Re: [Qemu-devel] [PATCH RFC v2 07/47] qapi: Generate a nicer struct for flat unions

[Markus Armbruster]

Eric Blake <address@hidden> writes:

> On 07/29/2015 01:33 AM, Markus Armbruster wrote:
>> Eric Blake <address@hidden> writes:
>> 
>>> On 07/01/2015 02:21 PM, Markus Armbruster wrote:
>>>> The struct generated for a flat union is weird: the members of its
>>>> base are at the end, except for the union tag, which is renamed to
>>>> 'kind' and put at the beginning.
>>>
>
>>> Therefore, it might be worth mentioning that avoiding the rename to
>>> 'kind' is a bug fix, not just a nicer struct :)
>> 
>> Cool!  I'll work (a variation of) this test case into my series.
>
> Another name collision bug: our code generates flat unions as:
>
> struct BlockdevOptions {
>     BlockdevDriver driver;
> ...
>     /* End fields inherited from BlockdevOptionsBase. */
>     /* union tag is BlockdevDriver driver */
>     union {
>         void *data;
>         BlockdevOptionsArchipelago *archipelago;
> ...
>
> 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.