Make Unpin safe to implement

Author: cramertj

src/liballoc/boxed.rs

@@ -850,4 +850,4 @@ impl<T: ?Sized> fmt::Pointer for PinBox<T> {
 impl<T: ?Sized + Unsize<U>, U: ?Sized> CoerceUnsized<PinBox<U>> for PinBox<T> {}
 
 #[unstable(feature = "pin", issue = "49150")]
-unsafe impl<T: ?Sized> Unpin for PinBox<T> {}
+impl<T: ?Sized> Unpin for PinBox<T> {}

src/libcore/marker.rs

@@ -605,7 +605,7 @@ unsafe impl<'a, T: ?Sized> Freeze for &'a mut T {}
 ///
 /// [`PinMut`]: ../mem/struct.PinMut.html
 #[unstable(feature = "pin", issue = "49150")]
-pub unsafe auto trait Unpin {}
+pub auto trait Unpin {}
 
 /// Implementations of `Copy` for primitive types.
 ///

src/libcore/mem.rs

@@ -1207,4 +1207,4 @@ impl<'a, T: ?Sized> fmt::Pointer for PinMut<'a, T> {
 impl<'a, T: ?Sized + Unsize<U>, U: ?Sized> CoerceUnsized<PinMut<'a, U>> for PinMut<'a, T> {}
 
 #[unstable(feature = "pin", issue = "49150")]
-unsafe impl<'a, T: ?Sized> Unpin for PinMut<'a, T> {}
+impl<'a, T: ?Sized> Unpin for PinMut<'a, T> {}