struct FixedStruct1 {
    a int
    b ?int
    c ?int = 4
}

// struct FixedStruct2 {
//     b ?int
// }

struct Encoder {}

struct Writer {}

fn write1[T](val T) {
    println(val)
}

fn (wr &Writer) write2[T](val T) {
    println(val)
}

fn encode_struct[T](val T) map[string][]string {
    wr := Writer{}
    mut out := map[string][]string{}
    $if T is $struct {
        $for field in T.fields {
            out[field.name] = []string{}
            value := val.$(field.name)
            $if field.typ is ?int {
                // work if comment lines 27 and 28
                write1(value)
                wr.write2(value)
                out[field.name] << '${value:d}'
            } $else {
                write1(value)
                wr.write2(value)
                out[field.name] << value.str()
            }
            // This work well
            $if field.is_option {
                write1(value)
                wr.write2(value)
                out[field.name] << '${value:d}'
            } $else {
                write1(value)
                wr.write2(value)
                out[field.name] << value.str()
            }
        }
    }
    return out
}

fn test_main() {
    // cgen error: cannot convert 'struct _option_int' to 'int'
    out := encode_struct(FixedStruct1{})
    assert out['a'] == ['0', '0']
    assert out['b'] == ['0', '0']
    assert out['c'] == ['4', '4']
}