Remove useless Disposable field

Author: manandre

src/libraries/System.Text.Json/src/System/Text/Json/Serialization/Converters/Collection/DictionaryDefaultConverter.cs

@@ -28,7 +28,7 @@ protected internal override bool OnWriteResume(
             if (state.Current.CollectionEnumerator == null)
             {
                 enumerator = value.GetEnumerator();
-                state.Current.Disposable = enumerator;
+                state.Current.CollectionEnumerator = enumerator;
                 if (!enumerator.MoveNext())
                 {
                     enumerator.Dispose();

src/libraries/System.Text.Json/src/System/Text/Json/Serialization/Converters/Collection/DictionaryOfTKeyTValueConverter.cs

@@ -32,7 +32,7 @@ protected internal override bool OnWriteResume(
             if (state.Current.CollectionEnumerator == null)
             {
                 enumerator = value.GetEnumerator();
-                state.Current.Disposable = enumerator;
+                state.Current.CollectionEnumerator = enumerator;
                 if (!enumerator.MoveNext())
                 {
                     enumerator.Dispose();

src/libraries/System.Text.Json/src/System/Text/Json/Serialization/Converters/Collection/IEnumerableDefaultConverter.cs

@@ -22,7 +22,7 @@ protected override bool OnWriteResume(Utf8JsonWriter writer, TCollection value,
             if (state.Current.CollectionEnumerator == null)
             {
                 enumerator = value.GetEnumerator();
-                state.Current.Disposable = enumerator;
+                state.Current.CollectionEnumerator = enumerator;
                 if (!enumerator.MoveNext())
                 {
                     enumerator.Dispose();

src/libraries/System.Text.Json/src/System/Text/Json/Serialization/WriteStack.cs

@@ -309,31 +309,27 @@ public void DisposePendingDisposablesOnException()
             Exception? exception = null;
 
             Debug.Assert(Current.AsyncDisposable is null);
-            DisposeFrame(Current.CollectionEnumerator, Current.Disposable, ref exception);
+            DisposeFrame(Current.CollectionEnumerator, ref exception);
 
             int stackSize = Math.Max(_count, _continuationCount);
             for (int i = 0; i < stackSize - 1; i++)
             {
                 Debug.Assert(_stack[i].AsyncDisposable is null);
-                DisposeFrame(_stack[i].CollectionEnumerator, _stack[i].Disposable, ref exception);
+                DisposeFrame(_stack[i].CollectionEnumerator, ref exception);
             }
 
             if (exception is not null)
             {
                 ExceptionDispatchInfo.Capture(exception).Throw();
             }
 
-            static void DisposeFrame(IEnumerator? collectionEnumerator, IDisposable? disposable, ref Exception? exception)
+            static void DisposeFrame(IEnumerator? collectionEnumerator, ref Exception? exception)
             {
                 try
                 {
-                    if (collectionEnumerator is IDisposable disposableEnumerator)
+                    if (collectionEnumerator is IDisposable disposable)
                     {
-                        disposableEnumerator.Dispose();
-                    }
-                    else
-                    {
-                        disposable?.Dispose();
+                        disposable.Dispose();
                     }
                 }
                 catch (Exception e)
@@ -351,37 +347,33 @@ public async ValueTask DisposePendingDisposablesOnExceptionAsync()
         {
             Exception? exception = null;
 
-            exception = await DisposeFrame(Current.CollectionEnumerator, Current.AsyncDisposable, Current.Disposable, exception).ConfigureAwait(false);
+            exception = await DisposeFrame(Current.CollectionEnumerator, Current.AsyncDisposable, exception).ConfigureAwait(false);
 
             int stackSize = Math.Max(_count, _continuationCount);
             for (int i = 0; i < stackSize - 1; i++)
             {
-                exception = await DisposeFrame(_stack[i].CollectionEnumerator, _stack[i].AsyncDisposable, _stack[i].Disposable, exception).ConfigureAwait(false);
+                exception = await DisposeFrame(_stack[i].CollectionEnumerator, _stack[i].AsyncDisposable, exception).ConfigureAwait(false);
             }
 
             if (exception is not null)
             {
                 ExceptionDispatchInfo.Capture(exception).Throw();
             }
 
-            static async ValueTask<Exception?> DisposeFrame(IEnumerator? collectionEnumerator, IAsyncDisposable? asyncDisposable, IDisposable? disposable, Exception? exception)
+            static async ValueTask<Exception?> DisposeFrame(IEnumerator? collectionEnumerator, IAsyncDisposable? asyncDisposable, Exception? exception)
             {
                 Debug.Assert(!(collectionEnumerator is not null && asyncDisposable is not null));
 
                 try
                 {
-                    if (collectionEnumerator is IDisposable disposableEnumerator)
+                    if (collectionEnumerator is IDisposable disposable)
                     {
-                        disposableEnumerator.Dispose();
+                        disposable.Dispose();
                     }
                     else if (asyncDisposable is not null)
                     {
                         await asyncDisposable.DisposeAsync().ConfigureAwait(false);
                     }
-                    else
-                    {
-                        disposable?.Dispose();
-                    }
                 }
                 catch (Exception e)
                 {

src/libraries/System.Text.Json/src/System/Text/Json/Serialization/WriteStackFrame.cs

@@ -18,11 +18,6 @@ internal struct WriteStackFrame
         /// </summary>
         public IEnumerator? CollectionEnumerator;
 
-        /// <summary>
-        /// The enumerator for resumable disposables.
-        /// </summary>
-        public IDisposable? Disposable;
-
         /// <summary>
         /// The enumerator for resumable async disposables.
         /// </summary>