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<i32>`
   = 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<Output = Arc<RefCell<i32>>>`, 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<i32>`
   = 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<Output = Arc<RefCell<i32>>>`, 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<i32>` cannot be shared between threads safely
  --> $DIR/issue-68112.rs:65:18
   |
LL |     require_send(send_fut);
   |     ------------ ^^^^^^^^ `RefCell<i32>` cannot be shared between threads safely
   |     |
   |     required by a bound introduced by this call
   |
   = help: the trait `Sync` is not implemented for `RefCell<i32>`
   = note: if you want to do aliasing and mutation between multiple threads, use `std::sync::RwLock` instead
   = note: required for `Arc<RefCell<i32>>` 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) -> T {
   |  _______________________________^
LL | |     t
LL | | }
   | |_^
note: required because it appears within the type `impl Future<Output = Arc<RefCell<i32>>>`
  --> $DIR/issue-68112.rs:53:31
   |
LL | fn make_non_send_future2() -> impl Future<Output = Arc<RefCell<i32>>> {
   |                               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
   = note: required because it captures the following types: `ResumeTy`, `impl Future<Output = Arc<RefCell<i32>>>`, `()`, `i32`, `Ready<i32>`
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`.