On 07/30/2015 09:44 AM, Markus Armbruster wrote: >>>> which means that if we name any of the branches 'data' (that is, if >>>> 'data' is a member of the enum discriminator), things fail to compile. >>>> We could probably fix that by naming our dummy branch '_data'. >>> >>> I wonder whether member data is actually used. I'll find out. >> >> The dealloc visitor uses 'data' being non-null as a flag on whether to >> deallocate the union even if the tag was invalid for some reason; or >> more importantly, if parsing consumed the tag but then detected an error >> while parsing the union, leaving the union branch partially allocated. >> To avoid a leak, we have to deallocate the branch. >> >> But if the tag was invalid, then why did we ever allocate the union in >> the first place, and how do we prove we are calling the correct free-ing >> function? And if the tag is valid, why can't we just guarantee that the >> union is 0-initialized and that deleting the branch will work through >> the correct branch type instead of worrying about 'data'? > > Good questions. Someone will have to review and fix this code. Let's > add a FIXME so we don't forget. Care to propose one?
Sure; see 12.6/47 (since that is close to several other patches adding FIXME comments). -- Eric Blake eblake redhat com +1-919-301-3266 Libvirt virtualization library http://libvirt.org
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