qapi: add 'if' to union members

Add 'if' key to union members:

{ 'union': 'TestIfUnion', 'data':
    'mem': { 'type': 'str', 'if': 'COND'} }

The generated code remains unconditional for now. Later patches
generate the conditionals.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20181213123724.4866-16-marcandre.lureau@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>

docs/devel/qapi-code-gen.txt

@@ -754,7 +754,7 @@ gets its generated code guarded like this:
 
 Where a member can be defined with a single string value for its type,
 it is also possible to supply a dictionary instead with both 'type'
-and 'if' keys. (TODO: union and alternate)
+and 'if' keys. (TODO: alternate)
 
 Example: a conditional 'bar' member
 

scripts/qapi/common.py

@@ -803,7 +803,7 @@ def check_union(expr, info):
         check_name(info, "Member of union '%s'" % name, key)
 
         check_known_keys(info, "member '%s' of union '%s'" % (key, name),
-                         value, ['type'], [])
+                         value, ['type'], ['if'])
         # Each value must name a known type
         check_type(info, "Member '%s' of union '%s'" % (key, name),
                    value['type'],
@@ -1483,8 +1483,8 @@ class QAPISchemaObjectTypeVariants(object):
 class QAPISchemaObjectTypeVariant(QAPISchemaObjectTypeMember):
     role = 'branch'
 
-    def __init__(self, name, typ):
+    def __init__(self, name, typ, ifcond=None):
-        QAPISchemaObjectTypeMember.__init__(self, name, typ, False)
+        QAPISchemaObjectTypeMember.__init__(self, name, typ, False, ifcond)
 
 
 class QAPISchemaAlternateType(QAPISchemaType):
@@ -1757,14 +1757,14 @@ class QAPISchema(object):
     def _make_variant(self, case, typ):
         return QAPISchemaObjectTypeVariant(case, typ)
 
-    def _make_simple_variant(self, case, typ, info):
+    def _make_simple_variant(self, case, typ, ifcond, info):
         if isinstance(typ, list):
             assert len(typ) == 1
             typ = self._make_array_type(typ[0], info)
         typ = self._make_implicit_object_type(
             typ, info, None, self.lookup_type(typ),
             'wrapper', [self._make_member('data', typ, None, info)])
-        return QAPISchemaObjectTypeVariant(case, typ)
+        return QAPISchemaObjectTypeVariant(case, typ, ifcond)
 
     def _def_union_type(self, expr, info, doc):
         name = expr['union']
@@ -1782,9 +1782,10 @@ class QAPISchema(object):
                         for (key, value) in data.items()]
             members = []
         else:
-            variants = [self._make_simple_variant(key, value['type'], info)
+            variants = [self._make_simple_variant(key, value['type'],
+                                                  value.get('if'), info)
                         for (key, value) in data.items()]
-            enum = [{'name': v.name} for v in variants]
+            enum = [{'name': v.name, 'if': v.ifcond} for v in variants]
             typ = self._make_implicit_enum_type(name, info, ifcond, enum)
             tag_member = QAPISchemaObjectTypeMember('type', typ, False)
             members = [tag_member]

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

@@ -210,7 +210,9 @@
   [ 'foo', { 'name' : 'bar', 'if': 'defined(TEST_IF_ENUM_BAR)' } ],
   'if': 'defined(TEST_IF_ENUM)' }
 
-{ 'union': 'TestIfUnion', 'data': { 'foo': 'TestStruct' },
+{ 'union': 'TestIfUnion', 'data':
+  { 'foo': 'TestStruct',
+    'union_bar': { 'type': 'str', 'if': 'defined(TEST_IF_UNION_BAR)'} },
   'if': 'defined(TEST_IF_UNION) && defined(TEST_IF_STRUCT)' }
 
 { 'command': 'TestIfUnionCmd', 'data': { 'union_cmd_arg': 'TestIfUnion' },

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

@@ -280,11 +280,15 @@ object q_obj_TestStruct-wrapper
     member data: TestStruct optional=False
 enum TestIfUnionKind
     member foo
+    member union_bar
+        if ['defined(TEST_IF_UNION_BAR)']
     if ['defined(TEST_IF_UNION) && defined(TEST_IF_STRUCT)']
 object TestIfUnion
     member type: TestIfUnionKind optional=False
     tag type
     case foo: q_obj_TestStruct-wrapper
+    case union_bar: q_obj_str-wrapper
+        if ['defined(TEST_IF_UNION_BAR)']
     if ['defined(TEST_IF_UNION) && defined(TEST_IF_STRUCT)']
 object q_obj_TestIfUnionCmd-arg
     member union_cmd_arg: TestIfUnion optional=False

tests/qapi-schema/test-qapi.py

@@ -68,6 +68,7 @@ class QAPISchemaTestVisitor(QAPISchemaVisitor):
             print('    tag %s' % variants.tag_member.name)
             for v in variants.variants:
                 print('    case %s: %s' % (v.name, v.type.name))
+                QAPISchemaTestVisitor._print_if(v.ifcond, indent=8)
 
     @staticmethod
     def _print_if(ifcond, indent=4):