[material_ui, cupertino_ui] Localizations by justinmc · Pull Request #12119 · flutter/packages

justinmc · 2026-07-06T20:25:46Z

This PR attempts to solve the flutter_localizations problem for material_ui and cupertino_ui. The crux of the problem is that apps that import flutter_localizations were getting a version of GlobalMaterialLocalizations that uses flutter/flutter's MaterialLocalizations instead of the one in material_ui (and the same thing for Cupertino). This PR moves these classes into material_ui and cupertino_ui, while keeping other localization code inside flutter_localizations.

How this PR was created

Similar to #11888, this PR copies history from flutter/flutter. All commits are preserved as-is, plus one final commit from me that is a squash of all of my work on this PR. This PR should be landed as a merge without squash.

git filter-repo --path-glob "packages/flutter_localizations/lib/src/l10n/cupertino_*.arb" --path packages/flutter_localizations/lib/src/l10n/generated_cupertino_localizations.dart --path packages/flutter_localizations/lib/src/cupertino_localizations.dart --path packages/flutter_localizations/test/cupertino/ --path-glob "packages/flutter_localizations/lib/src/l10n/material_*.arb" --path packages/flutter_localizations/lib/src/l10n/generated_material_localizations.dart --path packages/flutter_localizations/lib/src/material_localizations.dart --path packages/flutter_localizations/test/material --path packages/flutter_localizations/test/test_utils.dart --path dev/tools/localization/gen_cupertino_localizations.dart --path dev/tools/localization/gen_material_localizations.dart --path dev/tools/localization/language_subtag_registry.dart --path dev/tools/localization/localizations_utils.dart --path dev/tools/localization/localizations_validator.dart --path dev/tools/localization/bin/encode_kn_arb_files.dart --path dev/tools/localization/bin/gen_localizations.dart --path dev/tools/localization/bin/gen_missing_localizations.dart
cd ../packages
git remote add source-origin ../flutter
git fetch source-origin
git merge source-origin/master --allow-unrelated-histories

Before

As described in flutter/flutter#188757, a typical localized app like the following would encounter runtime type errors:

import 'package:flutter_localizations/flutter_localizations.dart';
import 'package:material_ui/material_ui.dart';

...

localizationsDelegates: const <LocalizationsDelegate<dynamic>>[
  GlobalCupertinoLocalizations.delegate,
  GlobalMaterialLocalizations.delegate,
  GlobalWidgetsLocalizations.delegate,
],

After

import 'package:material_ui/material_ui.dart';

...

localizationsDelegates: const <LocalizationsDelegate<dynamic>>[
   ...GlobalMaterialLocalizations.delegates,
],

Open Questions

~~I put the l10n folder in side of <material_ui or cupertino_ui>/lib/l10n because that's what the docs said. Should it be in src/?~~
- Yes, I've moved it to src/.
I put the generation scripts inside of packages/material_ui/tools/l10n. Is there a better spot? Is it ok that cupertino_ui has to use a script inside of material_ui? The reason why I didn't split the scripts in two is that there would be large amounts of code duplication. I have moved it to the root of the repo at /script/l10n

TODOs

~~Update l10n README files.~~
Make a plan to update flutter.dev (see [material_ui, cupertino_ui] Localizations #12119 (review)).
Move l10n scripts to root /script/ folder (see [material_ui, cupertino_ui] Localizations #12119 (comment)).
Squash all of my own commits.

Resources

Fixes flutter/flutter#188757

…e class with date time formatting (#29767)

…n the instructions (#30527)

…t of gen_localizations.dart (#29822)

Updating flutter fork

…nd generate one for cupertino english and french (#29824)

Updating flutter fork

…nguages (#31644)

…orted languages (#31644)" (#32470) This reverts commit 5c3c680.

…ted languages (#32513)

Corects a bnuch of typeos throuhgout teh Fluter codebsae. Made use of the `misspell` tool: https://github.com/client9/misspell

dart-lang/sdk#36900

* Refresh .arb files * Refresh localizations

Updates localizations to match what is now generated. It's unclear what caused the change: it didn't happen because of a flutter PR change, so we're still looking for where the source of the non-determinism is. In the meantime, this will fix the build.

* Sort Localization generation output - When creating locales that were assumed from existing locales, the file that is used is non-deterministic. This adds a sort to the iterator to ensure that the same existing locale is used to generate the assumed locale - When generating material, cupertino and date localizations, the generated getters were not sorted. This introduces an alphabetic sort * remove main.dart.snapshot

No code changes, just comments: I spell-checked all the comments in the repo.

* Update project.pbxproj files to say Flutter rather than Chromium Also, the templates now have an empty organization so that we don't cause people to give their apps a Flutter copyright. * Update the copyright notice checker to require a standard notice on all files * Update copyrights on Dart files. (This was a mechanical commit.) * Fix weird license headers on Dart files that deviate from our conventions; relicense Shrine. Some were already marked "The Flutter Authors", not clear why. Their dates have been normalized. Some were missing the blank line after the license. Some were randomly different in trivial ways for no apparent reason (e.g. missing the trailing period). * Clean up the copyrights in non-Dart files. (Manual edits.) Also, make sure templates don't have copyrights. * Fix some more ORGANIZATIONNAMEs

Piinks · 2026-07-09T20:29:05Z

We should make sure that we update flutter.dev/to/internationalization to reflect this as we prepare to ship. So in flutter_localizations, will we deprecate the material and cupertino related bits and eventually remove?

Sorry, this comment posted as incomplete. Updated.

QuncCccccc

I haven't finished review. Just did a quick look. I'll do another round of review and verify the process to add new strings and export translations from translation console.

QuncCccccc · 2026-07-09T20:12:51Z

+//
+// These classes are constructed by the [getCupertinoTranslation] method at the
+// bottom of this file, and used by the [_GlobalCupertinoLocalizationsDelegate.load]
+// method defined in `cupertino_ui/lib/src/cupertino_localizations.dart`.


Suggested change

// method defined in `cupertino_ui/lib/src/cupertino_localizations.dart`.

// method defined in `cupertino_ui/lib/src/global_cupertino_localizations.dart`.

QuncCccccc · 2026-07-09T20:18:09Z

+   String get showMenuTooltip;
+   ```
+   to the localizations class `CupertinoLocalizations`,
+   in [`packages/cupertino_ui/lib/src/cupertino_localizations.dart`](https://github.com/flutter/packages/blob/main/packages/cupertino_ui/lib/src/cupertino_localizations.dart);


Suggested change

in [`packages/cupertino_ui/lib/src/cupertino_localizations.dart`](https://github.com/flutter/packages/blob/main/packages/cupertino_ui/lib/src/cupertino_localizations.dart);

in [`packages/cupertino_ui/lib/src/cupertino_localizations.dart`](https://github.com/flutter/packages/blob/main/packages/cupertino_ui/lib/src/localizations.dart);

QuncCccccc · 2026-07-09T20:20:38Z

+   @override
+   String aboutListTileTitle(String applicationName) => 'About $applicationName';
+   ```
+   For messages with parameters, do also add the function to `GlobalCupertinoLocalizations`  in [`packages/flutter_localizations/lib/src/cupertino_localizations.dart`](https://github.com/flutter/flutter/blob/main/packages/flutter_localizations/lib/src/cupertino_localizations.dart), and add a raw getter as demonstrated below:


Should this be

Suggested change

For messages with parameters, do also add the function to `GlobalCupertinoLocalizations` in [`packages/flutter_localizations/lib/src/cupertino_localizations.dart`](https://github.com/flutter/flutter/blob/main/packages/flutter_localizations/lib/src/cupertino_localizations.dart), and add a raw getter as demonstrated below:

For messages with parameters, do also add the function to `GlobalCupertinoLocalizations` in [`packages/cupertino_ui/lib/src/global_cupertino_localizations.dart`](https://github.com/flutter/packages/blob/main/packages/cupertino_ui/lib/src/global_cupertino_localizations.dart), and add a raw getter as demonstrated below:

QuncCccccc · 2026-07-09T20:22:22Z

+   until they can be translated.
+
+   Finally you need to re-generate
+   lib/src/l10n/generated_material_localizations.dart by running:


Suggested change

lib/src/l10n/generated_material_localizations.dart by running:

lib/src/l10n/generated_cupertino_localizations.dart by running:

QuncCccccc · 2026-07-09T20:24:59Z

+2. Update the .arb files. Modify the out-of-date English strings in
+   `lib/scr/l10n/cupertino_en.arb`.
+
+   You also need to re-generate `lib/src/l10n/localizations.dart` by running:


Suggested change

You also need to re-generate `lib/src/l10n/localizations.dart` by running:

You also need to re-generate `lib/src/l10n/generated_cupertino_localizations.dart` by running:

QuncCccccc · 2026-07-09T20:44:59Z

+//
+// These classes are constructed by the [getCupertinoTranslation] method at the
+// bottom of this file, and used by the [_GlobalCupertinoLocalizationsDelegate.load]
+// method defined in `flutter_localizations/lib/src/cupertino_localizations.dart`.


Suggested change

// method defined in `flutter_localizations/lib/src/cupertino_localizations.dart`.

// method defined in `cupertino_ui/lib/src/global_cupertino_localizations.dart`.

QuncCccccc · 2026-07-09T20:51:58Z

+
+import 'dart:collection';
+
+import 'package:material_ui/material_ui.dart';


The generated_material_localizations.dart shows the header should be

Suggested change

import 'package:material_ui/material_ui.dart';

import 'package:flutter/widgets.dart';

QuncCccccc · 2026-07-09T20:52:14Z

+import 'package:material_ui/material_ui.dart';
+import 'package:intl/intl.dart' as intl;
+
+import '../material_localizations.dart';


import '../global_material_localizations.dart';
import '../time.dart';
import '../typography.dart';

QuncCccccc · 2026-07-09T20:52:38Z

+import '../material_localizations.dart';
+
+// The classes defined here encode all of the translations found in the
+// `flutter_localizations/lib/src/l10n/*.arb` files.


Suggested change

// `flutter_localizations/lib/src/l10n/*.arb` files.

// `material_ui/lib/src/l10n/*.arb` files.

QuncCccccc · 2026-07-09T20:52:59Z

+//
+// These classes are constructed by the [getMaterialTranslation] method at the
+// bottom of this file, and used by the [_MaterialLocalizationsDelegate.load]
+// method defined in `flutter_localizations/lib/src/material_localizations.dart`.


Suggested change

// method defined in `flutter_localizations/lib/src/material_localizations.dart`.

// method defined in `material_ui/lib/src/global_material_localizations.dart`.

Thank you so much for the attention to detail in your review! I missed so many of these out of date paths and stuff that would have confused our users.

elliette · 2026-07-10T18:05:19Z

Note: To get this to work with the demo app in flutter/flutter#188757, I had to do the following:

import 'package:flutter_localizations/flutter_localizations.dart'
    show GlobalWidgetsLocalizations;
import 'package:material_ui/material_ui.dart';

(as noted in PR description)

but also, I had to change:

MaterialApp(
      locale: const Locale('es'),
      supportedLocales: const <Locale>[Locale('en'), Locale('es')],
      localizationsDelegates: const <LocalizationsDelegate<dynamic>>[
        GlobalMaterialLocalizations.delegate,
        GlobalWidgetsLocalizations.delegate,
        GlobalCupertinoLocalizations.delegate,
      ],
      home: const HomeScreen(),
)

to

MaterialApp(
      locale: const Locale('es'),
      supportedLocales: const <Locale>[Locale('en'), Locale('es')],
      localizationsDelegates: const <LocalizationsDelegate<dynamic>>[
        ...GlobalMaterialLocalizations.delegates,  <-- use delegateS
        GlobalWidgetsLocalizations.delegate,
              <-- remove Cupertino localizations
      ],
      home: const HomeScreen(),
)

I originally tried the following, but got this runtime error:

import 'package:flutter_localizations/flutter_localizations.dart' show GlobalWidgetsLocalizations, GlobalCupertinoLocalizations;
import 'package:material_ui/material_ui.dart';

MaterialApp(
      locale: const Locale('es'),
      supportedLocales: const <Locale>[Locale('en'), Locale('es')],
      localizationsDelegates: const <LocalizationsDelegate<dynamic>>[
        GlobalMaterialLocalizations.delegate,
        GlobalWidgetsLocalizations.delegate,
        GlobalCupertinoLocalizations.delegate,
      ],
      home: const HomeScreen(),
    )

Warning: This application's locale, es, is not supported by all of its localization delegates.

• A CupertinoLocalizations delegate that supports the es locale was not found.

If the application is built using GlobalMaterialLocalizations.delegate, consider using GlobalMaterialLocalizations.delegates (plural) instead, as that will automatically declare the appropriate Cupertino localizations.

The declared supported locales for this app are: en, es

See https://flutter.dev/to/internationalization/ for more information about configuring an app's locale, supportedLocales, and localizationsDelegates parameters.

elliette · 2026-07-10T17:39:46Z

@@ -21,17 +21,23 @@ dependencies:
    sdk: flutter
  # This is not unpinned currently.
  # See https://github.com/flutter/flutter/issues/185017


Comment should be above material_color_utilities

elliette · 2026-07-10T18:12:23Z

+
+// Examples can assume:
+// import 'package:flutter_localizations/flutter_localizations.dart';
+// import 'package:flutter/material.dart';


Should this comment be updated?

Here as well:

packages/packages/material_ui/lib/src/app.dart

Line 558 in 527ad97

/// // import 'package:flutter_localizations/flutter_localizations.dart';

elliette · 2026-07-10T18:15:43Z

+
+/// Only used to generate localization strings for the Kannada locale ('kn') because
+/// some of the localized strings contain characters that can crash Emacs on Linux.
+/// See packages/flutter_localizations/lib/src/l10n/README for more information.


Maybe: "See packages/flutter_localizations/lib/src/l10n/README in the Flutter SDK for more information" ?

elliette · 2026-07-10T18:16:42Z

+// replaced by JSON escapes. This is done because some of those strings
+// contain characters that can crash Emacs on Linux. There is more information
+// here: https://github.com/flutter/flutter/issues/36704 and in the README
+// in flutter_localizations/packages/lib/src/l10n.


Ditto here - maybe add "in the Flutter SDK"

justinmc · 2026-07-10T18:43:41Z

@elliette Good catch, when I tested this I didn't use GlobalCupertinoLocalizations. I think the best way to solve this is the following:

import 'package:material_ui/material_ui.dart';
// No flutter_localizations needed.

...

localizationsDelegates: const <LocalizationsDelegate<dynamic>>[
  ...GlobalMaterialLocalizations.delegates,
  // No GlobalWidgetsLocalizations needed, because it's included in the above line.
],

I'm open to other recommendations but I'll update the description up top with this for now.

justinmc · 2026-07-10T19:22:23Z

We should make sure that we update https://flutter.dev/to/internationalization to reflect this as we prepare to ship.

I've added this to my checklist doc and my comms doc.

So in flutter_localizations, will we deprecate the material and cupertino related bits and eventually remove?

Yes, I've added this to my checklist doc as well.

Tim Sneath and others added 30 commits April 5, 2019 11:39

Replace flutter.io with flutter.dev (#30562)

a41358a

Cupertino localization step 6: add a GlobalCupertinoLocalizations bas…

b407dc9

…e class with date time formatting (#29767)

Cupertino localization step 11: add more translation clarifications i…

0e4d73d

…n the instructions (#30527)

Cupertino localization step 7: modularize material specific things ou…

ac00c6e

…t of gen_localizations.dart (#29822)

Merge pull request flutter#2 from flutter/master

aab2495

Updating flutter fork

Cupertino localization step 8: create a gen_cupertino_localizations a…

65c4a5b

…nd generate one for cupertino english and french (#29824)

Add support for the Kazakh language (#31578)

3477c93

CupertinoPicker fidelity revision (#31464)

182f3d7

Merge pull request flutter#4 from flutter/master

d7b4c3d

Updating flutter fork

Cupertino Turkish Translation (#32013)

08a539f

Cupertino localization step 9: add tests (#29954)

91bbe82

Cupertino localization step 12: push translation for all supported la…

5c3c680

…nguages (#31644)

Revert "Cupertino localization step 12: push translation for all supp…

8a946c5

…orted languages (#31644)" (#32470) This reverts commit 5c3c680.

Merge branch 'master' into master

c3a5cc5

Cupertino localization step 12 try 2: push translation for all suppor…

da0f202

…ted languages (#32513)

Correct typos (#33322)

0783589

Corects a bnuch of typeos throuhgout teh Fluter codebsae. Made use of the `misspell` tool: https://github.com/client9/misspell

Updated localizations (#33883)

3489c61

Prepare for Uint8List SDK breaking changes (#34295)

8046e18

dart-lang/sdk#36900

Update Localizations: added 24 new locales (reprise) (#36589)

7b797fb

Add support for the Kannada (kn) locale (#37026)

2859d7e

Localization refresh (#42025)

f8bf064

* Refresh .arb files * Refresh localizations

Make sure all our .dart files have license headers (#44467)

98c9a13

Spell check of Flutter docs (#45200)

fb61f6b

No code changes, just comments: I spell-checked all the comments in the repo.

implicit-casts:false in dev (#45787)

f971b18

implicit-casts:false in flutter_localizations (#45241)

dc6c13b

Move localization executables to bin folder (#46251)

9ec4adf

enable lint prefer_final_in_for_each (#47724)

88dd71a

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Fix path for cupertino localization test

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Code review

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justinmc added 3 commits July 10, 2026 10:24

Move l10n scripts to root script folder.

3c22397

l10n script regenerated as dart package to have its own deps

ab35a71

README fixes for script move

96fd965

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Whoops don't need these (generated by dart create)

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Code review updates from @elliette.

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	// method defined in `cupertino_ui/lib/src/cupertino_localizations.dart`.
	// method defined in `cupertino_ui/lib/src/global_cupertino_localizations.dart`.

	in [`packages/cupertino_ui/lib/src/cupertino_localizations.dart`](https://github.com/flutter/packages/blob/main/packages/cupertino_ui/lib/src/cupertino_localizations.dart);
	in [`packages/cupertino_ui/lib/src/cupertino_localizations.dart`](https://github.com/flutter/packages/blob/main/packages/cupertino_ui/lib/src/localizations.dart);

	For messages with parameters, do also add the function to `GlobalCupertinoLocalizations` in [`packages/flutter_localizations/lib/src/cupertino_localizations.dart`](https://github.com/flutter/flutter/blob/main/packages/flutter_localizations/lib/src/cupertino_localizations.dart), and add a raw getter as demonstrated below:
	For messages with parameters, do also add the function to `GlobalCupertinoLocalizations` in [`packages/cupertino_ui/lib/src/global_cupertino_localizations.dart`](https://github.com/flutter/packages/blob/main/packages/cupertino_ui/lib/src/global_cupertino_localizations.dart), and add a raw getter as demonstrated below:

	lib/src/l10n/generated_material_localizations.dart by running:
	lib/src/l10n/generated_cupertino_localizations.dart by running:

	You also need to re-generate `lib/src/l10n/localizations.dart` by running:
	You also need to re-generate `lib/src/l10n/generated_cupertino_localizations.dart` by running:

	// method defined in `flutter_localizations/lib/src/cupertino_localizations.dart`.
	// method defined in `cupertino_ui/lib/src/global_cupertino_localizations.dart`.


		import 'dart:collection';

		import 'package:material_ui/material_ui.dart';

	import 'package:material_ui/material_ui.dart';
	import 'package:flutter/widgets.dart';

	// `flutter_localizations/lib/src/l10n/*.arb` files.
	// `material_ui/lib/src/l10n/*.arb` files.

	// method defined in `flutter_localizations/lib/src/material_localizations.dart`.
	// method defined in `material_ui/lib/src/global_material_localizations.dart`.

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elliette commented Jul 10, 2026

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