|  | 
          When available, Asio can use the std::error_code
          and std::system_error classes for reporting errors.
          In this case, the names asio::error_code
          and asio::system_error will be typedefs for these
          standard classes.
        
          System error support is automatically enabled for g++
          4.6 and later, when the -std=c++0x or -std=gnu++0x
          compiler options are used. It may be disabled by defining ASIO_DISABLE_STD_SYSTEM_ERROR, or explicitly
          enabled for other compilers by defining ASIO_HAS_STD_SYSTEM_ERROR.