Ticket #32144: 32144.diff

src/wp-includes/taxonomy.php

@@ -3926 +3926 @@
  * @param string $taxonomy  The taxonomy which determines the hierarchy of the terms.
  * @param array  $ancestors Term ancestors that have already been identified. Passed by reference, to keep track of
  *                          found terms when recursing the hierarchy. The array of located ancestors is used to prevent
- *                          infinite recursion loops.
+ *                          infinite recursion loops. For performance, term_ids are used as array keys, with 1 as value.
  * @return array The subset of $terms that are descendants of $term_id.
  */
 function _get_term_children( $term_id, $terms, $taxonomy, &$ancestors = array() ) {
@@ -3942 +3942 @@
 
         // Include the term itself in the ancestors array, so we can properly detect when a loop has occurred.
         if ( empty( $ancestors ) ) {
-                $ancestors[] = $term_id;
+                $ancestors[ $term_id ] = 1;
         }
 
         foreach ( (array) $terms as $term ) {
@@ -3955 +3955 @@
                 }
 
                 // Don't recurse if we've already identified the term as a child - this indicates a loop.
-                if ( in_array( $term->term_id, $ancestors ) ) {
+                if ( isset( $ancestors[ $term->term_id ] ) ) {
                         continue;
                 }
 
@@ -3968 +3968 @@
                         if ( !isset($has_children[$term->term_id]) )
                                 continue;
 
-                        if ( $use_id ) {
-                                $ancestors = array_merge( $ancestors, $term_list );
-                        } else {
-                                $ancestors = array_merge( $ancestors, wp_list_pluck( $term_list, 'term_id' ) );
-                        }
+                        $ancestors[ $term->term_id ] = 1;;
 
                         if ( $children = _get_term_children( $term->term_id, $terms, $taxonomy, $ancestors) )
                                 $term_list = array_merge($term_list, $children);