// without breaking existing files.
	if nextId := len(idToTypeSlice); nextId > firstUserId {
		panic(fmt.Sprintln("nextId too large:", nextId))
	}
	idToTypeSlice = idToTypeSlice[:firstUserId]
	registerBasics()
	wireTypeUserInfo = userType(wireTypeType)
}

// Array type
type arrayType struct {
	CommonType
	Elem typeId
	Len  int
}

func newArrayType(name string) *arrayType {