Deprecation: #88569 - Locales::initialize() in favor of regular singleton instance

See Issue #88569

Description

The method TYPO3\CMS\Core\Localization\Locales::initialize() has been marked as deprecated. It was a workaround to re-initialize the Singleton Instance of the PHP class Locales for user-defined locales, which were loaded by an extensions’ ext_localconf.php.

Locales is now initialized only when needed, and not during the early bootstrap process, making this functionality obsolete, as this is taken care of within the regular constructor.

Impact

Calling TYPO3\CMS\Core\Localization\Locales::initialize() will trigger a PHP E_USER_DEPRECATED error.

Affected Installations

Any TYPO3 installation with a third-party extension calling Locales::initialize() directly.

Migration

Replace the function call by a regular GeneralUtility::makeInstance(Locales::class); or use Dependency Injection (Constructor Injection or ObjectManager) to fetch an instance of the Locales class.