a trait
  --> $DIR/ice-return-unsized-can-impl-2.rs:6:19
   |
LL |     fn f(a: A) -> A;
   |                   ^
   |
help: `A` is dyn-incompatible, use `impl A` to return an opaque type, as long as you return a single underlying type
   |
LL |     fn f(a: A) -> impl A;
   |                   ++++

error: aborting due to 4 previous errors

For more information about this error, try `rustc --explain E0782`.
