From 583f4d6fdd96f0f25f39018a9b160654e3f9aa01 Mon Sep 17 00:00:00 2001 From: John Snow Date: Fri, 15 Mar 2024 16:22:53 +0100 Subject: [PATCH] qapi/schema: fix typing for QAPISchemaVariants.tag_member There are two related changes here: (1) We need to perform type narrowing for resolving the type of tag_member during check(), and (2) tag_member is a delayed initialization field, but we can hide it behind a property that raises an Exception if it's called too early. This simplifies the typing in quite a few places and avoids needing to assert that the "tag_member is not None" at a dozen callsites, which can be confusing and suggest the wrong thing to a drive-by contributor. Signed-off-by: John Snow Reviewed-by: Markus Armbruster Signed-off-by: Markus Armbruster Message-ID: <20240315152301.3621858-18-armbru@redhat.com> --- scripts/qapi/schema.py | 22 +++++++++++++++++++--- 1 file changed, 19 insertions(+), 3 deletions(-) diff --git a/scripts/qapi/schema.py b/scripts/qapi/schema.py index 74b0d7b007..9c138badb0 100644 --- a/scripts/qapi/schema.py +++ b/scripts/qapi/schema.py @@ -627,25 +627,39 @@ class QAPISchemaVariants: assert isinstance(v, QAPISchemaVariant) self._tag_name = tag_name self.info = info - self.tag_member = tag_member + self._tag_member: Optional[QAPISchemaObjectTypeMember] = tag_member self.variants = variants + @property + def tag_member(self) -> 'QAPISchemaObjectTypeMember': + if self._tag_member is None: + raise RuntimeError( + "QAPISchemaVariants has no tag_member property until " + "after check() has been run." + ) + return self._tag_member + def set_defined_in(self, name): for v in self.variants: v.set_defined_in(name) def check(self, schema, seen): if self._tag_name: # union - self.tag_member = seen.get(c_name(self._tag_name)) + # We need to narrow the member type: + tmp = seen.get(c_name(self._tag_name)) + assert tmp is None or isinstance(tmp, QAPISchemaObjectTypeMember) + self._tag_member = tmp + base = "'base'" # Pointing to the base type when not implicit would be # nice, but we don't know it here - if not self.tag_member or self._tag_name != self.tag_member.name: + if not self._tag_member or self._tag_name != self._tag_member.name: raise QAPISemError( self.info, "discriminator '%s' is not a member of %s" % (self._tag_name, base)) # Here we do: + assert self.tag_member.defined_in base_type = schema.lookup_type(self.tag_member.defined_in) assert base_type if not base_type.is_implicit(): @@ -666,11 +680,13 @@ class QAPISchemaVariants: "discriminator member '%s' of %s must not be conditional" % (self._tag_name, base)) else: # alternate + assert self._tag_member assert isinstance(self.tag_member.type, QAPISchemaEnumType) assert not self.tag_member.optional assert not self.tag_member.ifcond.is_present() if self._tag_name: # union # branches that are not explicitly covered get an empty type + assert self.tag_member.defined_in cases = {v.name for v in self.variants} for m in self.tag_member.type.members: if m.name not in cases: -- 2.39.2