Switch to FuturesOrdered dynamically in try_join_all

[ibraheemdev]

Continuation of #2412.

[ibraheemdev]

error[E0277]: `*const ()` cannot be sent between threads safely
   --> futures/tests/auto_traits.rs:579:5
    |
579 |     assert_impl!(TryJoinAll<SendTryFuture<()>>: Send);
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `*const ()` cannot be sent between threads safely
    |
    = help: within `futures::stream::futures_ordered::OrderWrapper<Result<(), *const ()>>`, the trait `std::marker::Send` is not implemented for `*const ()`
    = note: required because it appears within the type `Result<(), *const ()>`
    = note: required because it appears within the type `futures::stream::futures_ordered::OrderWrapper<Result<(), *const ()>>`
    = note: required because of the requirements on the impl of `std::marker::Send` for `Unique<futures::stream::futures_ordered::OrderWrapper<Result<(), *const ()>>>`
    = note: required because it appears within the type `alloc::raw_vec::RawVec<futures::stream::futures_ordered::OrderWrapper<Result<(), *const ()>>>`
    = note: required because it appears within the type `Vec<futures::stream::futures_ordered::OrderWrapper<Result<(), *const ()>>>`
    = note: required because it appears within the type `BinaryHeap<futures::stream::futures_ordered::OrderWrapper<Result<(), *const ()>>>`
    = note: required because it appears within the type `futures::stream::FuturesOrdered<Pin<Box<(dyn futures::Future<Output = Result<(), *const ()>> + std::marker::Send + 'static)>>>`
    = note: required because it appears within the type `futures::stream::TryCollect<futures::stream::FuturesOrdered<Pin<Box<(dyn futures::Future<Output = Result<(), *const ()>> + std::marker::Send + 'static)>>>, Vec<()>>`
    = note: required because it appears within the type `futures::future::try_join_all::TryJoinAllKind<Pin<Box<(dyn futures::Future<Output = Result<(), *const ()>> + std::marker::Send + 'static)>>>`
    = note: required because it appears within the type `futures::future::TryJoinAll<Pin<Box<(dyn futures::Future<Output = Result<(), *const ()>> + std::marker::Send + 'static)>>>`

@taiki-e do you know why this is failing now?

[taiki-e]

The SendTryFuture has two parameters (Ok and Err), so you probably need to set both to ().

futures-rs/futures/tests/auto_traits.rs

Line 18 in d74763c

pub type SendTryFuture<T = *const (), E = *const ()> = SendFuture<Result<T, E>>;

like:

futures-rs/futures/tests/auto_traits.rs

Line 1657 in c0e9368

assert_impl!(TryBuffered<SendTryStream<SendTryFuture<(), ()>>>: Send);

[ibraheemdev]

@taiki-e this is ready to be merged.

[taiki-e]

Thanks!