Why do I get stack overflow?

[Ary Borenszweig]

When I compile this code I get "stack overflow" printed in the console. 
Anyone know why?

---
int fact(int X)() {
        if(X == 0) {
                return 1;
        } else {
                int temp = fact!(X - 1)();
                return X * temp;
        }
}
const someVar = fact!(0)();
---