error[E0277]: the trait bound `MyCall: Callback` is not satisfied --> $DIR/issue-75707.rs:15:9 | LL | f::>(); | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `Callback` is not implemented for `MyCall` | help: this trait has no implementations, consider adding one --> $DIR/issue-75707.rs:1:1 | LL | pub trait Callback { | ^^^^^^^^^^^^^^^^^^ note: required by a bound in `f` --> $DIR/issue-75707.rs:9:9 | LL | fn f() { | ^^^^^^^^^^ required by this bound in `f` error: aborting due to previous error For more information about this error, try `rustc --explain E0277`.