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Optimize ptr::replace #122601

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Merged
merged 1 commit into from
Mar 17, 2024
Merged

Optimize ptr::replace #122601

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5 changes: 2 additions & 3 deletions library/core/src/ptr/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1114,7 +1114,7 @@ const unsafe fn swap_nonoverlapping_simple_untyped<T>(x: *mut T, y: *mut T, coun
#[stable(feature = "rust1", since = "1.0.0")]
#[rustc_const_unstable(feature = "const_replace", issue = "83164")]
#[rustc_diagnostic_item = "ptr_replace"]
pub const unsafe fn replace<T>(dst: *mut T, mut src: T) -> T {
pub const unsafe fn replace<T>(dst: *mut T, src: T) -> T {
// SAFETY: the caller must guarantee that `dst` is valid to be
// cast to a mutable reference (valid for writes, aligned, initialized),
// and cannot overlap `src` since `dst` must point to a distinct
Expand All @@ -1128,9 +1128,8 @@ pub const unsafe fn replace<T>(dst: *mut T, mut src: T) -> T {
align: usize = align_of::<T>(),
) => is_aligned_and_not_null(addr, align)
);
mem::swap(&mut *dst, &mut src); // cannot overlap
mem::replace(&mut *dst, src)
}
src
}

/// Reads the value from `src` without moving it. This leaves the
Expand Down