Rollup merge of rust-lang#104320 - fee1-dead-contrib:use-derive-const-in-std, r=oli-obk

Use `derive_const` and rm manual StructuralEq impl

This does not change any semantics of the impl except for the const stability. It should be fine because trait methods and const bounds can never be used in stable without enabling `const_trait_impl`.

cc `@oli-obk`

Author: matthiaskrgr

core/src/cmp.rs

@@ -24,6 +24,7 @@
 
 use crate::const_closure::ConstFnMutClosure;
 use crate::marker::Destruct;
+#[cfg(bootstrap)]
 use crate::marker::StructuralPartialEq;
 
 use self::Ordering::*;
@@ -331,6 +332,7 @@ pub struct AssertParamIsEq<T: Eq + ?Sized> {
 /// assert_eq!(Ordering::Greater, result);
 /// ```
 #[derive(Clone, Copy, Eq, Debug, Hash)]
+#[cfg_attr(not(bootstrap), derive_const(PartialOrd, Ord, PartialEq))]
 #[stable(feature = "rust1", since = "1.0.0")]
 #[repr(i8)]
 pub enum Ordering {
@@ -877,10 +879,12 @@ pub macro Ord($item:item) {
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
+#[cfg(bootstrap)]
 impl StructuralPartialEq for Ordering {}
 
 #[stable(feature = "rust1", since = "1.0.0")]
 #[rustc_const_unstable(feature = "const_cmp", issue = "92391")]
+#[cfg(bootstrap)]
 impl const PartialEq for Ordering {
     #[inline]
     fn eq(&self, other: &Self) -> bool {
@@ -890,6 +894,7 @@ impl const PartialEq for Ordering {
 
 #[stable(feature = "rust1", since = "1.0.0")]
 #[rustc_const_unstable(feature = "const_cmp", issue = "92391")]
+#[cfg(bootstrap)]
 impl const Ord for Ordering {
     #[inline]
     fn cmp(&self, other: &Ordering) -> Ordering {
@@ -899,6 +904,7 @@ impl const Ord for Ordering {
 
 #[stable(feature = "rust1", since = "1.0.0")]
 #[rustc_const_unstable(feature = "const_cmp", issue = "92391")]
+#[cfg(bootstrap)]
 impl const PartialOrd for Ordering {
     #[inline]
     fn partial_cmp(&self, other: &Ordering) -> Option<Ordering> {

core/src/lib.rs

@@ -185,6 +185,7 @@
 #![feature(const_refs_to_cell)]
 #![feature(decl_macro)]
 #![feature(deprecated_suggestion)]
+#![cfg_attr(not(bootstrap), feature(derive_const))]
 #![feature(doc_cfg)]
 #![feature(doc_notable_trait)]
 #![feature(rustdoc_internals)]