In insert_unique_unchecked return a reference to just inserted key an…

…d value

src/map.rs

@@ -1281,6 +1281,8 @@ where
     /// Insert a key-value pair into the map without checking
     /// if the key already exists in the map.
     ///
+    /// Returns a reference to the key and value just inserted.
+    ///
     /// This operation is safe if a key does not exist in the map.
     ///
     /// However, if a key exists in the map already, the behavior is unspecified:
@@ -1297,10 +1299,13 @@ where
     /// For example, when constructing a map from another map, we know
     /// that keys are unique.
     #[cfg_attr(feature = "inline-more", inline)]
-    pub fn insert_unique_unchecked(&mut self, k: K, v: V) {
+    pub fn insert_unique_unchecked(&mut self, k: K, v: V) -> (&K, &mut V) {
         let hash = make_insert_hash::<K, S>(&self.hash_builder, &k);
-        self.table
+        let bucket = self
+            .table
             .insert(hash, (k, v), make_hasher::<K, _, V, S>(&self.hash_builder));
+        let (k, v) = unsafe { bucket.as_mut() };
+        (k, v)
     }
 
     /// Tries to insert a key-value pair into the map, and returns
@@ -3926,8 +3931,10 @@ mod test_map {
     #[test]
     fn test_insert_unique_unchecked() {
         let mut map = HashMap::new();
-        map.insert_unique_unchecked(10, 11);
-        map.insert_unique_unchecked(20, 21);
+        let (k, v) = map.insert_unique_unchecked(10, 11);
+        assert_eq!((&10, &mut 11), (k, v));
+        let (k, v) = map.insert_unique_unchecked(20, 21);
+        assert_eq!((&20, &mut 21), (k, v));
         assert_eq!(Some(&11), map.get(&10));
         assert_eq!(Some(&21), map.get(&20));
         assert_eq!(None, map.get(&30));

src/set.rs

@@ -993,6 +993,8 @@ where
 
     /// Insert a value the set without checking if the value already exists in the set.
     ///
+    /// Returns a reference to the value just inserted.
+    ///
     /// This operation is safe if a value does not exist in the set.
     ///
     /// However, if a value exists in the set already, the behavior is unspecified:
@@ -1009,8 +1011,8 @@ where
     /// For example, when constructing a set from another set, we know
     /// that values are unique.
     #[cfg_attr(feature = "inline-more", inline)]
-    pub fn insert_unique_unchecked(&mut self, value: T) {
-        self.map.insert_unique_unchecked(value, ());
+    pub fn insert_unique_unchecked(&mut self, value: T) -> &T {
+        self.map.insert_unique_unchecked(value, ()).0
     }
 
     /// Adds a value to the set, replacing the existing value, if any, that is equal to the given