Re: [Qemu-block] [Qemu-devel] [PATCH v4 07/10] qapi: Don't special-case simple union wrappers

[Markus Armbruster]

Eric Blake <address@hidden> writes:

> On 03/08/2016 08:59 AM, Markus Armbruster wrote:
>> Eric Blake <address@hidden> writes:
>> 
>>> Simple unions were carrying a special case that hid their 'data'
>>> QMP member from the resulting C struct, via the hack method
>>> QAPISchemaObjectTypeVariant.simple_union_type().  But by using
>>> the work we started by unboxing flat union and alternate
>>> branches, coupled with the ability to visit the members of an
>>> implicit type, we can now expose the simple union's implicit
>>> type in qapi-types.h:
>>>
>
>>> +++ b/scripts/qapi.py
>>> @@ -1006,7 +1006,6 @@ class QAPISchemaObjectType(QAPISchemaType):
>>>          return c_name(self.name) + pointer_suffix
>>>
>>>      def c_unboxed_type(self):
>>> -        assert not self.is_implicit()
>> 
>> Doesn't this belong into PATCH 04?
>> 
>>>          return c_name(self.name)
>
> Maybe. Patch 3 kept the assertion out of straight code refactoring, and
> patch 4 didn't use c_unboxed_type(), so this was the first place where I
> had to weaken the assertion.  But moving it into patch 4 doesn't seem
> like it would hurt, as it is still semantically related to the fact that
> we are planning on allowing an unboxed implicit type.

PATCH 04 drops the assertion from c_name().  Let's keep the two
consistent.

>>> -        visit_type_%(c_type)s_members(v, &obj->u.%(c_name)s, &err);
>>> -''',
>>> -                             c_type=var.type.c_name(),
>>> -                             c_name=c_name(var.name))
>>> -            ret += mcgen('''
>>> -        break;
>>> -''')
>>> +                                           
>>> variants.tag_member.type.prefix),
>>> +                         c_type=var.type.c_name(), c_name=c_name(var.name))
>>>
>>>          ret += mcgen('''
>>>      default:
>> 
>> This stupid special case has given us enough trouble, good to see it
>> gone!
>
> Yeah, it was a nice feeling to get to this point!