【C++】尝试实现 `is

还有行为和 std::is_constructible 不一致的地方：

class Test {
	~Test() = delete ;
};
std::is_constructible::value ==> false

#include 
#include 

template
struct is_reference : std::is_same > {};

template
inline constexpr bool is_reference_v = ! is_reference::value ;


#if 1

template
struct is_constructible_impl : std::false_type {};

template
struct is_constructible_impl< void , T&, Args&...> : std::true_type {};

template
struct is_constructible_impl< void , T&, Args...> : std::false_type {};

template
struct is_constructible_impl< void , T&, Args&&...> : std::false_type {};
//=======================================================================
template
struct is_constructible_impl< void , T&&, Args...> : std::true_type {};

template
struct is_constructible_impl< void , T&&, Args&...> : std::false_type {};

template
struct is_constructible_impl< void , T&&, Args&&...> : std::true_type {};

template
struct is_constructible_impl()...) ), void() ) , 
                            T, Args...> : std::true_type {};

template
struct is_constructible : is_constructible_impl {};

#else
using std::is_constructible;
#endif


// TEST CASE
static_assert(is_constructible::value);
static_assert(!is_constructible::value );

static_assert(is_constructible::value);
static_assert(is_constructible::value);
static_assert(is_constructible::value);

//左侧是左值引用时，右侧只能是左值引用；
static_assert(is_constructible::value); 
static_assert(!is_constructible::value); 
static_assert(!is_constructible::value); 

//左侧是右值引用时，右侧不能是左值引用
static_assert(!is_constructible::value); 
static_assert( is_constructible::value); 
static_assert( is_constructible::value); 

static_assert(is_constructible::value);
static_assert(!is_constructible::value);
static_assert(!is_constructible::value);
static_assert(!is_constructible::value);
static_assert(is_constructible::value);