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std::chrono::year_month_weekday_last:: operator sys_days, std::chrono::year_month_weekday_last:: operator local_days

From cppreference.net
C++
Date and time library
std::chrono::year_month_weekday_last
constexpr operator std:: chrono :: sys_days ( ) const noexcept ;
(1) (since C++20)
constexpr explicit operator std:: chrono :: local_days ( ) const noexcept ;
(2) (since C++20)

Converts * this to a std::chrono::time_point representing the same date as this year_month_weekday_last .

1) If ok() is true , returns a sys_days that represents the last weekday() of the year() and month() . Otherwise, the returned value is unspecified.
2) Same as (1) , but returns local_days instead of sys_days . Equivalent to local_days ( sys_days ( * this ) . time_since_epoch ( ) ) .

Example

Run this code 
#include <chrono>
#include <iostream>
using namespace std::chrono;
int main()
{
    constexpr auto ymwdl{Tuesday[last]/11/2021};
    static_assert(static_cast<local_days>(ymwdl) ==
                  static_cast<local_days>(November/30/2021));
    // convert from field-based to serial-based to add days
    constexpr auto sd = static_cast<sys_days>(ymwdl);
    constexpr year_month_day ymd{sd + days(42)};
    std::cout << ymd << '\n';
}

Output: 

2022-01-11