Fixed changing supportedLocales fails to update the locale #178526

shivanuj13 · 2025-11-14T12:40:42Z

Recompute the resolved locale in LocalizationsResolver.update(...) and notify listeners
only when the resolved locale actually changes. Previously, updating WidgetsApp.supportedLocales
did not always propagate to the app locale because the resolver did not re-resolve and
notify listeners. This change fixes that bug and adds unit tests.

Fixes #117210

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I followed the breaking change policy and added Data Driven Fixes where supported.
All existing and new tests are passing.

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Code Review

This pull request addresses a bug where changes to supportedLocales were not consistently propagating to the application's locale. The proposed solution correctly re-evaluates the resolved locale within LocalizationsResolver.update and triggers a notification only when the locale has actually changed, which is an efficient approach. The addition of unit tests is commendable, as they thoroughly verify both the bug fix and the conditional notification logic. The changes are well-implemented and align with the project's coding standards.

packages/flutter/test/widgets/localizations_test.dart

shivanuj13 · 2025-11-18T03:42:24Z

@victorsanni I have updated this PR with your suggested change.

victorsanni

Can you run dart format packages/flutter/test/widgets/localizations_test.dart to fix the Linux analyze failure?

victorsanni · 2025-11-19T01:48:55Z

packages/flutter/lib/src/widgets/localizations.dart

+      WidgetsBinding.instance.platformDispatcher.locales,
+      _supportedLocales,
+    );
+    if (newLocale != _resolvedLocale) {


Maybe we can share code with didChangeLocales?

refactored the code to reuse this in didChangeLocals as well.

victorsanni · 2025-11-20T20:23:59Z

Hi @shivanuj13, this is the failing customer test. Can you confirm if it is related to the changes in this PR?

victorsanni · 2025-11-20T21:44:57Z

Can you confirm if it is related to the changes in this PR?

Actually scrap that, I've seen this same failure across unrelated PRs.

packages/flutter/lib/src/widgets/localizations.dart

victorsanni

I'm wondering if in widgets/app.dart we should only call update if any localization properties change, or if that is needless since it's mostly a parameter passthrough. Any thoughts?

packages/flutter/lib/src/widgets/localizations.dart

shivanuj13 · 2025-11-24T19:10:21Z

I went through widgets/app.dart and realized that we should only call update if any properties have changed. Therefore, we don't need to check them again (e.g., supportedLocales != _supportedLocales) inside LocalizationsResolver. I don't foresee any side effects from this change. Am i missing something?

chunhtai

LGTM

Piinks

Thanks for contributing!

auto-submit · 2025-11-24T22:28:42Z

autosubmit label was removed for flutter/flutter/178526, because - The status or check suite Google testing has failed. Please fix the issues identified (or deflake) before re-applying this label.

victorsanni · 2025-11-24T22:34:19Z

Same google testing failures as before... I'm surprised 74e8c5d passed google testing but the latest commit doesn't.

victorsanni · 2025-11-25T01:08:27Z

packages/flutter/lib/src/widgets/localizations.dart

    _supportedLocales = supportedLocales;
+    _updateResolvedLocale(WidgetsBinding.instance.platformDispatcher.locales);


This code block from your previous commit will fix the Google testing:

Suggested change

_supportedLocales = supportedLocales;

_updateResolvedLocale(WidgetsBinding.instance.platformDispatcher.locales);

if (_supportedLocales != supportedLocales) {

_updateResolvedLocale(WidgetsBinding.instance.platformDispatcher.locales);

_supportedLocales = supportedLocales;

}

Can we add a test for this? The fact that Google testing triggers it and we don't is an indication we should probably test for it here.

I think i have already aded a test that verify LocalizationsResolver does not notify if supportedLocales is unchanged. do we need to add a test for any other specific case?

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flutter/flutter@7b98d50...022b155 2025-11-27 [email protected] Make tree green again by fixing lints (flutter/flutter#179186) 2025-11-26 [email protected] Add shared Darwin implementation for plugins (flutter/flutter#176495) 2025-11-26 [email protected] Fixed changing supportedLocales fails to update the locale (flutter/flutter#178526) 2025-11-26 [email protected] [ Tool ] Remove --no-sandbox when launching web apps on Chrome device (flutter/flutter#178670) 2025-11-26 [email protected] Build hooks: Don't require toolchain for unit tests (flutter/flutter#178954) 2025-11-26 [email protected] Fix a small typo in `HandlerCompat.java` docs (flutter/flutter#178595) 2025-11-26 [email protected] Roll Fuchsia Linux SDK from nzuAxCJGeJbkZCTkr... to _e9MNK4nfBOrERVP_... (flutter/flutter#179130) 2025-11-26 [email protected] Make sure that a CupertinoActivityIndicator doesn't crash in 0x0 envi… (flutter/flutter#178565) 2025-11-26 [email protected] [native assets] Bump minimum iOS version from 12 to 13 (flutter/flutter#179079) 2025-11-26 [email protected] Documents and fixes behavior when clipping background filter fragment shader (flutter/flutter#178940) 2025-11-26 [email protected] Replace the hardcoded link with an actual link tag in `PlatformChannel.java‎` docs (flutter/flutter#178588) 2025-11-26 [email protected] Roll Packages from cc3dca6 to 5d8d954 (5 revisions) (flutter/flutter#179140) 2025-11-26 [email protected] Add more templates that the UIScene migrator can match against (flutter/flutter#179044) 2025-11-26 [email protected] Remove deprecated activeColor in `dynamic_content_color.0.dart`‎ example (flutter/flutter#178961) 2025-11-26 [email protected] Remove deprecated `activeColor` in `decorated_sliver.1.dart‎` example (flutter/flutter#178959) 2025-11-26 [email protected] Small refactor in `PlayStoreDeferredComponentManager.java‎` (flutter/flutter#178586) 2025-11-26 [email protected] Roll Dart SDK from 9e605f706cdf to 1d8dc04bd1d7 (4 revisions) (flutter/flutter#179080) 2025-11-26 [email protected] Fix error when generating pt_BR localizations (flutter/flutter#175832) 2025-11-26 [email protected] Roll Fuchsia Test Scripts from JUeFbA8y0E-_pj-bg... to MHF-UAfO6sVKqSEYk... (flutter/flutter#179151) 2025-11-26 [email protected] Add flutter_lints to samples (flutter/flutter#179091) If this roll has caused a breakage, revert this CL and stop the roller using the controls here: https://autoroll.skia.org/r/flutter-packages Please CC [email protected],[email protected] on the revert to ensure that a human is aware of the problem. To file a bug in Packages: https://github.com/flutter/flutter/issues/new/choose To report a problem with the AutoRoller itself, please file a bug: https://issues.skia.org/issues/new?component=1389291&template=1850622 Documentation for the AutoRoller is here: https://skia.googlesource.com/buildbot/+doc/main/autoroll/README.md

…78526)  Recompute the resolved locale in LocalizationsResolver.update(...) and notify listeners only when the resolved locale actually changes. Previously, updating WidgetsApp.supportedLocales did not always propagate to the app locale because the resolver did not re-resolve and notify listeners. This change fixes that bug and adds unit tests. Fixes [https://github.com/flutter/flutter/issues/117210](https://github.com/flutter/flutter/issues/117210) ## Pre-launch Checklist - [x] I read the [Contributor Guide] and followed the process outlined there for submitting PRs. - [x] I read the [Tree Hygiene] wiki page, which explains my responsibilities. - [x] I read and followed the [Flutter Style Guide], including [Features we expect every widget to implement]. - [x] I signed the [CLA]. - [x] I listed at least one issue that this PR fixes in the description above. - [x] I updated/added relevant documentation (doc comments with `///`). - [x] I added new tests to check the change I am making, or this PR is [test-exempt]. - [x] I followed the [breaking change policy] and added [Data Driven Fixes] where supported. - [x] All existing and new tests are passing. If you need help, consider asking for advice on the #hackers-new channel on [Discord]. **Note**: The Flutter team is currently trialing the use of [Gemini Code Assist for GitHub](https://developers.google.com/gemini-code-assist/docs/review-github-code). Comments from the `gemini-code-assist` bot should not be taken as authoritative feedback from the Flutter team. If you find its comments useful you can update your code accordingly, but if you are unsure or disagree with the feedback, please feel free to wait for a Flutter team member's review for guidance on which automated comments should be addressed.  [Contributor Guide]: https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#overview [Tree Hygiene]: https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md [test-exempt]: https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#tests [Flutter Style Guide]: https://github.com/flutter/flutter/blob/main/docs/contributing/Style-guide-for-Flutter-repo.md [Features we expect every widget to implement]: https://github.com/flutter/flutter/blob/main/docs/contributing/Style-guide-for-Flutter-repo.md#features-we-expect-every-widget-to-implement [CLA]: https://cla.developers.google.com/ [flutter/tests]: https://github.com/flutter/tests [breaking change policy]: https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#handling-breaking-changes [Discord]: https://github.com/flutter/flutter/blob/main/docs/contributing/Chat.md [Data Driven Fixes]: https://github.com/flutter/flutter/blob/main/docs/contributing/Data-driven-Fixes.md --------- Co-authored-by: anuj.kumar <[email protected]>

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WidgetsApp: Changing supportedLocales fails to update the locale #117210

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Fix supportedLocales not updating resolved locale #178583

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anuj.kumar added 7 commits November 25, 2025 10:11

fix: fixed changing supportedLocales fails to update the locale

e808986

chore: fixed linting issue in test file

5d15a02

chore: Refactor didChangeLocales to improve locale resolution and lis…

5878d88

…tener notification

chore: format localizations test file

cd972b4

chore: added check for resolve locals only when supportedLocales is u…

84a0f7b

…pdated

perf: trigger localization update only when necessary in app.dart

21a9c3c

pref: added checks around supportedLocals to prevent unneccery update

efcd6f6

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Roll Flutter from 7b98d50631e5 to 022b155d1b76 (20 revisions) flutter/packages#10530

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96550423a Fixed changing supportedLocales fails to update the locale (f…

e6189b8

…lutter/flutter#178526)

		_supportedLocales = supportedLocales;
		_updateResolvedLocale(WidgetsBinding.instance.platformDispatcher.locales);

Fixed changing supportedLocales fails to update the locale #178526

Fixed changing supportedLocales fails to update the locale #178526

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