src/test/run-pass/impl-trait/bounds_regression.rs

// Copyright 2018 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.

pub trait FakeGenerator {
    type Yield;
    type Return;
}

pub trait FakeFuture {
    type Output;
}

pub fn future_from_generator<
    T: FakeGenerator<Yield = ()>
>(x: T) -> impl FakeFuture<Output = T::Return> {
    GenFuture(x)
}

struct GenFuture<T: FakeGenerator<Yield = ()>>(T);

impl<T: FakeGenerator<Yield = ()>> FakeFuture for GenFuture<T> {
    type Output = T::Return;
}

fn main() {}