Passing rvalues to functions expecting const ref

[Minas Mina]

There's another problem though:

struct Vector3
{
	float x, y, z;
	
	this(float _x, float _y, float _z)
	{
		x = _x;
		y = _y;
		z = _z;
	}
	
	// the binary +, - operators are defined
}

Vector3 cross(const ref Vector3 a, const ref Vector3 b);
...

Vector3 n = cross(b-a, c-a);


raytracing/triangle.d(58): Error: function 
raytracing.vector.cross (ref const(Vector3) a, ref const(Vector3) 
b) is not callable using argument types (Vector3,Vector3)
raytracing/triangle.d(58): Error: this.b.opBinary(this.a) is not 
an lvalue
raytracing/triangle.d(58): Error: this.c.opBinary(this.a) is not 
an lvalue

That's what I actually want.