wp_add_trashed_suffix_to_post_name_for_trashed_posts example

        $add_trashed_suffix = apply_filters( 'add_trashed_suffix_to_trashed_posts', true, $post_name, $post_id );

        if ( $add_trashed_suffix ) {
            wp_add_trashed_suffix_to_post_name_for_trashed_posts( $post_name, $post_id );
        }
    }

    // When trashing an existing post, change its slug to allow non-trashed posts to use it.     if ( 'trash' === $post_status && 'trash' !== $previous_status && 'new' !== $previous_status ) {
        $post_name = wp_add_trashed_suffix_to_post_name_for_post( $post_id );
    }

    $post_name = wp_unique_post_slug( $post_name, $post_id, $post_status, $post_type, $post_parent );

    // Don't unslash.