🚀 go-pugleaf

In article <5386@holden.lulea.trab.se> jbn@lulea.trab.se (Johan Bengtsson) writes:
|That two non-generic pointers of the same type (possibly converted from
|pointer-to-derived) to different objects or data members should be
|guaranteed to compare unequal.
|
|Please? (:-)

Either you are misstating what you think you are stating, or I am 
misunderstanding what you are stating, or else I strongly disagree,
because I would counterclaim that pointer equality in the following
example is a legal and perfectly reasonable, and efficient, implementation.
On the contrary, requiring unnecessary and unexpected padding within
structures just to meet your new requirements would be extremely 
undesirable, in my opinion.  If you want object addresses to be
unique, then write your code so that they are unique.  Don't ask the
compiler to put the padding in for you.



#include	<stdio.h>

class A {};

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

main()
{
	B b;
	A* p1; 
	A* p2;

	p1 = &b;
	p2 = &(b.a);

	if (p1 == p2)
		printf("equal %lX %lX\n", (long)p1, (long)p2);
	else
		printf("unequal %lX %LX\n", (long)p1, (long)p2);

	return 0;
}