Auto merge of rust-lang#80400 - adlerd:hashclone, r=Mark-Simulacrum

Use `clone_from` from `hashbrown::{HashMap,HashSet}`.

This change updates the `std` hash collections to use `hashbrown`'s `clone_from`, which was itself added in rust-lang#70052. Deriving `Clone` does not add a `clone_from` impl and uses the trait default, which calls `clone`.

Fixes rust-lang#28481

Author: bors

library/std/src/collections/hash/map.rs

@@ -195,7 +195,6 @@ use crate::sys;
 /// // use the values stored in map
 /// ```
 
-#[derive(Clone)]
 #[cfg_attr(not(test), rustc_diagnostic_item = "hashmap_type")]
 #[stable(feature = "rust1", since = "1.0.0")]
 pub struct HashMap<K, V, S = RandomState> {
@@ -1029,6 +1028,24 @@ where
     }
 }
 
+#[stable(feature = "rust1", since = "1.0.0")]
+impl<K, V, S> Clone for HashMap<K, V, S>
+where
+    K: Clone,
+    V: Clone,
+    S: Clone,
+{
+    #[inline]
+    fn clone(&self) -> Self {
+        Self { base: self.base.clone() }
+    }
+
+    #[inline]
+    fn clone_from(&mut self, other: &Self) {
+        self.base.clone_from(&other.base);
+    }
+}
+
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<K, V, S> PartialEq for HashMap<K, V, S>
 where

library/std/src/collections/hash/set.rs

@@ -106,7 +106,6 @@ use super::map::{map_try_reserve_error, RandomState};
 /// [`HashMap`]: crate::collections::HashMap
 /// [`RefCell`]: crate::cell::RefCell
 /// [`Cell`]: crate::cell::Cell
-#[derive(Clone)]
 #[cfg_attr(not(test), rustc_diagnostic_item = "hashset_type")]
 #[stable(feature = "rust1", since = "1.0.0")]
 pub struct HashSet<T, S = RandomState> {
@@ -932,6 +931,23 @@ where
     }
 }
 
+#[stable(feature = "rust1", since = "1.0.0")]
+impl<T, S> Clone for HashSet<T, S>
+where
+    T: Clone,
+    S: Clone,
+{
+    #[inline]
+    fn clone(&self) -> Self {
+        Self { base: self.base.clone() }
+    }
+
+    #[inline]
+    fn clone_from(&mut self, other: &Self) {
+        self.base.clone_from(&other.base);
+    }
+}
+
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<T, S> PartialEq for HashSet<T, S>
 where