wp-includes/nav-menu.php:1334Prevents menu items from being their own parent.
arrayfunction _wp_reset_invalid_menu_item_parent( $menu_item_data ) { if ( ! is_array( $menu_item_data ) ) { return $menu_item_data; } if ( ! empty( $menu_item_data['ID'] ) && ! empty( $menu_item_data['menu_item_parent'] ) && (int) $menu_item_data['ID'] === (int) $menu_item_data['menu_item_parent'] ) { $menu_item_data['menu_item_parent'] = 0; } return $menu_item_data;}Introduced in 6.2.0. Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-includes/nav-menu.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.