error[E0596]: cannot borrow `*x` as mutable, as it is behind a `&` reference --> $DIR/borrowck-call-method-from-mut-aliasable.rs:17:5 | LL | x.h(); | ^^^^^ `x` is a `&` reference, so the data it refers to cannot be borrowed as mutable | help: consider changing this to be a mutable reference | LL | fn b(x: &mut Foo) { | +++ error: aborting due to previous error For more information about this error, try `rustc --explain E0596`.