Skip to content

Constify a few (Partial)Ord impls #92390

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 3 commits into from
Jul 26, 2022
Merged

Constify a few (Partial)Ord impls #92390

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
3 commits
Select commit Hold shift + click to select a range
9fc5463
Constify a few const `(Partial)Ord` impls
fee1-dead Dec 29, 2021
a89510e
Add issue numbers
fee1-dead Dec 29, 2021
65fca6d
add const hack comment
fee1-dead Jan 14, 2022
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
74 changes: 55 additions & 19 deletions library/core/src/cmp.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -22,6 +22,8 @@

#![stable(feature = "rust1", since = "1.0.0")]

use crate::marker::Destruct;

use self::Ordering::*;

/// Trait for equality comparisons which are [partial equivalence
Expand Down Expand Up @@ -603,7 +605,8 @@ impl Ordering {
pub struct Reverse<T>(#[stable(feature = "reverse_cmp_key", since = "1.19.0")] pub T);

#[stable(feature = "reverse_cmp_key", since = "1.19.0")]
impl<T: PartialOrd> PartialOrd for Reverse<T> {
#[rustc_const_unstable(feature = "const_cmp", issue = "92391")]
impl<T: ~const PartialOrd> const PartialOrd for Reverse<T> {
#[inline]
fn partial_cmp(&self, other: &Reverse<T>) -> Option<Ordering> {
other.0.partial_cmp(&self.0)
Expand Down Expand Up @@ -761,6 +764,7 @@ impl<T: Clone> Clone for Reverse<T> {
#[doc(alias = ">=")]
#[stable(feature = "rust1", since = "1.0.0")]
#[rustc_diagnostic_item = "Ord"]
#[const_trait]
pub trait Ord: Eq + PartialOrd<Self> {
/// This method returns an [`Ordering`] between `self` and `other`.
///
Expand Down Expand Up @@ -796,8 +800,15 @@ pub trait Ord: Eq + PartialOrd<Self> {
fn max(self, other: Self) -> Self
where
Self: Sized,
Self: ~const Destruct,
{
max_by(self, other, Ord::cmp)
// HACK(fee1-dead): go back to using `self.max_by(other, Ord::cmp)`
// when trait methods are allowed to be used when a const closure is
// expected.
match self.cmp(&other) {
Ordering::Less | Ordering::Equal => other,
Ordering::Greater => self,
}
}

/// Compares and returns the minimum of two values.
Expand All @@ -816,8 +827,15 @@ pub trait Ord: Eq + PartialOrd<Self> {
fn min(self, other: Self) -> Self
where
Self: Sized,
Self: ~const Destruct,
{
min_by(self, other, Ord::cmp)
// HACK(fee1-dead): go back to using `self.min_by(other, Ord::cmp)`
// when trait methods are allowed to be used when a const closure is
// expected.
match self.cmp(&other) {
Ordering::Less | Ordering::Equal => self,
Ordering::Greater => other,
}
}

/// Restrict a value to a certain interval.
Expand All @@ -841,6 +859,8 @@ pub trait Ord: Eq + PartialOrd<Self> {
fn clamp(self, min: Self, max: Self) -> Self
where
Self: Sized,
Self: ~const Destruct,
Self: ~const PartialOrd,
{
assert!(min <= max);
if self < min {
Expand All @@ -862,15 +882,17 @@ pub macro Ord($item:item) {
}

#[stable(feature = "rust1", since = "1.0.0")]
impl Ord for Ordering {
#[rustc_const_unstable(feature = "const_cmp", issue = "92391")]
impl const Ord for Ordering {
#[inline]
fn cmp(&self, other: &Ordering) -> Ordering {
(*self as i32).cmp(&(*other as i32))
}
}

#[stable(feature = "rust1", since = "1.0.0")]
impl PartialOrd for Ordering {
#[rustc_const_unstable(feature = "const_cmp", issue = "92391")]
impl const PartialOrd for Ordering {
#[inline]
fn partial_cmp(&self, other: &Ordering) -> Option<Ordering> {
(*self as i32).partial_cmp(&(*other as i32))
Expand Down Expand Up @@ -1187,8 +1209,9 @@ pub macro PartialOrd($item:item) {
#[inline]
#[must_use]
#[stable(feature = "rust1", since = "1.0.0")]
#[rustc_const_unstable(feature = "const_cmp", issue = "92391")]
#[cfg_attr(not(test), rustc_diagnostic_item = "cmp_min")]
pub fn min<T: Ord>(v1: T, v2: T) -> T {
pub const fn min<T: ~const Ord + ~const Destruct>(v1: T, v2: T) -> T {
v1.min(v2)
}

Expand Down Expand Up @@ -1250,8 +1273,9 @@ pub fn min_by_key<T, F: FnMut(&T) -> K, K: Ord>(v1: T, v2: T, mut f: F) -> T {
#[inline]
#[must_use]
#[stable(feature = "rust1", since = "1.0.0")]
#[rustc_const_unstable(feature = "const_cmp", issue = "92391")]
#[cfg_attr(not(test), rustc_diagnostic_item = "cmp_max")]
pub fn max<T: Ord>(v1: T, v2: T) -> T {
pub const fn max<T: ~const Ord + ~const Destruct>(v1: T, v2: T) -> T {
v1.max(v2)
}

Expand Down Expand Up @@ -1304,7 +1328,8 @@ mod impls {
macro_rules! partial_eq_impl {
($($t:ty)*) => ($(
#[stable(feature = "rust1", since = "1.0.0")]
impl PartialEq for $t {
#[rustc_const_unstable(feature = "const_cmp", issue = "92391")]
impl const PartialEq for $t {
#[inline]
fn eq(&self, other: &$t) -> bool { (*self) == (*other) }
#[inline]
Expand All @@ -1314,7 +1339,8 @@ mod impls {
}

#[stable(feature = "rust1", since = "1.0.0")]
impl PartialEq for () {
#[rustc_const_unstable(feature = "const_cmp", issue = "92391")]
impl const PartialEq for () {
#[inline]
fn eq(&self, _other: &()) -> bool {
true
Expand All @@ -1341,7 +1367,8 @@ mod impls {
macro_rules! partial_ord_impl {
($($t:ty)*) => ($(
#[stable(feature = "rust1", since = "1.0.0")]
impl PartialOrd for $t {
#[rustc_const_unstable(feature = "const_cmp", issue = "92391")]
impl const PartialOrd for $t {
#[inline]
fn partial_cmp(&self, other: &$t) -> Option<Ordering> {
match (*self <= *other, *self >= *other) {
Expand All @@ -1364,15 +1391,17 @@ mod impls {
}

#[stable(feature = "rust1", since = "1.0.0")]
impl PartialOrd for () {
#[rustc_const_unstable(feature = "const_cmp", issue = "92391")]
impl const PartialOrd for () {
#[inline]
fn partial_cmp(&self, _: &()) -> Option<Ordering> {
Some(Equal)
}
}

#[stable(feature = "rust1", since = "1.0.0")]
impl PartialOrd for bool {
#[rustc_const_unstable(feature = "const_cmp", issue = "92391")]
impl const PartialOrd for bool {
#[inline]
fn partial_cmp(&self, other: &bool) -> Option<Ordering> {
Some(self.cmp(other))
Expand All @@ -1384,7 +1413,8 @@ mod impls {
macro_rules! ord_impl {
($($t:ty)*) => ($(
#[stable(feature = "rust1", since = "1.0.0")]
impl PartialOrd for $t {
#[rustc_const_unstable(feature = "const_cmp", issue = "92391")]
impl const PartialOrd for $t {
#[inline]
fn partial_cmp(&self, other: &$t) -> Option<Ordering> {
Some(self.cmp(other))
Expand All @@ -1400,7 +1430,8 @@ mod impls {
}

#[stable(feature = "rust1", since = "1.0.0")]
impl Ord for $t {
#[rustc_const_unstable(feature = "const_cmp", issue = "92391")]
impl const Ord for $t {
#[inline]
fn cmp(&self, other: &$t) -> Ordering {
// The order here is important to generate more optimal assembly.
Expand All @@ -1414,15 +1445,17 @@ mod impls {
}

#[stable(feature = "rust1", since = "1.0.0")]
impl Ord for () {
#[rustc_const_unstable(feature = "const_cmp", issue = "92391")]
impl const Ord for () {
#[inline]
fn cmp(&self, _other: &()) -> Ordering {
Equal
}
}

#[stable(feature = "rust1", since = "1.0.0")]
impl Ord for bool {
#[rustc_const_unstable(feature = "const_cmp", issue = "92391")]
impl const Ord for bool {
#[inline]
fn cmp(&self, other: &bool) -> Ordering {
// Casting to i8's and converting the difference to an Ordering generates
Expand All @@ -1441,7 +1474,8 @@ mod impls {
ord_impl! { char usize u8 u16 u32 u64 u128 isize i8 i16 i32 i64 i128 }

#[unstable(feature = "never_type", issue = "35121")]
impl PartialEq for ! {
#[rustc_const_unstable(feature = "const_cmp", issue = "92391")]
impl const PartialEq for ! {
fn eq(&self, _: &!) -> bool {
*self
}
Expand All @@ -1451,14 +1485,16 @@ mod impls {
impl Eq for ! {}

#[unstable(feature = "never_type", issue = "35121")]
impl PartialOrd for ! {
#[rustc_const_unstable(feature = "const_cmp", issue = "92391")]
impl const PartialOrd for ! {
fn partial_cmp(&self, _: &!) -> Option<Ordering> {
*self
}
}

#[unstable(feature = "never_type", issue = "35121")]
impl Ord for ! {
#[rustc_const_unstable(feature = "const_cmp", issue = "92391")]
impl const Ord for ! {
fn cmp(&self, _: &!) -> Ordering {
*self
}
Expand Down
1 change: 1 addition & 0 deletions library/core/src/lib.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -105,6 +105,7 @@
#![feature(const_cell_into_inner)]
#![feature(const_char_convert)]
#![feature(const_clone)]
#![feature(const_cmp)]
#![feature(const_discriminant)]
#![feature(const_eval_select)]
#![feature(const_float_bits_conv)]
Expand Down