Breaking: #107784 - Remove backend layout data provider registration via $GLOBALS 

Description 

The possibility to register backend layout data provider via $GLOBALS['TYPO3_CONF_VARS']['SC_OPTIONS']['BackendLayoutDataProvider'] has been replaced by autoconfiguration via the page_layout.data_provider service tag. The tag is automatically added based on the implemented DataProviderInterface. However, manual configuration in the Services.yaml is still possible, especially in case no autoconfiguration is enabled. Developers however need to adapt existing implementations by adding the new method getIdentifier(), as outlined in the appropriate feature description.

In addition, the possibility to dynamically add backend layout data providers to the global DataProviderCollection by using their add() method has been removed. Developers are advised to make data providers available in the service container as described above.

Impact 

Utilizing the $GLOBALS['TYPO3_CONF_VARS']['SC_OPTIONS']['BackendLayoutDataProvider'] array won't have any effect anymore in TYPO3 v14.0+.

Affected installations 

All installations where $GLOBALS['TYPO3_CONF_VARS']['SC_OPTIONS']['BackendLayoutDataProvider'] is used for backend layout data provider registration are affected. This registration is normally done in an ext_localconf.php file. The extension scanner will report any usages.

Migration 

Migrate existing registrations to the new autoconfigured-based approach.

Before:

use Vendor\MyExtension\View\BackendLayout\MyLayoutDataProvider;

$GLOBALS['TYPO3_CONF_VARS']['SC_OPTIONS']['BackendLayoutDataProvider']['my_provider']
    = MyLayoutDataProvider::class;

After:

use TYPO3\CMS\Backend\View\BackendLayout\DataProviderInterface;

final class MyLayoutDataProvider implements DataProviderInterface
{
    // ...

    public function getIdentifier(): string
    {
        return 'my_provider';
    }
}

If you need to support multiple TYPO3 Core versions at once, make sure to implement both registration methods (via $GLOBALS and using autoconfiguration). Make sure to implement the new method getIdentifier(), which is backwards compatible (even if not used in older TYPO3 versions).