error[E0277]: the trait bound `T: Foo` is not satisfied --> $DIR/wf.rs:5:14 | LL | trait B = A; | ^^^^ the trait `Foo` is not implemented for `T` | note: required by a bound in `A` --> $DIR/wf.rs:4:12 | LL | trait A {} | ^^^ required by this bound in `A` help: consider restricting type parameter `T` | LL | trait B = A; | +++++ error: aborting due to 1 previous error For more information about this error, try `rustc --explain E0277`.