From c2c183387e4ab9007d37d70cd28277e0dcd555ea Mon Sep 17 00:00:00 2001
From: davidhicks980 <59215665+davidhicks980@users.noreply.github.com>
Date: Thu, 20 Jun 2024 14:10:05 -0400
Subject: [PATCH] [material/menu_anchor.dart] Remove _MenuAnchorState from
 parent when disposed. (#149586)

`_MenuAnchorState` now removes itself from its parent regardless of whether `_MenuAnchorState._isOpen` is true.

Before, _MenuAnchorState would only detach itself when `_MenuAnchorState._isOpen == true`. This led to _MenuAnchorState being retained until an anchor's parent was disposed.

Before:

https://github.com/flutter/flutter/assets/59215665/48f1617a-a3d0-49ab-a767-f41e3a30ea41

After:

https://github.com/flutter/flutter/assets/59215665/31312bb6-49ec-4083-b8de-e9ae2a42a8b3

Fixes https://github.com/flutter/flutter/issues/149584

I was a bit unsure what the best way of testing this change would be, and wanted feedback from the Flutter team. Is there a way for us to view at the instance count of `_MenuAnchorState`, or expose `_MenuAnchorState._anchorChildren.length` for testing?

- [] I added new tests to check the change I am making, or this PR is [test-exempt].
---
 .../flutter/lib/src/material/menu_anchor.dart |  4 +-
 .../test/material/menu_anchor_test.dart       | 46 +++++++++++++++++++
 2 files changed, 49 insertions(+), 1 deletion(-)

diff --git a/packages/flutter/lib/src/material/menu_anchor.dart b/packages/flutter/lib/src/material/menu_anchor.dart
index 04b7865106d..45f4f240b47 100644
--- a/packages/flutter/lib/src/material/menu_anchor.dart
+++ b/packages/flutter/lib/src/material/menu_anchor.dart
@@ -328,8 +328,10 @@ class _MenuAnchorState extends State<MenuAnchor> {
     assert(_debugMenuInfo('Disposing of $this'));
     if (_isOpen) {
       _close(inDispose: true);
-      _parent?._removeChild(this);
     }
+
+    _parent?._removeChild(this);
+    _parent = null;
     _anchorChildren.clear();
     _menuController._detach(this);
     _internalMenuController = null;
diff --git a/packages/flutter/test/material/menu_anchor_test.dart b/packages/flutter/test/material/menu_anchor_test.dart
index 85676da1834..5063d286160 100644
--- a/packages/flutter/test/material/menu_anchor_test.dart
+++ b/packages/flutter/test/material/menu_anchor_test.dart
@@ -8,6 +8,7 @@ import 'package:flutter/material.dart';
 import 'package:flutter/rendering.dart';
 import 'package:flutter/services.dart';
 import 'package:flutter_test/flutter_test.dart';
+import 'package:leak_tracker/leak_tracker.dart';
 
 import '../widgets/semantics_tester.dart';
 
@@ -3803,6 +3804,51 @@ void main() {
         ..rect(color: overlayColor.withOpacity(0.1)),
     );
   });
+
+  testWidgets('Garbage collector destroys child _MenuAnchorState after parent is closed', (WidgetTester tester) async {
+      // Regression test for https://github.com/flutter/flutter/issues/149584
+      await tester.pumpWidget(
+        MaterialApp(
+          home: MenuAnchor(
+            controller: controller,
+            menuChildren: const <Widget>[
+              SubmenuButton(
+                menuChildren: <Widget>[],
+                child: Text(''),
+              )
+            ],
+          ),
+        ),
+      );
+
+      controller.open();
+      await tester.pump();
+
+      final WeakReference<State> state =
+        WeakReference<State>(
+          tester.firstState<State<SubmenuButton>>(
+            find.byType(SubmenuButton),
+          ),
+        );
+      expect(state.target, isNotNull);
+
+      controller.close();
+      await tester.pump();
+
+      controller.open();
+      await tester.pump();
+
+      controller.close();
+      await tester.pump();
+
+      // Garbage collect. 1 should be enough, but 3 prevents flaky tests.
+      await tester.runAsync<void>(() async {
+        await forceGC(fullGcCycles: 3);
+      });
+
+      expect(state.target, isNull);
+    }, skip: kIsWeb // [intended] ForceGC does not work in web and in release mode. See https://api.flutter.dev/flutter/package-leak_tracker_leak_tracker/forceGC.html
+  );
 }
 
 List<Widget> createTestMenus({