use std::{convert::Infallible, future::Future};

trait Trait {}

impl<Fut> Trait for fn(&u8, &u16) -> Fut where Fut: Future<Output = Result<(), Infallible>> {}

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

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

pub fn check2() {
    let f = coerce_to_fn_ptr(lol as AsyncFn<_>);
    //check()
}

type AsyncFn<Fut>
where
    Fut: Future<Output = Result<(), Infallible>>,
= fn(&u8, &u16) -> Fut;

#[inline]
fn coerce_to_fn_ptr<Fut>(f: AsyncFn<Fut>) -> AsyncFn<Fut>
where
    Fut: Future<Output = Result<(), Infallible>>,
{
    f
}