9 Forward<(Box<dyn Future<Error = u32>>,)>,
11 b.map_err(|_| ()).join();
18 impl<I: Future<Error = E>, E> Future for (I,) {
22 struct Forward<T: Future> {
26 impl<T: Future> Future for Forward<T>
30 type Error = T::Error;
36 fn map_err<F, E>(self, _: F) -> (Self, F)
38 F: FnOnce(Self::Error) -> E,
44 fn join(self) -> (MaybeDone<Self>, ())
52 impl<S: ?Sized + Future> Future for Box<S> {
53 type Error = S::Error;
56 enum MaybeDone<A: Future> {
60 impl<U, A: Future, F> Future for (A, F)
62 F: FnOnce(A::Error) -> U,