qapi: Add feature flags to enum members

This is quite similar to commit 84ab008687 "qapi: Add feature flags to
struct members", only for enums instead of structs.

Special feature flag 'deprecated' is silently ignored there.  This is
okay only because it will be implemented shortly.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <20211025042405.3762351-3-armbru@redhat.com>
Reviewed-by: John Snow <jsnow@redhat.com>

scripts/qapi/expr.py

@@ -472,7 +472,7 @@ def check_enum(expr: _JSONObject, info: QAPISourceInfo) -> None:
                   for m in members]
     for member in members:
         source = "'data' member"
-        check_keys(member, info, source, ['name'], ['if'])
+        check_keys(member, info, source, ['name'], ['if', 'features'])
         member_name = member['name']
         check_name_is_str(member_name, info, source)
         source = "%s '%s'" % (source, member_name)
@@ -483,6 +483,7 @@ def check_enum(expr: _JSONObject, info: QAPISourceInfo) -> None:
                          permit_upper=permissive,
                          permit_underscore=permissive)
         check_if(member, info, source)
+        check_features(member.get('features'), info)
 
 
 def check_struct(expr: _JSONObject, info: QAPISourceInfo) -> None:

scripts/qapi/introspect.py

@@ -275,12 +275,13 @@ const QLitObject %(c_name)s = %(c_string)s;
             obj['features'] = self._gen_features(features)
         self._trees.append(Annotated(obj, ifcond, comment))
 
-    @staticmethod
-    def _gen_enum_member(member: QAPISchemaEnumMember
+    def _gen_enum_member(self, member: QAPISchemaEnumMember
                          ) -> Annotated[SchemaInfoEnumMember]:
         obj: SchemaInfoEnumMember = {
             'name': member.name,
         }
+        if member.features:
+            obj['features'] = self._gen_features(member.features)
         return Annotated(obj, member.ifcond)
 
     def _gen_object_member(self, member: QAPISchemaObjectTypeMember

scripts/qapi/schema.py

@@ -708,6 +708,19 @@ class QAPISchemaMember:
 class QAPISchemaEnumMember(QAPISchemaMember):
     role = 'value'
 
+    def __init__(self, name, info, ifcond=None, features=None):
+        super().__init__(name, info, ifcond)
+        for f in features or []:
+            assert isinstance(f, QAPISchemaFeature)
+            f.set_defined_in(name)
+        self.features = features or []
+
+    def connect_doc(self, doc):
+        super().connect_doc(doc)
+        if doc:
+            for f in self.features:
+                doc.connect_feature(f)
+
 
 class QAPISchemaFeature(QAPISchemaMember):
     role = 'feature'
@@ -980,9 +993,14 @@ class QAPISchema:
                                   QAPISchemaIfCond(f.get('if')))
                 for f in features]
 
+    def _make_enum_member(self, name, ifcond, features, info):
+        return QAPISchemaEnumMember(name, info,
+                                    QAPISchemaIfCond(ifcond),
+                                    self._make_features(features, info))
+
     def _make_enum_members(self, values, info):
-        return [QAPISchemaEnumMember(v['name'], info,
-                                     QAPISchemaIfCond(v.get('if')))
+        return [self._make_enum_member(v['name'], v.get('if'),
+                                       v.get('features'), info)
                 for v in values]
 
     def _make_array_type(self, element_type, info):