immutable struct A
{
	struct B
	{
		int x;
	}
	
	int x;
	static int y;
}

void main()
{
	A.y = 42; // works
	A a;
	// a.x = 42; // fails
	A.B b;
	b.x = 42; // works
}

-------------------------------------

Applying const/immutable qualifier to aggregate definition propagates it only to fields and methods of struct/class. static fields and nested definitions are left mutable which is extremely confusing and inconsistent with usual transitivity.