/in/foo.cc: In function 'int w(int, int, int)':
/in/foo.cc:11:12: warning: pointer to a function used in arithmetic [-Wpointer-arith]
  return w[a][b][c];
            ^
/in/foo.cc:11:15: warning: pointer to a function used in arithmetic [-Wpointer-arith]
  return w[a][b][c];
               ^
/in/foo.cc:11:18: warning: pointer to a function used in arithmetic [-Wpointer-arith]
  return w[a][b][c];
                  ^
/in/foo.cc:11:18: error: invalid conversion from 'int (*)(int, int, int)' to 'int' [-fpermissive]