std::experimental::atomic_weak_ptr<T>::is_lock_free
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                    < cpp | experimental | atomic weak ptr
                    
                                                            
                    |   bool is_lock_free() const noexcept;  | 
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Checks whether the atomic operations on all objects of this type are lock-free.
Parameters
(none)
Return value
true if the atomic operations on the objects of this type are lock-free, false otherwise.
See also
  specializes atomic operations for std::shared_ptr (function template)  |