foo.cc: In function ‘std::vector<int> mul(std::vector<int>&, int)’:
foo.cc:37:30: warning: comparison of integer expressions of different signedness: ‘int’ and ‘std::vector<int>::size_type’ {aka ‘long unsigned int’} [-Wsign-compare]
   37 |     for (int i = 0, t = 0; i < A.size() || t; i++)
      |                            ~~^~~~~~~~~~
foo.cc:39:15: warning: comparison of integer expressions of different signedness: ‘int’ and ‘std::vector<int>::size_type’ {aka ‘long unsigned int’} [-Wsign-compare]
   39 |         if (i < A.size())
      |             ~~^~~~~~~~~~