Why am I getting this message? The compiler is clang. Here is a simple program where it occurs for examples sake:

#include

int fib(int);
int main()
{
    int i;
    scanf("%d",&i);
    printf("The fibonacci number that is %i'th in the sequence is %i \n", i, fib(i));
return 0;
}

int fib(int n)
{
    if (n==1 || n==0) return 1;
    else return fib(n-1)+fib(n-2);
}