error: lifetime may not live long enough --> $DIR/ex3-both-anon-regions-using-trait-objects.rs:2:3 | LL | fn foo(x:Box , y: Vec<&u8>, z: &u8) { | - - let's call the lifetime of this reference `'1` | | | let's call the lifetime of this reference `'2` LL | y.push(z); | ^^^^^^^^^ argument requires that `'1` must outlive `'2` | help: consider introducing a named lifetime parameter | LL | fn foo<'a>(x:Box , y: Vec<&'a u8>, z: &'a u8) { | ++++ ++ ++ error[E0596]: cannot borrow `y` as mutable, as it is not declared as mutable --> $DIR/ex3-both-anon-regions-using-trait-objects.rs:2:3 | LL | fn foo(x:Box , y: Vec<&u8>, z: &u8) { | - help: consider changing this to be mutable: `mut y` LL | y.push(z); | ^^^^^^^^^ cannot borrow as mutable error: aborting due to 2 previous errors For more information about this error, try `rustc --explain E0596`.