std::chrono::operator==,<=>(std::chrono::month_day)
From cppreference.com
                    
                                        
                    
                    
                                                            
                    | constexpr bool operator==( const std::chrono::month_day& x, const std::chrono::month_day& y ) noexcept; | (1) | (since C++20) | 
| constexpr std::strong_ordering operator!=( const std::chrono::month_day& x, const std::chrono::month_day& y ) noexcept; | (2) | (since C++20) | 
Compares two month_day objects.
Return value
1) x.month() == y.month() && x.day() == y.day()
2) x.month() <=> y.month() != 0 ? x.month() <=> y.month() : x.day() <=> y.day()