check.rawExpr(T, x, e, nil, false)
	check.exclude(x, 1<<novalue|1<<builtin|1<<typexpr)
	check.singleValue(x)
}

// genericExpr is like expr but the result may also be generic.
func (check *Checker) genericExpr(x *operand, e syntax.Expr) {
	check.rawExpr(nil, x, e, nil, true)
	check.exclude(x, 1<<novalue|1<<builtin|1<<typexpr)
	check.singleValue(x)
}

	// x may be generic

	switch x.mode {
	case invalid:
		check.use(e.Index)
		return false

	case typexpr:
		// type instantiation
		x.mode = invalid
		// TODO(gri) here we re-evaluate e.X - try to avoid this
		x.typ = check.varType(e)
		if isValid(x.typ) {
			x.mode = typexpr
		}
		return false

	case value:
		if sig, _ := under(x.typ).(*Signature); sig != nil && sig.TypeParams().Len() > 0 {

	// x may be generic

	switch x.mode {
	case invalid:
		check.use(e.Indices...)
		return false

	case typexpr:
		// type instantiation
		x.mode = invalid
		// TODO(gri) here we re-evaluate e.X - try to avoid this
		x.typ = check.varType(e.Orig)
		if isValid(x.typ) {
			x.mode = typexpr
		}
		return false

	case value:
		if sig, _ := under(x.typ).(*Signature); sig != nil && sig.TypeParams().Len() > 0 {

	// record the type for ...T.
	if variadic {
		last := params[len(params)-1]
		last.typ = &Slice{elem: last.typ}
		check.recordTypeAndValue(list[len(list)-1].Type, typexpr, last.typ, nil)
	}

	return

	// record the type for ...T.
	if variadic {
		last := params[len(params)-1]
		last.typ = &Slice{elem: last.typ}
		check.recordTypeAndValue(list.List[len(list.List)-1].Type, typexpr, last.typ, nil)
	}

	return

func (tv TypeAndValue) IsVoid() bool {
	return tv.mode == novalue
}

// IsType reports whether the corresponding expression specifies a type.
func (tv TypeAndValue) IsType() bool {
	return tv.mode == typexpr
}

// IsBuiltin reports whether the corresponding expression denotes
// a (possibly parenthesized) built-in function.
func (tv TypeAndValue) IsBuiltin() bool {
	return tv.mode == builtin
}

func (tv TypeAndValue) IsVoid() bool {
	return tv.mode == novalue
}

// IsType reports whether the corresponding expression specifies a type.
func (tv TypeAndValue) IsType() bool {
	return tv.mode == typexpr
}

// IsBuiltin reports whether the corresponding expression denotes
// a (possibly parenthesized) built-in function.
func (tv TypeAndValue) IsBuiltin() bool {
	return tv.mode == builtin
}

		if i > 0 {
			s += "->"
		}
		s += p.Name()
	}
	return s
}

// objDecl type-checks the declaration of obj in its respective (file) environment.
// For the meaning of def, see Checker.definedType, in typexpr.go.
func (check *Checker) objDecl(obj Object, def *TypeName) {
	if check.conf.Trace && obj.Type() == nil {
		if check.indent == 0 {
			fmt.Println() // empty line between top-level objects for readability
		}

		switch x.mode {
		default:
			if kind == statement {
				return
			}
			msg = "is not used"
			code = UnusedExpr
		case builtin:
			msg = "must be called"
			code = UncalledBuiltin
		case typexpr:
			msg = "is not an expression"
			code = NotAnExpr
		}
		check.errorf(&x, code, "%s %s", &x, msg)

	case *syntax.SendStmt:
		var ch, val operand
		check.expr(nil, &ch, s.Chan)

		if i > 0 {
			s += "->"
		}
		s += p.Name()
	}
	return s
}

// objDecl type-checks the declaration of obj in its respective (file) environment.
// For the meaning of def, see Checker.definedType, in typexpr.go.
func (check *Checker) objDecl(obj Object, def *TypeName) {
	if check.conf._Trace && obj.Type() == nil {
		if check.indent == 0 {
			fmt.Println() // empty line between top-level objects for readability
		}