error[E0621]: explicit lifetime required in the type of `y` --> $DIR/ex2a-push-one-existing-name.rs:6:5 | LL | fn foo<'a>(x: &mut Vec<Ref<'a, i32>>, y: Ref<i32>) { | -------- help: add explicit lifetime `'a` to the type of `y`: `Ref<'a, i32>` LL | x.push(y); | ^^^^^^^^^ lifetime `'a` required error: aborting due to previous error For more information about this error, try `rustc --explain E0621`.