#include <chrono>

namespace {
	struct any {
		template<class T> any(const T &);
	};
	
	template<class A, class B>
	decltype(operator*(std::declval<A>(), std::declval<B>()), std::true_type())
	help_are_multiplicable(A, B);
	
	std::false_type help_are_multiplicable(any, any);
	
	template<class A, class B>
	class are_multiplicable : public decltype(help_are_multiplicable(std::declval<A>(),
	                                                                 std::declval<B>())) { };
}

namespace {
	template<class A, class B>
	decltype(operator/(std::declval<A>(), std::declval<B>()), std::true_type())
	help_are_divisible(A, B);
	
	std::false_type help_are_divisible(any, any);
	
	template<class A, class B>
	class are_divisible : public decltype(help_are_divisible(std::declval<A>(),
	                                                         std::declval<B>())) { };
}

static_assert(!are_divisible<int,std::chrono::seconds>::value, "OK");
static_assert(!are_multiplicable<std::chrono::seconds,std::chrono::seconds>::value, "fails"); // expect-error