/in/foo.cc: In function 'int find(std::__cxx11::string&, char)':
/in/foo.cc:4:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i=0;i<s.size();i++)if(c==s[i])return i;
                 ~^~~~~~~~~
/in/foo.cc: In function 'bool xx(std::__cxx11::string, std::__cxx11::string)':
/in/foo.cc:20:1: warning: control reaches end of non-void function [-Wreturn-type]
 }
 ^