qapi: Fix to .check() empty structs just once

QAPISchemaObjectType.check() does nothing for types that have been
checked already.  Except the "has been checked" predicate is broken
for empty types: self.members is [] then, which isn't true.  The bug
is harmless, but fix it anyway: use self.member is not None instead.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20190914153506.2151-18-armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>

diff --git a/scripts/qapi/common.py b/scripts/qapi/common.py
index 7e79c42b6a54ed5e862d9672ecbff6e62b380b44..e2c87d1349d7d8f874f3a23da1c81c53aaecc17b 100644 (file)
--- a/scripts/qapi/common.py
+++ b/scripts/qapi/common.py
@@ -1406,7 +1406,7 @@ class QAPISchemaObjectType(QAPISchemaType):
         if self.members is False:               # check for cycles
             raise QAPISemError(self.info,
                                "Object %s contains itself" % self.name)
-        if self.members:
+        if self.members is not None:            # already checked
             return
         self.members = False                    # mark as being checked
         seen = OrderedDict()