66 lines
1.3 KiB
Rust
66 lines
1.3 KiB
Rust
|
//@ edition:2021
|
||
|
|
//@ check-pass
|
||
|
|
|
||
|
|
#![feature(type_alias_impl_trait)]
|
||
|
|
#![feature(closure_lifetime_binder)]
|
||
|
|
|
||
|
|
use std::future::Future;
|
||
|
|
|
||
|
|
trait AsyncFn<I, R>: FnMut(I) -> Self::Fut {
|
||
|
|
type Fut: Future<Output = R>;
|
||
|
|
}
|
||
|
|
|
||
|
|
impl<F, I, R, Fut> AsyncFn<I, R> for F
|
||
|
|
where
|
||
|
|
Fut: Future<Output = R>,
|
||
|
|
F: FnMut(I) -> Fut,
|
||
|
|
{
|
||
|
|
type Fut = Fut;
|
||
|
|
}
|
||
|
|
|
||
|
|
async fn call<C, R, F>(mut ctx: C, mut f: F) -> Result<R, ()>
|
||
|
|
where
|
||
|
|
F: for<'a> AsyncFn<&'a mut C, Result<R, ()>>,
|
||
|
|
{
|
||
|
|
loop {
|
||
|
|
match f(&mut ctx).await {
|
||
|
|
Ok(val) => return Ok(val),
|
||
|
|
Err(_) => continue,
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
trait Cap<'a> {}
|
||
|
|
impl<T> Cap<'_> for T {}
|
||
|
|
|
||
|
|
fn works(ctx: &mut usize) {
|
||
|
|
let mut inner = 0;
|
||
|
|
|
||
|
|
type Ret<'a, 'b: 'a> = impl Future<Output = Result<usize, ()>> + 'a + Cap<'b>;
|
||
|
|
|
||
|
|
let callback = for<'a, 'b> |c: &'a mut &'b mut usize| -> Ret<'a, 'b> {
|
||
|
|
inner += 1;
|
||
|
|
async move {
|
||
|
|
let _c = c;
|
||
|
|
Ok(1usize)
|
||
|
|
}
|
||
|
|
};
|
||
|
|
call(ctx, callback);
|
||
|
|
}
|
||
|
|
|
||
|
|
fn doesnt_work_but_should(ctx: &mut usize) {
|
||
|
|
let mut inner = 0;
|
||
|
|
|
||
|
|
type Ret<'a, 'b: 'a> = impl Future<Output = Result<usize, ()>> + 'a + Cap<'b>;
|
||
|
|
|
||
|
|
call(ctx, for<'a, 'b> |c: &'a mut &'b mut usize| -> Ret<'a, 'b> {
|
||
|
|
inner += 1;
|
||
|
|
async move {
|
||
|
|
let _c = c;
|
||
|
|
Ok(1usize)
|
||
|
|
}
|
||
|
|
});
|
||
|
|
}
|
||
|
|
|
||
|
|
fn main() {}
|