问initializer_list构造函数的问题？

struct element 
{
	int a;
	std::string b;
	
	element() {}

	element(int a, std::string b)
		: a(a), b(b)
	{
	}
};

class buffer
{
public:
	buffer() {}

	buffer(std::initializer_list<element>& elements)
		: m_elements(elements)
	{
	}

	std::vector<element>& GetElement() { return m_elements; }
private:
	std::vector<element> m_elements;
};

int main()
{
	element a(3, "abc");
	element b(111, "efg");
	
	buffer buffer = { a, b };
}