std::latch::wait
From cppreference.com
                    
                                        
                    
                    
                                                            
                    |   void wait() const;  | 
(since C++20) | |
Blocks the calling thread until the internal counter reaches 0. If it is zero already, returns immediately.
Parameters
(none)
Return value
(none)
Exceptions
Throws std::system_error with an error code allowed for mutex types on error.