Deprecate decoupled localizations, add dart fixes by Piinks · Pull Request #192954 · flutter/flutter

Piinks · 2026-09-17T21:54:54Z

Deprecates the Material and Cupertino localization classes and symbols in package:flutter_localizations in favor of package:material_ui/material_ui.dart and package:cupertino_ui/cupertino_ui.dart, and adds dart fix migrations.

Deprecates GlobalMaterialLocalizations, kMaterialSupportedLanguages, getMaterialTranslation, and all generated MaterialLocalization* classes in flutter_localizations in favor of package:material_ui/material_ui.dart.
Deprecates GlobalCupertinoLocalizations, kCupertinoSupportedLanguages, getCupertinoTranslation, and all generated CupertinoLocalization* classes in flutter_localizations in favor of package:cupertino_ui/cupertino_ui.dart.
Updates dev/tools/localization/bin/gen_localizations.dart to generate the @Deprecated annotations as well as the corresponding dart fix rules (fix_material_localizations.yaml and fix_cupertino_localizations.yaml).
Adds dart fix golden tests under packages/flutter_localizations/test_fixes/ and enables runFixTests('flutter_localizations') in CI.

Part of #172935

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gemini-code-assist

Code Review

This pull request introduces automated data-driven fixes to support migrating localization classes from flutter_localizations to external packages like material_ui and cupertino_ui. It updates the localization generator to add deprecation annotations to generated classes, constructors, variables, and factory functions, and outputs YAML transform files for the dart fix tool. Feedback on the changes suggests refactoring the collection of generated class names from a List to a Set to avoid duplicate entries and duplicate transform blocks in the generated YAML. Additionally, it is recommended to use the explicit package URI package:flutter_localizations/flutter_localizations.dart instead of the relative path in the generated fix files to ensure robust resolution by the analyzer.

gemini-code-assist · 2026-09-17T21:56:41Z

+  String? deprecatedReplacementPackage,
+  List<String>? generatedClassNames,
 }) {


Using a Set instead of a List for generatedClassNames prevents duplicate class names from being added and subsequently generating duplicate transform blocks in the output YAML files.

Suggested change

String? deprecatedReplacementPackage,

List<String>? generatedClassNames,

}) {

String? deprecatedReplacementPackage,

Set<String>? generatedClassNames,

}) {

References

Suggest simplification and refactoring: Assess whether the code can be made simpler or refactored to enhance readability and maintainability. ^(link)

gemini-code-assist · 2026-09-17T21:56:41Z

          supportedLanguagesDocMacro: widgetsSupportedLanguagesDocMacro,
        )
      : null;
+  final materialGeneratedClasses = <String>[];


Initialize materialGeneratedClasses as a Set to ensure uniqueness of the generated class names.

Suggested change

final materialGeneratedClasses = <String>[];

final materialGeneratedClasses = <String>{};

References

Suggest simplification and refactoring: Assess whether the code can be made simpler or refactored to enhance readability and maintainability. ^(link)

I think Gemini is right? No need to do this multiple times for the same string.

gemini-code-assist · 2026-09-17T21:56:41Z

+          generatedClassNames: materialGeneratedClasses,
        )
      : null;
+  final cupertinoGeneratedClasses = <String>[];


Initialize cupertinoGeneratedClasses as a Set to ensure uniqueness of the generated class names.

Suggested change

final cupertinoGeneratedClasses = <String>[];

final cupertinoGeneratedClasses = <String>{};

References

Suggest simplification and refactoring: Assess whether the code can be made simpler or refactored to enhance readability and maintainability. ^(link)

gemini-code-assist · 2026-09-17T21:56:41Z

+  required String baseClass,
+  required String supportedLanguagesConstant,
+  required String factoryName,
+  required List<String> generatedClassNames,


Update the parameter type of generatedClassNames to Set to match the updated caller types and guarantee uniqueness.

Suggested change

required List<String> generatedClassNames,

required Set<String> generatedClassNames,

References

Suggest simplification and refactoring: Assess whether the code can be made simpler or refactored to enhance readability and maintainability. ^(link)

gemini-code-assist · 2026-09-17T21:56:41Z

+  final buffer = StringBuffer('''
+# 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.
+
+# THIS FILE IS GENERATED. DO NOT EDIT BY HAND.
+#
+# This file is generated by:
+#   dart dev/tools/localization/bin/gen_localizations.dart --overwrite
+
+# For details regarding the *Flutter Fix* feature, see
+# https://flutter.dev/to/flutter-fix
+
+# Every fix must be tested. See the
+# flutter/packages/flutter_localizations/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.
+
+version: 1
+transforms:
+  - title: "Migrate to '$replacementPackageUri'"
+    date: 2026-09-17
+    element:
+      uris: ['flutter_localizations.dart']
+      class: '$baseClass'
+    changes:
+      - kind: 'replacedBy'
+        newElement:
+          uris: ['$replacementPackageUri']
+          class: '$baseClass'
+
+  - title: "Migrate to '$replacementPackageUri'"
+    date: 2026-09-17
+    element:
+      uris: ['flutter_localizations.dart']
+      variable: '$supportedLanguagesConstant'
+    changes:
+      - kind: 'replacedBy'
+        newElement:
+          uris: ['$replacementPackageUri']
+          variable: '$supportedLanguagesConstant'
+
+  - title: "Migrate to '$replacementPackageUri'"
+    date: 2026-09-17
+    element:
+      uris: ['flutter_localizations.dart']
+      function: '$factoryName'
+    changes:
+      - kind: 'replacedBy'
+        newElement:
+          uris: ['$replacementPackageUri']
+          function: '$factoryName'
+''');
+
+  for (final className in generatedClassNames) {
+    buffer.write('''
+
+  - title: "Migrate to '$replacementPackageUri'"
+    date: 2026-09-17
+    element:
+      uris: ['flutter_localizations.dart']
+      class: '$className'
+    changes:
+      - kind: 'replacedBy'
+        newElement:
+          uris: ['$replacementPackageUri']
+          class: '$className'
+''');
+  }


Using the explicit package URI package:flutter_localizations/flutter_localizations.dart instead of the relative/shortened flutter_localizations.dart is the standard practice for Flutter's data-driven fixes and ensures robust resolution by the analyzer.

final buffer = StringBuffer(''' # 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. # THIS FILE IS GENERATED. DO NOT EDIT BY HAND. # # This file is generated by: # dart dev/tools/localization/bin/gen_localizations.dart --overwrite # For details regarding the *Flutter Fix* feature, see # https://flutter.dev/to/flutter-fix # Every fix must be tested. See the # flutter/packages/flutter_localizations/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. version: 1 transforms: - title: "Migrate to '$replacementPackageUri'" date: 2026-09-17 element: uris: ['package:flutter_localizations/flutter_localizations.dart'] class: '$baseClass' changes: - kind: 'replacedBy' newElement: uris: ['$replacementPackageUri'] class: '$baseClass' - title: "Migrate to '$replacementPackageUri'" date: 2026-09-17 element: uris: ['package:flutter_localizations/flutter_localizations.dart'] variable: '$supportedLanguagesConstant' changes: - kind: 'replacedBy' newElement: uris: ['$replacementPackageUri'] variable: '$supportedLanguagesConstant' - title: "Migrate to '$replacementPackageUri'" date: 2026-09-17 element: uris: ['package:flutter_localizations/flutter_localizations.dart'] function: '$factoryName' changes: - kind: 'replacedBy' newElement: uris: ['$replacementPackageUri'] function: '$factoryName' '''); for (final className in generatedClassNames) { buffer.write(''' - title: "Migrate to '$replacementPackageUri'" date: 2026-09-17 element: uris: ['package:flutter_localizations/flutter_localizations.dart'] class: '$className' changes: - kind: 'replacedBy' newElement: uris: ['$replacementPackageUri'] class: '$className' '''); }

References

Suggest simplification and refactoring: Assess whether the code can be made simpler or refactored to enhance readability and maintainability. ^(link)

Sounds reasonable but I'm not sure what the best practice is.

The bot's claim is backwards. Across all existing fix_data files in the repo (packages/flutter/lib/fix_data/, packages/flutter_test/lib/fix_data/, packages/flutter_driver/lib/fix_data/) as well as Data-driven-Fixes.md:191, relative URIs (uris: ['flutter_driver.dart'], uris: ['material.dart']) are the standard convention for elements defined in the same package, while full package:... URIs are used for external packages in newElement.

justinmc

LGTM 👍

justinmc · 2026-09-17T22:39:13Z

          supportedLanguagesDocMacro: widgetsSupportedLanguagesDocMacro,
        )
      : null;
+  final materialGeneratedClasses = <String>[];


I think Gemini is right? No need to do this multiple times for the same string.

justinmc · 2026-09-17T22:40:23Z

+  final buffer = StringBuffer('''
+# 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.
+
+# THIS FILE IS GENERATED. DO NOT EDIT BY HAND.
+#
+# This file is generated by:
+#   dart dev/tools/localization/bin/gen_localizations.dart --overwrite
+
+# For details regarding the *Flutter Fix* feature, see
+# https://flutter.dev/to/flutter-fix
+
+# Every fix must be tested. See the
+# flutter/packages/flutter_localizations/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.
+
+version: 1
+transforms:
+  - title: "Migrate to '$replacementPackageUri'"
+    date: 2026-09-17
+    element:
+      uris: ['flutter_localizations.dart']
+      class: '$baseClass'
+    changes:
+      - kind: 'replacedBy'
+        newElement:
+          uris: ['$replacementPackageUri']
+          class: '$baseClass'
+
+  - title: "Migrate to '$replacementPackageUri'"
+    date: 2026-09-17
+    element:
+      uris: ['flutter_localizations.dart']
+      variable: '$supportedLanguagesConstant'
+    changes:
+      - kind: 'replacedBy'
+        newElement:
+          uris: ['$replacementPackageUri']
+          variable: '$supportedLanguagesConstant'
+
+  - title: "Migrate to '$replacementPackageUri'"
+    date: 2026-09-17
+    element:
+      uris: ['flutter_localizations.dart']
+      function: '$factoryName'
+    changes:
+      - kind: 'replacedBy'
+        newElement:
+          uris: ['$replacementPackageUri']
+          function: '$factoryName'
+''');
+
+  for (final className in generatedClassNames) {
+    buffer.write('''
+
+  - title: "Migrate to '$replacementPackageUri'"
+    date: 2026-09-17
+    element:
+      uris: ['flutter_localizations.dart']
+      class: '$className'
+    changes:
+      - kind: 'replacedBy'
+        newElement:
+          uris: ['$replacementPackageUri']
+          class: '$className'
+''');
+  }


Sounds reasonable but I'm not sure what the best practice is.

justinmc · 2026-09-17T22:41:05Z

+  'Use GlobalCupertinoLocalizations from package:cupertino_ui/cupertino_ui.dart instead. '
+  'This feature was deprecated after v3.47.0-0.0.pre.',
+)
 abstract class GlobalCupertinoLocalizations implements CupertinoLocalizations {


There are some usages of these classes that are causing CI to fail.

justinmc · 2026-09-17T22:43:25Z

+    # Since these test cases live inside the `flutter_localizations` package, the
+    # lint `deprecated_member_use_from_same_package` is required in
+    # order to trigger them. Customer code (which lives outside of the
+    # `flutter_localizations` package) will be triggered by the analyzer warning
+    # `deprecated_member_use`, which is enabled by default.
+    - deprecated_member_use_from_same_package


Do we need to remove this when the deprecated code gets deleted? Maybe create an issue and/or a TODO.

No, test_fixes/analysis_options.yaml (with deprecated_member_use_from_same_package) and the fix_data / test_fixes files are permanent and identical packages/flutter/test_fixes/analysis_options.yaml, packages/flutter_test/test_fixes/analysis_options.yaml, and packages/flutter_driver/test_fixes/analysis_options.yaml. Per Data-driven-Fixes.md:32, dart fix rules continue to work and be tested in test_fixes/ even after deprecated APIs are removed (at which point the undefined_identifier / undefined_class diagnostic triggers the exact same fix).

This is the first time this package is adopting dart fix, which is why it stands out. :)

QuncCccccc · 2026-09-17T22:47:09Z

+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:flutter_localizations/flutter_localizations.dart';


Should this import be removed from the expected output?

package:flutter_localizations/flutter_localizations.dart is not deprecated as a whole library (since GlobalWidgetsLocalizations and WidgetsLocalization* remain in flutter_localizations). Therefore, these are element-level replacedBy transforms rather than a library-level replacedBy transform. In dart fix, element-level replacedBy transforms add the new library import (package:material_ui/material_ui.dart) so the migrated symbols resolve, and do not remove existing imports (the same behavior occurs in packages/flutter/test_fixes/material/material.dart.expect).

flutter-dashboard · 2026-09-17T23:14:12Z

Golden file changes have been found for this pull request. Click here to view and triage (e.g. because this is an intentional change).

If you are still iterating on this change and are not ready to resolve the images on the Flutter Gold dashboard, consider marking this PR as a draft pull request above. You will still be able to view image results on the dashboard, commenting will be silenced, and the check will not try to resolve itself until marked ready for review.

For more guidance, visit Writing a golden file test for package:flutter.

Reviewers: Read the Tree Hygiene page and make sure this patch meets those guidelines before LGTMing.

Changes reported for pull request #192954 at sha 9db5446

QuncCccccc

LGTM. Thanks for adding this!

Flutter deprecated GlobalMaterialLocalizations and GlobalCupertinoLocalizations, in favor of package:material_ui and package:cupertino_ui: flutter/flutter#192954 Without this change, `tools/check analyze` fails with a deprecated_member_use info on each of them, in lib/generated/l10n/zulip_localizations.dart. That has been breaking CI on every branch, most recently: https://github.com/zulip/zulip-flutter/actions/runs/35577698483/job/106263172114 Both lines are written by gen-l10n itself, and come back on every `flutter gen-l10n`. So suppress them through gen-l10n's own `header` option, which gets regenerated along with them. See zulip#2463 for the migration, which waits in part on gen-l10n learning about the new packages: flutter/flutter#191072 Co-Authored-By: Claude Opus 5 (1M context) <[email protected]>

Deprecate decoupled localizations, add dart fixes

78b0f0f

Piinks requested review from QuncCccccc and justinmc September 17, 2026 21:54

flutter-dashboard Bot added the CICD Run CI/CD label Sep 17, 2026

gemini-code-assist Bot reviewed Sep 17, 2026

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Fix CI

9db5446

justinmc previously approved these changes Sep 17, 2026

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QuncCccccc reviewed Sep 17, 2026

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flutter-dashboard Bot added the will affect goldens Changes to golden files label Sep 17, 2026

Review feedback

aad800a

Piinks dismissed justinmc’s stale review via aad800a September 17, 2026 23:17

Piinks requested review from QuncCccccc and justinmc September 17, 2026 23:18

QuncCccccc approved these changes Sep 17, 2026

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Piinks added the autosubmit Merge PR when tree becomes green via auto submit App label Sep 17, 2026

auto-submit Bot added this pull request to the merge queue Sep 18, 2026

Merged via the queue into flutter:master with commit d704f3a Sep 18, 2026
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flutter-dashboard Bot removed the autosubmit Merge PR when tree becomes green via auto submit App label Sep 18, 2026

justinmc mentioned this pull request Sep 25, 2026

Flutter Notable Commits - 2026 #181433

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	final materialGeneratedClasses = <String>[];
	final materialGeneratedClasses = <String>{};

	final cupertinoGeneratedClasses = <String>[];
	final cupertinoGeneratedClasses = <String>{};

	required List<String> generatedClassNames,
	required Set<String> generatedClassNames,

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Piinks commented Sep 17, 2026

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