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core: Improve the documentation for funnel shifts #154150

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core: Improve the documentation for funnel shifts #154150

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b25e6b4
core: Rename funnel shift `rhs` parameter to `right`
tgross35 Mar 20, 2026
da63b59
core: Use the same width for integer primitive literals in docs
tgross35 Mar 20, 2026
aa98b14
core: Improve the documentation for funnel shifts
tgross35 Mar 20, 2026
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14 changes: 7 additions & 7 deletions library/core/src/intrinsics/fallback.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -151,11 +151,11 @@ impl_disjoint_bitor! {
pub const trait FunnelShift: Copy + 'static {
/// See [`super::unchecked_funnel_shl`]; we just need the trait indirection to handle
/// different types since calling intrinsics with generics doesn't work.
unsafe fn unchecked_funnel_shl(self, rhs: Self, shift: u32) -> Self;
unsafe fn unchecked_funnel_shl(self, right: Self, shift: u32) -> Self;

/// See [`super::unchecked_funnel_shr`]; we just need the trait indirection to handle
/// different types since calling intrinsics with generics doesn't work.
unsafe fn unchecked_funnel_shr(self, rhs: Self, shift: u32) -> Self;
unsafe fn unchecked_funnel_shr(self, right: Self, shift: u32) -> Self;
}

macro_rules! impl_funnel_shifts {
Expand All @@ -164,7 +164,7 @@ macro_rules! impl_funnel_shifts {
impl const FunnelShift for $type {
#[cfg_attr(miri, track_caller)]
#[inline]
unsafe fn unchecked_funnel_shl(self, rhs: Self, shift: u32) -> Self {
unsafe fn unchecked_funnel_shl(self, right: Self, shift: u32) -> Self {
// This implementation is also used by Miri so we have to check the precondition.
// SAFETY: this is guaranteed by the caller
unsafe { super::assume(shift < $type::BITS) };
Expand All @@ -181,20 +181,20 @@ macro_rules! impl_funnel_shifts {
unsafe {
super::disjoint_bitor(
super::unchecked_shl(self, shift),
super::unchecked_shr(rhs, $type::BITS - shift),
super::unchecked_shr(right, $type::BITS - shift),
)
}
}
}

#[cfg_attr(miri, track_caller)]
#[inline]
unsafe fn unchecked_funnel_shr(self, rhs: Self, shift: u32) -> Self {
unsafe fn unchecked_funnel_shr(self, right: Self, shift: u32) -> Self {
// This implementation is also used by Miri so we have to check the precondition.
// SAFETY: this is guaranteed by the caller
unsafe { super::assume(shift < $type::BITS) };
if shift == 0 {
rhs
right
} else {
// SAFETY:
// - `shift < T::BITS`, which satisfies `unchecked_shr`
Expand All @@ -206,7 +206,7 @@ macro_rules! impl_funnel_shifts {
unsafe {
super::disjoint_bitor(
super::unchecked_shl(self, $type::BITS - shift),
super::unchecked_shr(rhs, shift),
super::unchecked_shr(right, shift),
)
}
}
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