🚀 go-pugleaf

In article <14216@ksr.com> jfw@ksr.com (John F. Woods) writes:
: msb@sq.sq.com (Mark Brader) writes:
: >> The Standard allows arbitrary padding between fields and after the
: >> last field.
: >Not quite; it allows padding so that the members are correctly aligned
: >for their types.  It does not say anything about padding being permitted
: >for any other reasons, and my interpretation is that it isn't.
:
: Please show a strictly conforming program which can tell the difference
: between "necessary" padding and "unnecessary" padding.

For example:

typedef struct {
	int     x;
	int     y;
} foo;
foo z;

main()
{
	printf("%d\n", (offsetof(foo, y) - offset(foo, x)) - sizeof(int));
	return (0);
}

should print 0 on any standards conforming compiler, if it is true
that the standard permits only padding for the purpose of
creating proper alignment. (I'll not argue the question of
whether it does. Since it would be a daft compiler that added
padding for any reason other than alignment, I think it not worth
arguing.)

---
Bill                            { uunet | decwrl | telesci }!twwells!bill
bill@twwells.com