std::future_errc

C++

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Technical Specifications

Thread support library

Threads
thread (C++11)
hardware_destructive_interference_sizehardware_constructive_interference_size (C++17)(C++17)
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mutex (C++11) recursive_mutex (C++11) shared_mutex (C++17)	timed_mutex (C++11) recursive_timed_mutex (C++11) shared_timed_mutex (C++14)
Generic lock management
lock_guard (C++11) scoped_lock (C++17) unique_lock (C++11) shared_lock (C++14) defer_lock_ttry_to_lock_tadopt_lock_t (C++11)(C++11)(C++11)	lock (C++11) try_lock (C++11) defer_locktry_to_lockadopt_lock (C++11)(C++11)(C++11) once_flag (C++11) call_once (C++11)
Condition variables
condition_variable (C++11)
condition_variable_any (C++11)
notify_all_at_thread_exit (C++11)
cv_status (C++11)
Futures
promise (C++11) future (C++11) shared_future (C++11) packaged_task (C++11) async (C++11)	launch (C++11) future_status (C++11) future_error (C++11) future_category (C++11) future_errc (C++11)

std::future_errc

Non-member functions

make_error_code

make_error_condition

Helper classes

is_error_code_enum

Defined in header <future>
enum class future_errc { broken_promise = /* implementation-defined */, future_already_retrieved = /* implementation-defined */, promise_already_satisfied = /* implementation-defined */, no_state = /* implementation-defined */ };		(since C++11)

The scoped enumeration std::future_errc defines the error codes reported by std::future and related classes in std::future_error exception objects. Only four error codes are required, although the implementation may define additional error codes. Because the appropriate specialization of std::is_error_code_enum is provided, values of type std::future_errc are implicitly convertible to std::error_code.

All error codes are distinct and non-zero.

(since C++14)

Member constants

Constant	Explanation
broken_promise	the asynchronous task abandoned its shared state
future_already_retrieved	the contents of shared state were already accessed through std::future
promise_already_satisfied	attempt to store a value in the shared state twice
no_state	attempt to access std::promise or std::future without an associated shared state

Non-member functions

make_error_code(std::future_errc) (C++11)	constructs a future error code (function)
make_error_condition(std::future_errc) (C++11)	constructs a future error_condition (function)

Helper classes

is_error_code_enum<std::future_errc> (C++11)

extends the type trait std::is_error_code_enum to identify future error codes (class template)

Notes

In C++11, broken_promise was specified to equal zero despite std::error_code/std::error_condition using zero to mean "no error". This was fixed in C++14.

See also

error_code (C++11)	holds a platform-dependent error code (class)
error_condition (C++11)	holds a portable error code (class)