[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 l10n. (#23853)

* Make progress indicators accessible

* add missing entry to material_mr.arb

Updating Flutter fork

…_en.arb (#29821)

…nd to make room for cupertino (#29644)

…#29708)

…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)

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.

QuncCccccc

I did another round of review and verified that we are able to add new strings to both MaterialLocalizations and CupertinoLocalizations, after fixing the comments below:) This is the test PR I created only for verification justinmc#2

QuncCccccc · 2026-07-11T21:23:51Z

Since we update the script localization, we should also update the first paragraph from

// This file has been automatically generated. Please do not edit it manually. // To regenerate the file, use: // dart packages/material_ui/script/l10n/bin/gen_localizations.dart --overwrite

to

// This file has been automatically generated. Please do not edit it manually. // To regenerate the file, use: // dart script/l10n/bin/gen_localizations.dart --overwrite

Sorry, the file shows Diff is too big to render, so I cannot directly suggest changes:).

QuncCccccc · 2026-07-11T21:27:22Z

+
+// This file has been automatically generated. Please do not edit it manually.
+// To regenerate the file, use:
+// dart packages/material_ui/script/l10n/bin/gen_localizations.dart --overwrite


Suggested change

// dart packages/material_ui/script/l10n/bin/gen_localizations.dart --overwrite

// dart script/l10n/bin/gen_localizations.dart --overwrite

QuncCccccc · 2026-07-11T21:31:04Z

+//
+// 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/global_cupertino_localizations.dart`.


Suggested change

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

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

When we run gen_localizations.dart, the header will be updated to above.

Indeed it worked 👍

QuncCccccc · 2026-07-11T21:48:02Z

+  generateConstructorForCountrySubClass ??= generateConstructor;
+  final output = StringBuffer();
+  output.writeln(
+    generateHeader('dart packages/material_ui/script/l10n/bin/gen_localizations.dart --overwrite'),


Suggested change

generateHeader('dart packages/material_ui/script/l10n/bin/gen_localizations.dart --overwrite'),

generateHeader('dart script/l10n/bin/gen_localizations.dart --overwrite'),

QuncCccccc · 2026-07-11T22:04:44Z

+The `.arb` files in this directory contain localized values (primarily strings)
+used by the Material library. The `generated_material_localizations.dart` file
+combines all of the localizations into a single Map that is linked with the rest
+of flutter_localizations package.


Suggested change

of flutter_localizations package.

of material_ui package.

QuncCccccc · 2026-07-11T22:04:58Z

+The `.arb` files in this directory contain localized values (primarily strings)
+used by the Cupertino library. The `generated_cupertino_localizations.dart` file
+combines all of the localizations into a single Map that is linked with the rest
+of flutter_localizations package.


Suggested change

of flutter_localizations package.

of cupertino_ui package.

QuncCccccc · 2026-07-11T23:46:51Z

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


Suggested change

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

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

justinmc · 2026-07-13T18:12:25Z

@QuncCccccc Thanks again for catching all of these that I missed! And thanks for testing adding a new string. I tried the same thing locally and got similarly good results.

Since we update the script localization, we should also update the first paragraph

Good call, I've updated the generation script to reflect this in d9f5dd6 and then regenerated those files in ff4a5ba. Bonus verification that the generation script works 👍 .

Piinks

LGTM

chunhtai

Code LGTM, left some comment on readme, don't want to block the merge so feel free to ignore them or address them as follow up

chunhtai · 2026-07-14T01:14:03Z

+
+   You also need to re-generate `lib/src/l10n/generated_cupertino_localizations.dart` by running:
+   ```
+   dart script/l10n/bin/gen_localizations.dart --overwrite


I think we should mention where should one run the script since this will affect which pubspec.yaml will be use

Done. The script also enforces that it's run from the repo root.

chunhtai · 2026-07-14T01:19:11Z

+You can see what that script would generate by running:
+
+```dart
+dart script/l10n/bin/gen_localizations.dart


chunhtai · 2026-07-14T01:19:21Z

+Actually update the generated files with:
+
+```dart
+dart script/l10n/bin/gen_localizations.dart --overwrite


here as well

chunhtai · 2026-07-14T01:20:30Z

+The `CupertinoLocalizations` class implementation uses these to lookup localized
+resource values.
+
+The gen_localizations script must be run by hand after .arb files have


this should probably be in the readme of the script directory

I've added this there along with brief sections about each script.

chunhtai · 2026-07-14T01:29:16Z

+   Finally you need to re-generate
+   lib/src/l10n/generated_material_localizations.dart by running:
+   ```
+   dart script/l10n/bin/gen_localizations.dart --overwrite


same for material readme

chunhtai · 2026-07-14T01:32:43Z

+This directory contains scripts for generating Dart localizations. Currently it
+is only used by material_ui and cupertino_ui.
+
+Originally, this code was located in flutter/flutter at


Should we mention this at all in this readme? This is good context during this transition, but not something necessary to know in order to use or work on this script

Good call, I've reworded and moved this section.

chunhtai · 2026-07-14T01:33:50Z

+
+For instructions on how to use these scripts to generate localizations for
+material_ui and cupertino_ui, see
+[packages/material_ui/lib/src/l10n/README.md](https://github.com/flutter/packages/blob/main/packages/material_ui/lib/src/l10n/README.md)


I wonder if this should be another way around to put the instruction here and let both readme link to this doc

This one I'll defer until after this PR while we're still feeling this out. I agree there's a lot of duplication here and order that could be improved. flutter/flutter#189450

justinmc · 2026-07-14T16:40:13Z

As soon as CI passes here, I will squash my commits to prepare the PR to land.

QuncCccccc

LGTM! Thank you!

elliette

Thank you! LGTM

stuartmorgan-g · 2026-07-14T17:22:06Z

+// Run this program from the root of the git repository.
+//
+// ```
+// dart dev/tools/localization/bin/gen_missing_localizations.dart


This path is no longer correct.

stuartmorgan-g · 2026-07-14T17:24:18Z

It's fine if you want to leave this, but we have a repo-level ignore for .dart_tool already.

Thanks I'll remove it, it was generated by dart create.

stuartmorgan-g · 2026-07-14T17:25:04Z

+name: l10n
+description: Generates localizations for material_ui and cupertino_ui.
+version: 1.0.0
+# repository: https://github.com/flutter/packages/tree/main/script/l10n


You should be able to omit this is this is just local tooling.

Also, presumably you want publish_to: none in this file.

stuartmorgan-g · 2026-07-14T17:25:30Z

+  path: ^1.9.0
+
+dev_dependencies:
+  lints: ^6.0.0


Is this actually used?

Another one from dart create, I'll remove it.

stuartmorgan-g · 2026-07-14T17:33:21Z

-  intl: any
+  intl: ^0.20.2
+  # This is not unpinned currently.
+  # See https://github.com/flutter/flutter/issues/185017


FWIW, this doesn't really clarify what the plan is for this package; that issue just discusses it in the context of flutter/flutter. I would assume that this would just become a standard unpinned ^ carat dependency in the context of a published package.

I've started a conversation in the issue about what to do about this, thanks for flagging.

stuartmorgan-g · 2026-07-14T17:34:16Z

            return found;
          });
          if (shouldWrite) {
+            // ignore: avoid_print


Optional, but I would remove these and just do an ignore for the whole file; that's how we generally handle things in bin or tool directories here.

flutter/flutter's flutter_localization package that relates to material_ui and cupertino_ui. Moves the code to the right place, makes sure it operates on the correct directories and works correctly and passes CI, and rewords docs and READMEs to reflect the changes. * Creates a *_ui/lib/src/l10n directory. * Moves dart classes into material_ui and cupertino_ui. * Moves the arb files into material_ui and cupertino_ui. * Moves the *_ui l10n tests and makes sure they pass. * Moves the localization scripts to script/l10n and updates them to work in their new location. * Moves READMEs and rewords them, and creates a new README for the scripts. * Updates the license headers to match flutter/packages. * Removed some tests that shouldn't come in until flutter/flutter#188473 is ported to flutter/packages. * Skips some tests that failed on web that were previously not run on the web at all.

Piinks · 2026-07-14T22:10:05Z

I think I'll need to push some buttons in the admin settings to land this with @stuartmorgan-g like we did for the main decoupling PR. I am standing by, let me know when you would like to do so. :)

justinmc · 2026-07-15T04:21:32Z

Go for it, thanks!

Hans Muller and others added 30 commits October 16, 2018 14:57

Updated Khmer and Turkish translations (#23165)

63d0f7e

Added Mongolian (mn) translations (#23168)

ccef3ed

Updated supportedLocales doc, etc (#23683)

b13fe81

Warn about supported locales that lack localizations (#23850)

1c1b2a6

scriptCode support in gen_localizations and strip scriptCodes for dat…

d3fc3c5

…e l10n. (#23853)

Add support for the Marathi language, locale mr_IN (#24353)

2ddaf1d

Make progress indicators accessible (#24275)

129352c

* Make progress indicators accessible

add missing entry to material_mr.arb (#24410)

394485f

* add missing entry to material_mr.arb

Added support for the Tamil language, locale ta_IN (#24553)

1e007f1

Update localizations (#25394)

fd34f50

Added support for Swahili (material_sw.arb) (#27506)

7168a56

Added support for the Galician language (material_es_GL.arb) (#27504)

b684285

Update material Galician (gl) translations filename (#27604)

ab15b2f

Add Armenian translations (#27865)

aedd29a

format parameter list (#27261)

ae4e0fa

set literal conversions (#27811)

d0e8c44

Update flutter_localizations translations (#29247)

02563fd

Cupertino localization step 1: add an English arb file (#29200)

b609700

Make real JSON in arb (#29463)

bbee559

Merge pull request #1 from flutter/master

e2c0b54

Updating Flutter fork

Cupertino localization step 1.5: fix a resource mismatch in cupertino…

5f691b3

…_en.arb (#29821)

Cupertino localization step 3: in-place move some material tools arou…

17f8bea

…nd to make room for cupertino (#29644)

Add needed singular resources for cupertino_en.arb (#30160)

c09baea

Cupertino localization step 5: add french arb as translated example (…

31074ba

…#29708)

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)

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[material_ui, cupertino_ui] Proposal: Unify localization generation instructions flutter/flutter#189450

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	// dart packages/material_ui/script/l10n/bin/gen_localizations.dart --overwrite
	// dart script/l10n/bin/gen_localizations.dart --overwrite

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

	generateHeader('dart packages/material_ui/script/l10n/bin/gen_localizations.dart --overwrite'),
	generateHeader('dart script/l10n/bin/gen_localizations.dart --overwrite'),

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

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justinmc commented Jul 6, 2026 •

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