/in/foo.cc: In function 'int main()':
/in/foo.cc:10:9: warning: unused variable 'b' [-Wunused-variable]
  int a, b;
         ^
/in/foo.cc: In function 'int ax(int)':
/in/foo.cc:8:1: warning: control reaches end of non-void function [-Wreturn-type]
 }
 ^