error[E0596]: cannot borrow `x` as mutable, as it is not declared as mutable --> $DIR/borrowck-mut-addr-of-imm-var.rs:3:25 | LL | let y: &mut isize = &mut x; | ^^^^^^ cannot borrow as mutable | help: consider changing this to be mutable | LL | let mut x: isize = 3; | +++ error: aborting due to previous error For more information about this error, try `rustc --explain E0596`.