error: future cannot be sent between threads safely
  --> $DIR/drop-track-field-assign-nonsend.rs:45:17
   |
LL |     assert_send(agent.handle());
   |                 ^^^^^^^^^^^^^^ future returned by `handle` is not `Send`
   |
   = help: within `impl Future<Output = ()>`, the trait `Send` is not implemented for `Rc<String>`
note: future is not `Send` as this value is used across an await
  --> $DIR/drop-track-field-assign-nonsend.rs:23:38
   |
LL |         let mut info = self.info_result.clone();
   |             -------- has type `InfoResult` which is not `Send`
...
LL |         let _ = send_element(element).await;
   |                                      ^^^^^^ await occurs here, with `mut info` maybe used later
LL |     }
   |     - `mut info` is later dropped here
note: required by a bound in `assert_send`
  --> $DIR/drop-track-field-assign-nonsend.rs:40:19
   |
LL | fn assert_send<T: Send>(_: T) {}
   |                   ^^^^ required by this bound in `assert_send`

error: aborting due to previous error