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doc: add Null-unchecked version section to mut pointer as_mut method #68054

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Jan 9, 2020
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doc: add Null-unchecked version section to mut pointer as_mut method #68054

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14 changes: 14 additions & 0 deletions src/libcore/ptr/mut_ptr.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -250,6 +250,20 @@ impl<T: ?Sized> *mut T {
/// *first_value = 4;
/// println!("{:?}", s); // It'll print: "[4, 2, 3]".
/// ```
///
/// # Null-unchecked version
///
/// If you are sure the pointer can never be null and are looking for some kind of
/// `as_mut_unchecked` that returns the `&mut T` instead of `Option<&mut T>`, know that
/// you can dereference the pointer directly.
///
/// ```
/// let mut s = [1, 2, 3];
/// let ptr: *mut u32 = s.as_mut_ptr();
/// let first_value = unsafe { &mut *ptr };
/// *first_value = 4;
/// println!("{:?}", s); // It'll print: "[4, 2, 3]".
/// ```
#[stable(feature = "ptr_as_ref", since = "1.9.0")]
#[inline]
pub unsafe fn as_mut<'a>(self) -> Option<&'a mut T> {
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