support ext type inheritance from builtin types

Cython/Compiler/ModuleNode.py

@@ -1996,7 +1996,8 @@ class ModuleNode(Nodes.Node, Nodes.BlockNode):
 
     def generate_base_type_import_code(self, env, entry, code):
         base_type = entry.type.base_type
-        if base_type and base_type.module_name != env.qualified_name:
+        if base_type and base_type.module_name != env.qualified_name \
+               and not base_type.is_builtin_type:
             self.generate_type_import_code(env, base_type, self.pos, code)
     
     def use_type_import_utility_code(self, env):

Cython/Compiler/Nodes.py

@@ -3192,7 +3192,9 @@ class CClassDefNode(ClassDefNode):
                 if base_class_entry:
                     if not base_class_entry.is_type:
                         error(self.pos, "'%s' is not a type name" % self.base_class_name)
-                    elif not base_class_entry.type.is_extension_type:
+                    elif not base_class_entry.type.is_extension_type and \
+                             not (base_class_entry.type.is_builtin_type and \
+                                  base_class_entry.type.objstruct_cname):
                         error(self.pos, "'%s' is not an extension type" % self.base_class_name)
                     elif not base_class_entry.type.is_complete():
                         error(self.pos, "Base class '%s' of type '%s' is incomplete" % (

Cython/Compiler/PyrexTypes.py

@@ -380,10 +380,17 @@ class BuiltinObjectType(PyObjectType):
     base_type = None
     module_name = '__builtin__'
 
+    # fields that let it look like an extension type
+    vtabslot_cname = None
+    vtabstruct_cname = None
+    vtabptr_cname = None
+    typedef_flag = True
+    is_external = True
+
     def __init__(self, name, cname, objstruct_cname=None):
         self.name = name
         self.cname = cname
-        self.typeptr_cname = "&" + cname
+        self.typeptr_cname = "(&%s)" % cname
         self.objstruct_cname = objstruct_cname
                                  
     def set_scope(self, scope):