std::chrono::operator+,std::chrono::operator-(std::chrono::year_month_day_last)(3)

NAME
std::chrono::operator+,std::chrono::operator-(std::chrono::year_month_day_last) - std::chrono::operator+,std::chrono::operator-(std::chrono::year_month_day_last)

Synopsis
   Defined in header <chrono>
   constexpr std::chrono::year_month_day_last
   operator+( const std::chrono::year_month_day_last& ymdl, const (since C++20)
   std::chrono::months& dm ) noexcept;
   constexpr std::chrono::year_month_day_last
   operator+( const std::chrono::months& dm, const (since C++20)
   std::chrono::year_month_day_last& ymdl ) noexcept;
   constexpr std::chrono::year_month_day_last
   operator+( const std::chrono::year_month_day_last& ymdl, const (since C++20)
   std::chrono::years& dy ) noexcept;
   constexpr std::chrono::year_month_day_last
   operator+( const std::chrono::years& dy, const (since C++20)
   std::chrono::year_month_day_last& ymdl ) noexcept;
   constexpr std::chrono::year_month_day_last
   operator-( const std::chrono::year_month_day_last& ymdl, const (since C++20)
   std::chrono::months& dm ) noexcept;
   constexpr std::chrono::year_month_day_last
   operator-( const std::chrono::year_month_day_last& ymdl, const (since C++20)
   std::chrono::years& dy ) noexcept;
   1-2) Adds dm.count() months to the date represented by ymdl. The result has the same
   year() and month() as std::chrono::year_month(ymdl.year(), ymdl.month()) + dm.
   3-4) Adds dy.count() years to the date represented by ymdl. The result is equivalent
   to std::chrono::year_month_day_last(ymdl.year() + dy, ymdl.month_day_last()).
   5) Subtracts dm.count() months from the date represented by ymdl. Equivalent to ymdl
   + -dm.
   6) Subtracts dy.count() years from the date represented by ymdl. Equivalent to ymdl
   + -dy.
   For durations that are convertible to both std::chrono::years and
   std::chrono::months, the years overloads (3,4,6) are preferred if the call would
   otherwise be ambiguous.

Example
// Run this code
 #include <iostream>
 #include <chrono>
 int main()
 {
     std::cout << std::boolalpha;
     auto ymdl {11/std::chrono::last/2020};
     ymdl = std::chrono::years(10) + ymdl;
     std::cout << (ymdl == std::chrono::day(30)/
                        std::chrono::November/
                        std::chrono::year(2030)) << ' ';
     ymdl = ymdl - std::chrono::months(6);
     std::cout << (ymdl == std::chrono::day(31)/
                        std::chrono::May/
                        std::chrono::year(2030)) << '\n';
 }

Output:
 true true