Ticket #20604: tax-query-no-results-on-or.diff

wp-includes/taxonomy.php

@@ -658 +658 @@
                 $join = '';
                 $where = array();
                 $i = 0;
+                $count = count( $this->queries );
 
-                foreach ( $this->queries as $query ) {
+                foreach ( $this->queries as $index => $query ) {
                         $this->clean_query( $query );
 
                         if ( is_wp_error( $query ) ) {
@@ -671 +672 @@
                         if ( 'IN' == $operator ) {
 
                                 if ( empty( $terms ) ) {
-                                        if ( 'OR' == $this->relation )
+                                        if ( 'OR' == $this->relation ) {
+                                                if ( $index + 1 === $count && empty( $where ) )
+                                                        return self::$no_results;
                                                 continue;
-                                        else
+                                        } else
                                                 return self::$no_results;
                                 }