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 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