Migrate TextField to Material 3 (#108366)

* Update input style

* generate M3 text style

* Add test

dev/tools/gen_defaults/bin/gen_defaults.dart

@@ -30,6 +30,7 @@ import 'package:gen_defaults/input_decorator_template.dart';
 import 'package:gen_defaults/navigation_bar_template.dart';
 import 'package:gen_defaults/navigation_rail_template.dart';
 import 'package:gen_defaults/surface_tint.dart';
+import 'package:gen_defaults/text_field_template.dart';
 import 'package:gen_defaults/typography_template.dart';
 
 Map<String, dynamic> _readTokenFile(String fileName) {
@@ -116,5 +117,6 @@ Future<void> main(List<String> args) async {
   NavigationBarTemplate('NavigationBar', '$materialLib/navigation_bar.dart', tokens).updateFile();
   NavigationRailTemplate('NavigationRail', '$materialLib/navigation_rail.dart', tokens).updateFile();
   SurfaceTintTemplate('SurfaceTint', '$materialLib/elevation_overlay.dart', tokens).updateFile();
+  TextFieldTemplate('TextField', '$materialLib/text_field.dart', tokens).updateFile();
   TypographyTemplate('Typography', '$materialLib/typography.dart', tokens).updateFile();
 }

dev/tools/gen_defaults/lib/text_field_template.dart

+// 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 'template.dart';
+
+class TextFieldTemplate extends TokenTemplate {
+  const TextFieldTemplate(super.blockName, super.fileName, super.tokens);
+
+  @override
+  String generate() => '''
+// Generated version ${tokens["version"]}
+
+TextStyle _m3InputStyle(BuildContext context) => ${textStyle("md.comp.filled-text-field.label-text")}!;
+''';
+}

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

@@ -1140,7 +1140,7 @@ class _TextFieldState extends State<TextField> with RestorationMixin implements
 
     final ThemeData theme = Theme.of(context);
     final DefaultSelectionStyle selectionStyle = DefaultSelectionStyle.of(context);
-    final TextStyle style = theme.textTheme.subtitle1!.merge(widget.style);
+    final TextStyle style = (theme.useMaterial3 ? _m3InputStyle(context) : theme.textTheme.subtitle1!).merge(widget.style);
     final Brightness keyboardAppearance = widget.keyboardAppearance ?? theme.brightness;
     final TextEditingController controller = _effectiveController;
     final FocusNode focusNode = _effectiveFocusNode;
@@ -1368,3 +1368,18 @@ class _TextFieldState extends State<TextField> with RestorationMixin implements
     );
   }
 }
+
+// BEGIN GENERATED TOKEN PROPERTIES - TextField
+
+// Do not edit by hand. The code between the "BEGIN GENERATED" and
+// "END GENERATED" comments are generated from data in the Material
+// Design token database by the script:
+//   dev/tools/gen_defaults/bin/gen_defaults.dart.
+
+// Token database version: v0_101
+
+// Generated version v0_101
+
+TextStyle _m3InputStyle(BuildContext context) => Theme.of(context).textTheme.bodyLarge!;
+
+// END GENERATED TOKEN PROPERTIES - TextField

packages/flutter/test/material/text_field_test.dart

@@ -7107,6 +7107,57 @@ void main() {
     expect(editableText.style.color, isNull);
   });
 
+  testWidgets('TextField style is merged with theme in Material 3', (WidgetTester tester) async {
+    // Regression test for https://github.com/flutter/flutter/issues/23994
+
+    final ThemeData themeData = ThemeData(
+      useMaterial3: true,
+      textTheme: TextTheme(
+        bodyLarge: TextStyle(
+          color: Colors.blue[500],
+        ),
+      ),
+    );
+
+    Widget buildFrame(TextStyle style) {
+      return MaterialApp(
+        theme: themeData,
+        home: Material(
+          child: Center(
+            child: TextField(
+              style: style,
+            ),
+          ),
+        ),
+      );
+    }
+
+    // Empty TextStyle is overridden by theme
+    await tester.pumpWidget(buildFrame(const TextStyle()));
+    EditableText editableText = tester.widget(find.byType(EditableText));
+    expect(editableText.style.color, themeData.textTheme.bodyLarge!.color);
+    expect(editableText.style.background, themeData.textTheme.bodyLarge!.background);
+    expect(editableText.style.shadows, themeData.textTheme.bodyLarge!.shadows);
+    expect(editableText.style.decoration, themeData.textTheme.bodyLarge!.decoration);
+    expect(editableText.style.locale, themeData.textTheme.bodyLarge!.locale);
+    expect(editableText.style.wordSpacing, themeData.textTheme.bodyLarge!.wordSpacing);
+
+    // Properties set on TextStyle override theme
+    const Color setColor = Colors.red;
+    await tester.pumpWidget(buildFrame(const TextStyle(color: setColor)));
+    editableText = tester.widget(find.byType(EditableText));
+    expect(editableText.style.color, setColor);
+
+    // inherit: false causes nothing to be merged in from theme
+    await tester.pumpWidget(buildFrame(const TextStyle(
+      fontSize: 24.0,
+      textBaseline: TextBaseline.alphabetic,
+      inherit: false,
+    )));
+    editableText = tester.widget(find.byType(EditableText));
+    expect(editableText.style.color, isNull);
+  });
+
   testWidgets('style enforces required fields', (WidgetTester tester) async {
     Widget buildFrame(TextStyle style) {
       return MaterialApp(