1 // { dg-additional-options "-std=c++14 -Wno-return-type" }
2
3 template<typename Signature>
4 class function;
5
6 template<typename R, typename... Args>
7 class invoker_base
8 {
9 public:
~invoker_base()10 virtual ~invoker_base() { }
11 };
12
13 template<typename F, typename R, typename... Args>
14 class functor_invoker : public invoker_base<R, Args...>
15 {
16 public:
functor_invoker(const F & f)17 explicit functor_invoker(const F& f) : f(f) { }
18 private:
19 F f;
20 };
21
22 template<typename R, typename... Args>
23 class function<R (Args...)> {
24 public:
25 template<typename F>
function(const F & f)26 function(const F& f) : invoker(0) {
27 invoker = new functor_invoker<F, R, Args...>(f);
28 }
~function()29 ~function() {
30 if (invoker)
31 delete invoker;
32 }
33 private:
34 invoker_base<R, Args...>* invoker;
35 };
36
37 template<typename>
38 struct unique_ptr { };
39
40 struct A {};
41 template <class...> struct typelist {};
42 template <class... Cs> unique_ptr<A> chooseB(typelist<Cs...>);
43 template <class... Cs, class Idx, class... Rest>
chooseB(typelist<Cs...> choices,Idx,Rest...rest)44 unique_ptr<A> chooseB(typelist<Cs...> choices, Idx, Rest... rest) {
45 auto f = [=](auto) { return [=] { return chooseB(choices, rest...); }; };
46 function<unique_ptr<A>()> fs[]{f(Cs{})...};
47 }
main()48 main() { chooseB(typelist<double, char>{}, 0, 1, 2); }
49