typeof() macro

[yumamur]

I assume this definition violates some rules

void	func(int x)
{
	typeof(x) k = x;
	if (k)
		++k;
	else
		--k;
}

and also this

void	func(int x)
{
	int	a;

	typeof(a) k = x;
	if (k)
	{
		typeof(x) b = 10;
		--b;
		++k;
	}
	else
		--k;
}