30 Thread support library [thread]

30.6 Futures [futures]

30.6.3 Class future_error [futures.future_error]

namespace std {
  class future_error : public logic_error {
  public:
    explicit future_error(future_errc e);

    const error_code& code() const noexcept;
    const char*       what() const noexcept;
  private:
    error_code ec_;  // exposition only
  };
}

explicit future_error(future_errc e);

1

Effects: Constructs an object of class future_error and initializes ec_ with make_error_code(e).

const error_code& code() const noexcept;

2

Returns: ec_.

const char* what() const noexcept;

3

Returns: An ntbs incorporating code().message().