/in/foo.cc: In member function 'int DateTime::calculateSeconds(const DateTime&) const':
/in/foo.cc:58:38: error: no matching function for call to 'DateTime::getDayOfYear(const DateTime&) const'
         seconds += getDayOfYear(other) * 24 * 60 * 60;
                                      ^
/in/foo.cc:90:9: note: candidate: int DateTime::getDayOfYear(const Date&) const
     int getDayOfYear(const Date& date) const {
         ^~~~~~~~~~~~
/in/foo.cc:90:9: note:   no known conversion for argument 1 from 'const DateTime' to 'const Date&'