error[E0038]: the trait alias `SelfInput` cannot be made into an object --> $DIR/self-in-generics.rs:8:19 | LL | pub fn f(_f: &dyn SelfInput) {} | ^^^^^^^^^ | = note: it cannot use `Self` as a type parameter in a supertrait or `where`-clause error: aborting due to 1 previous error For more information about this error, try `rustc --explain E0038`.