error[E0308]: mismatched types
  --> tests/compile-fail/span-input-setter.rs:10:21
   |
10 |     input.set_field(22);
   |           --------- ^^ expected `&mut _`, found integer
   |           |
   |           arguments to this method are incorrect
   |
   = note: expected mutable reference `&mut _`
                           found type `{integer}`
note: method defined here
  --> tests/compile-fail/span-input-setter.rs:3:5
   |
1  | #[salsa::input]
   | ---------------
2  | pub struct MyInput {
3  |     field: u32,
   |     ^^^^^
help: consider mutably borrowing here
   |
10 |     input.set_field(&mut 22);
   |                     ++++