error[E0308]: mismatched types
  --> $DIR/assignment-of-clone-call-on-ref-due-to-missing-bound.rs:18:39
   |
LL |             let mut x: HashSet<Day> = v.clone();
   |                        ------------   ^^^^^^^^^ expected `HashSet<Day>`, found `&HashSet<Day>`
   |                        |
   |                        expected due to this
   |
   = note: expected struct `HashSet<_>`
           found reference `&HashSet<_>`
note: `HashSet<Day>` does not implement `Clone`, so `&HashSet<Day>` was cloned instead
  --> $DIR/assignment-of-clone-call-on-ref-due-to-missing-bound.rs:18:39
   |
LL |             let mut x: HashSet<Day> = v.clone();
   |                                       ^
   = help: `Clone` is not implemented because the trait bound `Day: Clone` is not satisfied
help: consider annotating `Day` with `#[derive(Clone)]`
   |
LL + #[derive(Clone)]
LL | enum Day {
   |

error: aborting due to 1 previous error

For more information about this error, try `rustc --explain E0308`.