error[E0596]: cannot borrow `x` as mutable, as it is not declared as mutable --> $DIR/E0596.rs:6:13 | LL | let x = 1; | - help: consider changing this to be mutable: `mut x` LL | let y = &mut x; //[ast]~ ERROR [E0596] | ^^^^^^ cannot borrow as mutable error: aborting due to previous error For more information about this error, try `rustc --explain E0596`.