foo.cc: In function ‘std::vector<PolyTerm> mergePolynomials(const std::vector<PolyTerm>&, const std::vector<PolyTerm>&)’:
foo.cc:20:14: warning: comparison of integer expressions of different signedness: ‘int’ and ‘std::vector<PolyTerm>::size_type’ {aka ‘long unsigned int’} [-Wsign-compare]
   20 |     while (i < poly1.size() && j < poly2.size())
      |            ~~^~~~~~~~~~~~~~
foo.cc:20:34: warning: comparison of integer expressions of different signedness: ‘int’ and ‘std::vector<PolyTerm>::size_type’ {aka ‘long unsigned int’} [-Wsign-compare]
   20 |     while (i < poly1.size() && j < poly2.size())
      |                                ~~^~~~~~~~~~~~~~