error: `ref` directly on a function argument is ignored. Consider using a reference type instead.
  --> $DIR/toplevel_ref_arg_non_rustfix.rs:4:15
   |
LL | fn the_answer(ref mut x: u8) {
   |               ^^^^^^^^^
   |
   = note: `-D clippy::toplevel-ref-arg` implied by `-D warnings`

error: aborting due to previous error