73 lines
1.5 KiB
Rust
73 lines
1.5 KiB
Rust
#![feature(never_type)]
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use std::{future::Future, pin::Pin, task::Poll};
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use std::task::{Wake, Waker, Context};
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use std::sync::Arc;
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// See if we can run a basic `async fn`
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pub async fn foo(x: &u32, y: u32) -> u32 {
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let y = &y;
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let z = 9;
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let z = &z;
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let y = async { *y + *z }.await;
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let a = 10;
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let a = &a;
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*x + y + *a
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}
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async fn add(x: u32, y: u32) -> u32 {
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let a = async { x + y };
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a.await
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}
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async fn build_aggregate(a: u32, b: u32, c: u32, d: u32) -> u32 {
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let x = (add(a, b).await, add(c, d).await);
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x.0 + x.1
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}
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enum Never {}
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fn never() -> Never {
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panic!()
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}
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async fn includes_never(crash: bool, x: u32) -> u32 {
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let mut result = async { x * x }.await;
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if !crash {
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return result;
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}
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#[allow(unused)]
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let bad = never();
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result *= async { x + x }.await;
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drop(bad);
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result
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}
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async fn partial_init(x: u32) -> u32 {
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#[allow(unreachable_code)]
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let _x: (String, !) = (String::new(), return async { x + x }.await);
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}
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fn run_fut(mut fut: impl Future<Output=u32>, output: u32) {
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struct MyWaker;
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impl Wake for MyWaker {
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fn wake(self: Arc<Self>) {
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unimplemented!()
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}
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}
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let waker = Waker::from(Arc::new(MyWaker));
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let mut context = Context::from_waker(&waker);
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assert_eq!(unsafe { Pin::new_unchecked(&mut fut) }.poll(&mut context), Poll::Ready(output));
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}
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fn main() {
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let x = 5;
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run_fut(foo(&x, 7), 31);
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run_fut(build_aggregate(1, 2, 3, 4), 10);
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run_fut(includes_never(false, 4), 16);
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run_fut(partial_init(4), 8);
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}
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