/in/foo.cc: In member function 'void Date::sub(Date&)':
/in/foo.cc:69:25: warning: suggest parentheses around assignment used as truth value [-Wparentheses]
             if (m = da.m)
                         ^
/in/foo.cc:74:30: warning: suggest parentheses around assignment used as truth value [-Wparentheses]
                     if (i = m)
                              ^