Eric Blake <ebl...@redhat.com> writes: > Right now, our ad hoc parser ensures that we cannot have a > flat union that introduces any members that would clash with > non-variant members inherited from the union's base type (see > flat-union-clash-member.json). We want ObjectType.check() to
Recommend not to abbreviate QAPISchemaObjectType.check(). > make the same check, so we can later reduce some of the ad > hoc checks. > > We already have a map 'seen' of all non-variant members. We > still need to check for collisions between each variant type's > members and the non-variant ones. > > To know the variant type's members, we need to call > variant.type.check(). This also detects when a type contains > itself in a variant, exactly like the existing base.check() > detects when a type contains itself as a base. (Except that > we currently forbid anything but a struct as the type of a > variant, so we can't actually trigger this type of loop yet.) > > Slight complication: an alternate's variant can have arbitrary > type, but only an object type's check() may be called outside > QAPISchema.check(). We could either skip the call for variants > of alternates, or skip it for non-object types. For now, do > the latter, because it's easier. > > Then we call each variant member's check_clash() with the > appropriate 'seen' map. Since members of different variants > can't clash, we have to clone a fresh seen for each variant. > Wrap this in a new helper method Variants.check_clash(). Likewise: QAPISchemaObjectTypeVariants.check_clash(). > Note that cloning 'seen' inside Variants.check_clash() resembles > the one we just removed from Variants.check() in 'qapi: Drop Here, we can say .check_clash() and .check(), and leave the class to context. > obsolete tag value collision assertions'; the difference here is > that we are now checking for clashes among the qapi members of > the variant type, rather than for a single clash with the variant > tag name itself. > > Note that, by construction, collisions can't actually happen for > simple unions: each variant's type is a wrapper with a single > member 'data', which will never collide with the only non-variant > member 'type'. > > For alternates, there's nothing for a variant object type's > members to clash with, and therefore no need to call the new > variants.check_clash(). > > No change to generated code. > > Signed-off-by: Eric Blake <ebl...@redhat.com> Only commit message polishing, happy to do that in my tree.
