dcp check recursion

dcp-check-recursion

} else {
    if(allow_recursion) {
        last_argument_is_file = true

        for(src in srcs) {
            if (is_dir(src)) {
                last_argument_is_file = false
            }
        }

        if( number_of_source_files != 1 && last_argument_is_file ) {
            error(impossible_condition)
        } else {
            last_argument_is_dir = !last_argument_is_file
        }
    } else {
        last_argument_is_file = true
    }