>Modulo some administrative details, it's just "no object in memory may >be accessed using more than one type".
Ok ... I _think_ I see it. But doesn't that mean that like 90% of the casts used by C programmers are totally wrong? :-) > > but doesn't that depend on how you use it? > >Not in this case; the problem is that the cast to struct headname >causes it to read tqh_last from an item in memory that might be a >queue head but is probably actually a queue element. Alright, I think I understand. If tqe_prev pointed to a queue entry that would be the problem, because that memory already has a TAILQ_ENTRY type. So ... looking at this code ... it seems like the core problem is that TAILQ_HEAD and TAILQ_ENTRY are two different types (even though they literally the same structure layout). So if TAILQ_HEAD and TAILQ_ENTRY were the same structure, it wouldn't be an issue. It doesn't quite leap out to me how that would be possible without changing the API a bit. --Ken
