}
			return n.Pos()
		case *KeyValueExpr:
			m = n.Key
		// case *FuncLit:
		// case *ParenExpr:
		case *SelectorExpr:
			m = n.X
		case *IndexExpr:
			m = n.X
		// case *SliceExpr:
		case *AssertExpr:
			m = n.X
		case *TypeSwitchGuard:
			if n.Lhs != nil {
				m = n.Lhs
				continue
			}
			m = n.X
		case *Operation:
			if n.Y != nil {
				m = n.X
				continue
			}
			return n.Pos()

	case *IndexExpr:
		w.node(n.X)
		w.node(n.Index)

	case *SliceExpr:
		w.node(n.X)
		for _, x := range n.Index {
			if x != nil {
				w.node(x)
			}
		}

	case *AssertExpr:
		w.node(n.X)
		w.node(n.Type)

	case *TypeSwitchGuard:
		if n.Lhs != nil {
			w.node(n.Lhs)
		}
		w.node(n.X)

	case *Operation:
		w.node(n.X)
		if n.Y != nil {
			w.node(n.Y)

	{"SelectorExpr", `a@.b`},
	{"IndexExpr", `a@[i]`},

	{"SliceExpr", `a@[:]`},
	{"SliceExpr", `a@[i:]`},
	{"SliceExpr", `a@[:j]`},
	{"SliceExpr", `a@[i:j]`},
	{"SliceExpr", `a@[i:j:k]`},

	{"AssertExpr", `x@.(T)`},

	{"Operation", `@*b`},
	{"Operation", `@+b`},
	{"Operation", `@-b`},
	{"Operation", `@!b`},
	{"Operation", `@^b`},
	{"Operation", `@&b`},
	{"Operation", `@<-b`},

		// TODO(mdempsky): This is only needed to report the "3-index
		// slice of string" error when Index[2] is missing.
		Full bool
		expr
	}

	// X.(Type)
	AssertExpr struct {
		X    Expr
		Type Expr
		expr
	}

	// X.(type)
	// Lhs := X.(type)
	TypeSwitchGuard struct {
		Lhs *Name // nil means no Lhs :=
		X   Expr  // X.(type)
		expr
	}

		check.sliceExpr(x, e)
		if x.mode == invalid {
			goto Error
		}

	case *syntax.AssertExpr:
		check.expr(nil, x, e.X)
		if x.mode == invalid {
			goto Error
		}
		// x.(type) expressions are encoded via TypeSwitchGuards
		if e.Type == nil {
			check.error(e, InvalidSyntaxTree, "invalid use of AssertExpr")
			goto Error
		}
		if isTypeParam(x.typ) {

			p.printNode(i)
		}
		p.print(_Colon)
		if j := n.Index[1]; j != nil {
			p.printNode(j)
		}
		if k := n.Index[2]; k != nil {
			p.print(_Colon, k)
		}
		p.print(_Rbrack)

	case *AssertExpr:
		p.print(n.X, _Dot, _Lparen, n.Type, _Rparen)

	case *TypeSwitchGuard:
		if n.Lhs != nil {
			p.print(n.Lhs, blank, _Define, blank)
		}
		p.print(n.X, _Dot, _Lparen, _Type, _Rparen)

				p.next()
				if p.got(_Type) {
					t := new(TypeSwitchGuard)
					// t.Lhs is filled in by parser.simpleStmt
					t.pos = pos
					t.X = x
					x = t
				} else {
					t := new(AssertExpr)
					t.pos = pos
					t.X = x
					t.Type = p.type_()
					x = t
				}
				p.want(_Rparen)

			default:
				p.syntaxError("expected name or (")
				p.advance(_Semi, _Rparen)