std::future_errc

 

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Free functions for atomic flags atomic_flag_test_and_setatomic_flag_test_and_set_explicit (C++11)(C++11) atomic_flag_clearatomic_flag_clear_explicit (C++11)(C++11) atomic_flag_testatomic_flag_test_explicit (C++20)(C++20) atomic_flag_waitatomic_flag_wait_explicit (C++20)(C++20) atomic_flag_notify_one (C++20) atomic_flag_notify_all (C++20) Memory ordering memory_order (C++11) kill_dependency (C++11) atomic_thread_fence (C++11) atomic_signal_fence (C++11) Mutual exclusion 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) Semaphores counting_semaphorebinary_semaphore (C++20)(C++20) Latches and barriers latch (C++20) barrier (C++20) 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.

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)

Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

DR	Applied to	Behavior as published	Correct behavior
LWG 2056	C++11	broken_promise was specified to be zero which is conventionally used to mean "no error"	specified to be non-zero

See also

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