1 // PR c++/52892
2 // { dg-do compile { target c++11 } }
3 
fibonacci(__SIZE_TYPE__ val)4 constexpr __SIZE_TYPE__ fibonacci(__SIZE_TYPE__ val) {
5   return (val <= 2) ? 1 : fibonacci(val - 1) + fibonacci(val - 2);
6 }
7 
8 template <typename Function>
9 struct Defer {
DeferDefer10   constexpr Defer(const Function func_) : func(func_) { }
11 
12   const Function func;
13 
14   template <typename... Args>
15   constexpr auto operator () (const Args&... args) -> decltype(func(args...)) {
16     return func(args...);
17   }
18 };
19 
20 template <typename Function>
make_deferred(const Function f)21 constexpr Defer<Function> make_deferred(const Function f) {
22   return Defer<Function>(f);
23 }
24 
main()25 int main() {
26   constexpr auto deferred = make_deferred(&fibonacci);
27   static_assert(deferred(25) == 75025, "Static fibonacci call failed"); // { dg-error "no match for call" "" { target c++14 } }
28 }
29