On Thu, Apr 19, 2018 at 5:20 PM, Eric Blake <ebl...@redhat.com> wrote: > On 04/19/2018 10:01 AM, Marc-André Lureau wrote: >> All QObject types have the base QObject as their first field. This >> allows the simplification of qobject_to(). >> >> This explicitly guarantees that existing casts work correctly (even >> though we'd prefer to get rid of such casts in any location except the >> qobject.h macros) >> >> Signed-off-by: Marc-André Lureau <marcandre.lur...@redhat.com> >> Reviewed-by: Eric Blake <ebl...@redhat.com> > > My R-b stands that this is correct from a coding point of view. But if > I read Markus' review correctly, we could omit this patch, fix the one > broken client in tests/check-qdict.c to use qobject_to() (why didn't you > fix that in v6)?, and then just apply patches 2-5 without this patch, > with no change in behavior and where we are no longer dependent on using > offset 0 (even though all current instances do). So, I'll leave that to > maintainer discretion. >
I don't think we have a good reason to allow offset different than 0. The fact that we have code that rely on that behaviour already is a sign that this could easily happen again, because it's the common pattern in C for inheritance, and static casting is allowed, for better or worse. -- Marc-André Lureau
