Helper for adapting structured bindings

StructuredBindings.h

//-------------------------------------------------------------------------------------------------
// Leaving this here for safe keeping but not integrating into my code just yet. It basically
// requires you to upgrade to Clang 8+ and newer versions of vs 2019 to work without weird compiler bugs.
//-------------------------------------------------------------------------------------------------

#include <tuple>

//-------------------------------------------------------------------------------------------------
// Helper to simplify generating custom structured bindings
// Usage:
// STRUCTURED_BINDING(KeyValuePair, 2)
// {
//	if constexpr (index == 0)
// 		return input.Key();
// 	else
// 		return input.Value();
// }
//-------------------------------------------------------------------------------------------------
#define STRUCTURED_BINDING(Type, Count) STRUCTURED_BINDING_V(Type, Count, input)
#define STRUCTURED_BINDING_V(Type, Count, arg) \
namespace std { \
	template <> struct tuple_size<Type> { enum { value = Count }; }; \
	template <size_t index> struct tuple_element<index, Type> { using type = decltype(get<index>(*((Type*)0))); }; \
} template <size_t index> auto get(Type const& arg)

//-------------------------------------------------------------------------------------------------
// Example custom iterator
//-------------------------------------------------------------------------------------------------
class Iterator
{
public:
	Iterator() = default;

	int const& Key() const { return k; }
	int const& Value() const { return v; }

private:
    int k;
    int v;
};

//-------------------------------------------------------------------------------------------------
// Create binding
//-------------------------------------------------------------------------------------------------
STRUCTURED_BINDING(Iterator, 2)
{
	if constexpr (index == 0)
		return input.Key();
	else
		return input.Value();
}

//-------------------------------------------------------------------------------------------------
// Example usage
//-------------------------------------------------------------------------------------------------
int main()
{
    int r = 0;

    Iterator arr[10];
    for (auto itr : arr)
    {
        auto const&[key, value] = itr;
        r += key + value;
    }

    for (auto const&[key, value] : arr)
    {
        r += key + value;
    }

    return 0;
}