src/test/run-pass/issue-38033.rs

   1 // Copyright 2016 The Rust Project Developers. See the COPYRIGHT
   2 // file at the top-level directory of this distribution and at
   3 // http://rust-lang.org/COPYRIGHT.
   4 //
   5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
   6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
   8 // option. This file may not be copied, modified, or distributed
   9 // except according to those terms.
  10
  11 use std::marker;
  12 use std::mem;
  13
  14 fn main() {
  15     let workers = (0..0).map(|_| result::<u32, ()>());
  16     drop(join_all(workers).poll());
  17 }
  18
  19 trait Future {
  20     type Item;
  21     type Error;
  22
  23     fn poll(&mut self) -> Result<Self::Item, Self::Error>;
  24 }
  25
  26 trait IntoFuture {
  27     type Future: Future<Item=Self::Item, Error=Self::Error>;
  28     type Item;
  29     type Error;
  30
  31     fn into_future(self) -> Self::Future;
  32 }
  33
  34 impl<F: Future> IntoFuture for F {
  35     type Future = F;
  36     type Item = F::Item;
  37     type Error = F::Error;
  38
  39     fn into_future(self) -> F {
  40         self
  41     }
  42 }
  43
  44 struct FutureResult<T, E> {
  45     _inner: marker::PhantomData<(T, E)>,
  46 }
  47
  48 fn result<T, E>() -> FutureResult<T, E> {
  49     loop {}
  50 }
  51
  52 impl<T, E> Future for FutureResult<T, E> {
  53     type Item = T;
  54     type Error = E;
  55
  56     fn poll(&mut self) -> Result<T, E> {
  57         loop {}
  58     }
  59 }
  60
  61 struct JoinAll<I>
  62     where I: IntoIterator,
  63           I::Item: IntoFuture,
  64 {
  65     elems: Vec<<I::Item as IntoFuture>::Item>,
  66 }
  67
  68 fn join_all<I>(_: I) -> JoinAll<I>
  69     where I: IntoIterator,
  70           I::Item: IntoFuture,
  71 {
  72     JoinAll { elems: vec![] }
  73 }
  74
  75 impl<I> Future for JoinAll<I>
  76     where I: IntoIterator,
  77           I::Item: IntoFuture,
  78 {
  79     type Item = Vec<<I::Item as IntoFuture>::Item>;
  80     type Error = <I::Item as IntoFuture>::Error;
  81
  82     fn poll(&mut self) -> Result<Self::Item, Self::Error> {
  83         let elems = mem::replace(&mut self.elems, Vec::new());
  84         Ok(elems.into_iter().map(|e| {
  85             e
  86         }).collect::<Vec<_>>())
  87     }
  88 }