Rollup merge of rust-lang#109980 - xfix:derive-string-partialeq, r=scottmcm

Derive String's PartialEq implementation

Author: matthiaskrgr

library/alloc/src/string.rs

@@ -359,7 +359,7 @@ use crate::vec::Vec;
 /// [Deref]: core::ops::Deref "ops::Deref"
 /// [`Deref`]: core::ops::Deref "ops::Deref"
 /// [`as_str()`]: String::as_str
-#[derive(PartialOrd, Eq, Ord)]
+#[derive(PartialEq, PartialOrd, Eq, Ord)]
 #[stable(feature = "rust1", since = "1.0.0")]
 #[cfg_attr(not(test), lang = "String")]
 pub struct String {
@@ -2207,14 +2207,6 @@ impl<'a, 'b> Pattern<'a> for &'b String {
     }
 }
 
-#[stable(feature = "rust1", since = "1.0.0")]
-impl PartialEq for String {
-    #[inline]
-    fn eq(&self, other: &String) -> bool {
-        PartialEq::eq(&self[..], &other[..])
-    }
-}
-
 macro_rules! impl_eq {
     ($lhs:ty, $rhs: ty) => {
         #[stable(feature = "rust1", since = "1.0.0")]