A possible implementation of `std::experimental::is_detected` is available here: https://en.cppreference.com/w/cpp/experimental/is_detected#Possible_implementation

That can even be pared down to something as simple as:

```
namespace detail {
template <class AlwaysVoid, template<class...> class Op, class... Args>
struct detector {
    using value_t = std::false_type;
};

template <template<class...> class Op, class... Args>
struct detector<std::void_t<Op<Args...>>, Op, Args...> {
    using value_t = std::true_type;
};
} // namespace detail

template <template<class...> class Op, class... Args>
using is_detected = typename detail::detector<void, Op, Args...>::value_t;

template <template<class...> class Op, class... Args>
const auto is_detected_v = is_detected<Op, Args...>::value;
```

For example [this](https://coliru.stacked-crooked.com/a/bf4610faee27d420) also works on Visual Studio 2017 and latter.