src/test/ui/issues/issue-38033.rs

   1 // run-pass
   2 use std::marker;
   3 use std::mem;
   4
   5 fn main() {
   6     let workers = (0..0).map(|_| result::<u32, ()>());
   7     drop(join_all(workers).poll());
   8 }
   9
  10 trait Future {
  11     type Item;
  12     type Error;
  13
  14     fn poll(&mut self) -> Result<Self::Item, Self::Error>;
  15 }
  16
  17 trait IntoFuture {
  18     type Future: Future<Item=Self::Item, Error=Self::Error>;
  19     type Item;
  20     type Error;
  21
  22     fn into_future(self) -> Self::Future;
  23 }
  24
  25 impl<F: Future> IntoFuture for F {
  26     type Future = F;
  27     type Item = F::Item;
  28     type Error = F::Error;
  29
  30     fn into_future(self) -> F {
  31         self
  32     }
  33 }
  34
  35 struct FutureResult<T, E> {
  36     _inner: marker::PhantomData<(T, E)>,
  37 }
  38
  39 fn result<T, E>() -> FutureResult<T, E> {
  40     loop {}
  41 }
  42
  43 impl<T, E> Future for FutureResult<T, E> {
  44     type Item = T;
  45     type Error = E;
  46
  47     fn poll(&mut self) -> Result<T, E> {
  48         loop {}
  49     }
  50 }
  51
  52 struct JoinAll<I>
  53     where I: IntoIterator,
  54           I::Item: IntoFuture,
  55 {
  56     elems: Vec<<I::Item as IntoFuture>::Item>,
  57 }
  58
  59 fn join_all<I>(_: I) -> JoinAll<I>
  60     where I: IntoIterator,
  61           I::Item: IntoFuture,
  62 {
  63     JoinAll { elems: vec![] }
  64 }
  65
  66 impl<I> Future for JoinAll<I>
  67     where I: IntoIterator,
  68           I::Item: IntoFuture,
  69 {
  70     type Item = Vec<<I::Item as IntoFuture>::Item>;
  71     type Error = <I::Item as IntoFuture>::Error;
  72
  73     fn poll(&mut self) -> Result<Self::Item, Self::Error> {
  74         let elems = mem::replace(&mut self.elems, Vec::new());
  75         Ok(elems.into_iter().map(|e| {
  76             e
  77         }).collect::<Vec<_>>())
  78     }
  79 }