Revert "Fix 25807: implement move for sliver multibox widget (#29188)" (#31497)

This reverts commit 77ab0b83.

packages/flutter/lib/src/material/tabs.dart

@@ -1116,7 +1116,6 @@ class _TabBarViewState extends State<TabBarView> {
   TabController _controller;
   PageController _pageController;
   List<Widget> _children;
-  List<Widget> _childrenWithKey;
   int _currentIndex;
   int _warpUnderwayCount = 0;
 
@@ -1158,7 +1157,7 @@ class _TabBarViewState extends State<TabBarView> {
   @override
   void initState() {
     super.initState();
-    _updateChildren();
+    _children = widget.children;
   }
 
   @override
@@ -1175,7 +1174,7 @@ class _TabBarViewState extends State<TabBarView> {
     if (widget.controller != oldWidget.controller)
       _updateTabController();
     if (widget.children != oldWidget.children && _warpUnderwayCount == 0)
-      _updateChildren();
+      _children = widget.children;
   }
 
   @override
@@ -1186,11 +1185,6 @@ class _TabBarViewState extends State<TabBarView> {
     super.dispose();
   }
 
-  void _updateChildren() {
-    _children = widget.children;
-    _childrenWithKey = KeyedSubtree.ensureUniqueKeysForList(widget.children);
-  }
-
   void _handleTabControllerAnimationTick() {
     if (_warpUnderwayCount > 0 || !_controller.indexIsChanging)
       return; // This widget is driving the controller's animation.
@@ -1213,30 +1207,28 @@ class _TabBarViewState extends State<TabBarView> {
       return _pageController.animateToPage(_currentIndex, duration: kTabScrollDuration, curve: Curves.ease);
 
     assert((_currentIndex - previousIndex).abs() > 1);
-    final int initialPage = _currentIndex > previousIndex
-        ? _currentIndex - 1
-        : _currentIndex + 1;
-    final List<Widget> originalChildren = _childrenWithKey;
+    int initialPage;
     setState(() {
       _warpUnderwayCount += 1;
-
-      _childrenWithKey = List<Widget>.from(_childrenWithKey, growable: false);
-      final Widget temp = _childrenWithKey[initialPage];
-      _childrenWithKey[initialPage] = _childrenWithKey[previousIndex];
-      _childrenWithKey[previousIndex] = temp;
+      _children = List<Widget>.from(widget.children, growable: false);
+      if (_currentIndex > previousIndex) {
+        _children[_currentIndex - 1] = _children[previousIndex];
+        initialPage = _currentIndex - 1;
+      } else {
+        _children[_currentIndex + 1] = _children[previousIndex];
+        initialPage = _currentIndex + 1;
+      }
     });
+
     _pageController.jumpToPage(initialPage);
 
     await _pageController.animateToPage(_currentIndex, duration: kTabScrollDuration, curve: Curves.ease);
     if (!mounted)
       return Future<void>.value();
+
     setState(() {
       _warpUnderwayCount -= 1;
-      if (widget.children != _children) {
-        _updateChildren();
-      } else {
-        _childrenWithKey = originalChildren;
-      }
+      _children = widget.children;
     });
   }
 
@@ -1272,7 +1264,7 @@ class _TabBarViewState extends State<TabBarView> {
         dragStartBehavior: widget.dragStartBehavior,
         controller: _pageController,
         physics: widget.physics == null ? _kTabBarViewPhysics : _kTabBarViewPhysics.applyTo(widget.physics),
-        children: _childrenWithKey,
+        children: _children,
       ),
     );
   }

packages/flutter/lib/src/rendering/sliver_multi_box_adaptor.dart

@@ -85,8 +85,7 @@ abstract class RenderSliverBoxChildManager {
   /// list).
   int get childCount;
 
-  /// Called during [RenderSliverMultiBoxAdaptor.adoptChild] or
-  /// [RenderSliverMultiBoxAdaptor.move].
+  /// Called during [RenderSliverMultiBoxAdaptor.adoptChild].
   ///
   /// Subclasses must ensure that the [SliverMultiBoxAdaptorParentData.index]
   /// field of the child's [RenderObject.parentData] accurately reflects the
@@ -194,12 +193,7 @@ abstract class RenderSliverMultiBoxAdaptor extends RenderSliver
   RenderSliverMultiBoxAdaptor({
     @required RenderSliverBoxChildManager childManager,
   }) : assert(childManager != null),
-       _childManager = childManager {
-    assert(() {
-      _debugDanglingKeepAlives = <RenderBox>[];
-      return true;
-    }());
-  }
+       _childManager = childManager;
 
   @override
   void setupParentData(RenderObject child) {
@@ -220,27 +214,6 @@ abstract class RenderSliverMultiBoxAdaptor extends RenderSliver
   /// The nodes being kept alive despite not being visible.
   final Map<int, RenderBox> _keepAliveBucket = <int, RenderBox>{};
 
-  List<RenderBox> _debugDanglingKeepAlives;
-
-  /// Indicates whether integrity check is enabled.
-  ///
-  /// Setting this property to true will immediately perform an integrity check.
-  ///
-  /// The integrity check consists of:
-  ///
-  /// 1. Verify that the children index in childList is in ascending order.
-  /// 2. Verify that there is no dangling keepalive child as the result of [move].
-  bool get debugChildIntegrityEnabled => _debugChildIntegrityEnabled;
-  bool _debugChildIntegrityEnabled = true;
-  set debugChildIntegrityEnabled(bool enabled) {
-    assert(enabled != null);
-    assert(() {
-      _debugChildIntegrityEnabled = enabled;
-      return _debugVerifyChildOrder() &&
-        (!_debugChildIntegrityEnabled || _debugDanglingKeepAlives.isEmpty);
-    }());
-  }
-
   @override
   void adoptChild(RenderObject child) {
     super.adoptChild(child);
@@ -251,70 +224,21 @@ abstract class RenderSliverMultiBoxAdaptor extends RenderSliver
 
   bool _debugAssertChildListLocked() => childManager.debugAssertChildListLocked();
 
-  /// Verify that the child list index is in strictly increasing order.
-  ///
-  /// This has no effect in release builds.
-  bool _debugVerifyChildOrder(){
-    if (_debugChildIntegrityEnabled) {
-      RenderBox child = firstChild;
-      int index;
-      while (child != null) {
-        index = indexOf(child);
-        child = childAfter(child);
-        assert(child == null || indexOf(child) > index);
-      }
-    }
-    return true;
-  }
-
   @override
   void insert(RenderBox child, { RenderBox after }) {
     assert(!_keepAliveBucket.containsValue(child));
     super.insert(child, after: after);
     assert(firstChild != null);
-    assert(_debugVerifyChildOrder());
-  }
-
-  @override
-  void move(RenderBox child, { RenderBox after }) {
-    // There are two scenarios:
-    //
-    // 1. The child is not keptAlive.
-    // The child is in the childList maintained by ContainerRenderObjectMixin.
-    // We can call super.move and update parentData with the new slot.
-    //
-    // 2. The child is keptAlive.
-    // In this case, the child is no longer in the childList but might be stored in
-    // [_keepAliveBucket]. We need to update the location of the child in the bucket.
-    final SliverMultiBoxAdaptorParentData childParentData = child.parentData;
-    if (!childParentData.keptAlive) {
-      super.move(child, after: after);
-      childManager.didAdoptChild(child); // updates the slot in the parentData
-      // Its slot may change even if super.move does not change the position.
-      // In this case, we still want to mark as needs layout.
-      markNeedsLayout();
-    } else {
-      // If the child in the bucket is not current child, that means someone has
-      // already moved and replaced current child, and we cannot remove this child.
-      if (_keepAliveBucket[childParentData.index] == child) {
-        _keepAliveBucket.remove(childParentData.index);
+    assert(() {
+      int index = indexOf(firstChild);
+      RenderBox child = childAfter(firstChild);
+      while (child != null) {
+        assert(indexOf(child) > index);
+        index = indexOf(child);
+        child = childAfter(child);
       }
-      assert(() {
-        _debugDanglingKeepAlives.remove(child);
-        return true;
-      }());
-      // Update the slot and reinsert back to _keepAliveBucket in the new slot.
-      childManager.didAdoptChild(child);
-      // If there is an existing child in the new slot, that mean that child will
-      // be moved to other index. In other cases, the existing child should have been
-      // removed by updateChild. Thus, it is ok to overwrite it.
-      assert(() {
-        if (_keepAliveBucket.containsKey(childParentData.index))
-          _debugDanglingKeepAlives.add(_keepAliveBucket[childParentData.index]);
-        return true;
-      }());
-      _keepAliveBucket[childParentData.index] = child;
-    }
+      return true;
+    }());
   }
 
   @override
@@ -325,10 +249,6 @@ abstract class RenderSliverMultiBoxAdaptor extends RenderSliver
       return;
     }
     assert(_keepAliveBucket[childParentData.index] == child);
-    assert(() {
-      _debugDanglingKeepAlives.remove(child);
-      return true;
-    }());
     _keepAliveBucket.remove(childParentData.index);
     dropChild(child);
   }

packages/flutter/lib/src/widgets/framework.dart

@@ -149,13 +149,6 @@ abstract class GlobalKey<T extends State<StatefulWidget>> extends Key {
     assert(() {
       assert(parent != null);
       if (_debugReservations.containsKey(this) && _debugReservations[this] != parent) {
-        // Reserving a new parent while the old parent is not attached is ok.
-        // This can happen when a renderObject detaches and re-attaches to rendering
-        // tree multiple times.
-        if (_debugReservations[this].renderObject?.attached == false) {
-          _debugReservations[this] = parent;
-          return true;
-        }
         // It's possible for an element to get built multiple times in one
         // frame, in which case it'll reserve the same child's key multiple
         // times. We catch multiple children of one widget having the same key

packages/flutter/test/material/tabs_test.dart

@@ -49,7 +49,6 @@ class StateMarkerState extends State<StateMarker> {
 }
 
 class AlwaysKeepAliveWidget extends StatefulWidget {
-  const AlwaysKeepAliveWidget({ Key key}) : super(key: key);
   static String text = 'AlwaysKeepAlive';
   @override
   AlwaysKeepAliveState createState() => AlwaysKeepAliveState();
@@ -1988,56 +1987,6 @@ void main() {
 
   });
 
-  testWidgets('Skipping tabs with global key does not crash', (WidgetTester tester) async {
-    // Regression test for https://github.com/flutter/flutter/issues/24660
-    final List<String> tabs = <String>[
-      'Tab1',
-      'Tab2',
-      'Tab3',
-      'Tab4',
-    ];
-    final TabController controller = TabController(
-      vsync: const TestVSync(),
-      length: tabs.length,
-    );
-    await tester.pumpWidget(
-      MaterialApp(
-        home: Align(
-          alignment: Alignment.topLeft,
-          child: SizedBox(
-            width: 300.0,
-            height: 200.0,
-            child: Scaffold(
-              appBar: AppBar(
-                title: const Text('tabs'),
-                bottom: TabBar(
-                  controller: controller,
-                  tabs: tabs.map<Widget>((String tab) => Tab(text: tab)).toList(),
-                ),
-              ),
-              body: TabBarView(
-                controller: controller,
-                children: <Widget>[
-                  Text('1', key: GlobalKey()),
-                  Text('2', key: GlobalKey()),
-                  Text('3', key: GlobalKey()),
-                  Text('4', key: GlobalKey()),
-                ],
-              ),
-            ),
-          ),
-        ),
-      ),
-    );
-    expect(find.text('1'), findsOneWidget);
-    expect(find.text('4'), findsNothing);
-    await tester.tap(find.text('Tab4'));
-    await tester.pumpAndSettle();
-    expect(controller.index, 3);
-    expect(find.text('4'), findsOneWidget);
-    expect(find.text('1'), findsNothing);
-  });
-
   testWidgets('Skipping tabs with a KeepAlive child works', (WidgetTester tester) async {
     // Regression test for https://github.com/flutter/flutter/issues/11895
     final List<String> tabs = <String>[
@@ -2069,7 +2018,7 @@ void main() {
               body: TabBarView(
                 controller: controller,
                 children: <Widget>[
-                  AlwaysKeepAliveWidget(key: UniqueKey()),
+                  AlwaysKeepAliveWidget(),
                   const Text('2'),
                   const Text('3'),
                   const Text('4'),

packages/flutter/test/widgets/box_sliver_mismatch_test.dart

@@ -9,10 +9,10 @@ import 'package:flutter/widgets.dart';
 void main() {
   testWidgets('Sliver in a box', (WidgetTester tester) async {
     await tester.pumpWidget(
-      DecoratedBox(
-        decoration: const BoxDecoration(),
+      const DecoratedBox(
+        decoration: BoxDecoration(),
         child: SliverList(
-          delegate: SliverChildListDelegate(const <Widget>[]),
+          delegate: SliverChildListDelegate(<Widget>[]),
         ),
       ),
     );
@@ -21,9 +21,9 @@ void main() {
 
     await tester.pumpWidget(
       Row(
-        children: <Widget>[
+        children: const <Widget>[
           SliverList(
-            delegate: SliverChildListDelegate(const <Widget>[]),
+            delegate: SliverChildListDelegate(<Widget>[]),
           ),
         ],
       ),

packages/flutter/test/widgets/framework_test.dart

@@ -451,41 +451,6 @@ void main() {
     expect(count, 2);
   });
 
-  testWidgets('GlobalKey - dettach and re-attach child to different parents', (WidgetTester tester) async {
-    await tester.pumpWidget(Directionality(
-      textDirection: TextDirection.ltr,
-      child: Center(
-        child: Container(
-          height: 100,
-          child: CustomScrollView(
-            controller: ScrollController(),
-            slivers: <Widget>[
-              SliverList(
-                delegate: SliverChildListDelegate(<Widget>[
-                  Text('child', key: GlobalKey()),
-                ]),
-              )
-            ],
-          ),
-        ),
-      ),
-    ));
-    final SliverMultiBoxAdaptorElement element = tester.element(find.byType(SliverList));
-    Element childElement;
-    // Removing and recreating child with same Global Key should not trigger
-    // duplicate key error.
-    element.visitChildren((Element e) {
-      childElement = e;
-    });
-    element.removeChild(childElement.renderObject);
-    element.createChild(0, after: null);
-    element.visitChildren((Element e) {
-      childElement = e;
-    });
-    element.removeChild(childElement.renderObject);
-    element.createChild(0, after: null);
-  });
-
   testWidgets('Defunct setState throws exception', (WidgetTester tester) async {
     StateSetter setState;
 

packages/flutter/test/widgets/slivers_appbar_floating_pinned_test.dart

@@ -22,12 +22,12 @@ void main() {
             data: const MediaQueryData(),
             child: CustomScrollView(
               controller: controller,
-              slivers: <Widget>[
-                const SliverAppBar(floating: true, pinned: true, expandedHeight: 200.0, title: Text('A')),
-                const SliverAppBar(primary: false, pinned: true, title: Text('B')),
+              slivers: const <Widget>[
+                SliverAppBar(floating: true, pinned: true, expandedHeight: 200.0, title: Text('A')),
+                SliverAppBar(primary: false, pinned: true, title: Text('B')),
                 SliverList(
                   delegate: SliverChildListDelegate(
-                    const <Widget>[
+                    <Widget>[
                       Text('C'),
                       Text('D'),
                       SizedBox(height: 500.0),

packages/flutter/test/widgets/slivers_appbar_floating_test.dart

@@ -203,9 +203,9 @@ void main() {
           physics: const BouncingScrollPhysics(),
           slivers: <Widget>[
             SliverPersistentHeader(delegate: TestDelegate(), floating: true),
-            SliverList(
+            const SliverList(
               delegate: SliverChildListDelegate(<Widget>[
-                const SizedBox(
+                SizedBox(
                   height: 300.0,
                   child: Text('X'),
                 ),

packages/flutter/test/widgets/slivers_appbar_pinned_test.dart

@@ -258,9 +258,9 @@ void main() {
           physics: const BouncingScrollPhysics(),
           slivers: <Widget>[
             SliverPersistentHeader(delegate: TestDelegate(), pinned: true),
-            SliverList(
+            const SliverList(
               delegate: SliverChildListDelegate(<Widget>[
-                const SizedBox(
+                SizedBox(
                   height: 300.0,
                   child: Text('X'),
                 ),

packages/flutter/test/widgets/slivers_appbar_scrolling_test.dart

@@ -75,38 +75,6 @@ void main() {
   });
 
   testWidgets('Sliver appbars - scrolling - overscroll gap is below header', (WidgetTester tester) async {
-    await tester.pumpWidget(
-      Directionality(
-        textDirection: TextDirection.ltr,
-        child: CustomScrollView(
-          physics: const BouncingScrollPhysics(),
-          slivers: <Widget>[
-            SliverPersistentHeader(delegate: TestDelegate()),
-            SliverList(
-              delegate: SliverChildListDelegate(<Widget>[
-                const SizedBox(
-                  height: 300.0,
-                  child: Text('X'),
-                ),
-              ]),
-            ),
-          ],
-        ),
-      ),
-    );
-
-    expect(tester.getTopLeft(find.byType(Container)), Offset.zero);
-    expect(tester.getTopLeft(find.text('X')), const Offset(0.0, 200.0));
-
-    final ScrollPosition position = tester.state<ScrollableState>(find.byType(Scrollable)).position;
-    position.jumpTo(-50.0);
-    await tester.pump();
-
-    expect(tester.getTopLeft(find.byType(Container)), Offset.zero);
-    expect(tester.getTopLeft(find.text('X')), const Offset(0.0, 250.0));
-  });
-
-  testWidgets('Sliver appbars const child delegate - scrolling - overscroll gap is below header', (WidgetTester tester) async {
     await tester.pumpWidget(
       Directionality(
         textDirection: TextDirection.ltr,
@@ -115,7 +83,7 @@ void main() {
           slivers: <Widget>[
             SliverPersistentHeader(delegate: TestDelegate()),
             const SliverList(
-              delegate: SliverChildListDelegate.fixed(<Widget>[
+              delegate: SliverChildListDelegate(<Widget>[
                 SizedBox(
                   height: 300.0,
                   child: Text('X'),

packages/flutter/test/widgets/slivers_block_test.dart

@@ -9,28 +9,6 @@ import 'package:flutter/widgets.dart';
 import '../rendering/mock_canvas.dart';
 
 Future<void> test(WidgetTester tester, double offset) {
-  return tester.pumpWidget(
-    Directionality(
-      textDirection: TextDirection.ltr,
-      child: Viewport(
-        offset: ViewportOffset.fixed(offset),
-        slivers: <Widget>[
-          SliverList(
-            delegate: SliverChildListDelegate(const <Widget>[
-              SizedBox(height: 400.0, child: Text('a')),
-              SizedBox(height: 400.0, child: Text('b')),
-              SizedBox(height: 400.0, child: Text('c')),
-              SizedBox(height: 400.0, child: Text('d')),
-              SizedBox(height: 400.0, child: Text('e')),
-            ]),
-          ),
-        ],
-      ),
-    ),
-  );
-}
-
-Future<void> testWithConstChildDelegate(WidgetTester tester, double offset) {
   return tester.pumpWidget(
     Directionality(
       textDirection: TextDirection.ltr,
@@ -38,7 +16,7 @@ Future<void> testWithConstChildDelegate(WidgetTester tester, double offset) {
         offset: ViewportOffset.fixed(offset),
         slivers: const <Widget>[
           SliverList(
-            delegate: SliverChildListDelegate.fixed(<Widget>[
+            delegate: SliverChildListDelegate(<Widget>[
               SizedBox(height: 400.0, child: Text('a')),
               SizedBox(height: 400.0, child: Text('b')),
               SizedBox(height: 400.0, child: Text('c')),
@@ -98,39 +76,6 @@ void main() {
     ], 'ab');
   });
 
-  testWidgets('Viewport+SliverBlock basic test with constant SliverChildListDelegate', (WidgetTester tester) async {
-    await testWithConstChildDelegate(tester, 0.0);
-    expect(tester.renderObject<RenderBox>(find.byType(Viewport)).size, equals(const Size(800.0, 600.0)));
-    verify(tester, <Offset>[
-      const Offset(0.0, 0.0),
-      const Offset(0.0, 400.0),
-    ], 'ab');
-
-    await testWithConstChildDelegate(tester, 200.0);
-    verify(tester, <Offset>[
-      const Offset(0.0, -200.0),
-      const Offset(0.0, 200.0),
-    ], 'ab');
-
-    await testWithConstChildDelegate(tester, 600.0);
-    verify(tester, <Offset>[
-      const Offset(0.0, -200.0),
-      const Offset(0.0, 200.0),
-    ], 'bc');
-
-    await testWithConstChildDelegate(tester, 900.0);
-    verify(tester, <Offset>[
-      const Offset(0.0, -100.0),
-      const Offset(0.0, 300.0),
-    ], 'cd');
-
-    await testWithConstChildDelegate(tester, 200.0);
-    verify(tester, <Offset>[
-      const Offset(0.0, -200.0),
-      const Offset(0.0, 200.0),
-    ], 'ab');
-  });
-
   testWidgets('Viewport with GlobalKey reparenting', (WidgetTester tester) async {
     final Key key1 = GlobalKey();
     final ViewportOffset offset = ViewportOffset.zero();
@@ -205,9 +150,9 @@ void main() {
         textDirection: TextDirection.ltr,
         child: Viewport(
           offset: offset,
-          slivers: <Widget>[
+          slivers: const <Widget>[
             SliverList(
-              delegate: SliverChildListDelegate(const <Widget>[
+              delegate: SliverChildListDelegate(<Widget>[
                 SizedBox(height: 251.0, child: Text('a')),
                 SizedBox(height: 252.0, child: Text('b')),
               ]),
@@ -316,9 +261,9 @@ void main() {
         textDirection: TextDirection.ltr,
         child: Viewport(
           offset: ViewportOffset.zero(),
-          slivers: <Widget>[
+          slivers: const <Widget>[
             SliverList(
-              delegate: SliverChildListDelegate(const <Widget>[
+              delegate: SliverChildListDelegate(<Widget>[
                 SizedBox(height: 400.0, child: Text('a')),
               ]),
             ),
@@ -334,9 +279,9 @@ void main() {
         textDirection: TextDirection.ltr,
         child: Viewport(
           offset: ViewportOffset.fixed(100.0),
-          slivers: <Widget>[
+          slivers: const <Widget>[
             SliverList(
-              delegate: SliverChildListDelegate(const <Widget>[
+              delegate: SliverChildListDelegate(<Widget>[
                 SizedBox(height: 400.0, child: Text('a')),
               ]),
             ),
@@ -352,9 +297,9 @@ void main() {
         textDirection: TextDirection.ltr,
         child: Viewport(
           offset: ViewportOffset.fixed(100.0),
-          slivers: <Widget>[
+          slivers: const <Widget>[
             SliverList(
-              delegate: SliverChildListDelegate(const <Widget>[
+              delegate: SliverChildListDelegate(<Widget>[
                 SizedBox(height: 4000.0, child: Text('a')),
               ]),
             ),
@@ -370,9 +315,9 @@ void main() {
         textDirection: TextDirection.ltr,
         child: Viewport(
           offset: ViewportOffset.zero(),
-          slivers: <Widget>[
+          slivers: const <Widget>[
             SliverList(
-              delegate: SliverChildListDelegate(const <Widget>[
+              delegate: SliverChildListDelegate(<Widget>[
                 SizedBox(height: 4000.0, child: Text('a')),
               ]),
             ),

packages/flutter/test/widgets/slivers_test.dart

@@ -206,8 +206,7 @@ void main() {
       addRepaintBoundaries: false,
       addSemanticIndexes: false,
     );
-    final KeyedSubtree wrapped = builderThrowsDelegate.build(null, 0);
-    expect(wrapped.child, errorText);
+    expect(builderThrowsDelegate.build(null, 0), errorText);
     expect(tester.takeException(), 'builder');
     ErrorWidget.builder = oldBuilder;
   });