Why do you want to remove the deprecation?

Because we are using it still in core and don't have a solution to not use it anymore. Yes, namespaces and auto-loading are the future, but there are situations where people need to override that and for those cases we still need this.

Places where we use JLoader::register in the core:

F:\Users\Richard\Documents\GitHub\joomla-cms>findstr /s /c:"JLoader::register(" *.php
administrator\components\com_actionlogs\src\Helper\ActionlogsHelper.php:            \JLoader::register($cName, $file);
administrator\components\com_categories\src\Model\CategoriesModel.php:        \JLoader::register($hname, JPATH_SITE . '/components/' . $component . '/helpers/association.php');
administrator\components\com_categories\src\Model\CategoryModel.php:                \JLoader::register($cName, $path);
administrator\components\com_categories\src\Model\CategoryModel.php:        \JLoader::register($hname, JPATH_SITE . '/components/' . $component . '/helpers/association.php');
administrator\components\com_installer\src\Model\DatabaseModel.php:\JLoader::register('JoomlaInstallerScript', JPATH_ADMINISTRATOR . '/components/com_admin/script.php');
administrator\components\com_joomlaupdate\src\Model\UpdateModel.php:        \JLoader::register('JoomlaInstallerScript', JPATH_ADMINISTRATOR . '/components/com_admin/script.php');
build\phpstan\joomla-bootstrap.php:JLoader::register('JNamespacePsr4Map', JPATH_LIBRARIES . '/namespacemap.php');
components\com_ajax\ajax.php:            JLoader::register($class, $helperFile);
components\com_ajax\ajax.php:            JLoader::register($class, $helperFile);
components\com_tags\src\Helper\RouteHelper.php:            \JLoader::register($explodedRouter[0], $routerFile);
libraries\bootstrap.php:JLoader::register('Crypto', JPATH_LIBRARIES . '/php-encryption/Crypto.php');
libraries\bootstrap.php:JLoader::register('PasswordHash', JPATH_LIBRARIES . '/phpass/PasswordHash.php');
libraries\cms.php:JLoader::register('Crypto', JPATH_LIBRARIES . '/php-encryption/Crypto.php');
libraries\import.legacy.php:JLoader::register('PasswordHash', JPATH_LIBRARIES . '/phpass/PasswordHash.php');
libraries\import.php:JLoader::register('PasswordHash', JPATH_LIBRARIES . '/phpass/PasswordHash.php');
libraries\src\Adapter\Adapter.php:        \JLoader::register($class, $fullpath);
libraries\src\Application\ExtensionNamespaceMapper.php:        \JLoader::register('JNamespacePsr4Map', JPATH_LIBRARIES . '/namespacemap.php');
libraries\src\Cache\CacheController.php:                    \JLoader::register($class, $path);
libraries\src\Cache\CacheStorage.php:            \JLoader::register($class, $path);
libraries\src\Console\RemoveOldFilesCommand.php:        \JLoader::register('JoomlaInstallerScript', JPATH_ADMINISTRATOR . '/components/com_admin/script.php');
libraries\src\Extension\LegacyComponent.php:        \JLoader::register($className, $file);
libraries\src\HTML\HTMLHelper.php:            \JLoader::register($className, $path);
libraries\src\HTML\HTMLHelper.php:                \JLoader::register($className, $path);
libraries\src\Installer\Installer.php:                \JLoader::register($class, $this->_basepath . '/' . $this->_adapterfolder . '/' . $fileName);
libraries\src\Installer\InstallerAdapter.php:            \JLoader::register($classname, $manifestScriptFile);
libraries\src\MVC\Factory\LegacyFactory.php:            \JLoader::register($viewClass, $path);
libraries\src\MVC\View\ListView.php:        \JLoader::register($helperClass, JPATH_COMPONENT . '/helpers/' . $componentName . '.php');
libraries\src\Service\Provider\Config.php:                    \JLoader::register('JConfig', JPATH_CONFIGURATION . '/configuration.php');
modules\mod_languages\src\Helper\LanguagesHelper.php:                \JLoader::register($class, JPATH_SITE . '/components/' . $option . '/helpers/association.php');
plugins\finder\categories\src\Extension\Categories.php:        \JLoader::register($class, JPATH_SITE . '/components/' . $extension_element . '/helpers/route.php');
plugins\system\languagefilter\src\Extension\LanguageFilter.php:                \JLoader::register($cName, Path::clean(JPATH_SITE . '/components/' . $option . '/helpers/association.php'));

F:\Users\Richard\Documents\GitHub\joomla-cms>

I agree with Hannes, I don't see it as realistic that we can change all that in the next few weeks or months so we can remove the method in 6.0 as the deprecation method says.

So either we go the way of this PR here, or we at least change the 6.0 in the deprecation message to at least 7.0.

Most of the places where we use this function is either left for backwards compatibility or in deprecated functions. So this deprecation should be left in place and changed to 7.0. But please do not send a wrong signal and support a feature which was ok in PHP 4, but not nowadays.

Most of the places where we use this function is either left for backwards compatibility or in deprecated functions. So this deprecation should be left in place and changed to 7.0. But please do not send a wrong signal and support a feature which was ok in PHP 4, but not nowadays.

I agree, we should not remove the deprecation but change it to 7.

@Hackwar Could you do that? If done, I could merge by review. Thanks in advance.