Is it intentional that forward references in unittests aren't supported nor detected?

[Trass3r]

void main()
{
}

unittest
{
	struct S
	{
		S2 s;
	}
	
	struct S2
	{
	}
	
	S s;
}

yields:
unittests.d(9): Error: identifier 'S2' is not defined
unittests.d(9): Error: S2 is used as a type
unittests.d(8): Error: no size for type _error_
Error: no size for type _error_


while putting S2 in front of S works makes it work.

Is this intentional?