#include <iostream>
 
template <typename T, unsigned int D> struct Vec
{
	static_assert(D && 0, "Invalid dimension for vector!");
};
 
template <typename T> struct Vec<T, 1>             {union {T x, r;};};
template <typename T> struct Vec<T, 2> : Vec<T, 1> {union {T y, g;};};
template <typename T> struct Vec<T, 3> : Vec<T, 2> {union {T z, b;};};
template <typename T> struct Vec<T, 4> : Vec<T, 3> {union {T w, a;};};
 
int main()
{
	Vec<float, 3> v;
	v.x = 1;
	v.y = 2;
	v.z = 3;
 
	return 0;
}

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