key := p.parseType()
	p.expect(token.RBRACK)
	value := p.parseType()

	return &ast.MapType{Map: pos, Key: key, Value: value}
}

func (p *parser) parseChanType() *ast.ChanType {
	if p.trace {
		defer un(trace(p, "ChanType"))
	}

	pos := p.pos
	dir := ast.SEND | ast.RECV
	var arrow token.Pos
	if p.tok == token.CHAN {
		p.next()
		if p.tok == token.ARROW {
			arrow = p.pos

		// the channel type parsed already:
		//
		//   <-(chan E)   =>  (<-chan E)
		//   <-(chan<-E)  =>  (<-chan (<-E))

		if _, ok := x.(*ChanType); ok {
			// x is a channel type => re-associate <-
			dir := SendOnly
			t := x
			for dir == SendOnly {
				c, ok := t.(*ChanType)
				if !ok {
					break
				}
				dir = c.Dir
				if dir == RecvOnly {
					// t is type <-chan E but <-<-chan E is not permitted

	p.expect(token.LBRACK)
	key := p.parseType()
	p.expect(token.RBRACK)
	value := p.parseType()

	return &ast.MapType{pos, key, value}
}

func (p *parser) parseChanType() *ast.ChanType {
	if p.trace {
		defer un(trace(p, "ChanType"))
	}

	pos := p.pos
	dir := ast.SEND | ast.RECV
	if p.tok == token.CHAN {
		p.next()
		if p.tok == token.ARROW {
			p.next()
			dir = ast.SEND
		}
	} else {

	BothDir = RecvDir | SendDir             // chan
)

// arrayType represents a fixed array type.
type arrayType = abi.ArrayType

// chanType represents a channel type.
type chanType = abi.ChanType

// funcType represents a function type.
//
// A *rtype for each in and out parameter is stored in an array that
// directly follows the funcType (and possibly its uncommonType). So

}

// Chan contains Type fields specific to channel types.
type Chan struct {
	Elem *Type   // element type
	Dir  ChanDir // channel direction
}

// chanType returns t's extra channel-specific fields.
func (t *Type) chanType() *Chan {
	t.wantEtype(TCHAN)
	return t.extra.(*Chan)
}

type Tuple struct {
	first  *Type
	second *Type

func isTypeElem(x ast.Expr) bool {
	switch x := x.(type) {
	case *ast.ArrayType, *ast.StructType, *ast.FuncType, *ast.InterfaceType, *ast.MapType, *ast.ChanType:
		return true
	case *ast.UnaryExpr:
		return x.Op == token.TILDE
	case *ast.BinaryExpr:
		return isTypeElem(x.X) || isTypeElem(x.Y)
	case *ast.ParenExpr:
		return isTypeElem(x.X)
	}
	return false

		*ast.IndexExpr,
		*ast.SliceExpr,
		*ast.TypeAssertExpr,
		*ast.StarExpr,
		*ast.KeyValueExpr,
		*ast.ArrayType,
		*ast.StructType,
		*ast.FuncType,
		*ast.InterfaceType,
		*ast.MapType,
		*ast.ChanType:
		// These expression are never untyped - nothing to do.
		// The respective sub-expressions got their final types
		// upon assignment or use.
		if debug {

		*syntax.ListExpr,
		//*syntax.StarExpr,
		*syntax.KeyValueExpr,
		*syntax.ArrayType,
		*syntax.StructType,
		*syntax.FuncType,
		*syntax.InterfaceType,
		*syntax.MapType,
		*syntax.ChanType:
		// These expression are never untyped - nothing to do.
		// The respective sub-expressions got their final types
		// upon assignment or use.
		if debug {

		// type that contains a pointer.
		if unionWithPointer[t.X] {
			return true
		}
		return p.hasPointer(f, t.X, false)
	case *ast.FuncType, *ast.InterfaceType, *ast.MapType, *ast.ChanType:
		return true
	case *ast.Ident:
		// TODO: Handle types defined within function.
		for _, d := range p.Decl {
			gd, ok := d.(*ast.GenDecl)
			if !ok || gd.Tok != token.TYPE {
				continue
			}

	}

	// Needed by the prettyprinter code for interface inspection.
	for _, typ := range []string{
		"type:internal/abi.Type",
		"type:internal/abi.ArrayType",
		"type:internal/abi.ChanType",
		"type:internal/abi.FuncType",
		"type:internal/abi.MapType",
		"type:internal/abi.PtrType",
		"type:internal/abi.SliceType",
		"type:internal/abi.StructType",
		"type:internal/abi.InterfaceType",