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|
// edition:2018
use std::{
cell::RefCell,
future::Future,
pin::Pin,
sync::Arc,
task::{Context, Poll},
};
fn require_send(_: impl Send) {}
struct Ready<T>(Option<T>);
impl<T: Unpin> Future for Ready<T> {
type Output = T;
fn poll(mut self: Pin<&mut Self>, _cx: &mut Context<'_>) -> Poll<T> {
Poll::Ready(self.0.take().unwrap())
}
}
fn ready<T>(t: T) -> Ready<T> {
Ready(Some(t))
}
fn make_non_send_future1() -> impl Future<Output = Arc<RefCell<i32>>> {
ready(Arc::new(RefCell::new(0)))
}
fn test1() {
let send_fut = async {
let non_send_fut = make_non_send_future1();
let _ = non_send_fut.await;
ready(0).await;
};
require_send(send_fut);
//~^ ERROR future cannot be sent between threads
}
fn test1_no_let() {
let send_fut = async {
let _ = make_non_send_future1().await;
ready(0).await;
};
require_send(send_fut);
//~^ ERROR future cannot be sent between threads
}
async fn ready2<T>(t: T) -> T {
t
}
fn make_non_send_future2() -> impl Future<Output = Arc<RefCell<i32>>> {
ready2(Arc::new(RefCell::new(0)))
}
// Ideally this test would have diagnostics similar to the test above, but right
// now it doesn't.
fn test2() {
let send_fut = async {
let non_send_fut = make_non_send_future2();
let _ = non_send_fut.await;
ready(0).await;
};
require_send(send_fut);
//~^ ERROR `RefCell<i32>` cannot be shared between threads safely
}
fn main() {}
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