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improve documentation of pointer::align_offset

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This commit is contained in:
Maybe Waffle 2022-08-02 03:51:51 +04:00
parent 127b6c4c18
commit a7c45ec867
2 changed files with 19 additions and 16 deletions
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18
library/core/src/ptr/mut_ptr.rs
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@ -1545,21 +1545,23 @@ impl<T: ?Sized> *mut T {
/// Accessing adjacent `u8` as `u16`
///
/// ```
/// # fn foo(n: usize) {
/// # use std::mem::align_of;
/// use std::mem::align_of;
///
/// # unsafe {
/// let mut x = [5u8, 6, 7, 8, 9];
/// let ptr = x.as_mut_ptr().add(n);
/// let mut x = [5_u8, 6, 7, 8, 9];
/// let ptr = x.as_mut_ptr();
/// let offset = ptr.align_offset(align_of::<u16>());
/// if offset < x.len() - n - 1 {
/// let u16_ptr = ptr.add(offset) as *mut u16;
/// assert_ne!(*u16_ptr, 500);
///
/// if offset < x.len() - 1 {
/// let u16_ptr = ptr.add(offset).cast::<u16>();
/// *u16_ptr = 0;
/// } else {
/// // while the pointer can be aligned via `offset`, it would point
/// // outside the allocation
/// }
/// # } }
///
/// assert!(x == [0, 0, 7, 8, 9] || x == [5, 0, 0, 8, 9]);
/// # }
/// ```
#[stable(feature = "align_offset", since = "1.36.0")]
#[rustc_const_unstable(feature = "const_align_offset", issue = "90962")]