add some const classes (#21954)

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

@@ -357,7 +357,7 @@ class _NestedScrollViewState extends State<NestedScrollView> {
 }
 
 class _NestedScrollViewCustomScrollView extends CustomScrollView {
-  _NestedScrollViewCustomScrollView({
+  const _NestedScrollViewCustomScrollView({
     @required Axis scrollDirection,
     @required bool reverse,
     @required ScrollPhysics physics,

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

@@ -58,8 +58,7 @@ class AndroidView extends StatefulWidget {
   /// The `viewType` and `hitTestBehavior` parameters must not be null.
   /// If `creationParams` is not null then `creationParamsCodec` must not be null.
   /// {@endtemplate}
-  AndroidView({ // ignore: prefer_const_constructors_in_immutables
-                // TODO(aam): Remove lint ignore above once https://dartbug.com/34297 is fixed
+  const AndroidView({
     Key key,
     @required this.viewType,
     this.onPlatformViewCreated,

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

@@ -50,8 +50,7 @@ abstract class ScrollView extends StatelessWidget {
   /// Creates a widget that scrolls.
   ///
   /// If the [primary] argument is true, the [controller] must be null.
-  ScrollView({ // ignore: prefer_const_constructors_in_immutables
-               // TODO(aam): Remove lint ignore above once dartbug.com/34297 is fixed
+  const ScrollView({
     Key key,
     this.scrollDirection = Axis.vertical,
     this.reverse = false,
@@ -67,8 +66,8 @@ abstract class ScrollView extends StatelessWidget {
            'Primary ScrollViews obtain their ScrollController via inheritance from a PrimaryScrollController widget. '
            'You cannot both set primary to true and pass an explicit controller.'
        ),
-       primary = primary ?? controller == null && scrollDirection == Axis.vertical,
-       physics = physics ?? (primary == true || (primary == null && controller == null && scrollDirection == Axis.vertical) ? const AlwaysScrollableScrollPhysics() : null),
+       primary = primary ?? controller == null && identical(scrollDirection, Axis.vertical),
+       physics = physics ?? (primary == true || (primary == null && controller == null && identical(scrollDirection, Axis.vertical)) ? const AlwaysScrollableScrollPhysics() : null),
        super(key: key);
 
   /// The axis along which the scroll view scrolls.
@@ -386,7 +385,7 @@ class CustomScrollView extends ScrollView {
   /// Creates a [ScrollView] that creates custom scroll effects using slivers.
   ///
   /// If the [primary] argument is true, the [controller] must be null.
-  CustomScrollView({
+  const CustomScrollView({
     Key key,
     Axis scrollDirection = Axis.vertical,
     bool reverse = false,
@@ -428,7 +427,7 @@ abstract class BoxScrollView extends ScrollView {
   /// Creates a [ScrollView] uses a single child layout model.
   ///
   /// If the [primary] argument is true, the [controller] must be null.
-  BoxScrollView({
+  const BoxScrollView({
     Key key,
     Axis scrollDirection = Axis.vertical,
     bool reverse = false,
@@ -912,7 +911,7 @@ class ListView extends BoxScrollView {
   ///
   /// For example, a custom child model can control the algorithm used to
   /// estimate the size of children that are not actually visible.
-  ListView.custom({
+  const ListView.custom({
     Key key,
     Axis scrollDirection = Axis.vertical,
     bool reverse = false,
@@ -1219,7 +1218,7 @@ class GridView extends BoxScrollView {
   /// a [SliverChildBuilderDelegate] or use the [GridView.builder] constructor.
   ///
   /// The [gridDelegate] and [childrenDelegate] arguments must not be null.
-  GridView.custom({
+  const GridView.custom({
     Key key,
     Axis scrollDirection = Axis.vertical,
     bool reverse = false,

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

@@ -183,8 +183,7 @@ import 'scrollable.dart';
 /// * [Scrollable], which handles arbitrary scrolling effects.
 class SingleChildScrollView extends StatelessWidget {
   /// Creates a box in which a single widget can be scrolled.
-  SingleChildScrollView({ // ignore: prefer_const_constructors_in_immutables
-                          // TODO(aam): Remove lint ignore above once dartbug.com/34297 is fixed
+  const SingleChildScrollView({
     Key key,
     this.scrollDirection = Axis.vertical,
     this.reverse = false,
@@ -198,7 +197,7 @@ class SingleChildScrollView extends StatelessWidget {
           'Primary ScrollViews obtain their ScrollController via inheritance from a PrimaryScrollController widget. '
           'You cannot both set primary to true and pass an explicit controller.'
        ),
-       primary = primary ?? controller == null && scrollDirection == Axis.vertical,
+       primary = primary ?? controller == null && identical(scrollDirection, Axis.vertical),
        super(key: key);
 
   /// The axis along which the scroll view scrolls.

packages/flutter/test/cupertino/nav_bar_test.dart

@@ -602,10 +602,10 @@ void main() {
       'Border is displayed by default in sliver nav bar',
       (WidgetTester tester) async {
     await tester.pumpWidget(
-      CupertinoApp(
+      const CupertinoApp(
         home: CupertinoPageScaffold(
           child: CustomScrollView(
-            slivers: const <Widget>[
+            slivers: <Widget>[
               CupertinoSliverNavigationBar(
                 largeTitle: Text('Large Title'),
               ),
@@ -632,10 +632,10 @@ void main() {
       'Border is not displayed when null in sliver nav bar',
       (WidgetTester tester) async {
     await tester.pumpWidget(
-      CupertinoApp(
+      const CupertinoApp(
         home: CupertinoPageScaffold(
           child: CustomScrollView(
-            slivers: const <Widget>[
+            slivers: <Widget>[
               CupertinoSliverNavigationBar(
                 largeTitle: Text('Large Title'),
                 border: null,
@@ -659,10 +659,10 @@ void main() {
   testWidgets('CupertinoSliverNavigationBar has semantics', (WidgetTester tester) async {
     final SemanticsTester semantics = SemanticsTester(tester);
 
-    await tester.pumpWidget(CupertinoApp(
+    await tester.pumpWidget(const CupertinoApp(
       home: CupertinoPageScaffold(
         child: CustomScrollView(
-          slivers: const <Widget>[
+          slivers: <Widget>[
             CupertinoSliverNavigationBar(
               largeTitle: Text('Large Title'),
               border: null,
@@ -706,10 +706,10 @@ void main() {
       'Border can be overridden in sliver nav bar',
       (WidgetTester tester) async {
     await tester.pumpWidget(
-      CupertinoApp(
+      const CupertinoApp(
         home: CupertinoPageScaffold(
           child: CustomScrollView(
-            slivers: const <Widget>[
+            slivers: <Widget>[
               CupertinoSliverNavigationBar(
                 largeTitle: Text('Large Title'),
                 border: Border(

packages/flutter/test/cupertino/route_test.dart

@@ -48,9 +48,9 @@ void main() {
       CupertinoPageRoute<void>(
         title: 'An iPod',
         builder: (BuildContext context) {
-          return CupertinoPageScaffold(
+          return const CupertinoPageScaffold(
             child: CustomScrollView(
-              slivers: const <Widget>[
+              slivers: <Widget>[
                 CupertinoSliverNavigationBar(),
               ],
             ),

packages/flutter/test/cupertino/scrollbar_paint_test.dart

@@ -9,11 +9,11 @@ import '../rendering/mock_canvas.dart';
 
 void main() {
   testWidgets('Paints iOS spec', (WidgetTester tester) async {
-    await tester.pumpWidget(Directionality(
+    await tester.pumpWidget(const Directionality(
       textDirection: TextDirection.ltr,
       child: CupertinoScrollbar(
         child: SingleChildScrollView(
-          child: const SizedBox(width: 4000.0, height: 4000.0),
+          child: SizedBox(width: 4000.0, height: 4000.0),
         ),
       ),
     ));

packages/flutter/test/cupertino/scrollbar_test.dart

@@ -9,11 +9,11 @@ import '../rendering/mock_canvas.dart';
 
 void main() {
   testWidgets('Scrollbar never goes away until finger lift', (WidgetTester tester) async {
-    await tester.pumpWidget(Directionality(
+    await tester.pumpWidget(const Directionality(
       textDirection: TextDirection.ltr,
       child: CupertinoScrollbar(
         child: SingleChildScrollView(
-          child: const SizedBox(width: 4000.0, height: 4000.0),
+          child: SizedBox(width: 4000.0, height: 4000.0),
         ),
       ),
     ));
@@ -45,11 +45,11 @@ void main() {
 
   testWidgets('Scrollbar is not smaller than minLength with large scroll views',
           (WidgetTester tester) async {
-    await tester.pumpWidget(Directionality(
+    await tester.pumpWidget(const Directionality(
       textDirection: TextDirection.ltr,
       child: CupertinoScrollbar(
         child: SingleChildScrollView(
-          child: const SizedBox(width: 800.0, height: 20000.0),
+          child: SizedBox(width: 800.0, height: 20000.0),
         ),
       ),
     ));

packages/flutter/test/material/scrollbar_paint_test.dart

@@ -9,11 +9,11 @@ import '../rendering/mock_canvas.dart';
 
 void main() {
   testWidgets('Viewport basic test (LTR)', (WidgetTester tester) async {
-    await tester.pumpWidget(Directionality(
+    await tester.pumpWidget(const Directionality(
       textDirection: TextDirection.ltr,
       child: Scrollbar(
         child: SingleChildScrollView(
-          child: const SizedBox(width: 4000.0, height: 4000.0),
+          child: SizedBox(width: 4000.0, height: 4000.0),
         ),
       ),
     ));
@@ -23,11 +23,11 @@ void main() {
   });
 
   testWidgets('Viewport basic test (RTL)', (WidgetTester tester) async {
-    await tester.pumpWidget(Directionality(
+    await tester.pumpWidget(const Directionality(
       textDirection: TextDirection.rtl,
       child: Scrollbar(
         child: SingleChildScrollView(
-          child: const SizedBox(width: 4000.0, height: 4000.0),
+          child: SizedBox(width: 4000.0, height: 4000.0),
         ),
       ),
     ));

packages/flutter/test/material/scrollbar_test.dart

@@ -113,9 +113,9 @@ void main() {
           data: ThemeData(
             platform: platform
           ),
-          child: Scrollbar(
+          child: const Scrollbar(
             child: SingleChildScrollView(
-              child: const SizedBox(width: 4000.0, height: 4000.0),
+              child: SizedBox(width: 4000.0, height: 4000.0),
             ),
           ),
         ),

packages/flutter/test/widgets/overscroll_indicator_test.dart

@@ -24,10 +24,10 @@ Future<void> slowDrag(WidgetTester tester, Offset start, Offset offset) async {
 void main() {
   testWidgets('Overscroll indicator color', (WidgetTester tester) async {
     await tester.pumpWidget(
-      Directionality(
+      const Directionality(
         textDirection: TextDirection.ltr,
         child: CustomScrollView(
-          slivers: const <Widget>[
+          slivers: <Widget>[
             SliverToBoxAdapter(child: SizedBox(height: 2000.0)),
           ],
         ),
@@ -70,8 +70,8 @@ void main() {
             scrollDirection: Axis.horizontal,
             child: Container(
                 width: 600.0,
-                child: CustomScrollView(
-                  slivers: const <Widget>[
+                child: const CustomScrollView(
+                  slivers: <Widget>[
                       SliverToBoxAdapter(child: SizedBox(height: 2000.0)),
                   ],
                 ),
@@ -91,10 +91,10 @@ void main() {
 
   testWidgets('Overscroll indicator changes side when you drag on the other side', (WidgetTester tester) async {
     await tester.pumpWidget(
-      Directionality(
+      const Directionality(
         textDirection: TextDirection.ltr,
         child: CustomScrollView(
-          slivers: const <Widget>[
+          slivers: <Widget>[
             SliverToBoxAdapter(child: SizedBox(height: 2000.0)),
           ],
         ),
@@ -129,10 +129,10 @@ void main() {
 
   testWidgets('Overscroll indicator changes side when you shift sides', (WidgetTester tester) async {
     await tester.pumpWidget(
-      Directionality(
+      const Directionality(
         textDirection: TextDirection.ltr,
         child: CustomScrollView(
-          slivers: const <Widget>[
+          slivers: <Widget>[
             SliverToBoxAdapter(child: SizedBox(height: 2000.0)),
           ],
         ),
@@ -165,11 +165,11 @@ void main() {
   group('Flipping direction of scrollable doesn\'t change overscroll behavior', () {
     testWidgets('down', (WidgetTester tester) async {
       await tester.pumpWidget(
-        Directionality(
+        const Directionality(
           textDirection: TextDirection.ltr,
           child: CustomScrollView(
-            physics: const AlwaysScrollableScrollPhysics(),
-            slivers: const <Widget>[
+            physics: AlwaysScrollableScrollPhysics(),
+            slivers: <Widget>[
               SliverToBoxAdapter(child: SizedBox(height: 20.0)),
             ],
           ),
@@ -185,12 +185,12 @@ void main() {
 
     testWidgets('up', (WidgetTester tester) async {
       await tester.pumpWidget(
-        Directionality(
+        const Directionality(
           textDirection: TextDirection.ltr,
           child: CustomScrollView(
             reverse: true,
-            physics: const AlwaysScrollableScrollPhysics(),
-            slivers: const <Widget>[
+            physics: AlwaysScrollableScrollPhysics(),
+            slivers: <Widget>[
               SliverToBoxAdapter(child: SizedBox(height: 20.0)),
             ],
           ),
@@ -207,11 +207,11 @@ void main() {
 
   testWidgets('Overscroll in both directions', (WidgetTester tester) async {
     await tester.pumpWidget(
-      Directionality(
+      const Directionality(
         textDirection: TextDirection.ltr,
         child: CustomScrollView(
-          physics: const AlwaysScrollableScrollPhysics(),
-          slivers: const <Widget>[
+          physics: AlwaysScrollableScrollPhysics(),
+          slivers: <Widget>[
             SliverToBoxAdapter(child: SizedBox(height: 20.0)),
           ],
         ),
@@ -230,12 +230,12 @@ void main() {
 
   testWidgets('Overscroll horizontally', (WidgetTester tester) async {
     await tester.pumpWidget(
-      Directionality(
+      const Directionality(
         textDirection: TextDirection.ltr,
         child: CustomScrollView(
           scrollDirection: Axis.horizontal,
-          physics: const AlwaysScrollableScrollPhysics(),
-          slivers: const <Widget>[
+          physics: AlwaysScrollableScrollPhysics(),
+          slivers: <Widget>[
             SliverToBoxAdapter(child: SizedBox(height: 20.0)),
           ],
         ),
@@ -283,11 +283,11 @@ void main() {
         textDirection: TextDirection.ltr,
         child: ScrollConfiguration(
           behavior: TestScrollBehavior1(),
-          child: CustomScrollView(
+          child: const CustomScrollView(
             scrollDirection: Axis.horizontal,
-            physics: const AlwaysScrollableScrollPhysics(),
+            physics: AlwaysScrollableScrollPhysics(),
             reverse: true,
-            slivers: const <Widget>[
+            slivers: <Widget>[
               SliverToBoxAdapter(child: SizedBox(height: 20.0)),
             ],
           ),
@@ -305,10 +305,10 @@ void main() {
         textDirection: TextDirection.ltr,
         child: ScrollConfiguration(
           behavior: TestScrollBehavior2(),
-          child: CustomScrollView(
+          child: const CustomScrollView(
             scrollDirection: Axis.horizontal,
-            physics: const AlwaysScrollableScrollPhysics(),
-            slivers: const <Widget>[
+            physics: AlwaysScrollableScrollPhysics(),
+            slivers: <Widget>[
               SliverToBoxAdapter(child: SizedBox(height: 20.0)),
             ],
           ),

packages/flutter/test/widgets/platform_view_test.dart

@@ -23,7 +23,7 @@ void main() {
       viewsController.registerViewType('webview');
 
       await tester.pumpWidget(
-        Center(
+        const Center(
           child: SizedBox(
             width: 200.0,
             height: 100.0,
@@ -47,7 +47,7 @@ void main() {
       viewsController.registerViewType('webview');
 
       await tester.pumpWidget(
-        Center(
+        const Center(
           child: SizedBox(
             width: 200.0,
             height: 100.0,
@@ -55,7 +55,7 @@ void main() {
               viewType: 'webview',
               layoutDirection: TextDirection.ltr,
               creationParams: 'creation parameters',
-              creationParamsCodec: const StringCodec(),
+              creationParamsCodec: StringCodec(),
             ),
           ),
         ),
@@ -85,7 +85,7 @@ void main() {
       viewsController.registerViewType('webview');
 
       await tester.pumpWidget(
-        Center(
+        const Center(
           child: SizedBox(
             width: 0.0,
             height: 0.0,
@@ -105,7 +105,7 @@ void main() {
       final FakeAndroidPlatformViewsController viewsController = FakeAndroidPlatformViewsController();
       viewsController.registerViewType('webview');
       await tester.pumpWidget(
-        Center(
+        const Center(
           child: SizedBox(
             width: 200.0,
             height: 100.0,
@@ -117,7 +117,7 @@ void main() {
       viewsController.resizeCompleter = Completer<void>();
 
       await tester.pumpWidget(
-        Center(
+        const Center(
           child: SizedBox(
             width: 100.0,
             height: 50.0,
@@ -156,7 +156,7 @@ void main() {
       viewsController.registerViewType('webview');
       viewsController.registerViewType('maps');
       await tester.pumpWidget(
-        Center(
+        const Center(
           child: SizedBox(
             width: 200.0,
             height: 100.0,
@@ -166,7 +166,7 @@ void main() {
       );
 
       await tester.pumpWidget(
-        Center(
+        const Center(
           child: SizedBox(
             width: 200.0,
             height: 100.0,
@@ -188,7 +188,7 @@ void main() {
       final FakeAndroidPlatformViewsController viewsController = FakeAndroidPlatformViewsController();
       viewsController.registerViewType('webview');
       await tester.pumpWidget(
-        Center(
+        const Center(
           child: SizedBox(
             width: 200.0,
             height: 100.0,
@@ -253,7 +253,7 @@ void main() {
       final FakeAndroidPlatformViewsController viewsController = FakeAndroidPlatformViewsController();
       viewsController.registerViewType('webview');
       await tester.pumpWidget(
-        Align(
+        const Align(
           alignment: Alignment.topLeft,
           child: SizedBox(
             width: 200.0,
@@ -294,7 +294,7 @@ void main() {
                   numPointerDownsOnParent++;
                 },
               ),
-              Positioned(
+              const Positioned(
                 child: SizedBox(
                   width: 200.0,
                   height: 100.0,
@@ -339,7 +339,7 @@ void main() {
                   numPointerDownsOnParent++;
                 },
               ),
-              Positioned(
+              const Positioned(
                 child: SizedBox(
                   width: 200.0,
                   height: 100.0,
@@ -387,7 +387,7 @@ void main() {
                   numPointerDownsOnParent++;
                 },
               ),
-              Positioned(
+              const Positioned(
                 child: SizedBox(
                   width: 200.0,
                   height: 100.0,
@@ -428,7 +428,7 @@ void main() {
           alignment: Alignment.topLeft,
           child: Container(
             margin: const EdgeInsets.all(10.0),
-            child: SizedBox(
+            child: const SizedBox(
               width: 200.0,
               height: 100.0,
               child: AndroidView(viewType: 'webview', layoutDirection: TextDirection.ltr),
@@ -456,7 +456,7 @@ void main() {
       final FakeAndroidPlatformViewsController viewsController = FakeAndroidPlatformViewsController();
       viewsController.registerViewType('maps');
       await tester.pumpWidget(
-        Center(
+        const Center(
           child: SizedBox(
             width: 200.0,
             height: 100.0,
@@ -474,7 +474,7 @@ void main() {
       );
 
       await tester.pumpWidget(
-        Center(
+        const Center(
           child: SizedBox(
             width: 200.0,
             height: 100.0,
@@ -497,7 +497,7 @@ void main() {
       final FakeAndroidPlatformViewsController viewsController = FakeAndroidPlatformViewsController();
       viewsController.registerViewType('maps');
       await tester.pumpWidget(
-        Directionality(
+        const Directionality(
           textDirection: TextDirection.rtl,
           child: Center(
             child: SizedBox(
@@ -518,7 +518,7 @@ void main() {
       );
 
       await tester.pumpWidget(
-        Directionality(
+        const Directionality(
           textDirection: TextDirection.ltr,
           child: Center(
             child: SizedBox(
@@ -553,7 +553,7 @@ void main() {
               onVerticalDragStart: (DragStartDetails d) {
                 verticalDragAcceptedByParent = true;
               },
-              child: SizedBox(
+              child: const SizedBox(
                 width: 200.0,
                 height: 100.0,
                 child: AndroidView(viewType: 'webview', layoutDirection: TextDirection.ltr),
@@ -637,7 +637,7 @@ void main() {
               verticalDragAcceptedByParent = true;
             },
             onLongPress: () {},
-            child: SizedBox(
+            child: const SizedBox(
               width: 200.0,
               height: 100.0,
               child: AndroidView(
@@ -669,7 +669,7 @@ void main() {
       final FakeAndroidPlatformViewsController viewsController = FakeAndroidPlatformViewsController();
       viewsController.registerViewType('webview');
       await tester.pumpWidget(
-        Align(
+        const Align(
           alignment: Alignment.topLeft,
           child: SizedBox(
             width: 200.0,
@@ -686,7 +686,7 @@ void main() {
       await gesture.moveBy(const Offset(0.0, 100.0));
 
       await tester.pumpWidget(
-        Align(
+        const Align(
           alignment: Alignment.topLeft,
           child: SizedBox(
             width: 200.0,

packages/flutter/test/widgets/scroll_notification_test.dart

@@ -16,8 +16,8 @@ void main() {
           notification = value;
         return false;
       },
-      child: SingleChildScrollView(
-        child: const SizedBox(height: 1200.0)
+      child: const SingleChildScrollView(
+        child: SizedBox(height: 1200.0)
       )
     ));
 
@@ -70,7 +70,7 @@ void main() {
             },
             child: Container(
               padding: const EdgeInsets.all(50.0),
-              child: SingleChildScrollView(child: const SizedBox(height: 1200.0))
+              child: const SingleChildScrollView(child: SizedBox(height: 1200.0))
             )
           )
         )

packages/flutter/test/widgets/scroll_view_test.dart

@@ -182,7 +182,7 @@ void main() {
   });
 
   testWidgets('Vertical CustomScrollViews are primary by default', (WidgetTester tester) async {
-    final CustomScrollView view = CustomScrollView(scrollDirection: Axis.vertical);
+    const CustomScrollView view = CustomScrollView(scrollDirection: Axis.vertical);
     expect(view.primary, isTrue);
   });
 
@@ -200,7 +200,7 @@ void main() {
   });
 
   testWidgets('Horizontal CustomScrollViews are non-primary by default', (WidgetTester tester) async {
-    final CustomScrollView view = CustomScrollView(scrollDirection: Axis.horizontal);
+    const CustomScrollView view = CustomScrollView(scrollDirection: Axis.horizontal);
     expect(view.primary, isFalse);
   });
 
@@ -249,7 +249,7 @@ void main() {
         textDirection: TextDirection.ltr,
         child: PrimaryScrollController(
           controller: primaryScrollController,
-          child: CustomScrollView(primary: true),
+          child: const CustomScrollView(primary: true),
         ),
       ),
     );

packages/flutter/test/widgets/scrollable_test.dart

@@ -11,8 +11,8 @@ Future<void> pumpTest(WidgetTester tester, TargetPlatform platform) async {
     theme: ThemeData(
       platform: platform,
     ),
-    home: CustomScrollView(
-      slivers: const <Widget>[
+    home: const CustomScrollView(
+      slivers: <Widget>[
         SliverToBoxAdapter(child: SizedBox(height: 2000.0)),
       ],
     ),

packages/flutter/test/widgets/single_child_scroll_view_test.dart

@@ -131,12 +131,12 @@ void main() {
   });
 
   testWidgets('Vertical SingleChildScrollViews are primary by default', (WidgetTester tester) async {
-    final SingleChildScrollView view = SingleChildScrollView(scrollDirection: Axis.vertical);
+    const SingleChildScrollView view = SingleChildScrollView(scrollDirection: Axis.vertical);
     expect(view.primary, isTrue);
   });
 
   testWidgets('Horizontal SingleChildScrollViews are non-primary by default', (WidgetTester tester) async {
-    final SingleChildScrollView view = SingleChildScrollView(scrollDirection: Axis.horizontal);
+    const SingleChildScrollView view = SingleChildScrollView(scrollDirection: Axis.horizontal);
     expect(view.primary, isFalse);
   });