case *parse.ChainNode:
		return s.validateType(s.evalChainNode(dot, arg, nil, missingVal), typ)
	}
	switch typ.Kind() {
	case reflect.Bool:
		return s.evalBool(typ, n)
	case reflect.Complex64, reflect.Complex128:
		return s.evalComplex(typ, n)
	case reflect.Float32, reflect.Float64:
		return s.evalFloat(typ, n)

func (c CodeVal) Marker() SyncMarker { return SyncVal }
func (c CodeVal) Value() int         { return int(c) }

// Note: These values are public and cannot be changed without
// updating the go/types importers.

const (
	ValBool CodeVal = iota
	ValString
	ValInt64
	ValBigInt
	ValBigRat
	ValBigFloat
)

// A CodeType distinguishes among go/types.Type encodings.
type CodeType int

		w.scalar(val)
	}
}

func (w *Encoder) scalar(val constant.Value) {
	switch v := constant.Val(val).(type) {
	default:
		errorf("unhandled %v (%v)", val, val.Kind())
	case bool:
		w.Code(ValBool)
		w.Bool(v)
	case string:
		w.Code(ValString)
		w.String(v)
	case int64:
		w.Code(ValInt64)
		w.Int64(v)
	case *big.Int:
		w.Code(ValBigInt)
		w.bigInt(v)
	case *big.Rat:

	}
	return val
}

func (r *Decoder) scalar() constant.Value {
	switch tag := CodeVal(r.Code(SyncVal)); tag {
	default:
		panic(fmt.Errorf("unexpected scalar tag: %v", tag))

	case ValBool:
		return constant.MakeBool(r.Bool())
	case ValString:
		return constant.MakeString(r.String())
	case ValInt64:
		return constant.MakeInt64(r.Int64())
	case ValBigInt:
		return constant.Make(r.bigInt())