opCall with struct alias this

[Patric Dexheimer via Digitalmars-d-learn]

struct Base(T){
	static T opCall(Args...)( Args args ){
		writeln(args);
		writeln("opCall");
		T t;
		return t;
	}
}

struct Data{
	Base!Data b;
	alias b this;
}

void main()
{	
         // Expected: opCall of Base!Data, but get error
	// auto x = Data(10);
         // opCall called. What just happened here?
         // never saw anything about init as function.
	auto y = Data.init(10);
}