1error[E0308]: mismatched types 2 --> $DIR/mut-cross-borrowing.rs:7:7 3 | 4LL | f(x) 5 | ^ 6 | | 7 | expected `&mut isize`, found struct `Box` 8 | help: consider mutably borrowing here: `&mut x` 9 | 10 = note: expected mutable reference `&mut isize` 11 found struct `Box<{integer}>` 12 13error: aborting due to previous error 14 15For more information about this error, try `rustc --explain E0308`. 16