error[E0308]: mismatched types --> $DIR/trait-hrtb.rs:13:39 | LL | let y: Box Foo<'a>> = x; | ^ one type is more general than the other | = note: expected trait object `dyn for<'a> Foo<'a>` found trait object `dyn Foo<'_>` error: aborting due to 1 previous error For more information about this error, try `rustc --explain E0308`.