/in/foo.cc: In function 'int main()':
/in/foo.cc:4:5: warning: unused variable 'a' [-Wunused-variable]
    4 | int a,b;
      |     ^
/in/foo.cc:4:7: warning: unused variable 'b' [-Wunused-variable]
    4 | int a,b;
      |       ^