namespace std {
class error_category;
const error_category& generic_category() noexcept;
const error_category& system_category() noexcept;
class error_code;
class error_condition;
class system_error;
template<class T>
struct is_error_code_enum : public false_type {};
template<class T>
struct is_error_condition_enum : public false_type {};
enum class errc {
address_family_not_supported, address_in_use, address_not_available, already_connected, argument_list_too_long, argument_out_of_domain, bad_address, bad_file_descriptor, bad_message, broken_pipe, connection_aborted, connection_already_in_progress, connection_refused, connection_reset, cross_device_link, destination_address_required, device_or_resource_busy, directory_not_empty, executable_format_error, file_exists, file_too_large, filename_too_long, function_not_supported, host_unreachable, identifier_removed, illegal_byte_sequence, inappropriate_io_control_operation, interrupted, invalid_argument, invalid_seek, io_error, is_a_directory, message_size, network_down, network_reset, network_unreachable, no_buffer_space, no_child_process, no_link, no_lock_available, no_message_available, no_message, no_protocol_option, no_space_on_device, no_stream_resources, no_such_device_or_address, no_such_device, no_such_file_or_directory, no_such_process, not_a_directory, not_a_socket, not_a_stream, not_connected, not_enough_memory, not_supported, operation_canceled, operation_in_progress, operation_not_permitted, operation_not_supported, operation_would_block, owner_dead, permission_denied, protocol_error, protocol_not_supported, read_only_file_system, resource_deadlock_would_occur, resource_unavailable_try_again, result_out_of_range, state_not_recoverable, stream_timeout, text_file_busy, timed_out, too_many_files_open_in_system, too_many_files_open, too_many_links, too_many_symbolic_link_levels, value_too_large, wrong_protocol_type, };
template<> struct is_error_condition_enum<errc> : true_type {};
error_code make_error_code(errc e) noexcept;
template<class charT, class traits>
basic_ostream<charT, traits>&
operator<<(basic_ostream<charT, traits>& os, const error_code& ec);
error_condition make_error_condition(errc e) noexcept;
bool operator==(const error_code& lhs, const error_code& rhs) noexcept;
bool operator==(const error_code& lhs, const error_condition& rhs) noexcept;
bool operator==(const error_condition& lhs, const error_code& rhs) noexcept;
bool operator==(const error_condition& lhs, const error_condition& rhs) noexcept;
bool operator!=(const error_code& lhs, const error_code& rhs) noexcept;
bool operator!=(const error_code& lhs, const error_condition& rhs) noexcept;
bool operator!=(const error_condition& lhs, const error_code& rhs) noexcept;
bool operator!=(const error_condition& lhs, const error_condition& rhs) noexcept;
bool operator< (const error_code& lhs, const error_code& rhs) noexcept;
bool operator< (const error_condition& lhs, const error_condition& rhs) noexcept;
template<class T> struct hash;
template<> struct hash<error_code>;
template<> struct hash<error_condition>;
template<class T>
inline constexpr bool is_error_code_enum_v = is_error_code_enum<T>::value;
template<class T>
inline constexpr bool is_error_condition_enum_v = is_error_condition_enum<T>::value;
}The value of each
enum errc constant shall be the same as
the value of the
<cerrno> macro shown in the above synopsis
.Whether
or not the
<system_error> implementation exposes the
<cerrno>
macros is unspecified
.The
is_error_code_enum and
is_error_condition_enum may be
specialized for program-defined types to indicate that such types are eligible
for
class error_code and
class error_condition automatic
conversions, respectively
.