Re: [Qemu-devel] [PULL 14/15] qapi: Don't box branches of flat unions

[Eric Blake <eblake@redhat.com>]

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On 02/23/2016 08:18 AM, Eric Blake wrote:

>>
>> I could visit_type_QCryptoBlockOptionsLUKS_fields(v, opts.u.luks, errp)
>> but the '_fields' methods are all declared static in qapi-visit.c
>> preventing their use.
>>
>> IMHO, now that QAPI inlines the flat unions, we should be making
>> the _fields() methods public.
> 
> But my suggestion would just be a hack. Yours makes more sense in the
> long run, so I'll go ahead and propose that patch.

Another alternative, but not my preference (mentioning only for
completeness):

We could change the contract of visit_type_FOO(&obj) to say that if it
points to non-NULL, we just visit the fields in place.  All callers
would then be required to set *obj = NULL prior to visit_type_FOO(&obj)
for existing semantics, and you would set *obj = &parent.u.luks for new
semantics.

But this would entail an audit of existing callers (too many are passing
uninitialized pointers, which must now be initialized), and feels a bit
too complex.

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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