Deprecate ButtonBar, ButtonBarThemeData, and ThemeData.buttonBarTheme (#145523)

fixes [Deprecate `ButtonBar`](https://github.com/flutter/flutter/issues/127955)

### Code sample

<details>
<summary>expand to view the code sample</summary> 

```dart
import 'package:flutter/material.dart';

void main() => runApp(const MyApp());

class MyApp extends StatelessWidget {
  const MyApp({super.key});

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      theme: ThemeData(
        buttonBarTheme: const ButtonBarThemeData(
          alignment: MainAxisAlignment.spaceEvenly,
        ),
      ),
      home: Scaffold(
        body: ButtonBar(
          alignment: MainAxisAlignment.spaceEvenly,
          children: <Widget>[
            TextButton(
              onPressed: () {},
              child: const Text('Button 1'),
            ),
            TextButton(
              onPressed: () {},
              child: const Text('Button 2'),
            ),
            TextButton(
              onPressed: () {},
              child: const Text('Button 3'),
            ),
          ],
        ),
      ),
    );
  }
}
```

</details>

## Data driven fix

### Before executing `dart fix --apply`
```dart
  return MaterialApp(
      theme: ThemeData(
        buttonBarTheme: const ButtonBarThemeData(
          alignment: MainAxisAlignment.spaceEvenly,
        ),
      ),
      home: Scaffold(
        body: ButtonBar(
          alignment: MainAxisAlignment.spaceEvenly,
          children: <Widget>[
            TextButton(
              onPressed: () {},
              child: const Text('Button 1'),
            ),
            TextButton(
              onPressed: () {},
              child: const Text('Button 2'),
            ),
            TextButton(
              onPressed: () {},
              child: const Text('Button 3'),
            ),
          ],
        ),
      ),
    );
```

### After executing `dart fix --apply`
```dart
    return MaterialApp(
      theme: ThemeData(

      ),
      home: Scaffold(
        body: OverflowBar(
          alignment: MainAxisAlignment.spaceEvenly,
          children: <Widget>[
            TextButton(
              onPressed: () {},
              child: const Text('Button 1'),
            ),
            TextButton(
              onPressed: () {},
              child: const Text('Button 2'),
            ),
            TextButton(
              onPressed: () {},
              child: const Text('Button 3'),
            ),
          ],
        ),
      ),
    );
```

packages/flutter/lib/fix_data/fix_material/fix_button_bar.yaml

@@ -0,0 +1,40 @@
+# Copyright 2014 The Flutter Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+# For details regarding the *Flutter Fix* feature, see
+# https://flutter.dev/docs/development/tools/flutter-fix
+
+# Please add new fixes to the top of the file, separated by one blank line
+# from other fixes. In a comment, include a link to the PR where the change
+# requiring the fix was made.
+
+# Every fix must be tested. See the flutter/packages/flutter/test_fixes/README.md
+# file for instructions on testing these data driven fixes.
+
+# For documentation about this file format, see
+# https://dart.dev/go/data-driven-fixes.
+
+# * Fixes in this file are for ButtonBar from the Material library. *
+#   For fixes to
+#     * AppBarTheme: fix_app_bar_theme.yaml
+#     * AppBar: fix_app_bar.yaml
+#     * ButtonBar: fix_button_bar.yaml
+#     * ColorScheme: fix_color_scheme.yaml
+#     * Material (general): fix_material.yaml
+#     * SliverAppBar: fix_sliver_app_bar.yaml
+#     * TextTheme: fix_text_theme.yaml
+#     * ThemeData: fix_theme_data.yaml
+version: 1
+transforms:
+  # Changes made in https://github.com/flutter/flutter/pull/145523
+  - title: "Migrate to 'OverflowBar'"
+    date: 2024-02-28
+    element:
+      uris: [ 'material.dart' ]
+      class: 'ButtonBar'
+    changes:
+      - kind: 'rename'
+        newName: 'OverflowBar'
+
+# Before adding a new fix: read instructions at the top of this file.

packages/flutter/lib/fix_data/fix_material/fix_theme_data.yaml

@@ -1698,4 +1698,15 @@ transforms:
       - kind: 'removeParameter'
         name: 'useMaterial3'
 
+  # Changes made in https://github.com/flutter/flutter/pull/145523
+  - title: "Remove 'buttonBarTheme'"
+    date: 2024-04-28
+    element:
+      uris: [ 'material.dart' ]
+      constructor: ''
+      inClass: 'ThemeData'
+    changes:
+      - kind: 'removeParameter'
+        name: 'buttonBarTheme'
+
 # Before adding a new fix: read instructions at the top of this file.

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

@@ -79,11 +79,19 @@ import 'dialog.dart';
 ///  * [Card], at the bottom of which it is common to place a [ButtonBar].
 ///  * [Dialog], which uses a [ButtonBar] for its actions.
 ///  * [ButtonBarTheme], which configures the [ButtonBar].
+@Deprecated(
+  'Use OverflowBar instead. '
+  'This feature was deprecated after v3.21.0-10.0.pre.',
+)
 class ButtonBar extends StatelessWidget {
   /// Creates a button bar.
   ///
   /// Both [buttonMinWidth] and [buttonHeight] must be non-negative if they
   /// are not null.
+  @Deprecated(
+    'Use OverflowBar instead. '
+    'This feature was deprecated after v3.21.0-10.0.pre.',
+  )
   const ButtonBar({
     super.key,
     this.alignment,

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

@@ -27,12 +27,20 @@ import 'theme.dart';
 ///    its subtree.
 ///  * [ButtonBar], which uses this to configure itself and its children
 ///    button widgets.
+@Deprecated(
+  'Use OverflowBar instead. '
+  'This feature was deprecated after v3.21.0-10.0.pre.',
+)
 @immutable
 class ButtonBarThemeData with Diagnosticable {
   /// Constructs the set of properties used to configure [ButtonBar] widgets.
   ///
   /// Both [buttonMinWidth] and [buttonHeight] must be non-negative if they
   /// are not null.
+  @Deprecated(
+    'Use OverflowBar instead. '
+    'This feature was deprecated after v3.21.0-10.0.pre.',
+  )
   const ButtonBarThemeData({
     this.alignment,
     this.mainAxisSize,

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

@@ -327,7 +327,6 @@ class ThemeData with Diagnosticable {
     BottomAppBarTheme? bottomAppBarTheme,
     BottomNavigationBarThemeData? bottomNavigationBarTheme,
     BottomSheetThemeData? bottomSheetTheme,
-    ButtonBarThemeData? buttonBarTheme,
     ButtonThemeData? buttonTheme,
     CardTheme? cardTheme,
     CheckboxThemeData? checkboxTheme,
@@ -366,6 +365,11 @@ class ThemeData with Diagnosticable {
     TimePickerThemeData? timePickerTheme,
     ToggleButtonsThemeData? toggleButtonsTheme,
     TooltipThemeData? tooltipTheme,
+    @Deprecated(
+      'Use OverflowBar instead. '
+      'This feature was deprecated after v3.21.0-10.0.pre.',
+    )
+    ButtonBarThemeData? buttonBarTheme,
   }) {
     // GENERAL CONFIGURATION
     cupertinoOverrideTheme = cupertinoOverrideTheme?.noDefault();
@@ -500,7 +504,6 @@ class ThemeData with Diagnosticable {
     bottomAppBarTheme ??= const BottomAppBarTheme();
     bottomNavigationBarTheme ??= const BottomNavigationBarThemeData();
     bottomSheetTheme ??= const BottomSheetThemeData();
-    buttonBarTheme ??= const ButtonBarThemeData();
     cardTheme ??= const CardTheme();
     checkboxTheme ??= const CheckboxThemeData();
     chipTheme ??= const ChipThemeData();
@@ -538,6 +541,8 @@ class ThemeData with Diagnosticable {
     timePickerTheme ??= const TimePickerThemeData();
     toggleButtonsTheme ??= const ToggleButtonsThemeData();
     tooltipTheme ??= const TooltipThemeData();
+    // DEPRECATED (newest deprecations at the bottom)
+    buttonBarTheme ??= const ButtonBarThemeData();
     return ThemeData.raw(
       // For the sanity of the reader, make sure these properties are in the same
       // order in every place that they are separated by section comments (e.g.
@@ -591,7 +596,6 @@ class ThemeData with Diagnosticable {
       bottomAppBarTheme: bottomAppBarTheme,
       bottomNavigationBarTheme: bottomNavigationBarTheme,
       bottomSheetTheme: bottomSheetTheme,
-      buttonBarTheme: buttonBarTheme,
       buttonTheme: buttonTheme,
       cardTheme: cardTheme,
       checkboxTheme: checkboxTheme,
@@ -630,6 +634,8 @@ class ThemeData with Diagnosticable {
       timePickerTheme: timePickerTheme,
       toggleButtonsTheme: toggleButtonsTheme,
       tooltipTheme: tooltipTheme,
+      // DEPRECATED (newest deprecations at the bottom)
+      buttonBarTheme: buttonBarTheme,
     );
   }
 
@@ -696,7 +702,6 @@ class ThemeData with Diagnosticable {
     required this.bottomAppBarTheme,
     required this.bottomNavigationBarTheme,
     required this.bottomSheetTheme,
-    required this.buttonBarTheme,
     required this.buttonTheme,
     required this.cardTheme,
     required this.checkboxTheme,
@@ -735,7 +740,17 @@ class ThemeData with Diagnosticable {
     required this.timePickerTheme,
     required this.toggleButtonsTheme,
     required this.tooltipTheme,
-  });
+    // DEPRECATED (newest deprecations at the bottom)
+    @Deprecated(
+      'Use OverflowBar instead. '
+      'This feature was deprecated after v3.21.0-10.0.pre.',
+    )
+    ButtonBarThemeData? buttonBarTheme,
+  }) : // DEPRECATED (newest deprecations at the bottom)
+       // should not be `required`, use getter pattern to avoid breakages.
+       _buttonBarTheme = buttonBarTheme,
+        // DEPRECATED (newest deprecations at the bottom)
+       assert(buttonBarTheme != null);
 
   /// Create a [ThemeData] based on the colors in the given [colorScheme] and
   /// text styles of the optional [textTheme].
@@ -1248,9 +1263,6 @@ class ThemeData with Diagnosticable {
   /// A theme for customizing the color, elevation, and shape of a bottom sheet.
   final BottomSheetThemeData bottomSheetTheme;
 
-  /// A theme for customizing the appearance and layout of [ButtonBar] widgets.
-  final ButtonBarThemeData buttonBarTheme;
-
   /// Defines the default configuration of button widgets, like [DropdownButton]
   /// and [ButtonBar].
   final ButtonThemeData buttonTheme;
@@ -1390,6 +1402,14 @@ class ThemeData with Diagnosticable {
   /// This is the value returned from [TooltipTheme.of].
   final TooltipThemeData tooltipTheme;
 
+  /// A theme for customizing the appearance and layout of [ButtonBar] widgets.
+  @Deprecated(
+    'Use OverflowBar instead. '
+    'This feature was deprecated after v3.21.0-10.0.pre.',
+  )
+  ButtonBarThemeData get buttonBarTheme => _buttonBarTheme!;
+  final ButtonBarThemeData? _buttonBarTheme;
+
   /// Creates a copy of this theme but with the given fields replaced with the new values.
   ///
   /// The [brightness] value is applied to the [colorScheme].
@@ -1449,7 +1469,6 @@ class ThemeData with Diagnosticable {
     BottomAppBarTheme? bottomAppBarTheme,
     BottomNavigationBarThemeData? bottomNavigationBarTheme,
     BottomSheetThemeData? bottomSheetTheme,
-    ButtonBarThemeData? buttonBarTheme,
     ButtonThemeData? buttonTheme,
     CardTheme? cardTheme,
     CheckboxThemeData? checkboxTheme,
@@ -1497,6 +1516,11 @@ class ThemeData with Diagnosticable {
       'This feature was deprecated after v3.13.0-0.2.pre.',
     )
     bool? useMaterial3,
+    @Deprecated(
+      'Use OverflowBar instead. '
+      'This feature was deprecated after v3.21.0-10.0.pre.',
+    )
+    ButtonBarThemeData? buttonBarTheme,
   }) {
     cupertinoOverrideTheme = cupertinoOverrideTheme?.noDefault();
     return ThemeData.raw(
@@ -1554,7 +1578,6 @@ class ThemeData with Diagnosticable {
       bottomAppBarTheme: bottomAppBarTheme ?? this.bottomAppBarTheme,
       bottomNavigationBarTheme: bottomNavigationBarTheme ?? this.bottomNavigationBarTheme,
       bottomSheetTheme: bottomSheetTheme ?? this.bottomSheetTheme,
-      buttonBarTheme: buttonBarTheme ?? this.buttonBarTheme,
       buttonTheme: buttonTheme ?? this.buttonTheme,
       cardTheme: cardTheme ?? this.cardTheme,
       checkboxTheme: checkboxTheme ?? this.checkboxTheme,
@@ -1593,6 +1616,7 @@ class ThemeData with Diagnosticable {
       timePickerTheme: timePickerTheme ?? this.timePickerTheme,
       toggleButtonsTheme: toggleButtonsTheme ?? this.toggleButtonsTheme,
       tooltipTheme: tooltipTheme ?? this.tooltipTheme,
+      buttonBarTheme: buttonBarTheme ?? _buttonBarTheme,
     );
   }
 
@@ -1747,7 +1771,6 @@ class ThemeData with Diagnosticable {
       bottomAppBarTheme: BottomAppBarTheme.lerp(a.bottomAppBarTheme, b.bottomAppBarTheme, t),
       bottomNavigationBarTheme: BottomNavigationBarThemeData.lerp(a.bottomNavigationBarTheme, b.bottomNavigationBarTheme, t),
       bottomSheetTheme: BottomSheetThemeData.lerp(a.bottomSheetTheme, b.bottomSheetTheme, t)!,
-      buttonBarTheme: ButtonBarThemeData.lerp(a.buttonBarTheme, b.buttonBarTheme, t)!,
       buttonTheme: t < 0.5 ? a.buttonTheme : b.buttonTheme,
       cardTheme: CardTheme.lerp(a.cardTheme, b.cardTheme, t),
       checkboxTheme: CheckboxThemeData.lerp(a.checkboxTheme, b.checkboxTheme, t),
@@ -1786,6 +1809,7 @@ class ThemeData with Diagnosticable {
       timePickerTheme: TimePickerThemeData.lerp(a.timePickerTheme, b.timePickerTheme, t),
       toggleButtonsTheme: ToggleButtonsThemeData.lerp(a.toggleButtonsTheme, b.toggleButtonsTheme, t)!,
       tooltipTheme: TooltipThemeData.lerp(a.tooltipTheme, b.tooltipTheme, t)!,
+      buttonBarTheme: ButtonBarThemeData.lerp(a.buttonBarTheme, b.buttonBarTheme, t),
     );
   }
 
@@ -1847,7 +1871,6 @@ class ThemeData with Diagnosticable {
         other.bottomAppBarTheme == bottomAppBarTheme &&
         other.bottomNavigationBarTheme == bottomNavigationBarTheme &&
         other.bottomSheetTheme == bottomSheetTheme &&
-        other.buttonBarTheme == buttonBarTheme &&
         other.buttonTheme == buttonTheme &&
         other.cardTheme == cardTheme &&
         other.checkboxTheme == checkboxTheme &&
@@ -1885,7 +1908,8 @@ class ThemeData with Diagnosticable {
         other.textSelectionTheme == textSelectionTheme &&
         other.timePickerTheme == timePickerTheme &&
         other.toggleButtonsTheme == toggleButtonsTheme &&
-        other.tooltipTheme == tooltipTheme;
+        other.tooltipTheme == tooltipTheme &&
+        other.buttonBarTheme == buttonBarTheme;
   }
 
   @override
@@ -1945,7 +1969,6 @@ class ThemeData with Diagnosticable {
       bottomAppBarTheme,
       bottomNavigationBarTheme,
       bottomSheetTheme,
-      buttonBarTheme,
       buttonTheme,
       cardTheme,
       checkboxTheme,
@@ -1984,6 +2007,8 @@ class ThemeData with Diagnosticable {
       timePickerTheme,
       toggleButtonsTheme,
       tooltipTheme,
+      // DEPRECATED (newest deprecations at the bottom)
+      buttonBarTheme,
     ];
     return Object.hashAll(values);
   }
@@ -2044,7 +2069,6 @@ class ThemeData with Diagnosticable {
     properties.add(DiagnosticsProperty<BottomAppBarTheme>('bottomAppBarTheme', bottomAppBarTheme, defaultValue: defaultData.bottomAppBarTheme, level: DiagnosticLevel.debug));
     properties.add(DiagnosticsProperty<BottomNavigationBarThemeData>('bottomNavigationBarTheme', bottomNavigationBarTheme, defaultValue: defaultData.bottomNavigationBarTheme, level: DiagnosticLevel.debug));
     properties.add(DiagnosticsProperty<BottomSheetThemeData>('bottomSheetTheme', bottomSheetTheme, defaultValue: defaultData.bottomSheetTheme, level: DiagnosticLevel.debug));
-    properties.add(DiagnosticsProperty<ButtonBarThemeData>('buttonBarTheme', buttonBarTheme, defaultValue: defaultData.buttonBarTheme, level: DiagnosticLevel.debug));
     properties.add(DiagnosticsProperty<ButtonThemeData>('buttonTheme', buttonTheme, level: DiagnosticLevel.debug));
     properties.add(DiagnosticsProperty<CardTheme>('cardTheme', cardTheme, level: DiagnosticLevel.debug));
     properties.add(DiagnosticsProperty<CheckboxThemeData>('checkboxTheme', checkboxTheme, defaultValue: defaultData.checkboxTheme, level: DiagnosticLevel.debug));
@@ -2083,6 +2107,8 @@ class ThemeData with Diagnosticable {
     properties.add(DiagnosticsProperty<TimePickerThemeData>('timePickerTheme', timePickerTheme, defaultValue: defaultData.timePickerTheme, level: DiagnosticLevel.debug));
     properties.add(DiagnosticsProperty<ToggleButtonsThemeData>('toggleButtonsTheme', toggleButtonsTheme, level: DiagnosticLevel.debug));
     properties.add(DiagnosticsProperty<TooltipThemeData>('tooltipTheme', tooltipTheme, level: DiagnosticLevel.debug));
+    // DEPRECATED (newest deprecations at the bottom)
+    properties.add(DiagnosticsProperty<ButtonBarThemeData>('buttonBarTheme', buttonBarTheme, defaultValue: defaultData.buttonBarTheme, level: DiagnosticLevel.debug));
   }
 }
 

packages/flutter/test_fixes/material/button_bar.dart

@@ -0,0 +1,14 @@
+// Copyright 2014 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:flutter/material.dart';
+
+void main() {
+  // Changes made in https://github.com/flutter/flutter/pull/145523
+  ButtonBar();
+
+  // Changes made in https://github.com/flutter/flutter/pull/145523
+  ThemeData theme = ThemeData();
+  theme = ThemeData(buttonBarTheme: ButtonBarThemeData());
+}

packages/flutter/test_fixes/material/button_bar.dart.expect

@@ -0,0 +1,14 @@
+// Copyright 2014 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:flutter/material.dart';
+
+void main() {
+  // Changes made in https://github.com/flutter/flutter/pull/145523
+  OverflowBar();
+
+  // Changes made in https://github.com/flutter/flutter/pull/145523
+  ThemeData theme = ThemeData();
+  theme = ThemeData();
+}