error: future cannot be sent between threads safely --> $DIR/issue-68112.rs:37:18 | LL | require_send(send_fut); | ^^^^^^^^ future created by async block is not `Send` | = help: the trait `Sync` is not implemented for `RefCell` = note: if you want to do aliasing and mutation between multiple threads, use `std::sync::RwLock` instead note: future is not `Send` as it awaits another future which is not `Send` --> $DIR/issue-68112.rs:34:17 | LL | let _ = non_send_fut.await; | ^^^^^^^^^^^^ await occurs here on type `impl Future>>`, which is not `Send` note: required by a bound in `require_send` --> $DIR/issue-68112.rs:14:25 | LL | fn require_send(_: impl Send) {} | ^^^^ required by this bound in `require_send` error: future cannot be sent between threads safely --> $DIR/issue-68112.rs:46:18 | LL | require_send(send_fut); | ^^^^^^^^ future created by async block is not `Send` | = help: the trait `Sync` is not implemented for `RefCell` = note: if you want to do aliasing and mutation between multiple threads, use `std::sync::RwLock` instead note: future is not `Send` as it awaits another future which is not `Send` --> $DIR/issue-68112.rs:43:17 | LL | let _ = make_non_send_future1().await; | ^^^^^^^^^^^^^^^^^^^^^^^ await occurs here on type `impl Future>>`, which is not `Send` note: required by a bound in `require_send` --> $DIR/issue-68112.rs:14:25 | LL | fn require_send(_: impl Send) {} | ^^^^ required by this bound in `require_send` error[E0277]: `RefCell` cannot be shared between threads safely --> $DIR/issue-68112.rs:65:18 | LL | require_send(send_fut); | ------------ ^^^^^^^^ `RefCell` cannot be shared between threads safely | | | required by a bound introduced by this call | = help: the trait `Sync` is not implemented for `RefCell` = note: if you want to do aliasing and mutation between multiple threads, use `std::sync::RwLock` instead = note: required for `Arc>` to implement `Send` note: required because it's used within this `async fn` body --> $DIR/issue-68112.rs:50:31 | LL | async fn ready2(t: T) -> T { | _______________________________^ LL | | t LL | | } | |_^ note: required because it appears within the type `impl Future>>` --> $DIR/issue-68112.rs:53:31 | LL | fn make_non_send_future2() -> impl Future>> { | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ = note: required because it captures the following types: `ResumeTy`, `impl Future>>`, `()`, `Ready` note: required because it's used within this `async` block --> $DIR/issue-68112.rs:60:20 | LL | let send_fut = async { | ____________________^ LL | | let non_send_fut = make_non_send_future2(); LL | | let _ = non_send_fut.await; LL | | ready(0).await; LL | | }; | |_____^ note: required by a bound in `require_send` --> $DIR/issue-68112.rs:14:25 | LL | fn require_send(_: impl Send) {} | ^^^^ required by this bound in `require_send` error: aborting due to 3 previous errors For more information about this error, try `rustc --explain E0277`.