In file included from main.cpp:16:0:
date.h: In constructor 'Date::Date(int, int, int)':
date.h:5:17: error: 'Date::year' will be initialized after [-Werror=reorder]
 int day, month, year;
                 ^~~~
date.h:5:10: error:   'int Date::month' [-Werror=reorder]
 int day, month, year;
          ^~~~~
date.h:51:1: error:   when initialized here [-Werror=reorder]
 Date(int year, int month, int day): year(year), month(month), day(day) {}
 ^~~~
date.h:5:10: error: 'Date::month' will be initialized after [-Werror=reorder]
 int day, month, year;
          ^~~~~
date.h:5:5: error:   'int Date::day' [-Werror=reorder]
 int day, month, year;
     ^~~
date.h:51:1: error:   when initialized here [-Werror=reorder]
 Date(int year, int month, int day): year(year), month(month), day(day) {}
 ^~~~
cc1plus: all warnings being treated as errors