error: lifetime may not live long enough --> $DIR/dyn-trait-underscore.rs:8:5 | LL | fn a(items: &[T]) -> Box> { | - let's call the lifetime of this reference `'1` LL | // ^^^^^^^^^^^^^^^^^^^^^ bound *here* defaults to `'static` LL | Box::new(items.iter()) | ^^^^^^^^^^^^^^^^^^^^^^ returning this value requires that `'1` must outlive `'static` | help: to declare that the trait object captures data from argument `items`, you can add an explicit `'_` lifetime bound | LL | fn a(items: &[T]) -> Box + '_> { | ++++ error: aborting due to 1 previous error