std::chrono::year_month_weekday_last::year_month_weekday_last
From cppreference.com
                    
                                        
                    < cpp | chrono | year month weekday last
                    
                                                            
                    |   constexpr year_month_weekday_last(const std::chrono::year& y, const std::chrono::month& m, const chrono::weekday_last& wdl) noexcept;  | 
(since C++20) | |
Constructs a year_month_weekday_last object storing the year y, the month m, and the weekday wdl.weekday(). The constructed object represents the last weekday of that year and month.
Notes
A year_month_weekday_last can also be created by combining one of the partial-date types std::chrono::year_month and std::chrono::month_weekday_last with the missing component (weekday_last and year, respectively) using operator/.
See also
|    (C++20)  | 
   conventional syntax for Gregorian calendar date creation   (function)  |