qapi: Factor out QAPISchemaObjectType.check_clash()

Consolidate two common sequences of clash detection into a
new QAPISchemaObjectType.check_clash() helper method.

No change to generated code.

Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <1447836791-369-13-git-send-email-eblake@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>

scripts/qapi.py

@@ -981,10 +981,8 @@ def check(self, schema):
         if self._base_name:
             self.base = schema.lookup_type(self._base_name)
             assert isinstance(self.base, QAPISchemaObjectType)
-            assert not self.base.variants       # not implemented
             self.base.check(schema)
-            for m in self.base.members:
-                m.check_clash(seen)
+            self.base.check_clash(schema, seen)
         for m in self.local_members:
             m.check(schema)
             m.check_clash(seen)
@@ -994,6 +992,11 @@ def check(self, schema):
             assert self.variants.tag_member in self.members
             self.variants.check_clash(schema, seen)
 
+    def check_clash(self, schema, seen):
+        assert not self.variants       # not implemented
+        for m in self.members:
+            m.check_clash(seen)
+
     def is_implicit(self):
         # See QAPISchema._make_implicit_object_type()
         return self.name[0] == ':'
@@ -1064,11 +1067,8 @@ def check_clash(self, schema, seen):
         for v in self.variants:
             # Reset seen map for each variant, since qapi names from one
             # branch do not affect another branch
-            vseen = dict(seen)
             assert isinstance(v.type, QAPISchemaObjectType)
-            assert not v.type.variants       # not implemented
-            for m in v.type.members:
-                m.check_clash(vseen)
+            v.type.check_clash(schema, dict(seen))
 
 
 class QAPISchemaObjectTypeVariant(QAPISchemaObjectTypeMember):