Re: [Qemu-devel] [PATCH v10 02/13] qapi: Forbid empty unions and useless alternates

2016-02-16 Thread Eric Blake
On 02/16/2016 09:08 AM, Markus Armbruster wrote: > Eric Blake writes: > >> Empty unions serve no purpose, and while we compile with gcc >> which permits them, strict C99 forbids them. We could inject >> a dummy member (and in fact, we do for empty structs), but while > > gen_variants() injects

Re: [Qemu-devel] [PATCH v10 02/13] qapi: Forbid empty unions and useless alternates

2016-02-16 Thread Markus Armbruster
Eric Blake writes: > Empty unions serve no purpose, and while we compile with gcc > which permits them, strict C99 forbids them. We could inject > a dummy member (and in fact, we do for empty structs), but while gen_variants() injects void *data. > empty structs make sense in qapi, Suggest t

[Qemu-devel] [PATCH v10 02/13] qapi: Forbid empty unions and useless alternates

2016-02-15 Thread Eric Blake
Empty unions serve no purpose, and while we compile with gcc which permits them, strict C99 forbids them. We could inject a dummy member (and in fact, we do for empty structs), but while empty structs make sense in qapi, empty unions don't add any expressiveness to the QMP language. So prohibit t