error[E0596]: cannot borrow `x` as mutable, as it is not declared as mutable --> $DIR/borrowck-auto-mut-ref-to-immut-var.rs:15:5 | LL | x.printme(); | ^ cannot borrow as mutable | help: consider changing this to be mutable | LL | let mut x = Foo { x: 3 }; | +++ error: aborting due to previous error For more information about this error, try `rustc --explain E0596`.