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Rollup merge of #100030 - WaffleLapkin:nice_pointer_sis, r=scottmcm

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cleanup code w/ pointers in std a little

Use pointer methods (`byte_add`, `null_mut`, etc) to make code in std a little nicer.
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Dylan DPC 2022-08-12 20:39:10 +05:30 • committed by GitHub
commit 51eed00ca9
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8 changed files with 33 additions and 26 deletions
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19
library/core/src/ptr/mut_ptr.rs
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@ -1545,20 +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 x = [5u8, 6u8, 7u8, 8u8, 9u8];
/// let ptr = x.as_ptr().add(n) as *const u8;
/// 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 *const u16;
/// assert_ne!(*u16_ptr, 500);
///
/// if offset < x.len() - 1 {
/// let u16_ptr = ptr.add(offset).cast::<u16>();
/// *u16_ptr = 0;
///
/// assert!(x == [0, 0, 7, 8, 9] || x == [5, 0, 0, 8, 9]);
/// } else {
/// // while the pointer can be aligned via `offset`, it would point
/// // outside the allocation
/// }
/// # } }
/// # }
/// ```
#[stable(feature = "align_offset", since = "1.36.0")]
#[rustc_const_unstable(feature = "const_align_offset", issue = "90962")]