SynchronizedEnumerator is dead

src/ObservableCollections/Internal/SynchronizedEnumerator.cs

@@ -1,46 +0,0 @@
-using System.Collections;
-using System.Collections.Generic;
-using System.Threading;
-
-namespace ObservableCollections.Internal
-{
-    internal class SynchronizedEnumerator<T> : IEnumerator<T>
-    {
-        bool isDisposed;
-        readonly object gate;
-        readonly bool lockTaken;
-        readonly IEnumerator<T> enumerator;
-
-        public SynchronizedEnumerator(object gate, IEnumerator<T> enumerator)
-        {
-            this.gate = gate;
-            this.enumerator = enumerator;
-            Monitor.Enter(gate, ref lockTaken);
-        }
-
-        public T Current => enumerator.Current;
-
-        object IEnumerator.Current => Current!;
-        public bool MoveNext() => enumerator.MoveNext();
-        public void Reset() => enumerator.Reset();
-
-        public void Dispose()
-        {
-            if (!isDisposed)
-            {
-                isDisposed = true;
-                try
-                {
-                    enumerator.Dispose();
-                }
-                finally
-                {
-                    if (lockTaken)
-                    {
-                        Monitor.Exit(gate);
-                    }
-                }
-            }
-        }
-    }
-}

src/ObservableCollections/ObservableDictionary.cs

@@ -211,7 +211,13 @@ namespace ObservableCollections
 
         public IEnumerator<KeyValuePair<TKey, TValue>> GetEnumerator()
         {
-            return new SynchronizedEnumerator<KeyValuePair<TKey, TValue>>(SyncRoot, dictionary.GetEnumerator());
+            lock (SyncRoot)
+            {
+                foreach (var item in dictionary)
+                {
+                    yield return item;
+                }
+            }
         }
 
         IEnumerator IEnumerable.GetEnumerator()

src/ObservableCollections/ObservableFixedSizeRingBuffer.cs

@@ -280,7 +280,13 @@ namespace ObservableCollections
 
         public IEnumerator<T> GetEnumerator()
         {
-            return new SynchronizedEnumerator<T>(SyncRoot, buffer.GetEnumerator());
+            lock (SyncRoot)
+            {
+                foreach (var item in buffer)
+                {
+                    yield return item;
+                }
+            }
         }
 
         IEnumerator IEnumerable.GetEnumerator()

src/ObservableCollections/ObservableList.cs

@@ -139,7 +139,13 @@ namespace ObservableCollections
 
         public IEnumerator<T> GetEnumerator()
         {
-            return new SynchronizedEnumerator<T>(SyncRoot, list.GetEnumerator());
+            lock (SyncRoot)
+            {
+                foreach (var item in list)
+                {
+                    yield return item;
+                }
+            }
         }
 
         IEnumerator IEnumerable.GetEnumerator()

src/ObservableCollections/ObservableQueue.cs

@@ -203,7 +203,13 @@ namespace ObservableCollections
 
         public IEnumerator<T> GetEnumerator()
         {
-            return new SynchronizedEnumerator<T>(SyncRoot, queue.GetEnumerator());
+            lock (SyncRoot)
+            {
+                foreach (var item in queue)
+                {
+                    yield return item;
+                }
+            }
         }
 
         IEnumerator IEnumerable.GetEnumerator()

src/ObservableCollections/ObservableRingBuffer.cs

@@ -195,7 +195,13 @@ namespace ObservableCollections
 
         public IEnumerator<T> GetEnumerator()
         {
-            return new SynchronizedEnumerator<T>(SyncRoot, buffer.GetEnumerator());
+            lock (SyncRoot)
+            {
+                foreach (var item in buffer)
+                {
+                    yield return item;
+                }
+            }
         }
 
         IEnumerator IEnumerable.GetEnumerator()