@[heap]
struct Package {
    str string
}

interface Parser {
    main &Package
}

struct ParserV1 {
mut:
    main &Package
}

fn new_0_parser() ?ParserV1 {
    return ParserV1{
        main: &Package{
            str: 'test'
        }
    }
}

fn new_parser() ?Parser {
    return Parser(new_0_parser()?)
}

struct Engine {
    parser Parser
}

fn test_cast_option_to_interface() {
    parser := new_parser()?
    assert parser.main.str == 'test'
    eprintln(voidptr(parser.main))
    e := Engine{
        parser: parser
    }
    assert e.parser.main.str == 'test'
    eprintln(voidptr(e.parser.main))
}