error[E0106]: missing lifetime specifier --> $DIR/impl-trait-missing-lifetime.rs:9:54 | LL | fn g(mut x: impl Iterator) -> Option<&'_ ()> { x.next() } | ^^ expected named lifetime parameter | = help: this function's return type contains a borrowed value, but there is no value for it to be borrowed from help: consider using the `'static` lifetime | LL | fn g(mut x: impl Iterator) -> Option<&'static ()> { x.next() } | ~~~~~~~ error[E0106]: missing lifetime specifier --> $DIR/impl-trait-missing-lifetime.rs:16:60 | LL | async fn i(mut x: impl Iterator) -> Option<&'_ ()> { x.next() } | ^^ expected named lifetime parameter | = help: this function's return type contains a borrowed value, but there is no value for it to be borrowed from help: consider using the `'static` lifetime | LL | async fn i(mut x: impl Iterator) -> Option<&'static ()> { x.next() } | ~~~~~~~ error: lifetime may not live long enough --> $DIR/impl-trait-missing-lifetime.rs:16:69 | LL | async fn i(mut x: impl Iterator) -> Option<&'_ ()> { x.next() } | ----------------------------------------------------------------- ^^^^^^^^ returning this value requires that `'1` must outlive `'static` | | | return type `impl Future>` contains a lifetime `'1` error: aborting due to 3 previous errors For more information about this error, try `rustc --explain E0106`.