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clippy fix: remove manual PartialEq::ne #143377

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c247336
clippy fix: remove or annotate manual PartialEq::ne
hkBst Jul 3, 2025
fbc5eeb
reduce repetition with macros
hkBst Jul 4, 2025
a31104c
make macro syntax more like rust syntax
hkBst Sep 17, 2025
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268 changes: 89 additions & 179 deletions library/core/src/cmp.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1861,8 +1861,6 @@ mod impls {
impl const PartialEq for $t {
#[inline]
fn eq(&self, other: &Self) -> bool { *self == *other }
#[inline]
fn ne(&self, other: &Self) -> bool { *self != *other }
Comment on lines -1864 to -1865
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Primitive ne isn't equivalent to !(*self == *other). This difference goes straight to MIR and codegen:

rust/compiler/rustc_codegen_ssa/src/mir/rvalue.rs

Lines 822 to 833 in 0fb279b

mir::BinOp::Ne
| mir::BinOp::Lt
| mir::BinOp::Gt
| mir::BinOp::Eq
| mir::BinOp::Le
| mir::BinOp::Ge => {
if is_float {
bx.fcmp(base::bin_op_to_fcmp_predicate(op), lhs, rhs)
} else {
bx.icmp(base::bin_op_to_icmp_predicate(op, is_signed), lhs, rhs)
}
}

Yes it can be trivially optimized away but why emit additional IR when you can emit less?

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Interesting! I suppose that treatment may be necessary in case these are implemented by inline assembly or via FFI.

Yes it can be trivially optimized away but why emit additional IR when you can emit less?

The documentation in this very file says that:

/// The default implementation of `ne` provides this consistency and is almost
/// always sufficient. It should not be overridden without very good reason.

Is the performance impact of emitting slightly more IR really a very good reason? I would expect it is on the edge of immeasurable.

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Is the performance impact of emitting slightly more IR really a very good reason? I would expect it is on the edge of immeasurable.

That is a very interesting question since we do in fact have some measurements! Let's at least find out if our existing ones would say anything.

}
)*)
}
Expand All @@ -1874,10 +1872,6 @@ mod impls {
fn eq(&self, _other: &()) -> bool {
true
}
#[inline]
fn ne(&self, _other: &()) -> bool {
false
}
}

partial_eq_impl! {
Expand Down Expand Up @@ -2075,185 +2069,101 @@ mod impls {
}
}

// & pointers
// reference types

#[stable(feature = "rust1", since = "1.0.0")]
#[rustc_const_unstable(feature = "const_cmp", issue = "143800")]
impl<A: PointeeSized, B: PointeeSized> const PartialEq<&B> for &A
where
A: [const] PartialEq<B>,
{
#[inline]
fn eq(&self, other: &&B) -> bool {
PartialEq::eq(*self, *other)
}
#[inline]
fn ne(&self, other: &&B) -> bool {
PartialEq::ne(*self, *other)
}
}
#[stable(feature = "rust1", since = "1.0.0")]
#[rustc_const_unstable(feature = "const_cmp", issue = "143800")]
impl<A: PointeeSized, B: PointeeSized> const PartialOrd<&B> for &A
where
A: [const] PartialOrd<B>,
{
#[inline]
fn partial_cmp(&self, other: &&B) -> Option<Ordering> {
PartialOrd::partial_cmp(*self, *other)
}
#[inline]
fn lt(&self, other: &&B) -> bool {
PartialOrd::lt(*self, *other)
}
#[inline]
fn le(&self, other: &&B) -> bool {
PartialOrd::le(*self, *other)
}
#[inline]
fn gt(&self, other: &&B) -> bool {
PartialOrd::gt(*self, *other)
}
#[inline]
fn ge(&self, other: &&B) -> bool {
PartialOrd::ge(*self, *other)
}
#[inline]
fn __chaining_lt(&self, other: &&B) -> ControlFlow<bool> {
PartialOrd::__chaining_lt(*self, *other)
}
#[inline]
fn __chaining_le(&self, other: &&B) -> ControlFlow<bool> {
PartialOrd::__chaining_le(*self, *other)
}
#[inline]
fn __chaining_gt(&self, other: &&B) -> ControlFlow<bool> {
PartialOrd::__chaining_gt(*self, *other)
}
#[inline]
fn __chaining_ge(&self, other: &&B) -> ControlFlow<bool> {
PartialOrd::__chaining_ge(*self, *other)
}
}
#[stable(feature = "rust1", since = "1.0.0")]
#[rustc_const_unstable(feature = "const_cmp", issue = "143800")]
impl<A: PointeeSized> const Ord for &A
where
A: [const] Ord,
{
#[inline]
fn cmp(&self, other: &Self) -> Ordering {
Ord::cmp(*self, *other)
}
macro_rules! impl_partial_eq {
(<$A:ident, $B:ident> for $(($ref_A:ty, $ref_B:ty))*) => ($(
#[stable(feature = "rust1", since = "1.0.0")]
#[rustc_const_unstable(feature = "const_cmp", issue = "143800")]
impl<$A, $B> const PartialEq<$ref_B> for $ref_A
where
$A: [const] PartialEq<$B> + PointeeSized,
$B: PointeeSized,
{
#[inline]
fn eq(&self, other: &$ref_B) -> bool {
PartialEq::eq(*self, *other)
}
// if <A as PartialEq<B>>::ne uses inline assembly or FFI, then
// this forwarding impl may be more efficient than the default impl
#[inline]
fn ne(&self, other: &$ref_B) -> bool {
PartialEq::ne(*self, *other)
}
}
)*)
}
#[stable(feature = "rust1", since = "1.0.0")]
#[rustc_const_unstable(feature = "const_cmp", issue = "143800")]
impl<A: PointeeSized> const Eq for &A where A: [const] Eq {}

// &mut pointers
impl_partial_eq!(<A, B> for (&A, &B) (&A, &mut B) (&mut A, &B) (&mut A, &mut B));

#[stable(feature = "rust1", since = "1.0.0")]
#[rustc_const_unstable(feature = "const_cmp", issue = "143800")]
impl<A: PointeeSized, B: PointeeSized> const PartialEq<&mut B> for &mut A
where
A: [const] PartialEq<B>,
{
#[inline]
fn eq(&self, other: &&mut B) -> bool {
PartialEq::eq(*self, *other)
}
#[inline]
fn ne(&self, other: &&mut B) -> bool {
PartialEq::ne(*self, *other)
}
}
#[stable(feature = "rust1", since = "1.0.0")]
#[rustc_const_unstable(feature = "const_cmp", issue = "143800")]
impl<A: PointeeSized, B: PointeeSized> const PartialOrd<&mut B> for &mut A
where
A: [const] PartialOrd<B>,
{
#[inline]
fn partial_cmp(&self, other: &&mut B) -> Option<Ordering> {
PartialOrd::partial_cmp(*self, *other)
}
#[inline]
fn lt(&self, other: &&mut B) -> bool {
PartialOrd::lt(*self, *other)
}
#[inline]
fn le(&self, other: &&mut B) -> bool {
PartialOrd::le(*self, *other)
}
#[inline]
fn gt(&self, other: &&mut B) -> bool {
PartialOrd::gt(*self, *other)
}
#[inline]
fn ge(&self, other: &&mut B) -> bool {
PartialOrd::ge(*self, *other)
}
#[inline]
fn __chaining_lt(&self, other: &&mut B) -> ControlFlow<bool> {
PartialOrd::__chaining_lt(*self, *other)
}
#[inline]
fn __chaining_le(&self, other: &&mut B) -> ControlFlow<bool> {
PartialOrd::__chaining_le(*self, *other)
}
#[inline]
fn __chaining_gt(&self, other: &&mut B) -> ControlFlow<bool> {
PartialOrd::__chaining_gt(*self, *other)
}
#[inline]
fn __chaining_ge(&self, other: &&mut B) -> ControlFlow<bool> {
PartialOrd::__chaining_ge(*self, *other)
}
}
#[stable(feature = "rust1", since = "1.0.0")]
#[rustc_const_unstable(feature = "const_cmp", issue = "143800")]
impl<A: PointeeSized> const Ord for &mut A
where
A: [const] Ord,
{
#[inline]
fn cmp(&self, other: &Self) -> Ordering {
Ord::cmp(*self, *other)
}
macro_rules! impl_partial_ord {
(<$A:ident, $B:ident> for $(($ref_A:ty, $ref_B:ty))*) => ($(
#[stable(feature = "rust1", since = "1.0.0")]
#[rustc_const_unstable(feature = "const_cmp", issue = "143800")]
impl<$A, $B> const PartialOrd<$ref_B> for $ref_A
where
$A: [const] PartialOrd<$B> + PointeeSized,
$B: PointeeSized,
{
#[inline]
fn partial_cmp(&self, other: &$ref_B) -> Option<Ordering> {
PartialOrd::partial_cmp(*self, *other)
}
#[inline]
fn lt(&self, other: &$ref_B) -> bool {
PartialOrd::lt(*self, *other)
}
#[inline]
fn le(&self, other: &$ref_B) -> bool {
PartialOrd::le(*self, *other)
}
#[inline]
fn gt(&self, other: &$ref_B) -> bool {
PartialOrd::gt(*self, *other)
}
#[inline]
fn ge(&self, other: &$ref_B) -> bool {
PartialOrd::ge(*self, *other)
}
#[inline]
fn __chaining_lt(&self, other: &$ref_B) -> ControlFlow<bool> {
PartialOrd::__chaining_lt(*self, *other)
}
#[inline]
fn __chaining_le(&self, other: &$ref_B) -> ControlFlow<bool> {
PartialOrd::__chaining_le(*self, *other)
}
#[inline]
fn __chaining_gt(&self, other: &$ref_B) -> ControlFlow<bool> {
PartialOrd::__chaining_gt(*self, *other)
}
#[inline]
fn __chaining_ge(&self, other: &$ref_B) -> ControlFlow<bool> {
PartialOrd::__chaining_ge(*self, *other)
}
}
)*)
}
#[stable(feature = "rust1", since = "1.0.0")]
#[rustc_const_unstable(feature = "const_cmp", issue = "143800")]
impl<A: PointeeSized> const Eq for &mut A where A: [const] Eq {}

#[stable(feature = "rust1", since = "1.0.0")]
#[rustc_const_unstable(feature = "const_cmp", issue = "143800")]
impl<A: PointeeSized, B: PointeeSized> const PartialEq<&mut B> for &A
where
A: [const] PartialEq<B>,
{
#[inline]
fn eq(&self, other: &&mut B) -> bool {
PartialEq::eq(*self, *other)
}
#[inline]
fn ne(&self, other: &&mut B) -> bool {
PartialEq::ne(*self, *other)
}
}
impl_partial_ord!(<A, B> for (&A, &B) /*(&A, &mut B) (&mut A, &B)*/ (&mut A, &mut B));

#[stable(feature = "rust1", since = "1.0.0")]
#[rustc_const_unstable(feature = "const_cmp", issue = "143800")]
impl<A: PointeeSized, B: PointeeSized> const PartialEq<&B> for &mut A
where
A: [const] PartialEq<B>,
{
#[inline]
fn eq(&self, other: &&B) -> bool {
PartialEq::eq(*self, *other)
}
#[inline]
fn ne(&self, other: &&B) -> bool {
PartialEq::ne(*self, *other)
}
macro_rules! impl_ord_eq {
(<$A:ident> for $($ref_A:ty),*) => ($(
#[stable(feature = "rust1", since = "1.0.0")]
#[rustc_const_unstable(feature = "const_cmp", issue = "143800")]
impl<$A: [const] Ord + PointeeSized> const Ord for $ref_A
{
#[inline]
fn cmp(&self, other: &Self) -> Ordering {
Ord::cmp(*self, *other)
}
}

#[stable(feature = "rust1", since = "1.0.0")]
#[rustc_const_unstable(feature = "const_cmp", issue = "143800")]
impl<$A: [const] Eq + PointeeSized> const Eq for $ref_A {}
)*)
}

impl_ord_eq!(<A> for &A, &mut A);
}
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