// be a placeholder for a receiver type parameter. In this case we can
			// resolve its type and object from Checker.recvTParamMap.
			if tpar := check.recvTParamMap[e]; tpar != nil {
				x.mode = typexpr
				x.typ = tpar
			} else {
				check.error(e, InvalidBlank, "cannot use _ as value or type")
			}
		} else {
			check.errorf(e, UndeclaredName, "undefined: %s", e.Value)
		}
		return

			// be a placeholder for a receiver type parameter. In this case we can
			// resolve its type and object from Checker.recvTParamMap.
			if tpar := check.recvTParamMap[e]; tpar != nil {
				x.mode = typexpr
				x.typ = tpar
			} else {
				check.error(e, InvalidBlank, "cannot use _ as value or type")
			}
		} else {
			check.errorf(e, UndeclaredName, "undefined: %s", e.Name)
		}
		return
	case universeComparable:

		case builtin:
			expr = predeclaredFuncs[x.id].name
		case typexpr:
			expr = TypeString(x.typ, qf)
		case constant_:
			expr = x.val.String()
		}
	}

	// <expr> (
	if expr != "" {
		buf.WriteString(expr)
		buf.WriteString(" (")
	}

	// <untyped kind>
	hasType := false
	switch x.mode {
	case invalid, novalue, builtin, typexpr:
		// no type
	default:

		case builtin:
			expr = predeclaredFuncs[x.id].name
		case typexpr:
			expr = TypeString(x.typ, qf)
		case constant_:
			expr = x.val.String()
		}
	}

	// <expr> (
	if expr != "" {
		buf.WriteString(expr)
		buf.WriteString(" (")
	}

	// <untyped kind>
	hasType := false
	switch x.mode {
	case invalid, novalue, builtin, typexpr:
		// no type
	default:

	} else {
		check.exprOrType(x, call.Fun, true)
	}
	// x.typ may be generic

	switch x.mode {
	case invalid:
		check.use(call.ArgList...)
		x.expr = call
		return statement

	case typexpr:
		// conversion
		check.nonGeneric(nil, x)
		if x.mode == invalid {
			return conversion
		}
		T := x.typ
		x.mode = invalid
		switch n := len(call.ArgList); n {
		case 0:

	} else {
		check.exprOrType(x, call.Fun, true)
	}
	// x.typ may be generic

	switch x.mode {
	case invalid:
		check.use(call.Args...)
		x.expr = call
		return statement

	case typexpr:
		// conversion
		check.nonGeneric(nil, x)
		if x.mode == invalid {
			return conversion
		}
		T := x.typ
		x.mode = invalid
		switch n := len(call.Args); n {
		case 0:

	// 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