1 // { dg-do compile { target c++11 } }
2 
3 template<class T>
4 struct IsNegative {
5   int dummy; // Workaround for empty class problem
IsNegativeIsNegative6   constexpr IsNegative() : dummy(0) {}
operatorIsNegative7   constexpr bool operator()(const T& x) {
8     return x < T(0);
9   }
10 };
11 
12 template<class T, int N, class Pred>
has_neg(T (& x)[N],Pred p)13 constexpr bool has_neg(T (&x)[N], Pred p) {
14   return p(x[0]) || p(x[1]);
15 }
16 
17 constexpr int a[] = {1, -2};
18 
19 constexpr auto answer = has_neg(a, IsNegative<int>{}); // #1
20 
21 static_assert(answer, "Error");
22