/in/foo.cc: In member function 'void UseVector::sub(const UseVector&, const UseVector&)':
/in/foo.cc:31:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for (i = 0; i < u1.data.size(); i++)
               ~~^~~~~~~~~~~~~~~~
/in/foo.cc:33:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
    for (j = 0; j < u2.data.size(); j++)
                ~~^~~~~~~~~~~~~~~~
/in/foo.cc:38:10: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
    if (j >= u2.data.size())
        ~~^~~~~~~~~~~~~~~~~
/in/foo.cc: In member function 'void UseVector::print()':
/in/foo.cc:46:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for (int i = 0; i < data.size(); i++)
                   ~~^~~~~~~~~~~~~