ice-104649/src/main.rs

use std::{
    future::Future,
    pin::Pin,
    task::{Context, Poll},
};

use futures::{stream, StreamExt};

pub struct JoinHandle<T>(T);

impl<T> Future for JoinHandle<T> {
    type Output = Result<T, ()>;

    fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
        loop {}
    }
}

pub fn spawn<T: Future>(future: T) -> JoinHandle<T::Output> {
    loop {}
}

fn main() {
    let bodies = stream::iter([])
        .map(|url: String| spawn(async { Result::Ok(url) }))
        .buffer_unordered(0);

    bodies.for_each(|b| async {
        match b {
            Ok(Ok(url)) => {}
            Err(e) => {}
            Ok(Err(e)) => {}
        }
    });
}