Ticket #19631: 19631.patch

src/wp-includes/query.php

@@ -2183 +2183 @@
                  */
                 do_action_ref_array( 'pre_get_posts', array( &$this ) );
 
+                if ( ! is_admin() && $this->is_main_query() ) {
+                        /**
+                         * Fires after the query variable object is created, but before the actual query is run.
+                         *
+                         * Note: If using conditional tags, use the method versions within the passed instance
+                         * (e.g. $this->is_main_query() instead of is_main_query()). This is because the functions
+                         * like is_main_query() test against the global $wp_query instance, not the passed one.
+                         *
+                         * @since 4.0.0
+                         *
+                         * @param WP_Query &$this The WP_Query instance (passed by reference).
+                         */
+                        do_action_ref_array( 'pre_main_query', array( &$this ) );
+                }
+
                 // Shorthand.
                 $q = &$this->query_vars;