std::mask_array<T>::mask_array
From cppreference.com
                    
                                        
                    < cpp | numeric | valarray | mask array
                    
                                                            
                    
| (1) | ||
|   private: mask_array();  | 
(until C++11) | |
|   public: mask_array() = delete;  | 
(since C++11) | |
|   public: mask_array( const mask_array& other );  | 
(2) | |
1) The default constructor is declared private and not defined(until C++11)explicitly defined as deleted(since C++11): 
mask_array is not DefaultConstructible.2) Constructs a 
mask_array from another mask_array other.Parameters
| other | - |  mask_array to initialize with
 | 
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 253 | C++98 | the copy constructor was private | made public |