Preserve metaclass when slots=True (#155)

dev-requirements.txt

@@ -3,3 +3,4 @@ pytest
 zope.interface
 pympler
 hypothesis
+six

src/attr/_make.py

@@ -362,7 +362,7 @@ def wrap(cls):
             cls_dict.pop("__dict__", None)
 
             qualname = getattr(cls, "__qualname__", None)
-            cls = type(cls.__name__, cls.__bases__, cls_dict)
+            cls = type(cls)(cls.__name__, cls.__bases__, cls_dict)
             if qualname is not None:
                 cls.__qualname__ = qualname
 

tests/test_dark_magic.py

@@ -3,6 +3,7 @@
 import pickle
 
 import pytest
+import six
 
 from hypothesis import given
 from hypothesis.strategies import booleans
@@ -82,6 +83,22 @@ class FrozenNoSlots(object):
     x = attr.ib()
 
 
+class Meta(type):
+    pass
+
+
+@attr.s
+@six.add_metaclass(Meta)
+class WithMeta(object):
+    pass
+
+
+@attr.s(slots=True)
+@six.add_metaclass(Meta)
+class WithMetaSlots(object):
+    pass
+
+
 class TestDarkMagic(object):
     """
     Integration tests.
@@ -231,3 +248,7 @@ def test_subclassing_frozen_gives_frozen(self):
 
         assert i.x == "foo"
         assert i.y == "bar"
+
+    @pytest.mark.parametrize("cls", [WithMeta, WithMetaSlots])
+    def test_metaclass_preserved(self, cls):
+        assert Meta == type(cls)