error[E0596]: cannot borrow `*x` as mutable, as it is behind a `&` reference --> $DIR/borrowck-fn-in-const-b.rs:7:9 | LL | fn broken(x: &Vec) { | ------------ help: consider changing this to be a mutable reference: `&mut Vec` LL | x.push(format!("this is broken")); | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `x` is a `&` reference, so the data it refers to cannot be borrowed as mutable error: aborting due to previous error For more information about this error, try `rustc --explain E0596`.