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// run-pass
// edition:2021
// check-run-results
#![feature(dyn_star)]
//~^ WARN the feature `dyn_star` is incomplete and may not be safe to use and/or cause compiler crashes
use std::future::Future;
async fn foo(f: dyn* Future<Output = i32>) {
println!("value: {}", f.await);
}
async fn async_main() {
foo(Box::pin(async { 1 })).await
}
// ------------------------------------------------------------------------- //
// Implementation Details Below...
use std::pin::Pin;
use std::task::*;
pub fn noop_waker() -> Waker {
let raw = RawWaker::new(std::ptr::null(), &NOOP_WAKER_VTABLE);
// SAFETY: the contracts for RawWaker and RawWakerVTable are upheld
unsafe { Waker::from_raw(raw) }
}
const NOOP_WAKER_VTABLE: RawWakerVTable = RawWakerVTable::new(noop_clone, noop, noop, noop);
unsafe fn noop_clone(_p: *const ()) -> RawWaker {
RawWaker::new(std::ptr::null(), &NOOP_WAKER_VTABLE)
}
unsafe fn noop(_p: *const ()) {}
fn main() {
let mut fut = async_main();
// Poll loop, just to test the future...
let waker = noop_waker();
let ctx = &mut Context::from_waker(&waker);
loop {
match unsafe { Pin::new_unchecked(&mut fut).poll(ctx) } {
Poll::Pending => {}
Poll::Ready(()) => break,
}
}
}
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