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