std::atomic_flag::atomic_flag (3) Linux Manual Page
std::atomic_flag::atomic_flag – std::atomic_flag::atomic_flag
Synopsis
Defined in header<atomic>
atomic_flag() noexcept;
(1)(since C++ 11)
atomic_flag(const atomic_flag &) = delete;
(2)(since C++ 11)Constructs a new std::atomic_flag.
1) Trivial default constructor, initializes std::atomic_flag to unspecified state.
2) The copy constructor is deleted; std::atomic_flag is not copyable.
In addition, std::atomic_flag can be value-initialized to clear state with the expression ATOMIC_FLAG_INIT. For an atomic_flag with static storage_duration, this guarantees static_initialization: the flag can be used in constructors of static objects.
See also
ATOMIC_FLAG_INIT initializes an std::atomic_flag to false
(C++11)