Localized messages are generated into source, not a synthetic package.

The flutter tool will no longer generate a synthetic package:flutter_gen or modify the package_config.json of the application. Applications or tools that previously referenced package:flutter_gen will instead reference source files generated into the application directly.

flutter_gen is a virtual (synthetic) package that is created by the flutter command-line tool to allow developers to import that package to access generated symbols and functionality, such as for internationalization. As the package is not listed in an app's pubspec.yaml, and is created via re-writing the (generated) package_config.json, numerous problems have been created.

This change only effects users that have the following in their pubspec.yaml:

flutter:
  generate: true

A synthetic package (package:flutter_gen) is created and referenced by the application:

import 'package:flutter_gen/gen_l10n/app_localizations.dart';
// ...
const MaterialApp(
  title: 'Localizations Sample App',
  localizationsDelegates: AppLocalizations.localizationsDelegates,
  supportedLocales: AppLocalizations.supportedLocales,
);

There are two ways to migrate away from importing package:flutter_gen:

1. Specify synthetic-package: false in the accompanying l10n.yaml file:

   yaml

   synthetic-package: false
   
   # The files are generated into the path specified by `arb-dir`
   arb-dir: lib/i18n
   
   # Or, specifically provide an output path:
   output-dir: lib/src/generated/i18n

2. Enable the explicit-package-dependencies feature flag:

   sh

   flutter config explicit-package-dependencies

Not released

Not released + 1, package:flutter_gen support will be removed.

Relevant Issues:

• Issue 73870, where package:flutter_gen pub problems are first found.
• Issue 102983, where package:flutter_gen problems are outlined.
• Issue 157819, where --implicit-pubspec-resolution is discussed.

Relevant Articles:

• Internationalizing Flutter apps, the canonical documentation for the feature.

Unless stated otherwise, the documentation on this site reflects the latest stable version of Flutter. Page last updated on 2024-11-18. View source or report an issue.