qapi: Add feature flags to struct members

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20200317115459.31821-21-armbru@redhat.com>

docs/devel/qapi-code-gen.txt

@@ -234,7 +234,9 @@ Syntax:
                '*features': FEATURES }
     MEMBERS = { MEMBER, ... }
     MEMBER = STRING : TYPE-REF
-           | STRING : { 'type': TYPE-REF, '*if': COND }
+           | STRING : { 'type': TYPE-REF,
+                        '*if': COND,
+                        '*features': FEATURES }
 
 Member 'struct' names the struct type.
 

qapi/introspect.json

@@ -206,11 +206,15 @@
 #           Future extension: if present and non-null, the parameter
 #           is optional, and defaults to this value.
 #
+# @features: names of features associated with the member, in no
+#            particular order.  (since 5.0)
+#
 # Since: 2.5
 ##
 { 'struct': 'SchemaInfoObjectMember',
-  'data': { 'name': 'str', 'type': 'str', '*default': 'any' } }
+  'data': { 'name': 'str', 'type': 'str', '*default': 'any',
 # @default's type must be null or match @type
+            '*features': [ 'str' ] } }
 
 ##
 # @SchemaInfoObjectVariant:

scripts/qapi/expr.py

@@ -167,8 +167,9 @@ def check_type(value, info, source,
                        allow_optional=True, permit_upper=permit_upper)
         if c_name(key, False) == 'u' or c_name(key, False).startswith('has_'):
             raise QAPISemError(info, "%s uses reserved name" % key_source)
-        check_keys(arg, info, key_source, ['type'], ['if'])
+        check_keys(arg, info, key_source, ['type'], ['if', 'features'])
         check_if(arg, info, key_source)
+        check_features(arg.get('features'), info)
         check_type(arg['type'], info, key_source, allow_array=True)
 
 

scripts/qapi/introspect.py

@@ -173,7 +173,7 @@ const QLitObject %(c_name)s = %(c_string)s;
         obj = {'name': member.name, 'type': self._use_type(member.type)}
         if member.optional:
             obj['default'] = None
-        return _make_tree(obj, member.ifcond, None)
+        return _make_tree(obj, member.ifcond, member.features)
 
     def _gen_variants(self, tag_name, variants):
         return {'tag': tag_name,

scripts/qapi/schema.py

@@ -668,18 +668,31 @@ class QAPISchemaFeature(QAPISchemaMember):
 
 
 class QAPISchemaObjectTypeMember(QAPISchemaMember):
-    def __init__(self, name, info, typ, optional, ifcond=None):
+    def __init__(self, name, info, typ, optional, ifcond=None, features=None):
         super().__init__(name, info, ifcond)
         assert isinstance(typ, str)
         assert isinstance(optional, bool)
+        for f in features or []:
+            assert isinstance(f, QAPISchemaFeature)
+            f.set_defined_in(name)
         self._type_name = typ
         self.type = None
         self.optional = optional
+        self.features = features or []
 
     def check(self, schema):
         assert self.defined_in
         self.type = schema.resolve_type(self._type_name, self.info,
                                         self.describe)
+        seen = {}
+        for f in self.features:
+            f.check_clash(self.info, seen)
+
+    def connect_doc(self, doc):
+        super().connect_doc(doc)
+        if doc:
+            for f in self.features:
+                doc.connect_feature(f)
 
 
 class QAPISchemaVariant(QAPISchemaObjectTypeMember):
@@ -962,7 +975,7 @@ class QAPISchema:
             name, info, doc, ifcond, features,
             self._make_enum_members(data, info), prefix))
 
-    def _make_member(self, name, typ, ifcond, info):
+    def _make_member(self, name, typ, ifcond, features, info):
         optional = False
         if name.startswith('*'):
             name = name[1:]
@@ -970,10 +983,12 @@ class QAPISchema:
         if isinstance(typ, list):
             assert len(typ) == 1
             typ = self._make_array_type(typ[0], info)
-        return QAPISchemaObjectTypeMember(name, info, typ, optional, ifcond)
+        return QAPISchemaObjectTypeMember(name, info, typ, optional, ifcond,
+                                          self._make_features(features, info))
 
     def _make_members(self, data, info):
-        return [self._make_member(key, value['type'], value.get('if'), info)
+        return [self._make_member(key, value['type'], value.get('if'),
+                                  value.get('features'), info)
                 for (key, value) in data.items()]
 
     def _def_struct_type(self, expr, info, doc):
@@ -996,7 +1011,7 @@ class QAPISchema:
             typ = self._make_array_type(typ[0], info)
         typ = self._make_implicit_object_type(
             typ, info, self.lookup_type(typ),
-            'wrapper', [self._make_member('data', typ, None, info)])
+            'wrapper', [self._make_member('data', typ, None, None, info)])
         return QAPISchemaVariant(case, info, typ, ifcond)
 
     def _def_union_type(self, expr, info, doc):

tests/qapi-schema/doc-good.json

@@ -78,10 +78,13 @@
 #
 # Features:
 # @variant1-feat: a feature
+# @member-feat: a member feature
 ##
 { 'struct': 'Variant1',
   'features': [ 'variant1-feat' ],
-  'data': { 'var1': { 'type': 'str', 'if': 'defined(IFSTR)' } } }
+  'data': { 'var1': { 'type': 'str',
+                      'features': [ 'member-feat' ],
+                      'if': 'defined(IFSTR)' } } }
 
 ##
 # @Variant2:

tests/qapi-schema/doc-good.out

@@ -21,6 +21,7 @@ object Base
 object Variant1
     member var1: str optional=False
         if ['defined(IFSTR)']
+        feature member-feat
     feature variant1-feat
 object Variant2
 object Object
@@ -135,6 +136,8 @@ Another paragraph (but no @var: line)
 
     feature=variant1-feat
 a feature
+    feature=member-feat
+a member feature
 doc symbol=Variant2
     body=
 

tests/qapi-schema/doc-good.texi

@@ -132,6 +132,8 @@ Not documented
 @table @asis
 @item @code{variant1-feat}
 a feature
+@item @code{member-feat}
+a member feature
 @end table
 
 @end deftp

tests/qapi-schema/qapi-schema-test.json

@@ -258,7 +258,7 @@
   'data': { 'foo': 'int' },
   'features': [] }
 { 'struct': 'FeatureStruct1',
-  'data': { 'foo': 'int' },
+  'data': { 'foo': { 'type': 'int', 'features': [ 'member-feature1' ] } },
   'features': [ 'feature1' ] }
 { 'struct': 'FeatureStruct2',
   'data': { 'foo': 'int' },

tests/qapi-schema/qapi-schema-test.out

@@ -359,6 +359,7 @@ object FeatureStruct0
     member foo: int optional=False
 object FeatureStruct1
     member foo: int optional=False
+        feature member-feature1
     feature feature1
 object FeatureStruct2
     member foo: int optional=False

tests/qapi-schema/test-qapi.py

@@ -55,6 +55,7 @@ class QAPISchemaTestVisitor(QAPISchemaVisitor):
             print('    member %s: %s optional=%s'
                   % (m.name, m.type.name, m.optional))
             self._print_if(m.ifcond, 8)
+            self._print_features(m.features, indent=8)
         self._print_variants(variants)
         self._print_if(ifcond)
         self._print_features(features)
@@ -96,11 +97,11 @@ class QAPISchemaTestVisitor(QAPISchemaVisitor):
             print('%sif %s' % (' ' * indent, ifcond))
 
     @classmethod
-    def _print_features(cls, features):
+    def _print_features(cls, features, indent=4):
         if features:
             for f in features:
-                print('    feature %s' % f.name)
-                cls._print_if(f.ifcond, 8)
+                print('%sfeature %s' % (' ' * indent, f.name))
+                cls._print_if(f.ifcond, indent + 4)
 
 
 def test_frontend(fname):