1 error: future cannot be sent between threads safely
2 --> $DIR/issue-70935-complex-spans.rs:13:45
4 LL | fn foo(tx: std::sync::mpsc::Sender<i32>) -> impl Future + Send {
5 | ^^^^^^^^^^^^^^^^^^ future created by async block is not `Send`
7 = help: the trait `Sync` is not implemented for `Sender<i32>`
8 note: future is not `Send` as this value is used across an await
9 --> $DIR/issue-70935-complex-spans.rs:19:11
13 LL | | foo(tx.clone());
15 | | - ^^^^^^ await occurs here, with the value maybe used later
17 | has type `[closure@$DIR/issue-70935-complex-spans.rs:17:13: 17:15]` which is not `Send`
18 note: the value is later dropped here
19 --> $DIR/issue-70935-complex-spans.rs:19:17
24 error: aborting due to previous error