/in/foo.cc: In function 'void test01(std::vector<int>&)':
/in/foo.cc:27:16: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   27 |   for(int i=0;i<s.size();i++)
      |               ~^~~~~~~~~
/in/foo.cc: In function 'std::vector<int> test04(int)':
/in/foo.cc:102:1: warning: control reaches end of non-void function [-Wreturn-type]
  102 | }
      | ^