Fix: TypeError when using properties, super(), and slots=True (#652)

changelog.d/747.change.rst

@@ -0,0 +1 @@
+Fixed ``TypeError`` when using properties, ``super()``, and ``slots=True``.

src/attr/_make.py

@@ -795,6 +795,13 @@ def _create_slots_class(self):
                 # Class- and staticmethods hide their functions inside.
                 # These might need to be rewritten as well.
                 closure_cells = getattr(item.__func__, "__closure__", None)
+            elif isinstance(item, property):
+                # Workaround for property `super()` (PY3-only).
+                # There is no universal way for other descriptors.
+                if PY2:
+                    closure_cells = None
+                else:
+                    closure_cells = getattr(item.fget, "__closure__", None)
             else:
                 closure_cells = getattr(item, "__closure__", None)
 

tests/test_slots.py

@@ -689,3 +689,27 @@ def test_getstate_set_state_force_true(self, cls):
         """
         assert None is not getattr(cls, "__getstate__", None)
         assert None is not getattr(cls, "__setstate__", None)
+
+
+@pytest.mark.skipif(PY2, reason="shortcut super() is PY3-only.")
+def test_slots_super_property_get():
+    """
+    In Python 3, the `super()` shortcut is allowed.
+    """
+
+    @attr.s(slots=True)
+    class A(object):
+        x = attr.ib()
+
+        @property
+        def f(self):
+            return self.x
+
+    @attr.s(slots=True)
+    class B(A):
+        @property
+        def f(self):
+            return super().f ** 2
+
+    assert B(11).f == 121
+    assert B(17).f == 289