131         bool $rootIsWildcard,  argument
140             return self::mergeSingletons($a, $b, $rootIsWildcard, $mergeCache);
145         if ($rootIsWildcard) {
168         return self::mergeArrays($a, $b, $rootIsWildcard, $mergeCache);
190      * @param bool                       $rootIsWildcard `true` if this is a local-context merge,
196         bool $rootIsWildcard,  argument
213         $rootMerge = self::mergeRoot($a, $b, $rootIsWildcard);
228             $parent = self::merge($a->parent, $b->parent, $rootIsWildcard, $mergeCache);
344         bool $rootIsWildcard  argument
346         if ($rootIsWildcard) {
406         bool $rootIsWildcard,  argument
455                     $mergedParent = self::merge($a_parent, $b_parent, $rootIsWildcard, $mergeCache);