error_code make_error_code(io_errc e) noexcept;
Returns: error_code(static_cast<int>(e), iostream_category()). error_condition make_error_condition(io_errc e) noexcept;
Returns: error_condition(static_cast<int>(e), iostream_category()). const error_category& iostream_category() noexcept;
Returns: A reference to an object of a type derived from class
error_category. The object's
default_error_condition and
equivalent virtual functions shall behave as specified for the class
error_category.The object's
name virtual function shall return a pointer to the string
"iostream".