Wordpress Rewrite stops working on php 7.2

Question

Can someone help me? This rewrite rule works on PHP 5.6, but no longer works on PHP 7.2 for odd reason. No PHP errors whatsoever its just white blank space.

Currently using Wordpress 5.1 as well.

/* adds the post name and the post id to the permalink structure of a listing */
function listing_rewrite() {
    global $wp_rewrite;
    $queryarg = 'post_type=listing&p=';
    $wp_rewrite->add_rewrite_tag('%list_id%', '([^/]+)', $queryarg);
    $wp_rewrite->add_permastruct('listing', '/%postname%-L%list_id%/', false);
}


/* add the post name and the post id to the url for a listing */
function listing_permalink($post_link, $id = 0, $leavename, $sample) {
    global $wp_rewrite;
    if (get_post_type($id) == "listing") {
        $post = &get_post($id);
        if ( is_wp_error( $post ) )
            return $post;
        $newlink = $wp_rewrite->get_extra_permastruct('listing');
        $newlink = str_replace("%list_id%", $post->ID, $newlink);
        $newlink = str_replace("%postname%", $post->post_name, $newlink);
        $newlink = home_url(user_trailingslashit($newlink));
        return $newlink;
    }
    return $post_link;
}

/* rewrite the urls to remove 'listing' and add -L%post_id% at the end */
add_action('init', 'listing_rewrite');
add_filter('post_type_link', 'listing_permalink', 1, 20);

Answer 1

Try changing this line:

add_filter('post_type_link', 'listing_permalink', 1, 20);

to

add_filter('post_type_link', 'listing_permalink', 1, 4);

You are currently suggesting that the callback will accept 20 arguments when it will actually only accept 4. These are supposed to match. ( https://developer.wordpress.org/reference/functions/add_filter/ ).