Constify Eq, Ord, PartialOrd

library/core/src/any.rs

@@ -705,7 +705,8 @@ impl dyn Any + Send + Sync {
 ///     std::mem::forget(fake_one_ring);
 /// }
 /// ```
-#[derive(Clone, Copy, Eq, PartialOrd, Ord)]
+#[derive(Copy, PartialOrd, Ord)]
+#[derive_const(Clone, Eq)]
 #[stable(feature = "rust1", since = "1.0.0")]
 #[lang = "type_id"]
 pub struct TypeId {

library/core/src/array/equality.rs

@@ -1,9 +1,10 @@
 use crate::cmp::BytewiseEq;
 
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<T, U, const N: usize> PartialEq<[U; N]> for [T; N]
+#[rustc_const_unstable(feature = "const_cmp", issue = "143800")]
+impl<T, U, const N: usize> const PartialEq<[U; N]> for [T; N]
 where
-    T: PartialEq<U>,
+    T: [const] PartialEq<U>,
 {
     #[inline]
     fn eq(&self, other: &[U; N]) -> bool {
@@ -16,9 +17,10 @@ where
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<T, U, const N: usize> PartialEq<[U]> for [T; N]
+#[rustc_const_unstable(feature = "const_cmp", issue = "143800")]
+impl<T, U, const N: usize> const PartialEq<[U]> for [T; N]
 where
-    T: PartialEq<U>,
+    T: [const] PartialEq<U>,
 {
     #[inline]
     fn eq(&self, other: &[U]) -> bool {
@@ -37,9 +39,10 @@ where
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<T, U, const N: usize> PartialEq<[U; N]> for [T]
+#[rustc_const_unstable(feature = "const_cmp", issue = "143800")]
+impl<T, U, const N: usize> const PartialEq<[U; N]> for [T]
 where
-    T: PartialEq<U>,
+    T: [const] PartialEq<U>,
 {
     #[inline]
     fn eq(&self, other: &[U; N]) -> bool {
@@ -58,9 +61,10 @@ where
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<T, U, const N: usize> PartialEq<&[U]> for [T; N]
+#[rustc_const_unstable(feature = "const_cmp", issue = "143800")]
+impl<T, U, const N: usize> const PartialEq<&[U]> for [T; N]
 where
-    T: PartialEq<U>,
+    T: [const] PartialEq<U>,
 {
     #[inline]
     fn eq(&self, other: &&[U]) -> bool {
@@ -73,9 +77,10 @@ where
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<T, U, const N: usize> PartialEq<[U; N]> for &[T]
+#[rustc_const_unstable(feature = "const_cmp", issue = "143800")]
+impl<T, U, const N: usize> const PartialEq<[U; N]> for &[T]
 where
-    T: PartialEq<U>,
+    T: [const] PartialEq<U>,
 {
     #[inline]
     fn eq(&self, other: &[U; N]) -> bool {
@@ -88,9 +93,10 @@ where
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<T, U, const N: usize> PartialEq<&mut [U]> for [T; N]
+#[rustc_const_unstable(feature = "const_cmp", issue = "143800")]
+impl<T, U, const N: usize> const PartialEq<&mut [U]> for [T; N]
 where
-    T: PartialEq<U>,
+    T: [const] PartialEq<U>,
 {
     #[inline]
     fn eq(&self, other: &&mut [U]) -> bool {
@@ -103,9 +109,10 @@ where
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<T, U, const N: usize> PartialEq<[U; N]> for &mut [T]
+#[rustc_const_unstable(feature = "const_cmp", issue = "143800")]
+impl<T, U, const N: usize> const PartialEq<[U; N]> for &mut [T]
 where
-    T: PartialEq<U>,
+    T: [const] PartialEq<U>,
 {
     #[inline]
     fn eq(&self, other: &[U; N]) -> bool {
@@ -122,14 +129,18 @@ where
 // __impl_slice_eq2! { [A; $N], &'b mut [B; $N] }
 
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<T: Eq, const N: usize> Eq for [T; N] {}
+#[rustc_const_unstable(feature = "const_cmp", issue = "143800")]
+impl<T: [const] Eq, const N: usize> const Eq for [T; N] {}
 
+#[const_trait]
+#[rustc_const_unstable(feature = "const_cmp", issue = "143800")]
 trait SpecArrayEq<Other, const N: usize>: Sized {
     fn spec_eq(a: &[Self; N], b: &[Other; N]) -> bool;
     fn spec_ne(a: &[Self; N], b: &[Other; N]) -> bool;
 }
 
-impl<T: PartialEq<Other>, Other, const N: usize> SpecArrayEq<Other, N> for T {
+#[rustc_const_unstable(feature = "const_cmp", issue = "143800")]
+impl<T: [const] PartialEq<Other>, Other, const N: usize> const SpecArrayEq<Other, N> for T {
     default fn spec_eq(a: &[Self; N], b: &[Other; N]) -> bool {
         a[..] == b[..]
     }
@@ -138,7 +149,8 @@ impl<T: PartialEq<Other>, Other, const N: usize> SpecArrayEq<Other, N> for T {
     }
 }
 
-impl<T: BytewiseEq<U>, U, const N: usize> SpecArrayEq<U, N> for T {
+#[rustc_const_unstable(feature = "const_cmp", issue = "143800")]
+impl<T: [const] BytewiseEq<U>, U, const N: usize> const SpecArrayEq<U, N> for T {
     fn spec_eq(a: &[T; N], b: &[U; N]) -> bool {
         // SAFETY: Arrays are compared element-wise, and don't add any padding
         // between elements, so when the elements are `BytewiseEq`, we can

library/core/src/array/mod.rs

@@ -206,15 +206,17 @@ impl const From<Infallible> for TryFromSliceError {
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<T, const N: usize> AsRef<[T]> for [T; N] {
+#[rustc_const_unstable(feature = "const_from", issue = "143773")]
+impl<T, const N: usize> const AsRef<[T]> for [T; N] {
     #[inline]
     fn as_ref(&self) -> &[T] {
         &self[..]
     }
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<T, const N: usize> AsMut<[T]> for [T; N] {
+#[rustc_const_unstable(feature = "const_from", issue = "143773")]
+impl<T, const N: usize> const AsMut<[T]> for [T; N] {
     #[inline]
     fn as_mut(&mut self) -> &mut [T] {
         &mut self[..]
@@ -248,7 +250,8 @@ impl<T, const N: usize> BorrowMut<[T]> for [T; N] {
 /// assert_eq!(512, u16::from_le_bytes(bytes_tail));
 /// ```
 #[stable(feature = "try_from", since = "1.34.0")]
-impl<T, const N: usize> TryFrom<&[T]> for [T; N]
+#[rustc_const_unstable(feature = "const_from", issue = "143773")]
+impl<T, const N: usize> const TryFrom<&[T]> for [T; N]
 where
     T: Copy,
 {
@@ -273,7 +276,8 @@ where
 /// assert_eq!(512, u16::from_le_bytes(bytes_tail));
 /// ```
 #[stable(feature = "try_from_mut_slice_to_array", since = "1.59.0")]
-impl<T, const N: usize> TryFrom<&mut [T]> for [T; N]
+#[rustc_const_unstable(feature = "const_from", issue = "143773")]
+impl<T, const N: usize> const TryFrom<&mut [T]> for [T; N]
 where
     T: Copy,
 {
@@ -298,7 +302,8 @@ where
 /// assert_eq!(512, u16::from_le_bytes(*bytes_tail));
 /// ```
 #[stable(feature = "try_from", since = "1.34.0")]
-impl<'a, T, const N: usize> TryFrom<&'a [T]> for &'a [T; N] {
+#[rustc_const_unstable(feature = "const_from", issue = "143773")]
+impl<'a, T, const N: usize> const TryFrom<&'a [T]> for &'a [T; N] {
     type Error = TryFromSliceError;
 
     #[inline]
@@ -320,7 +325,8 @@ impl<'a, T, const N: usize> TryFrom<&'a [T]> for &'a [T; N] {
 /// assert_eq!(512, u16::from_le_bytes(*bytes_tail));
 /// ```
 #[stable(feature = "try_from", since = "1.34.0")]
-impl<'a, T, const N: usize> TryFrom<&'a mut [T]> for &'a mut [T; N] {
+#[rustc_const_unstable(feature = "const_from", issue = "143773")]
+impl<'a, T, const N: usize> const TryFrom<&'a mut [T]> for &'a mut [T; N] {
     type Error = TryFromSliceError;
 
     #[inline]

library/core/src/ascii/ascii_char.rs

@@ -54,7 +54,8 @@ use crate::{assert_unsafe_precondition, fmt};
 /// [chart]: https://www.unicode.org/charts/PDF/U0000.pdf
 /// [NIST FIPS 1-2]: https://nvlpubs.nist.gov/nistpubs/Legacy/FIPS/fipspub1-2-1977.pdf
 /// [NamesList]: https://www.unicode.org/Public/15.0.0/ucd/NamesList.txt
-#[derive(Copy, Clone, Eq, PartialEq, Ord, PartialOrd, Hash)]
+#[derive(Copy, Hash)]
+#[derive_const(Clone, Eq, PartialEq, Ord, PartialOrd)]
 #[unstable(feature = "ascii_char", issue = "110998")]
 #[repr(u8)]
 pub enum AsciiChar {