/in/foo.cc: In function 'Result Match(std::__cxx11::string&)':
/in/foo.cc:15:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (int i = 0; i < s.length(); i++)
                     ~~^~~~~~~~~~~~
/in/foo.cc:22:12: warning: suggest explicit braces to avoid ambiguous 'else' [-Wparentheses]
         if (s[i] == ')')
            ^
/in/foo.cc:34:17: warning: 'tmp' may be used uninitialized in this function [-Wmaybe-uninitialized]
         r.index = tmp;
         ~~~~~~~~^~~~~