Ticket #24461: 24461.patch

src/wp-includes/taxonomy.php

@@ -3818 +3818 @@
  * @param string $taxonomy The taxonomy which determines the hierarchy of the terms.
  * @return array The subset of $terms that are descendants of $term_id.
  */
-function _get_term_children($term_id, $terms, $taxonomy) {
+function _get_term_children( $term_id, $terms, $taxonomy, &$ancestors = array() ) {
         $empty_array = array();
         if ( empty($terms) )
                 return $empty_array;
@@ -3829 +3829 @@
         if  ( ( 0 != $term_id ) && ! isset($has_children[$term_id]) )
                 return $empty_array;
 
+        // We check $ancestors to avoid recursion, so we need to be sure the term itself is listed.
+        if ( empty( $ancestors ) ) {
+                $ancestors[] = $term_id;
+        }
+
         foreach ( (array) $terms as $term ) {
                 $use_id = false;
                 if ( !is_object($term) ) {
@@ -3838 +3843 @@
                         $use_id = true;
                 }
 
-                if ( $term->term_id == $term_id ) {
+                // Don't recurse if we've already identified the term as a child - this indicates a loop.
+                if ( in_array( $term->term_id, $ancestors ) ) {
                         continue;
                 }
 
@@ -3851 +3857 @@
                         if ( !isset($has_children[$term->term_id]) )
                                 continue;
 
-                        if ( $children = _get_term_children($term->term_id, $terms, $taxonomy) )
+                        if ( $use_id ) {
+                                $ancestors = array_merge( $ancestors, $term_list );
+                        } else {
+                                $ancestors = array_merge( $ancestors, wp_list_pluck( $term_list, 'term_id' ) );
+                        }
+
+                        if ( $children = _get_term_children( $term->term_id, $terms, $taxonomy, $ancestors) )
                                 $term_list = array_merge($term_list, $children);
                 }
         }

tests/phpunit/tests/term/getTerms.php

@@ -394 +394 @@
                 add_filter( 'wp_update_term_parent', 'wp_check_term_hierarchy_for_loops', 10, 3 );
         }
 
+        /**
+         * @covers ::_get_term_children
+         * @ticket 24461
+         */
+        public function test__get_term_children_handles_cycles() {
+                remove_filter( 'wp_update_term_parent', 'wp_check_term_hierarchy_for_loops', 10 );
+
+                $c1 = $this->factory->category->create();
+                $c2 = $this->factory->category->create( array( 'parent' => $c1 ) );
+                $c3 = $this->factory->category->create( array( 'parent' => $c2 ) );
+                wp_update_term( $c1, 'category', array( 'parent' => $c3 ) );
+
+                add_filter( 'wp_update_term_parent', 'wp_check_term_hierarchy_for_loops', 10, 3 );
+
+                $result = _get_term_children( $c1, array( $c1, $c2, $c3 ), 'category' );
+
+                $this->assertEqualSets( array( $c2, $c3 ), $result );
+        }
+
+        /**
+         * @covers ::_get_term_children
+         * @ticket 24461
+         */
+        public function test__get_term_children_handles_cycles_when_terms_argument_contains_objects() {
+                remove_filter( 'wp_update_term_parent', 'wp_check_term_hierarchy_for_loops', 10 );
+
+                $c1 = $this->factory->category->create_and_get();
+                $c2 = $this->factory->category->create_and_get( array( 'parent' => $c1->term_id ) );
+                $c3 = $this->factory->category->create_and_get( array( 'parent' => $c2->term_id ) );
+                wp_update_term( $c1->term_id, 'category', array( 'parent' => $c3->term_id ) );
+
+                add_filter( 'wp_update_term_parent', 'wp_check_term_hierarchy_for_loops', 10, 3 );
+
+                $result = _get_term_children( $c1->term_id, array( $c1, $c2, $c3 ), 'category' );
+
+                $this->assertEqualSets( array( $c2, $c3 ), $result );
+        }
+
         public function test_get_terms_by_slug() {
                 $t1 = $this->factory->tag->create( array( 'slug' => 'foo' ) );
                 $t2 = $this->factory->tag->create( array( 'slug' => 'bar' ) );