TYPO3 Core

Following commit (https://review.typo3.org/#/c/23032/ - Ticket: http://forge.typo3.org/issues/51007) leads to defective behaivor in \TYPO3\CMS\Core\Utility\GeneralUtility::array_merge_recursive_overrule().

If you access TYPO3\CMS\Backend\UtilityBackendUtility::getModTSconfig() with a tsconfig string which only exists in pageTSConfig and not in userTSConfig, pageTSConfig value will be overruled by undefined userTSConfig setting.

This is reasoned by the changed default return value in TYPO3\CMS\Core\Utility\GeneralUtility\BackendUserAuthentication->getTSConfig() for undefined TSConfig settings. If there is no userTSConfig defined for given setting it will return

array('value' => NULL, 'properties' => NULL);

Subsequently the function TYPO3\CMS\Core\Utility\GeneralUtility::array_merge_recursive_overrule() merges userTSconfig and pageTSconfig wrong because of given value/properties array for undefined tsconfig setting. Actual value of pageTSconfig will be overruled by NULL value of userTSconfig.

I am not sure how a proper fix would look like. Reverting the change of http://forge.typo3.org/issues/51007 and updating doctype comment? Call array_merge_recursive_overrule in getModTSconfig with includeEmptyValues = false?