error: expected one of `)` or `,`, found `->`
  --> $DIR/issue-58856-2.rs:6:19
   |
LL |     fn how_are_you(&self -> Empty {
   |                   ^     -^^
   |                   |     |
   |                   |     help: `)` may belong here
   |                   unclosed delimiter

error: non-item in item list
  --> $DIR/issue-58856-2.rs:11:1
   |
LL | impl Howness for () {
   |                     - item list starts here
...
LL | }
   | ^
   | |
   | non-item starts here
   | item list ends here

error[E0407]: method `how_are_you` is not a member of trait `Howness`
  --> $DIR/issue-58856-2.rs:6:5
   |
LL | /     fn how_are_you(&self -> Empty {
LL | |
LL | |
LL | |         Empty
LL | |     }
   | |_____^ not a member of trait `Howness`

error: aborting due to 3 previous errors

For more information about this error, try `rustc --explain E0407`.