Re: [PATCH 04/22] qapi: Convert simple union InputEvent to flat one

[Eric Blake <eblake@redhat.com>]

On Mon, Sep 13, 2021 at 02:39:14PM +0200, Markus Armbruster wrote:
> Simple unions predate flat unions.  Having both complicates the QAPI
> schema language and the QAPI generator.  We haven't been using simple
> unions in new code for a long time, because they are less flexible and
> somewhat awkward on the wire.
> 
> To prepare for their removal, convert simple union InputEvent to an
> equivalent flat one.  Adds some boilerplate to the schema, which is a
> bit ugly, but a lot easier to maintain than the simple union feature.
> 
> Cc: Gerd Hoffmann <kraxel@redhat.com>
> Signed-off-by: Markus Armbruster <armbru@redhat.com>
> ---
>  qapi/ui.json | 42 ++++++++++++++++++++++++++++++++++++++----
>  1 file changed, 38 insertions(+), 4 deletions(-)

Same question as in 3/22:

> 
> diff --git a/qapi/ui.json b/qapi/ui.json
> index a6b0dce876..fe10d69431 100644
> --- a/qapi/ui.json
> +++ b/qapi/ui.json
> @@ -960,6 +960,38 @@
>    'data'  : { 'axis'    : 'InputAxis',
>                'value'   : 'int' } }
>  
> +##
> +# @InputEventKind:
> +#
> +# Since: 6.1

This should either be 6.2, or...

>  ##
>  # @InputEvent:
>  #
> @@ -975,10 +1007,12 @@
>  # Since: 2.0

...2.0.

>  ##
>  { 'union' : 'InputEvent',
> -  'data'  : { 'key'     : 'InputKeyEvent',
> -              'btn'     : 'InputBtnEvent',
> -              'rel'     : 'InputMoveEvent',
> -              'abs'     : 'InputMoveEvent' } }
> +  'base': { 'type': 'InputEventKind' },
> +  'discriminator': 'type',
> +  'data'  : { 'key'     : 'InputKeyEventWrapper',
> +              'btn'     : 'InputBtnEventWrapper',
> +              'rel'     : 'InputMoveEventWrapper',
> +              'abs'     : 'InputMoveEventWrapper' } }

But as with that patch, I trust your decision on docs, and the
conversion itself is sane.

Reviewed-by: Eric Blake <eblake@redhat.com>

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org