error[E0308]: `match` arms have incompatible types
  --> $DIR/issue-81839.rs:11:14
   |
LL | /     match num {
LL | |         1 => {
LL | |             cx.answer_str("hi");
   | |             --------------------
   | |             |                  |
   | |             |                  help: consider removing this semicolon
   | |             this is found to be of type `()`
LL | |         }
LL | |         _ => cx.answer_str("hi"),
   | |              ^^^^^^^^^^^^^^^^^^^ expected `()`, found opaque type
LL | |     }
   | |_____- `match` arms have incompatible types
   |
note: while checking the return type of the `async fn`
  --> $DIR/auxiliary/issue-81839.rs:6:49
   |
LL |     pub async fn answer_str(&self, _s: &str) -> Test {
   |                                                 ^^^^ checked the `Output` of this `async fn`, found opaque type
   = note: expected unit type `()`
            found opaque type `impl Future<Output = Test>`

error: aborting due to previous error

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