Re: [Qemu-devel] [PATCH v2 09/16] qapi: Permit alternates with just one branch

[Eric Blake]

On 9/10/19 1:37 AM, Markus Armbruster wrote:
> A union or alternate without branches makes no sense and doesn't work:
> it can't be instantiated.  A union or alternate with just one branch
> works, but is degenerate.  We accept the former, but reject the
> latter.  Weird.  docs/devel/qapi-code-gen.txt doesn't mention the
> difference.  It claims an alternate definition is "is similar to a
> simple union type".
> 
> Permit degenerate alternates to make them consistent with unions.
> 
> Signed-off-by: Markus Armbruster <address@hidden>
> ---
>  scripts/qapi/common.py                  | 6 ++----
>  tests/qapi-schema/alternate-empty.err   | 2 +-
>  tests/qapi-schema/alternate-empty.json  | 4 ++--
>  tests/qapi-schema/qapi-schema-test.json | 4 +++-
>  tests/qapi-schema/qapi-schema-test.out  | 6 ++++--
>  5 files changed, 12 insertions(+), 10 deletions(-)

Reviewed-by: Eric Blake <address@hidden>

(Might make sense if one of the branches is conditional, where depending
on compile-time options it could be a two-branch or a one-branch alternate)

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
Virtualization:  qemu.org | libvirt.org

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