"reached the recursion limit during monomorphization (selection ambiguity)" with join_all()

[dwrensha]

I expect the following program to compile without error.

extern crate futures; // version 0.1.9
use futures::{Future, future};

fn main() {
    let _ = future::join_all(vec![
        future::lazy(|| {
            future::ok::<(),()>(()).join(
                future::ok(()).and_then(|()| {
                    future::ok(()).map(|_| ())
                })
            )
        })
    ]);
}

Instead, rustc (stable, beta, and nightly) gives me

error: reached the recursion limit during monomorphization (selection ambiguity)

This problem seems to be related to rust-lang/rust#38033.

I am not sure whether this should be considered a rustc bug or a futures-rs bug. I think the problem could be sidestepped on the futures-rs side by making join_all()'s I::Item be an actual Future rather than an IntoFuture.

[alexcrichton]

What in the world is wrong with join_all?!

[alexcrichton]

I applied both #286 locally and removed IntoFuture in the implementation of JoinAll, but it still hit the recursion limit :\

[dwrensha]

Closing, as this error no longer happens.