Also drop+return value if replaced

Author: jonhoo

src/map.rs

@@ -1176,15 +1176,16 @@ where
 
                             // just remove the node if the value is the one we expected at method call
                             if observed_value.map(|ov| ov == ev).unwrap_or(true) {
+                                // we remember the old value so that we can return it and mark it for deletion below
+                                old_val = Some(ev);
+
                                 // found the node but we have a new value to replace the old one
                                 if let Some(nv) = new_value {
                                     n.value.store(Owned::new(nv), Ordering::SeqCst);
                                     // we are just replacing entry value and we do not want to remove the node
                                     // so we stop iterating here
                                     break;
                                 }
-                                // we remember the old value so that we can return it and mark it for deletion below
-                                old_val = Some(ev);
                                 // remove the BinEntry containing the removed key value pair from the bucket
                                 if !pred.is_null() {
                                     // either by changing the pointer of the previous BinEntry, if present
@@ -1701,7 +1702,7 @@ fn replace_existing() {
         let guard = epoch::pin();
         map.insert(42, 42, &guard);
         let old = map.replace_node(&42, Some(10), None, &guard);
-        assert!(old.is_none());
+        assert_eq!(old, Some(&42));
         assert_eq!(*map.get(&42, &guard).unwrap(), 10);
     }
 }
@@ -1714,7 +1715,7 @@ fn replace_existing_observed_value_matching() {
         map.insert(42, 42, &guard);
         let observed_value = Shared::from(map.get(&42, &guard).unwrap() as *const _);
         let old = map.replace_node(&42, Some(10), Some(observed_value), &guard);
-        assert!(old.is_none());
+        assert_eq!(old, Some(&42));
         assert_eq!(*map.get(&42, &guard).unwrap(), 10);
     }
 }