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Link to PhantomData in NonNull documentation #59427

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Mar 27, 2019
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Link to PhantomData in NonNull documentation #59427

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5 changes: 3 additions & 2 deletions src/libcore/ptr.rs
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Expand Up @@ -2869,10 +2869,10 @@ impl<'a, T: ?Sized> From<NonNull<T>> for Unique<T> {
/// However the pointer may still dangle if it isn't dereferenced.
///
/// Unlike `*mut T`, `NonNull<T>` is covariant over `T`. If this is incorrect
/// for your use case, you should include some PhantomData in your type to
/// for your use case, you should include some [`PhantomData`] in your type to
/// provide invariance, such as `PhantomData<Cell<T>>` or `PhantomData<&'a mut T>`.
/// Usually this won't be necessary; covariance is correct for most safe abstractions,
/// such as Box, Rc, Arc, Vec, and LinkedList. This is the case because they
/// such as `Box`, `Rc`, `Arc`, `Vec`, and `LinkedList`. This is the case because they
/// provide a public API that follows the normal shared XOR mutable rules of Rust.
///
/// Notice that `NonNull<T>` has a `From` instance for `&T`. However, this does
Expand All @@ -2883,6 +2883,7 @@ impl<'a, T: ?Sized> From<NonNull<T>> for Unique<T> {
/// it is your responsibility to ensure that `as_mut` is never called, and `as_ptr`
/// is never used for mutation.
///
/// [`PhantomData`]: ../marker/struct.PhantomData.html
/// [`UnsafeCell<T>`]: ../cell/struct.UnsafeCell.html
#[stable(feature = "nonnull", since = "1.25.0")]
#[repr(transparent)]
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