const std::optional<ManagedStackTrace>& definition_stack_trace)
    : index_(index),
      name_(name),
      var_(var),
      definition_stack_trace_(definition_stack_trace) {}

VariableInfo::VariableInfo(VariableInfo&& other)
    : index_(other.index_),
      var_(other.var_),
      definition_stack_trace_(other.definition_stack_trace_),
      lock_held_(other.lock_held_) {
  other.index_ = -1;

  void set_read_only() { read_only_ = true; }

  const std::optional<ManagedStackTrace>& definition_stack_trace() const {
    return definition_stack_trace_;
  }

  ~VariableInfo();

 private:
  int index_;
  std::string name_;
  Var* var_;
  std::optional<ManagedStackTrace> definition_stack_trace_;

  // We can't use a optional<mutex_lock> here because it confuses the compiler's

    }
    ResourceHandle handle = inputs[var_idx]->flat<ResourceHandle>()(0);
    if (handle.device() != dev->attributes().name()) {
      std::string definition_location =
          DefinitionLocationMsg(handle.definition_stack_trace());
      return errors::InvalidArgument(
          "Trying to access resource ", handle.name(), definition_location,
          " located in device ", handle.device(), " from device ",
          dev->attributes().name(),