1 error: future cannot be sent between threads safely
2 --> $DIR/issue-64130-non-send-future-diags.rs:21:5
4 LL | fn is_send<T: Send>(t: T) { }
5 | ---- required by this bound in `is_send`
8 | ^^^^^^^ future returned by `foo` is not `Send`
10 = help: within `impl Future`, the trait `Send` is not implemented for `MutexGuard<'_, u32>`
11 note: future is not `Send` as this value is used across an await
12 --> $DIR/issue-64130-non-send-future-diags.rs:15:5
14 LL | let g = x.lock().unwrap();
15 | - has type `MutexGuard<'_, u32>` which is not `Send`
17 | ^^^^^^^^^^^ await occurs here, with `g` maybe used later
19 | - `g` is later dropped here
21 error: aborting due to previous error