🚀 go-pugleaf

Jim Adcock is advocating that under some circumstances it
is ok for a compiler to put two A objects at the same location.

His example is

|> class A {};
|> 
|> class B : public A
|> {
|> public:
|> 	A a;	
|> };
|> 

	B b ;

Where he claims it is ok for b.a and (B&)a to compare equal.

I don't agree, but I'm wondering exactly what criteria he is applying.
Does anything go for A's.  E.g.

	void f() {
	    A a1, a2 ;  // can &a1==&a2 
	    ... ; 
        }

Is it only ok for "empty" classes? How about 

	struct D { int i; int j ; } ;

	void f() {
	    D d1, d2 ;
	    ... d1.i ... d2.j ...  // never use d1.j or d2.i 
            }

Can &d1==&d2.

  -- Jerry Schwarz