diff --git a/scripts/qapi-visit.py b/scripts/qapi-visit.py
index c493964..cfebcb7 100644
--- a/scripts/qapi-visit.py
+++ b/scripts/qapi-visit.py
@@ -12,7 +12,6 @@
 # This work is licensed under the terms of the GNU GPL, version 2.
 # See the COPYING file in the top-level directory.
 
-from ordereddict import OrderedDict
 from qapi import *
 import re
 
@@ -24,13 +23,13 @@ def generate_visit_implicit_struct(type):
         return ''
     implicit_structs_seen.add(type)
     ret = ''
-    if type not in struct_fields_seen:
+    if type.name not in struct_fields_seen:
         # Need a forward declaration
         ret += mcgen('''
 
 static void visit_type_%(c_type)s_fields(Visitor *m, %(c_type)s **obj, Error **errp);
 ''',
-                     c_type=type_name(type))
+                     c_type=type.c_name())
 
     ret += mcgen('''
 
@@ -46,7 +45,7 @@ static void visit_type_implicit_%(c_type)s(Visitor *m, %(c_type)s **obj, Error *
     error_propagate(errp, err);
 }
 ''',
-                 c_type=type_name(type))
+                 c_type=type.c_name())
     return ret
 
 def generate_visit_struct_fields(name, members, base = None):
@@ -74,24 +73,24 @@ if (err) {
     goto out;
 }
 ''',
-                     type=type_name(base), c_name=c_name('base'))
+                     type=base.c_name(), c_name=c_name('base'))
 
-    for argname, argentry, optional in parse_args(members):
-        if optional:
+    for memb in members:
+        if memb.optional:
             ret += mcgen('''
 visit_optional(m, &(*obj)->has_%(c_name)s, "%(name)s", &err);
 if (!err && (*obj)->has_%(c_name)s) {
 ''',
-                         c_name=c_name(argname), name=argname)
+                         c_name=c_name(memb.name), name=memb.name)
             push_indent()
 
         ret += mcgen('''
 visit_type_%(type)s(m, &(*obj)->%(c_name)s, "%(name)s", &err);
 ''',
-                     type=type_name(argentry), c_name=c_name(argname),
-                     name=argname)
+                     type=memb.type.c_name(), c_name=c_name(memb.name),
+                     name=memb.name)
 
-        if optional:
+        if memb.optional:
             pop_indent()
             ret += mcgen('''
 }
@@ -136,12 +135,7 @@ def generate_visit_struct_body(name):
 
     return ret
 
-def generate_visit_struct(expr):
-
-    name = expr['struct']
-    members = expr['data']
-    base = expr.get('base')
-
+def gen_visit_struct(name, base, members):
     ret = generate_visit_struct_fields(name, members, base)
 
     ret += mcgen('''
@@ -158,10 +152,10 @@ void visit_type_%(name)s(Visitor *m, %(name)s **obj, const char *name, Error **e
 ''')
     return ret
 
-def generate_visit_list(name):
+def gen_visit_list(name, element_type):
     return mcgen('''
 
-void visit_type_%(name)sList(Visitor *m, %(name)sList **obj, const char *name, Error **errp)
+void visit_type_%(name)s(Visitor *m, %(name)s **obj, const char *name, Error **errp)
 {
     Error *err = NULL;
     GenericList *i, **prev;
@@ -174,8 +168,8 @@ void visit_type_%(name)sList(Visitor *m, %(name)sList **obj, const char *name, E
     for (prev = (GenericList **)obj;
          !err && (i = visit_next_list(m, prev, &err)) != NULL;
          prev = &i) {
-        %(name)sList *native_i = (%(name)sList *)i;
-        visit_type_%(name)s(m, &native_i->value, NULL, &err);
+        %(name)s *native_i = (%(name)s *)i;
+        visit_type_%(c_elt_type)s(m, &native_i->value, NULL, &err);
     }
 
     error_propagate(errp, err);
@@ -185,7 +179,8 @@ out:
     error_propagate(errp, err);
 }
 ''',
-                name=type_name(name))
+                 name=c_name(name),
+                 c_elt_type=element_type.c_name())
 
 def generate_visit_enum(name):
     return mcgen('''
@@ -197,7 +192,7 @@ void visit_type_%(c_name)s(Visitor *m, %(c_name)s *obj, const char *name, Error
 ''',
                  c_name=c_name(name), name=name)
 
-def generate_visit_alternate(name, members):
+def gen_visit_alternate(name, variants):
     ret = mcgen('''
 
 void visit_type_%(name)s(Visitor *m, %(name)s **obj, const char *name, Error **errp)
@@ -216,25 +211,17 @@ void visit_type_%(name)s(Visitor *m, %(name)s **obj, const char *name, Error **e
 ''',
                 name=c_name(name))
 
-    # For alternate, always use the default enum type automatically generated
-    # as name + 'Kind'
-    disc_type = c_name(name) + 'Kind'
-
-    for key in members:
-        assert (members[key] in builtin_types.keys()
-            or find_struct(members[key])
-            or find_union(members[key])
-            or find_enum(members[key])), "Invalid alternate member"
-
-        enum_full_value = c_enum_const(disc_type, key)
+    for var in variants.variants:
+        enum_full_value = c_enum_const(variants.tag_member.type.name,
+                                       var.name)
         ret += mcgen('''
     case %(enum_full_value)s:
         visit_type_%(c_type)s(m, &(*obj)->%(c_name)s, name, &err);
         break;
 ''',
                 enum_full_value = enum_full_value,
-                c_type = type_name(members[key]),
-                c_name = c_name(key))
+                c_type=var.type.c_name(),
+                c_name=c_name(var.name))
 
     ret += mcgen('''
     default:
@@ -251,35 +238,17 @@ out:
 
     return ret
 
-
-def generate_visit_union(expr):
-
-    name = expr['union']
-    members = expr['data']
-
-    base = expr.get('base')
-    discriminator = expr.get('discriminator')
-
-    enum_define = discriminator_find_enum_define(expr)
-    if enum_define:
-        # Use the enum type as discriminator
-        ret = ""
-        disc_type = c_name(enum_define['enum_name'])
-    else:
-        # There will always be a discriminator in the C switch code, by default
-        # it is an enum type generated silently
-        ret = generate_visit_enum(name + 'Kind')
-        disc_type = c_name(name) + 'Kind'
+def gen_visit_union(name, base, variants):
+    ret = ''
 
     if base:
-        assert discriminator
-        base_fields = find_struct(base)['data'].copy()
-        del base_fields[discriminator]
-        ret += generate_visit_struct_fields(name, base_fields)
+        members = [m for m in base.members if m != variants.tag_member]
+        ret += generate_visit_struct_fields(name, members)
 
-    if discriminator:
-        for key in members:
-            ret += generate_visit_implicit_struct(members[key])
+    for var in variants.variants:
+        # Ugly special case for simple union TODO get rid of it
+        if not var.simple_union_type():
+            ret += generate_visit_implicit_struct(var.type)
 
     ret += mcgen('''
 
@@ -304,41 +273,44 @@ void visit_type_%(c_name)s(Visitor *m, %(c_name)s **obj, const char *name, Error
 ''',
                      name=c_name(name))
 
-    if not discriminator:
-        tag = 'kind'
-        disc_key = "type"
-    else:
-        tag = discriminator
-        disc_key = discriminator
+    disc_key = variants.tag_member.name
+    if not variants.tag_name:
+        # we pointlessly use a different key for simple unions
+        disc_key = 'type'
     ret += mcgen('''
-        visit_type_%(disc_type)s(m, &(*obj)->%(c_tag)s, "%(disc_key)s", &err);
+        visit_type_%(disc_type)s(m, &(*obj)->%(c_name)s, "%(disc_key)s", &err);
         if (err) {
             goto out_obj;
         }
         if (!visit_start_union(m, !!(*obj)->data, &err) || err) {
             goto out_obj;
         }
-        switch ((*obj)->%(c_tag)s) {
+        switch ((*obj)->%(c_name)s) {
 ''',
-                 disc_type = disc_type,
-                 c_tag=c_name(tag),
+                 disc_type=variants.tag_member.type.c_name(),
+                 # TODO ugly special case for simple union
+                 # Use same tag name in C as on the wire to get rid of
+                 # it, then: c_name=c_name(variants.tag_member.name)
+                 c_name=c_name(variants.tag_name or 'kind'),
                  disc_key = disc_key)
 
-    for key in members:
-        if not discriminator:
+    for var in variants.variants:
+        # TODO ugly special case for simple union
+        simple_union_type = var.simple_union_type()
+        if simple_union_type:
             fmt = 'visit_type_%(c_type)s(m, &(*obj)->%(c_name)s, "data", &err);'
         else:
             fmt = 'visit_type_implicit_%(c_type)s(m, &(*obj)->%(c_name)s, &err);'
 
-        enum_full_value = c_enum_const(disc_type, key)
+        enum_full_value = c_enum_const(variants.tag_member.type.name, var.name)
         ret += mcgen('''
         case %(enum_full_value)s:
             ''' + fmt + '''
             break;
 ''',
                 enum_full_value = enum_full_value,
-                c_type=type_name(members[key]),
-                c_name=c_name(key))
+                c_type=(simple_union_type or var.type).c_name(),
+                c_name=c_name(var.name))
 
     ret += mcgen('''
         default:
@@ -359,38 +331,68 @@ out:
 
     return ret
 
-def generate_declaration(name, builtin_type=False):
-    ret = ""
-    if not builtin_type:
-        name = c_name(name)
-        ret += mcgen('''
-
-void visit_type_%(name)s(Visitor *m, %(name)s **obj, const char *name, Error **errp);
-''',
-                     name=name)
-
-    ret += mcgen('''
-void visit_type_%(name)sList(Visitor *m, %(name)sList **obj, const char *name, Error **errp);
-''',
-                 name=name)
-
-    return ret
-
-def generate_enum_declaration(name):
-    ret = mcgen('''
-void visit_type_%(name)sList(Visitor *m, %(name)sList **obj, const char *name, Error **errp);
-''',
-                name=c_name(name))
-
-    return ret
-
-def generate_decl_enum(name):
+def gen_visit_decl(name, scalar=False):
+    c_type = c_name(name) + ' *'
+    if not scalar:
+        c_type += '*'
     return mcgen('''
-
-void visit_type_%(name)s(Visitor *m, %(name)s *obj, const char *name, Error **errp);
+void visit_type_%(c_name)s(Visitor *m, %(c_type)sobj, const char *name, Error **errp);
 ''',
-                 name=c_name(name))
+                 c_name=c_name(name), c_type=c_type)
 
+
+class QAPISchemaGenVisitVisitor(QAPISchemaVisitor):
+    def __init__(self):
+        self.decl = None
+        self.defn = None
+        self._btin = None
+
+    def visit_begin(self, schema):
+        self.decl = ''
+        self.defn = ''
+        self._btin = guardstart('QAPI_VISIT_BUILTIN')
+
+    def visit_end(self):
+        # To avoid header dependency hell, we always generate
+        # declarations for built-in types in our header files and
+        # simply guard them.  See also do_builtins (command line
+        # option -b).
+        self._btin += guardend('QAPI_VISIT_BUILTIN')
+        self.decl = self._btin + self.decl
+        self._btin = None
+
+    def visit_enum_type(self, name, info, values):
+        self.decl += gen_visit_decl(name, scalar=True)
+        self.defn += generate_visit_enum(name)
+
+    def visit_array_type(self, name, info, element_type):
+        decl = gen_visit_decl(name)
+        defn = gen_visit_list(name, element_type)
+        if isinstance(element_type, QAPISchemaBuiltinType):
+            self._btin += decl
+            if do_builtins:
+                self.defn += defn
+        else:
+            self.decl += decl
+            self.defn += defn
+
+    def visit_object_type(self, name, info, base, members, variants):
+        if info:
+            self.decl += gen_visit_decl(name)
+            if variants:
+                assert not members      # not implemented
+                self.defn += gen_visit_union(name, base, variants)
+            else:
+                self.defn += gen_visit_struct(name, base, members)
+
+    def visit_alternate_type(self, name, info, variants):
+        self.decl += gen_visit_decl(name)
+        self.defn += gen_visit_alternate(name, variants)
+
+# If you link code generated from multiple schemata, you want only one
+# instance of the code for built-in types.  Generate it only when
+# do_builtins, enabled by command line option -b.  See also
+# QAPISchemaGenVisitVisitor.visit_end().
 do_builtins = False
 
 (input_file, output_dir, do_c, do_h, prefix, opts) = \
@@ -446,56 +448,10 @@ fdecl.write(mcgen('''
 ''',
                   prefix=prefix))
 
-exprs = QAPISchema(input_file).get_exprs()
-
-# to avoid header dependency hell, we always generate declarations
-# for built-in types in our header files and simply guard them
-fdecl.write(guardstart("QAPI_VISIT_BUILTIN_VISITOR_DECL"))
-for typename in builtin_types.keys():
-    fdecl.write(generate_declaration(typename, builtin_type=True))
-fdecl.write(guardend("QAPI_VISIT_BUILTIN_VISITOR_DECL"))
-
-# ...this doesn't work for cases where we link in multiple objects that
-# have the functions defined, so we use -b option to provide control
-# over these cases
-if do_builtins:
-    for typename in builtin_types.keys():
-        fdef.write(generate_visit_list(typename))
-
-for expr in exprs:
-    if expr.has_key('struct'):
-        ret = generate_visit_struct(expr)
-        ret += generate_visit_list(expr['struct'])
-        fdef.write(ret)
-
-        ret = generate_declaration(expr['struct'])
-        fdecl.write(ret)
-    elif expr.has_key('union'):
-        ret = generate_visit_union(expr)
-        ret += generate_visit_list(expr['union'])
-        fdef.write(ret)
-
-        enum_define = discriminator_find_enum_define(expr)
-        ret = ""
-        if not enum_define:
-            ret = generate_decl_enum('%sKind' % expr['union'])
-        ret += generate_declaration(expr['union'])
-        fdecl.write(ret)
-    elif expr.has_key('alternate'):
-        ret = generate_visit_alternate(expr['alternate'], expr['data'])
-        ret += generate_visit_list(expr['alternate'])
-        fdef.write(ret)
-
-        ret = generate_decl_enum('%sKind' % expr['alternate'])
-        ret += generate_declaration(expr['alternate'])
-        fdecl.write(ret)
-    elif expr.has_key('enum'):
-        ret = generate_visit_list(expr['enum'])
-        ret += generate_visit_enum(expr['enum'])
-        fdef.write(ret)
-
-        ret = generate_decl_enum(expr['enum'])
-        ret += generate_enum_declaration(expr['enum'])
-        fdecl.write(ret)
+schema = QAPISchema(input_file)
+gen = QAPISchemaGenVisitVisitor()
+schema.visit(gen)
+fdef.write(gen.defn)
+fdecl.write(gen.decl)
 
 close_output(fdef, fdecl)
diff --git a/tests/qapi-schema/qapi-schema-test.json b/tests/qapi-schema/qapi-schema-test.json
index 257b4d4..b182174 100644
--- a/tests/qapi-schema/qapi-schema-test.json
+++ b/tests/qapi-schema/qapi-schema-test.json
@@ -39,8 +39,6 @@
   'data': { 'value1' : 'UserDefA',
             'value2' : 'UserDefB',
             'value3' : 'UserDefB' } }
-# FIXME generated visit_type_UserDefFlatUnion_fields() fails to visit
-# members of indirect base UserDefZero
 
 { 'struct': 'UserDefUnionBase',
   'base': 'UserDefZero',
@@ -57,7 +55,6 @@
 
 { 'alternate': 'UserDefAlternate',
   'data': { 'uda': 'UserDefA', 's': 'str', 'i': 'int' } }
-# FIXME only a declaration of visit_type_UserDefAlternateKind() generated
 
 { 'struct': 'UserDefC',
   'data': { 'string1': 'str', 'string2': 'str' } }
diff --git a/tests/test-qmp-input-strict.c b/tests/test-qmp-input-strict.c
index 68f855b..a2ae786 100644
--- a/tests/test-qmp-input-strict.c
+++ b/tests/test-qmp-input-strict.c
@@ -167,9 +167,9 @@ static void test_validate_union_flat(TestInputVisitorData *data,
 
     v = validate_test_init(data,
                            "{ 'enum1': 'value1', "
+                           "'integer': 41, "
                            "'string': 'str', "
                            "'boolean': true }");
-    /* TODO when generator bug is fixed, add 'integer': 41 */
 
     visit_type_UserDefFlatUnion(v, &tmp, NULL, &err);
     g_assert(!err);
@@ -272,7 +272,7 @@ static void test_validate_fail_union_flat_no_discrim(TestInputVisitorData *data,
     Visitor *v;
 
     /* test situation where discriminator field ('enum1' here) is missing */
-    v = validate_test_init(data, "{ 'string': 'c', 'string1': 'd', 'string2': 'e' }");
+    v = validate_test_init(data, "{ 'integer': 42, 'string': 'c', 'string1': 'd', 'string2': 'e' }");
 
     visit_type_UserDefFlatUnion2(v, &tmp, NULL, &err);
     g_assert(err);
diff --git a/tests/test-qmp-input-visitor.c b/tests/test-qmp-input-visitor.c
index a5cfefa..508c11a 100644
--- a/tests/test-qmp-input-visitor.c
+++ b/tests/test-qmp-input-visitor.c
@@ -307,15 +307,15 @@ static void test_visitor_in_union_flat(TestInputVisitorData *data,
 
     v = visitor_input_test_init(data,
                                 "{ 'enum1': 'value1', "
+                                "'integer': 41, "
                                 "'string': 'str', "
                                 "'boolean': true }");
-    /* TODO when generator bug is fixed, add 'integer': 41 */
 
     visit_type_UserDefFlatUnion(v, &tmp, NULL, &err);
     g_assert(err == NULL);
     g_assert_cmpint(tmp->enum1, ==, ENUM_ONE_VALUE1);
     g_assert_cmpstr(tmp->string, ==, "str");
-    /* TODO g_assert_cmpint(tmp->integer, ==, 41); */
+    g_assert_cmpint(tmp->integer, ==, 41);
     g_assert_cmpint(tmp->value1->boolean, ==, true);
     qapi_free_UserDefFlatUnion(tmp);
 }
