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Make mem::swap inlinable #107140

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Make mem::swap inlinable #107140

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8 changes: 7 additions & 1 deletion library/core/src/mem/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -732,7 +732,7 @@ pub const fn swap<T>(x: &mut T, y: &mut T) {
// tends to copy the whole thing to stack rather than doing it one part
// at a time, so instead treat them as one-element slices and piggy-back
// the slice optimizations that will split up the swaps.
if size_of::<T>() / align_of::<T>() > 4 {
if T::IS_BIG_SWAP {
// SAFETY: exclusive references always point to one non-overlapping
// element and are non-null and properly aligned.
return unsafe { ptr::swap_nonoverlapping(x, y, 1) };
Expand Down Expand Up @@ -1273,3 +1273,9 @@ pub trait SizedTypeProperties: Sized {
#[doc(hidden)]
#[unstable(feature = "sized_type_properties", issue = "none")]
impl<T> SizedTypeProperties for T {}

trait InternalSizedTypeProperties: Sized {
const IS_BIG_SWAP: bool = size_of::<Self>() / align_of::<Self>() > 4;
}

impl<T> InternalSizedTypeProperties for T {}