Update to a new pinning API.

5 files changed, 40 insertions, 313 deletions

diff --git a/src/liballoc/boxed.rs b/src/liballoc/boxed.rs
index c25f3eb8f17..fce6417186f 100644
--- a/src/liballoc/boxed.rs
+++ b/src/liballoc/boxed.rs
@@ -65,13 +65,12 @@ use core::hash::{Hash, Hasher};
 use core::iter::FusedIterator;
 use core::marker::{Unpin, Unsize};
 use core::mem;
-use core::pin::PinMut;
+use core::pin::Pin;
 use core::ops::{CoerceUnsized, Deref, DerefMut, Generator, GeneratorState};
 use core::ptr::{self, NonNull, Unique};
 use core::task::{Context, Poll, Spawn, SpawnErrorKind, SpawnObjError};
 
 use raw_vec::RawVec;
-use pin::PinBox;
 use str::from_boxed_utf8_unchecked;
 
 /// A pointer type for heap allocation.
@@ -97,6 +96,11 @@ impl<T> Box<T> {
     pub fn new(x: T) -> Box<T> {
         box x
     }
+
+    #[unstable(feature = "pin", issue = "49150")]
+    pub fn pinned(x: T) -> Pin<Box<T>> {
+        unsafe { Pin::new_unchecked(box x) }
+    }
 }
 
 impl<T: ?Sized> Box<T> {
@@ -427,6 +431,13 @@ impl<T> From<T> for Box<T> {
     }
 }
 
+#[unstable(feature = "pin", issue = "49150")]
+impl<T> From<Box<T>> for Pin<Box<T>> {
+    fn from(boxed: Box<T>) -> Self {
+        unsafe { Pin::new_unchecked(boxed) }
+    }
+}
+
 #[stable(feature = "box_from_slice", since = "1.17.0")]
 impl<'a, T: Copy> From<&'a [T]> for Box<[T]> {
     fn from(slice: &'a [T]) -> Box<[T]> {
@@ -764,8 +775,8 @@ impl<T> Generator for Box<T>
 impl<F: ?Sized + Future + Unpin> Future for Box<F> {
     type Output = F::Output;
 
-    fn poll(mut self: PinMut<Self>, cx: &mut Context) -> Poll<Self::Output> {
-        PinMut::new(&mut **self).poll(cx)
+    fn poll(mut self: Pin<&mut Self>, cx: &mut Context) -> Poll<Self::Output> {
+        F::poll(Pin::new(&mut *self), cx)
     }
 }
 
@@ -779,8 +790,8 @@ unsafe impl<'a, T, F> UnsafeFutureObj<'a, T> for Box<F>
 
     unsafe fn poll(ptr: *mut (), cx: &mut Context) -> Poll<T> {
         let ptr = ptr as *mut F;
-        let pin: PinMut<F> = PinMut::new_unchecked(&mut *ptr);
-        pin.poll(cx)
+        let pin: Pin<&mut F> = Pin::new_unchecked(&mut *ptr);
+        F::poll(pin, cx)
     }
 
     unsafe fn drop(ptr: *mut ()) {
@@ -818,9 +829,16 @@ impl<'a, F: Future<Output = ()> + 'a> From<Box<F>> for LocalFutureObj<'a, ()> {
     }
 }
 
-#[unstable(feature = "pin", issue = "49150")]
-impl<T: Unpin + ?Sized> From<PinBox<T>> for Box<T> {
-    fn from(pinned: PinBox<T>) -> Box<T> {
-        unsafe { PinBox::unpin(pinned) }
+#[unstable(feature = "futures_api", issue = "50547")]
+impl<'a, F: Future<Output = ()> + Send + 'a> From<Pin<Box<F>>> for FutureObj<'a, ()> {
+    fn from(boxed: Pin<Box<F>>) -> Self {
+        FutureObj::new(boxed)
+    }
+}
+
+#[unstable(feature = "futures_api", issue = "50547")]
+impl<'a, F: Future<Output = ()> + 'a> From<Pin<Box<F>>> for LocalFutureObj<'a, ()> {
+    fn from(boxed: Pin<Box<F>>) -> Self {
+        LocalFutureObj::new(boxed)
     }
 }
diff --git a/src/liballoc/lib.rs b/src/liballoc/lib.rs
index 676c977514f..18d8cd773eb 100644
--- a/src/liballoc/lib.rs
+++ b/src/liballoc/lib.rs
@@ -160,7 +160,6 @@ pub mod collections;
 pub mod sync;
 pub mod rc;
 pub mod raw_vec;
-pub mod pin;
 pub mod prelude;
 pub mod borrow;
 pub mod fmt;
diff --git a/src/liballoc/pin.rs b/src/liballoc/pin.rs
deleted file mode 100644
index 17bbc9882d9..00000000000
--- a/src/liballoc/pin.rs
+++ /dev/null
@@ -1,302 +0,0 @@
-//! Types which pin data to its location in memory
-//!
-//! It is sometimes useful to have objects that are guaranteed to not move,
-//! in the sense that their placement in memory does not change, and can thus be relied upon.
-//!
-//! A prime example of such a scenario would be building self-referencial structs,
-//! since moving an object with pointers to itself will invalidate them,
-//! which could cause undefined behavior.
-//!
-//! In order to prevent objects from moving, they must be *pinned*,
-//! by wrapping the data in pinning pointer types, such as [`PinMut`] and [`PinBox`],
-//! which are otherwise equivalent to `& mut` and [`Box`], respectively.
-//!
-//! First of all, these are pointer types because pinned data mustn't be passed around by value
-//! (that would change its location in memory).
-//! Secondly, since data can be moved out of `&mut` and [`Box`] with functions such as [`swap`],
-//! which causes their contents to swap places in memory,
-//! we need dedicated types that prohibit such operations.
-//!
-//! However, these restrictions are usually not necessary,
-//! so most types implement the [`Unpin`] auto-trait,
-//! which indicates that the type can be moved out safely.
-//! Doing so removes the limitations of pinning types,
-//! making them the same as their non-pinning counterparts.
-//!
-//! [`PinMut`]: struct.PinMut.html
-//! [`PinBox`]: struct.PinBox.html
-//! [`Unpin`]: trait.Unpin.html
-//! [`swap`]: ../../std/mem/fn.swap.html
-//! [`Box`]: ../boxed/struct.Box.html
-//!
-//! # Examples
-//!
-//! ```rust
-//! #![feature(pin)]
-//!
-//! use std::pin::PinBox;
-//! use std::marker::Pinned;
-//! use std::ptr::NonNull;
-//!
-//! // This is a self referencial struct since the slice field points to the data field.
-//! // We cannot inform the compiler about that with a normal reference,
-//! // since this pattern cannot be described with the usual borrowing rules.
-//! // Instead we use a raw pointer, though one which is known to not be null,
-//! // since we know it's pointing at the string.
-//! struct Unmovable {
-//!     data: String,
-//!     slice: NonNull<String>,
-//!     _pin: Pinned,
-//! }
-//!
-//! impl Unmovable {
-//!     // To ensure the data doesn't move when the function returns,
-//!     // we place it in the heap where it will stay for the lifetime of the object,
-//!     // and the only way to access it would be through a pointer to it.
-//!     fn new(data: String) -> PinBox<Self> {
-//!         let res = Unmovable {
-//!             data,
-//!             // we only create the pointer once the data is in place
-//!             // otherwise it will have already moved before we even started
-//!             slice: NonNull::dangling(),
-//!             _pin: Pinned,
-//!         };
-//!         let mut boxed = PinBox::new(res);
-//!
-//!         let slice = NonNull::from(&boxed.data);
-//!         // we know this is safe because modifying a field doesn't move the whole struct
-//!         unsafe { PinBox::get_mut(&mut boxed).slice = slice };
-//!         boxed
-//!     }
-//! }
-//!
-//! let unmoved = Unmovable::new("hello".to_string());
-//! // The pointer should point to the correct location,
-//! // so long as the struct hasn't moved.
-//! // Meanwhile, we are free to move the pointer around.
-//! # #[allow(unused_mut)]
-//! let mut still_unmoved = unmoved;
-//! assert_eq!(still_unmoved.slice, NonNull::from(&still_unmoved.data));
-//!
-//! // Since our type doesn't implement Unpin, this will fail to compile:
-//! // let new_unmoved = Unmovable::new("world".to_string());
-//! // std::mem::swap(&mut *still_unmoved, &mut *new_unmoved);
-//! ```
-
-#![unstable(feature = "pin", issue = "49150")]
-
-pub use core::pin::*;
-pub use core::marker::Unpin;
-
-use core::convert::From;
-use core::fmt;
-use core::future::{Future, FutureObj, LocalFutureObj, UnsafeFutureObj};
-use core::marker::Unsize;
-use core::ops::{CoerceUnsized, Deref, DerefMut};
-use core::task::{Context, Poll};
-
-use boxed::Box;
-
-/// A pinned, heap allocated reference.
-///
-/// This type is similar to [`Box`], except that it pins its value,
-/// which prevents it from moving out of the reference, unless it implements [`Unpin`].
-///
-/// See the [module documentation] for furthur explaination on pinning.
-///
-/// [`Box`]: ../boxed/struct.Box.html
-/// [`Unpin`]: ../../std/marker/trait.Unpin.html
-/// [module documentation]: index.html
-#[unstable(feature = "pin", issue = "49150")]
-#[fundamental]
-#[repr(transparent)]
-pub struct PinBox<T: ?Sized> {
-    inner: Box<T>,
-}
-
-#[unstable(feature = "pin", issue = "49150")]
-impl<T> PinBox<T> {
-    /// Allocate memory on the heap, move the data into it and pin it.
-    #[unstable(feature = "pin", issue = "49150")]
-    pub fn new(data: T) -> PinBox<T> {
-        PinBox { inner: Box::new(data) }
-    }
-}
-
-#[unstable(feature = "pin", issue = "49150")]
-impl<T: ?Sized> PinBox<T> {
-    /// Get a pinned reference to the data in this PinBox.
-    #[inline]
-    pub fn as_pin_mut<'a>(&'a mut self) -> PinMut<'a, T> {
-        unsafe { PinMut::new_unchecked(&mut *self.inner) }
-    }
-
-    /// Constructs a `PinBox` from a raw pointer.
-    ///
-    /// After calling this function, the raw pointer is owned by the
-    /// resulting `PinBox`. Specifically, the `PinBox` destructor will call
-    /// the destructor of `T` and free the allocated memory. Since the
-    /// way `PinBox` allocates and releases memory is unspecified, the
-    /// only valid pointer to pass to this function is the one taken
-    /// from another `PinBox` via the [`PinBox::into_raw`] function.
-    ///
-    /// This function is unsafe because improper use may lead to
-    /// memory problems. For example, a double-free may occur if the
-    /// function is called twice on the same raw pointer.
-    ///
-    /// [`PinBox::into_raw`]: struct.PinBox.html#method.into_raw
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// #![feature(pin)]
-    /// use std::pin::PinBox;
-    /// let x = PinBox::new(5);
-    /// let ptr = PinBox::into_raw(x);
-    /// let x = unsafe { PinBox::from_raw(ptr) };
-    /// ```
-    #[inline]
-    pub unsafe fn from_raw(raw: *mut T) -> Self {
-        PinBox { inner: Box::from_raw(raw) }
-    }
-
-    /// Consumes the `PinBox`, returning the wrapped raw pointer.
-    ///
-    /// After calling this function, the caller is responsible for the
-    /// memory previously managed by the `PinBox`. In particular, the
-    /// caller should properly destroy `T` and release the memory. The
-    /// proper way to do so is to convert the raw pointer back into a
-    /// `PinBox` with the [`PinBox::from_raw`] function.
-    ///
-    /// Note: this is an associated function, which means that you have
-    /// to call it as `PinBox::into_raw(b)` instead of `b.into_raw()`. This
-    /// is so that there is no conflict with a method on the inner type.
-    ///
-    /// [`PinBox::from_raw`]: struct.PinBox.html#method.from_raw
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// #![feature(pin)]
-    /// use std::pin::PinBox;
-    /// let x = PinBox::new(5);
-    /// let ptr = PinBox::into_raw(x);
-    /// ```
-    #[inline]
-    pub fn into_raw(b: PinBox<T>) -> *mut T {
-        Box::into_raw(b.inner)
-    }
-
-    /// Get a mutable reference to the data inside this PinBox.
-    ///
-    /// This function is unsafe. Users must guarantee that the data is never
-    /// moved out of this reference.
-    #[inline]
-    pub unsafe fn get_mut<'a>(this: &'a mut PinBox<T>) -> &'a mut T {
-        &mut *this.inner
-    }
-
-    /// Convert this PinBox into an unpinned Box.
-    ///
-    /// This function is unsafe. Users must guarantee that the data is never
-    /// moved out of the box.
-    #[inline]
-    pub unsafe fn unpin(this: PinBox<T>) -> Box<T> {
-        this.inner
-    }
-}
-
-#[unstable(feature = "pin", issue = "49150")]
-impl<T: ?Sized> From<Box<T>> for PinBox<T> {
-    fn from(boxed: Box<T>) -> PinBox<T> {
-        PinBox { inner: boxed }
-    }
-}
-
-#[unstable(feature = "pin", issue = "49150")]
-impl<T: ?Sized> Deref for PinBox<T> {
-    type Target = T;
-
-    fn deref(&self) -> &T {
-        &*self.inner
-    }
-}
-
-#[unstable(feature = "pin", issue = "49150")]
-impl<T: Unpin + ?Sized> DerefMut for PinBox<T> {
-    fn deref_mut(&mut self) -> &mut T {
-        &mut *self.inner
-    }
-}
-
-#[unstable(feature = "pin", issue = "49150")]
-impl<T: fmt::Display + ?Sized> fmt::Display for PinBox<T> {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        fmt::Display::fmt(&*self.inner, f)
-    }
-}
-
-#[unstable(feature = "pin", issue = "49150")]
-impl<T: fmt::Debug + ?Sized> fmt::Debug for PinBox<T> {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        fmt::Debug::fmt(&*self.inner, f)
-    }
-}
-
-#[unstable(feature = "pin", issue = "49150")]
-impl<T: ?Sized> fmt::Pointer for PinBox<T> {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        // It's not possible to extract the inner Uniq directly from the Box,
-        // instead we cast it to a *const which aliases the Unique
-        let ptr: *const T = &*self.inner;
-        fmt::Pointer::fmt(&ptr, f)
-    }
-}
-
-#[unstable(feature = "pin", issue = "49150")]
-impl<T: ?Sized + Unsize<U>, U: ?Sized> CoerceUnsized<PinBox<U>> for PinBox<T> {}
-
-#[unstable(feature = "pin", issue = "49150")]
-impl<T: ?Sized> Unpin for PinBox<T> {}
-
-#[unstable(feature = "futures_api", issue = "50547")]
-impl<F: ?Sized + Future> Future for PinBox<F> {
-    type Output = F::Output;
-
-    fn poll(mut self: PinMut<Self>, cx: &mut Context) -> Poll<Self::Output> {
-        self.as_pin_mut().poll(cx)
-    }
-}
-
-#[unstable(feature = "futures_api", issue = "50547")]
-unsafe impl<'a, T, F> UnsafeFutureObj<'a, T> for PinBox<F>
-    where F: Future<Output = T> + 'a
-{
-    fn into_raw(self) -> *mut () {
-        PinBox::into_raw(self) as *mut ()
-    }
-
-    unsafe fn poll(ptr: *mut (), cx: &mut Context) -> Poll<T> {
-        let ptr = ptr as *mut F;
-        let pin: PinMut<F> = PinMut::new_unchecked(&mut *ptr);
-        pin.poll(cx)
-    }
-
-    unsafe fn drop(ptr: *mut ()) {
-        drop(PinBox::from_raw(ptr as *mut F))
-    }
-}
-
-#[unstable(feature = "futures_api", issue = "50547")]
-impl<'a, F: Future<Output = ()> + Send + 'a> From<PinBox<F>> for FutureObj<'a, ()> {
-    fn from(boxed: PinBox<F>) -> Self {
-        FutureObj::new(boxed)
-    }
-}
-
-#[unstable(feature = "futures_api", issue = "50547")]
-impl<'a, F: Future<Output = ()> + 'a> From<PinBox<F>> for LocalFutureObj<'a, ()> {
-    fn from(boxed: PinBox<F>) -> Self {
-        LocalFutureObj::new(boxed)
-    }
-}
diff --git a/src/liballoc/rc.rs b/src/liballoc/rc.rs
index 4860daa11e2..3b8b65dc314 100644
--- a/src/liballoc/rc.rs
+++ b/src/liballoc/rc.rs
@@ -256,6 +256,7 @@ use core::marker::{Unsize, PhantomData};
 use core::mem::{self, align_of_val, forget, size_of_val};
 use core::ops::Deref;
 use core::ops::CoerceUnsized;
+use core::pin::Pin;
 use core::ptr::{self, NonNull};
 use core::convert::From;
 use core::usize;
@@ -321,6 +322,11 @@ impl<T> Rc<T> {
         }
     }
 
+    #[unstable(feature = "pin", issue = "49150")]
+    pub fn pinned(value: T) -> Pin<Rc<T>> {
+        unsafe { Pin::new_unchecked(Rc::new(value)) }
+    }
+
     /// Returns the contained value, if the `Rc` has exactly one strong reference.
     ///
     /// Otherwise, an [`Err`][result] is returned with the same `Rc` that was
diff --git a/src/liballoc/sync.rs b/src/liballoc/sync.rs
index 2cd7898f4c7..d9607af1902 100644
--- a/src/liballoc/sync.rs
+++ b/src/liballoc/sync.rs
@@ -26,6 +26,7 @@ use core::intrinsics::abort;
 use core::mem::{self, align_of_val, size_of_val};
 use core::ops::Deref;
 use core::ops::CoerceUnsized;
+use core::pin::Pin;
 use core::ptr::{self, NonNull};
 use core::marker::{Unsize, PhantomData};
 use core::hash::{Hash, Hasher};
@@ -296,6 +297,11 @@ impl<T> Arc<T> {
         Arc { ptr: Box::into_raw_non_null(x), phantom: PhantomData }
     }
 
+    #[unstable(feature = "pin", issue = "49150")]
+    pub fn pinned(data: T) -> Pin<Arc<T>> {
+        unsafe { Pin::new_unchecked(Arc::new(data)) }
+    }
+
     /// Returns the contained value, if the `Arc` has exactly one strong reference.
     ///
     /// Otherwise, an [`Err`][result] is returned with the same `Arc` that was