foo.cc: In function ‘int main()’:
foo.cc:15:27: warning: pointer to a function used in arithmetic [-Wpointer-arith]
   15 |                 sum+=fib[i];
      |                           ^
foo.cc:15:20: warning: pointer to a function used in arithmetic [-Wpointer-arith]
   15 |                 sum+=fib[i];
      |                 ~~~^~~~~~~~
foo.cc:15:20: error: invalid conversion from ‘int (*)(int)’ to ‘int’ [-fpermissive]
   15 |                 sum+=fib[i];
      |                 ~~~^~~~~~~~
      |                    |
      |                    int (*)(int)