Eric Blake <ebl...@redhat.com> writes: > On 03/26/2015 08:47 AM, Markus Armbruster wrote: >> Eric Blake <ebl...@redhat.com> writes: >> >>> Special-casing 'discriminator == {}' for handling anonymous unions >>> is getting awkward; since this particular type is not always a >>> dictionary on the wire, it is easier to treat it as a completely >>> different class of type, "alternate", so that if a type is listed >>> in the union_types array, we know it is not an anonymous union. >>> >>> This patch just further segregates union handling, to make sure that >>> anonymous unions are not stored in union_types, and splitting up >>> check_union() into separate functions. A future patch will change >>> the qapi grammar, and having the segregation already in place will >>> make it easier to deal with the distinct meta-type. >>> >>> Signed-off-by: Eric Blake <ebl...@redhat.com> >>> --- > >>> @@ -535,7 +546,8 @@ def find_struct(name): >>> >>> def add_union(definition): >>> global union_types >>> - union_types.append(definition) >>> + if definition.get('discriminator') != {}: >>> + union_types.append(definition) >>> >>> def find_union(name): >>> global union_types >> >> This is the only unobvious hunk. >> >> union_types is used only through find_union. The hunk makes >> find_union(N) return None when N names an anonymous union. >> >> find_union() is used in two places: >> >> * find_alternate_member_qtype() >> >> Patched further up. It really wants only non-anonymous unions, and >> this change to find_union() renders its check for anonymous unions >> superfluous. Good. >> >> * generate_visit_alternate() >> >> Asserts that each member's type is either a built-in type, a complex >> type, a union type, or an enum type. >> >> The change relaxes the assertion not to trigger on anonymous union >> types. Why is that okay? > > No, the change tightens the assertion so that it will now fail on an > anonymous union nested as a branch of another anonymous union (where > before it could silently pass the assertion), because the anonymous > union is no longer found by find_union(). And this is okay because the > earlier change to find_alternate_member_qtype means that we don't allow > nested anonymous unions, so making the assertion fail if an anonymous > union gets through anyway is correct.
Thanks for unconfusing me. Reviewed-by: Markus Armbruster <arm...@redhat.com>