Ticket #13976: nav-menu-item-id-filter.13976.diff

wp-includes/nav-menu-template.php

@@ -75 +75 @@
                 $class_names = join( ' ', apply_filters( 'nav_menu_css_class', array_filter( $classes ), $item ) );
                 $class_names = ' class="' . esc_attr( $class_names ) . '"';
 
-                $output .= $indent . '<li id="menu-item-'. $item->ID . '"' . $value . $class_names .'>';
+                $output .= $indent . '<li id="' . apply_filters( 'nav_menu_item_id', 'menu-item-'. $item->ID, $item, $args ) . '"' . $value . $class_names .'>';
 
                 $attributes  = ! empty( $item->attr_title ) ? ' title="'  . esc_attr( $item->attr_title ) .'"' : '';
                 $attributes .= ! empty( $item->target )     ? ' target="' . esc_attr( $item->target     ) .'"' : '';