panic("unreachable")
		}
		check.recordTypeAndValue(x, info.mode, info.typ, info.val)
	}
}

func (check *Checker) recordTypeAndValue(x syntax.Expr, mode operandMode, typ Type, val constant.Value) {
	assert(x != nil)
	assert(typ != nil)
	if mode == invalid {
		return // omit
	}
	if mode == constant_ {
		assert(val != nil)

		n := n.(*ParenExpr)
		fmt.Fprintf(s, "(%v)", n.X)

	case ONIL:
		fmt.Fprint(s, "nil")

	case OLITERAL:
		if n.Sym() != nil {
			fmt.Fprint(s, n.Sym())
			return
		}

		typ := n.Type()
		val := n.Val()

		// Special case for rune constants.
		if typ == types.RuneType || typ == types.UntypedRune {
			if x, ok := constant.Uint64Val(val); ok && x <= utf8.MaxRune {
				fmt.Fprintf(s, "%q", x)

func (*Ref) MarshalJSON() ([]byte, error) {
	return []byte(`"ref"`), nil
}

func (r *Ref) UnmarshalJSON([]byte) error {
	*r = 12
	return nil
}

// Val has Marshaler methods with value receiver.
type Val int

func (Val) MarshalJSON() ([]byte, error) {
	return []byte(`"val"`), nil
}

// RefText has Marshaler and Unmarshaler methods with pointer receiver.
type RefText int

					x.ITab = dt.ITab
					val = x
				} else if ir.IsNil(ncase.List[0]) {
				} else {
					base.Fatalf("unhandled type switch case %v", ncase.List[0])
				}
				val.SetType(caseVar.Type())
				val.SetTypecheck(1)
			}
			l := []ir.Node{
				ir.NewDecl(ncase.Pos(), ir.ODCL, caseVar),
				ir.NewAssignStmt(ncase.Pos(), caseVar, val),
			}
			typecheck.Stmts(l)
			sw.Compiled.Append(l...)
		}

		switch {
		case keepNull && val == nil:
			filteredMap[key] = nil
		case val != nil:
			switch typedVal := val.(type) {
			case map[string]interface{}:
				// Explicitly-set empty maps are treated as values instead of empty patches
				if len(typedVal) == 0 {
					if !keepNull {
						filteredMap[key] = typedVal
					}
					continue
				}

				var filteredSubMap map[string]interface{}

}

func (d Quantity) ConvertToType(typeVal ref.Type) ref.Val {
	switch typeVal {
	case quantityTypeValue:
		return d
	case types.TypeType:
		return quantityTypeValue
	default:
		return types.NewErr("type conversion error from '%s' to '%s'", quantityTypeValue, typeVal)
	}
}

func (d Quantity) Equal(other ref.Val) ref.Val {
	otherDur, ok := other.(Quantity)

	runtime.MapKeys(m, unsafe.Pointer(&keys))
	for _, k := range keys {
		if len(k.s) != 1 {
			t.Errorf("len(k.s) == %d, want 1", len(k.s))
		}
	}
}

func TestMapValues(t *testing.T) {
	type val struct {
		s   string
		pad [128]byte // sizeof(val) > abi.MapMaxElemBytes
	}
	m := map[int]val{1: {s: "a"}, 2: {s: "b"}}
	vals := make([]val, 0, len(m))
	runtime.MapValues(m, unsafe.Pointer(&vals))

}

// ConvertToType implements ref.Val.ConvertToType.
func (d IP) ConvertToType(typeVal ref.Type) ref.Val {
	switch typeVal {
	case IPType:
		return d
	case types.TypeType:
		return IPType
	case types.StringType:
		return types.String(d.Addr.String())
	}
	return types.NewErr("type conversion error from '%s' to '%s'", IPType, typeVal)
}

// Equal implements ref.Val.Equal.
func (d IP) Equal(other ref.Val) ref.Val {

	return nil, fmt.Errorf("type conversion error from 'Format' to '%v'", typeDesc)
}

func (d *Format) ConvertToType(typeVal ref.Type) ref.Val {
	switch typeVal {
	case FormatType:
		return d
	case types.TypeType:
		return FormatType
	default:
		return types.NewErr("type conversion error from '%s' to '%s'", FormatType, typeVal)
	}
}

func (d *Format) Equal(other ref.Val) ref.Val {
	otherDur, ok := other.(*Format)
	if !ok {

}

// ConvertToType implements ref.Val.ConvertToType.
func (d URL) ConvertToType(typeVal ref.Type) ref.Val {
	switch typeVal {
	case typeValue:
		return d
	case types.TypeType:
		return typeValue
	}
	return types.NewErr("type conversion error from '%s' to '%s'", typeValue, typeVal)
}

// Equal implements ref.Val.Equal.
func (d URL) Equal(other ref.Val) ref.Val {
	otherDur, ok := other.(URL)