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#if defined(__GNUC__) && ((__GNUC__ * 100 + __GNUC_MINOR__) < 407)
#define OLD_GNU
#endif
#ifdef OLD_GNU
template<int... Is>
struct Interface;
#endif
template<int I, int... Is>
struct Interface
#ifdef OLD_GNU
<I, Is...>
#endif
{
static int accumulate()
{
return I + Interface<Is...>::accumulate();
}
};
template<int I>
struct Interface<I>
{
static int accumulate()
{
return I;
}
};
// Note: split this into a separate test if a
// cxx_variadic_template_template_parameters feature is added.
template<typename T>
struct eval {
enum {
Matched = 0
};
};
template<template<typename...> class T, typename... U>
struct eval<T<U...> > {
enum {
Matched = 1
};
};
template<typename...>
struct A {
};
template<typename T>
struct B {
};
template<typename T, typename U>
struct C {
};
template<typename T, typename U, typename...>
struct D {
};
// Note: This test assumes that a compiler supporting this feature
// supports static_assert. Add a workaround if that does not hold.
static_assert(eval<A<> >::Matched, "A Matches");
static_assert(eval<A<int> >::Matched, "A Matches");
static_assert(eval<A<int, char> >::Matched, "A Matches");
static_assert(eval<B<int> >::Matched, "B Matches");
static_assert(eval<C<int, char> >::Matched, "C Matches");
static_assert(eval<D<int, char> >::Matched, "D Matches");
static_assert(eval<D<int, char, bool> >::Matched, "D Matches");
static_assert(eval<D<int, char, bool, double> >::Matched, "D Matches");
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