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    #![allow(non_snake_case)]

    use crate::future::{assert_future, try_maybe_done, TryMaybeDone};
    use core::fmt;
    use core::pin::Pin;
    use futures_core::future::{Future, TryFuture};
    use futures_core::task::{Context, Poll};
    use pin_project_lite::pin_project;

    macro_rules! generate {
        ($(
            $(#[$doc:meta])*
            ($Join:ident, <Fut1, $($Fut:ident),*>),
        )*) => ($(
            pin_project! {
                $(#[$doc])*
                #[must_use = "futures do nothing unless you `.await` or poll them"]
                pub struct $Join<Fut1: TryFuture, $($Fut: TryFuture),*> {
                    #[pin] Fut1: TryMaybeDone<Fut1>,
                    $(#[pin] $Fut: TryMaybeDone<$Fut>,)*
                }
            }

            impl<Fut1, $($Fut),*> fmt::Debug for $Join<Fut1, $($Fut),*>
            where
                Fut1: TryFuture + fmt::Debug,
                Fut1::Ok: fmt::Debug,
                Fut1::Error: fmt::Debug,
                $(
                    $Fut: TryFuture + fmt::Debug,
                    $Fut::Ok: fmt::Debug,
                    $Fut::Error: fmt::Debug,
                )*
            {
                fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
                    f.debug_struct(stringify!($Join))
                        .field("Fut1", &self.Fut1)
                        $(.field(stringify!($Fut), &self.$Fut))*
                        .finish()
                }
            }

            impl<Fut1, $($Fut),*> $Join<Fut1, $($Fut),*>
            where
                Fut1: TryFuture,
                $(
                    $Fut: TryFuture<Error=Fut1::Error>
                ),*
            {
                fn new(Fut1: Fut1, $($Fut: $Fut),*) -> Self {
                    Self {
                        Fut1: try_maybe_done(Fut1),
                        $($Fut: try_maybe_done($Fut)),*
                    }
                }
            }

            impl<Fut1, $($Fut),*> Future for $Join<Fut1, $($Fut),*>
            where
                Fut1: TryFuture,
                $(
                    $Fut: TryFuture<Error=Fut1::Error>
                ),*
            {
                type Output = Result<(Fut1::Ok, $($Fut::Ok),*), Fut1::Error>;

                fn poll(
                    self: Pin<&mut Self>, cx: &mut Context<'_>
                ) -> Poll<Self::Output> {
                    let mut all_done = true;
                    let mut futures = self.project();
                    all_done &= futures.Fut1.as_mut().poll(cx)?.is_ready();
                    $(
                        all_done &= futures.$Fut.as_mut().poll(cx)?.is_ready();
                    )*

                    if all_done {
                        Poll::Ready(Ok((
                            futures.Fut1.take_output().unwrap(),
                            $(
                                futures.$Fut.take_output().unwrap()
                            ),*
                        )))
                    } else {
                        Poll::Pending
                    }
                }
            }
        )*)
    }

    generate! {
        /// Future for the [`try_join`](try_join()) function.
        (TryJoin, <Fut1, Fut2>),

        /// Future for the [`try_join3`] function.
        (TryJoin3, <Fut1, Fut2, Fut3>),

        /// Future for the [`try_join4`] function.
        (TryJoin4, <Fut1, Fut2, Fut3, Fut4>),

        /// Future for the [`try_join5`] function.
        (TryJoin5, <Fut1, Fut2, Fut3, Fut4, Fut5>),
    }

    /// Joins the result of two futures, waiting for them both to complete or
    /// for one to produce an error.
    ///
    /// This function will return a new future which awaits both futures to
    /// complete. If successful, the returned future will finish with a tuple of
    /// both results. If unsuccessful, it will complete with the first error
    /// encountered.
    ///
    /// Note that this function consumes the passed futures and returns a
    /// wrapped version of it.
    ///
    /// # Examples
    ///
    /// When used on multiple futures that return [`Ok`], `try_join` will return
    /// [`Ok`] of a tuple of the values:
    ///
    /// ```
    /// # futures::executor::block_on(async {
    /// use futures::future;
    ///
    /// let a = future::ready(Ok::<i32, i32>(1));
    /// let b = future::ready(Ok::<i32, i32>(2));
    /// let pair = future::try_join(a, b);
    ///
    /// assert_eq!(pair.await, Ok((1, 2)));
    /// # });
    /// ```
    ///
    /// If one of the futures resolves to an error, `try_join` will return
    /// that error:
    ///
    /// ```
    /// # futures::executor::block_on(async {
    /// use futures::future;
    ///
    /// let a = future::ready(Ok::<i32, i32>(1));
    /// let b = future::ready(Err::<i32, i32>(2));
    /// let pair = future::try_join(a, b);
    ///
    /// assert_eq!(pair.await, Err(2));
    /// # });
    /// ```
    pub fn try_join<Fut1, Fut2>(future1: Fut1, future2: Fut2) -> TryJoin<Fut1, Fut2>
    where
        Fut1: TryFuture,
        Fut2: TryFuture<Error = Fut1::Error>,
    {
        assert_future::<Result<(Fut1::Ok, Fut2::Ok), Fut1::Error>, _>(TryJoin::new(future1, future2))
    }

    /// Same as [`try_join`](try_join()), but with more futures.
    ///
    /// # Examples
    ///
    /// ```
    /// # futures::executor::block_on(async {
    /// use futures::future;
    ///
    /// let a = future::ready(Ok::<i32, i32>(1));
    /// let b = future::ready(Ok::<i32, i32>(2));
    /// let c = future::ready(Ok::<i32, i32>(3));
    /// let tuple = future::try_join3(a, b, c);
    ///
    /// assert_eq!(tuple.await, Ok((1, 2, 3)));
    /// # });
    /// ```
    pub fn try_join3<Fut1, Fut2, Fut3>(
        future1: Fut1,
        future2: Fut2,
        future3: Fut3,
    ) -> TryJoin3<Fut1, Fut2, Fut3>
    where
        Fut1: TryFuture,
        Fut2: TryFuture<Error = Fut1::Error>,
        Fut3: TryFuture<Error = Fut1::Error>,
    {
        assert_future::<Result<(Fut1::Ok, Fut2::Ok, Fut3::Ok), Fut1::Error>, _>(TryJoin3::new(
            future1, future2, future3,
        ))
    }

    /// Same as [`try_join`](try_join()), but with more futures.
    ///
    /// # Examples
    ///
    /// ```
    /// # futures::executor::block_on(async {
    /// use futures::future;
    ///
    /// let a = future::ready(Ok::<i32, i32>(1));
    /// let b = future::ready(Ok::<i32, i32>(2));
    /// let c = future::ready(Ok::<i32, i32>(3));
    /// let d = future::ready(Ok::<i32, i32>(4));
    /// let tuple = future::try_join4(a, b, c, d);
    ///
    /// assert_eq!(tuple.await, Ok((1, 2, 3, 4)));
    /// # });
    /// ```
    pub fn try_join4<Fut1, Fut2, Fut3, Fut4>(
        future1: Fut1,
        future2: Fut2,
        future3: Fut3,
        future4: Fut4,
    ) -> TryJoin4<Fut1, Fut2, Fut3, Fut4>
    where
        Fut1: TryFuture,
        Fut2: TryFuture<Error = Fut1::Error>,
        Fut3: TryFuture<Error = Fut1::Error>,
        Fut4: TryFuture<Error = Fut1::Error>,
    {
        assert_future::<Result<(Fut1::Ok, Fut2::Ok, Fut3::Ok, Fut4::Ok), Fut1::Error>, _>(
            TryJoin4::new(future1, future2, future3, future4),
        )
    }

    /// Same as [`try_join`](try_join()), but with more futures.
    ///
    /// # Examples
    ///
    /// ```
    /// # futures::executor::block_on(async {
    /// use futures::future;
    ///
    /// let a = future::ready(Ok::<i32, i32>(1));
    /// let b = future::ready(Ok::<i32, i32>(2));
    /// let c = future::ready(Ok::<i32, i32>(3));
    /// let d = future::ready(Ok::<i32, i32>(4));
    /// let e = future::ready(Ok::<i32, i32>(5));
    /// let tuple = future::try_join5(a, b, c, d, e);
    ///
    /// assert_eq!(tuple.await, Ok((1, 2, 3, 4, 5)));
    /// # });
    /// ```
    pub fn try_join5<Fut1, Fut2, Fut3, Fut4, Fut5>(
        future1: Fut1,
        future2: Fut2,
        future3: Fut3,
        future4: Fut4,
        future5: Fut5,
    ) -> TryJoin5<Fut1, Fut2, Fut3, Fut4, Fut5>
    where
        Fut1: TryFuture,
        Fut2: TryFuture<Error = Fut1::Error>,
        Fut3: TryFuture<Error = Fut1::Error>,
        Fut4: TryFuture<Error = Fut1::Error>,
        Fut5: TryFuture<Error = Fut1::Error>,
    {
        assert_future::<Result<(Fut1::Ok, Fut2::Ok, Fut3::Ok, Fut4::Ok, Fut5::Ok), Fut1::Error>, _>(
            TryJoin5::new(future1, future2, future3, future4, future5),
        )
    }