mirror of
https://github.com/rust-lang/rust.git
synced 2024-10-31 06:22:00 +00:00
95 lines
2.0 KiB
Rust
95 lines
2.0 KiB
Rust
// edition:2021
|
|
// run-pass
|
|
// compile-flags: -Zdrop-tracking
|
|
|
|
#![feature(never_type)]
|
|
|
|
use std::future::Future;
|
|
|
|
// See if we can run a basic `async fn`
|
|
pub async fn foo(x: &u32, y: u32) -> u32 {
|
|
let y = &y;
|
|
let z = 9;
|
|
let z = &z;
|
|
let y = async { *y + *z }.await;
|
|
let a = 10;
|
|
let a = &a;
|
|
*x + y + *a
|
|
}
|
|
|
|
async fn add(x: u32, y: u32) -> u32 {
|
|
let a = async { x + y };
|
|
a.await
|
|
}
|
|
|
|
async fn build_aggregate(a: u32, b: u32, c: u32, d: u32) -> u32 {
|
|
let x = (add(a, b).await, add(c, d).await);
|
|
x.0 + x.1
|
|
}
|
|
|
|
enum Never {}
|
|
fn never() -> Never {
|
|
panic!()
|
|
}
|
|
|
|
async fn includes_never(crash: bool, x: u32) -> u32 {
|
|
let result = async { x * x }.await;
|
|
if !crash {
|
|
return result;
|
|
}
|
|
#[allow(unused)]
|
|
let bad = never();
|
|
result *= async { x + x }.await;
|
|
drop(bad);
|
|
result
|
|
}
|
|
|
|
async fn partial_init(x: u32) -> u32 {
|
|
#[allow(unreachable_code)]
|
|
let _x: (String, !) = (String::new(), return async { x + x }.await);
|
|
}
|
|
|
|
async fn read_exact(_from: &mut &[u8], _to: &mut [u8]) -> Option<()> {
|
|
Some(())
|
|
}
|
|
|
|
async fn hello_world() {
|
|
let data = [0u8; 1];
|
|
let mut reader = &data[..];
|
|
|
|
let mut marker = [0u8; 1];
|
|
read_exact(&mut reader, &mut marker).await.unwrap();
|
|
}
|
|
|
|
fn run_fut<T>(fut: impl Future<Output = T>) -> T {
|
|
use std::sync::Arc;
|
|
use std::task::{Context, Poll, Wake, Waker};
|
|
|
|
struct MyWaker;
|
|
impl Wake for MyWaker {
|
|
fn wake(self: Arc<Self>) {
|
|
unimplemented!()
|
|
}
|
|
}
|
|
|
|
let waker = Waker::from(Arc::new(MyWaker));
|
|
let mut context = Context::from_waker(&waker);
|
|
|
|
let mut pinned = Box::pin(fut);
|
|
loop {
|
|
match pinned.as_mut().poll(&mut context) {
|
|
Poll::Pending => continue,
|
|
Poll::Ready(v) => return v,
|
|
}
|
|
}
|
|
}
|
|
|
|
fn main() {
|
|
let x = 5;
|
|
assert_eq!(run_fut(foo(&x, 7)), 31);
|
|
assert_eq!(run_fut(build_aggregate(1, 2, 3, 4)), 10);
|
|
assert_eq!(run_fut(includes_never(false, 4)), 16);
|
|
assert_eq!(run_fut(partial_init(4)), 8);
|
|
run_fut(hello_world());
|
|
}
|