Redirect post/page IDs

function pm_deep_detect_permalinks() {
    global $wp, $wp_query;

    // Works only if 404 error is set before when the WP query is parsed
    if(empty($wp_query->query['do_not_redirect']) && is_numeric($wp->request)) {
        $post_id = (int) $wp->request;

        // Redirect to new permalink
        if($post_id) {
            $correct_permalink = get_permalink($post_id);
            wp_safe_redirect($correct_permalink, 301);
        }
    }
}
add_filter('template_redirect', 'pm_deep_detect_permalinks', 0);