I'd like to see all the places in my code (C++) which disregard return value of a function. How can I do it - with gcc or static code analysis tool?

Bad code example:

int f(int z) {
    return z + (z*2) + z/3 + z*z + 23;
}


int main()
{
  int i = 7;
  f(i); ///// <<----- here I disregard the return value

  return 1;
}

Update:

• it should work even if the function and its use are in different files
• free static check tool