qapi: New QAPISchemaBranches, QAPISchemaAlternatives

QAPISchemaVariants represents either a union type's branches, or an
alternate type's alternatives.  Much of its code is conditional on
which one it actually is.

Create QAPISchemaBranches for branches, and QAPISchemaAlternatives for
alternatives, both subtypes of QAPISchemaVariants.

Replace QAPISchemaVariants by one of them where possible.  Keep it
only where we actually deal with either of them.

QAPISchemaVariants.__init__() takes @tag_name and @tag_member, where
exactly one must be None: @tag_name for alternatives, @tag_member for
branches.  Let QAPISchemaBranches.__init__() take just @tag_name, and
QAPISchemaAlternatives.__init__() take just @tag_member.

A later patch will move the conditional code to the subtypes.

Signed-off-by: Markus Armbruster <armbru@redhat.com>

1 files changed, 4 insertions, 3 deletions

diff --git a/scripts/qapi/introspect.py b/scripts/qapi/introspect.py
index 4679b1bc2c..b866517942 100644
--- a/scripts/qapi/introspect.py
+++ b/scripts/qapi/introspect.py
@@ -26,6 +26,8 @@ from .common import c_name, mcgen
 from .gen import QAPISchemaMonolithicCVisitor
 from .schema import (
     QAPISchema,
+    QAPISchemaAlternatives,
+    QAPISchemaBranches,
     QAPISchemaArrayType,
     QAPISchemaBuiltinType,
     QAPISchemaEntity,
@@ -36,7 +38,6 @@ from .schema import (
     QAPISchemaObjectTypeMember,
     QAPISchemaType,
     QAPISchemaVariant,
-    QAPISchemaVariants,
 )
 from .source import QAPISourceInfo
 
@@ -335,7 +336,7 @@ const QLitObject %(c_name)s = %(c_string)s;
                                ifcond: QAPISchemaIfCond,
                                features: List[QAPISchemaFeature],
                                members: List[QAPISchemaObjectTypeMember],
-                               variants: Optional[QAPISchemaVariants]) -> None:
+                               variants: Optional[QAPISchemaBranches]) -> None:
         obj: SchemaInfoObject = {
             'members': [self._gen_object_member(m) for m in members]
         }
@@ -347,7 +348,7 @@ const QLitObject %(c_name)s = %(c_string)s;
     def visit_alternate_type(self, name: str, info: Optional[QAPISourceInfo],
                              ifcond: QAPISchemaIfCond,
                              features: List[QAPISchemaFeature],
-                             variants: QAPISchemaVariants) -> None:
+                             variants: QAPISchemaAlternatives) -> None:
         self._gen_tree(
             name, 'alternate',
             {'members': [Annotated({'type': self._use_type(m.type)},