PinMut::get_mut_unchecked, Add Sized bound to poll_unpin

[MajorBreakfast]

The new nightly (84804c387 2018-06-26) includes PinMut::get_mut & get_mut_unchecked!

• Replace PinMut::get_mut with get_mut_unchecked (this was renamed)
• Remove workaround that was used because the safe PinMut::get_mut didn't exist
• Use unsafe_pinned! macro in FutureOption
• Add Sized bound to poll_unpin methods. See error log below. I'm not sure how best to resolve this

Error log: The trait cannot be made into an object

error: the trait `stream::Stream` cannot be made into an object
  --> futures-core/src/stream/mod.rs:51:5
   |
51 | /     fn poll_next_unpin(&mut self, cx: &mut task::Context) -> Poll<Option<Self::Item>>
52 | |         where Self: Unpin
53 | |     {
54 | |         PinMut::new(self).poll_next(cx)
55 | |     }
   | |_____^
   |
note: lint level defined here
  --> futures-core/src/lib.rs:7:54
   |
7  | #![deny(missing_docs, missing_debug_implementations, warnings)]
   |                                                      ^^^^^^^^
   = note: #[deny(where_clauses_object_safety)] implied by #[deny(warnings)]
   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
   = note: for more information, see issue #51443 <https://github.com/rust-lang/rust/issues/51443>
   = note: method `poll_next_unpin` references the `Self` type in where clauses

error: the trait `future::CoreFutureExt` cannot be made into an object
  --> futures-core/src/future/mod.rs:20:5
   |
20 | /     fn poll_unpin(&mut self, cx: &mut task::Context) -> Poll<Self::Output>
21 | |         where Self: Unpin
22 | |     {
23 | |         PinMut::new(self).poll(cx)
24 | |     }
   | |_____^
   |
   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
   = note: for more information, see issue #51443 <https://github.com/rust-lang/rust/issues/51443>
   = note: method `poll_unpin` references the `Self` type in where clauses

error: the trait `stream::Stream` cannot be made into an object
  --> futures-core/src/stream/mod.rs:51:5
   |
51 | /     fn poll_next_unpin(&mut self, cx: &mut task::Context) -> Poll<Option<Self::Item>>
52 | |         where Self: Unpin
53 | |     {
54 | |         PinMut::new(self).poll_next(cx)
55 | |     }
   | |_____^
   |
note: lint level defined here
  --> futures-core/src/lib.rs:7:54
   |
7  | #![deny(missing_docs, missing_debug_implementations, warnings)]
   |                                                      ^^^^^^^^
   = note: #[deny(where_clauses_object_safety)] implied by #[deny(warnings)]
   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
   = note: for more information, see issue #51443 <https://github.com/rust-lang/rust/issues/51443>
   = note: method `poll_next_unpin` references the `Self` type in where clauses

error: the trait `future::CoreFutureExt` cannot be made into an object
  --> futures-core/src/future/mod.rs:20:5
   |
20 | /     fn poll_unpin(&mut self, cx: &mut task::Context) -> Poll<Self::Output>
21 | |         where Self: Unpin
22 | |     {
23 | |         PinMut::new(self).poll(cx)
24 | |     }
   | |_____^
   |
   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
   = note: for more information, see issue #51443 <https://github.com/rust-lang/rust/issues/51443>
   = note: method `poll_unpin` references the `Self` type in where clauses

[cramertj]

@MajorBreakfast LGTM-- I'll leave a comment on rust-lang/rust#51443.

[MajorBreakfast]

ˋpoll_unpin()ˋ will be less useful until this is sorted out. However we don‘t need to rely on it. I suppose this is also why it wasn‘t put into core. ˋPinMut:new()ˋ works just fine for now.