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Make Sub, Mul, Div and Rem const_traits #143000

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Jun 26, 2025
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Make Sub, Mul, Div and Rem const_traits #143000

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24 changes: 19 additions & 5 deletions library/core/src/ops/arith.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -179,12 +179,14 @@ add_impl! { usize u8 u16 u32 u64 u128 isize i8 i16 i32 i64 i128 f16 f32 f64 f128
/// ```
#[lang = "sub"]
#[stable(feature = "rust1", since = "1.0.0")]
#[rustc_const_unstable(feature = "const_ops", issue = "90080")]
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This an ancient, closed tracking issue. Should we really be using it for new constifications?

I think there should be new tracking issue created, everything else is too confusing.

#[rustc_on_unimplemented(
message = "cannot subtract `{Rhs}` from `{Self}`",
label = "no implementation for `{Self} - {Rhs}`",
append_const_msg
)]
#[doc(alias = "-")]
#[const_trait]
pub trait Sub<Rhs = Self> {
/// The resulting type after applying the `-` operator.
#[stable(feature = "rust1", since = "1.0.0")]
Expand All @@ -206,7 +208,8 @@ pub trait Sub<Rhs = Self> {
macro_rules! sub_impl {
($($t:ty)*) => ($(
#[stable(feature = "rust1", since = "1.0.0")]
impl Sub for $t {
#[rustc_const_unstable(feature = "const_ops", issue = "90080")]
impl const Sub for $t {
type Output = $t;

#[inline]
Expand Down Expand Up @@ -310,11 +313,13 @@ sub_impl! { usize u8 u16 u32 u64 u128 isize i8 i16 i32 i64 i128 f16 f32 f64 f128
/// ```
#[lang = "mul"]
#[stable(feature = "rust1", since = "1.0.0")]
#[rustc_const_unstable(feature = "const_ops", issue = "90080")]
#[diagnostic::on_unimplemented(
message = "cannot multiply `{Self}` by `{Rhs}`",
label = "no implementation for `{Self} * {Rhs}`"
)]
#[doc(alias = "*")]
#[const_trait]
pub trait Mul<Rhs = Self> {
/// The resulting type after applying the `*` operator.
#[stable(feature = "rust1", since = "1.0.0")]
Expand All @@ -336,7 +341,8 @@ pub trait Mul<Rhs = Self> {
macro_rules! mul_impl {
($($t:ty)*) => ($(
#[stable(feature = "rust1", since = "1.0.0")]
impl Mul for $t {
#[rustc_const_unstable(feature = "const_ops", issue = "90080")]
impl const Mul for $t {
type Output = $t;

#[inline]
Expand Down Expand Up @@ -444,11 +450,13 @@ mul_impl! { usize u8 u16 u32 u64 u128 isize i8 i16 i32 i64 i128 f16 f32 f64 f128
/// ```
#[lang = "div"]
#[stable(feature = "rust1", since = "1.0.0")]
#[rustc_const_unstable(feature = "const_ops", issue = "90080")]
#[diagnostic::on_unimplemented(
message = "cannot divide `{Self}` by `{Rhs}`",
label = "no implementation for `{Self} / {Rhs}`"
)]
#[doc(alias = "/")]
#[const_trait]
pub trait Div<Rhs = Self> {
/// The resulting type after applying the `/` operator.
#[stable(feature = "rust1", since = "1.0.0")]
Expand Down Expand Up @@ -476,7 +484,8 @@ macro_rules! div_impl_integer {
///
#[doc = $panic]
#[stable(feature = "rust1", since = "1.0.0")]
impl Div for $t {
#[rustc_const_unstable(feature = "const_ops", issue = "90080")]
impl const Div for $t {
type Output = $t;

#[inline]
Expand All @@ -496,7 +505,8 @@ div_impl_integer! {
macro_rules! div_impl_float {
($($t:ty)*) => ($(
#[stable(feature = "rust1", since = "1.0.0")]
impl Div for $t {
#[rustc_const_unstable(feature = "const_ops", issue = "90080")]
impl const Div for $t {
type Output = $t;

#[inline]
Expand Down Expand Up @@ -546,11 +556,13 @@ div_impl_float! { f16 f32 f64 f128 }
/// ```
#[lang = "rem"]
#[stable(feature = "rust1", since = "1.0.0")]
#[rustc_const_unstable(feature = "const_ops", issue = "90080")]
#[diagnostic::on_unimplemented(
message = "cannot calculate the remainder of `{Self}` divided by `{Rhs}`",
label = "no implementation for `{Self} % {Rhs}`"
)]
#[doc(alias = "%")]
#[const_trait]
pub trait Rem<Rhs = Self> {
/// The resulting type after applying the `%` operator.
#[stable(feature = "rust1", since = "1.0.0")]
Expand Down Expand Up @@ -578,7 +590,8 @@ macro_rules! rem_impl_integer {
///
#[doc = $panic]
#[stable(feature = "rust1", since = "1.0.0")]
impl Rem for $t {
#[rustc_const_unstable(feature = "const_ops", issue = "90080")]
impl const Rem for $t {
type Output = $t;

#[inline]
Expand Down Expand Up @@ -613,6 +626,7 @@ macro_rules! rem_impl_float {
/// assert_eq!(x % y, remainder);
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
#[rustc_const_unstable(feature = "const_ops", issue = "90080")]
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This isn't a const impl, how does it make any sense to mark it as rustc_const_unstable?

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This is apparently being addressed in #143040

impl Rem for $t {
type Output = $t;

Expand Down
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