vs_2019_16.8.5_intellisense_parse_failures.cpp

// Repro of intellisense parse errors for VS2019 16.8.5
// 
// Steps:
// 1. Add this file to a VC++ project in VS2019 16.8.5
// 2. Set C++ language level to /std:c++17 or higher
// 3. Right-click the code window > Rescan > Rescan File
// 4. Right-click the code window > Rescan > Display Browsing Database Errors
// 5. Observe that the parser generates 'VCTP001' warnings at the code regions marked below
//

#include <utility>
#include <type_traits>

namespace impl
{
	// VCTP001
	template <template <typename...> typename Trait, typename Enabler, typename... Args>
	struct is_detected_impl_ : std::false_type {};

	// VCTP001
	template <template <typename...> typename Trait, typename... Args>
	struct is_detected_impl_<Trait, std::void_t<Trait<Args...>>, Args...> : std::true_type {};

	// VCTP001
	template <template <typename...> typename Trait, typename... Args>
	inline constexpr auto is_detected_ = is_detected_impl_<Trait, void, Args...>::value;
}

// VCTP001
template <template <typename...> typename Trait, typename... Args>
inline constexpr auto is_detected = impl::is_detected_<Trait, Args...>;

// VCTP001
template <typename T>
using unary_predicate = bool(T)noexcept;

int main()
{

}