#![feature(unboxed_closures)]
use std::{convert::Infallible, future::Future};

trait Trait {}

impl<'a, F> Trait for F
where
    F: Fn<(&'a u8, &'a u16)>,
    F::Output: Future<Output = Result<(), Infallible>>,
{
}

async fn lol(_: &u8, _: &u16) -> Result<(), Infallible> {Ok(())}

fn check<T: Trait>(_: T) {}

pub fn check2() {
    check(lol)
}