don't use a slot wrapper from a different special method (closes #14658)

This also alters the fix to #11603. Specifically, setting __repr__ to
object.__str__ now raises a recursion RuntimeError when str() or repr() is
called instead of silently bypassing the recursion. I believe this behavior is
more correct.

Lib/test/test_descr.py

@@ -4591,7 +4591,15 @@ order (MRO) for bases """
             pass
         Foo.__repr__ = Foo.__str__
         foo = Foo()
-        str(foo)
+        self.assertRaises(RuntimeError, str, foo)
+        self.assertRaises(RuntimeError, repr, foo)
+
+    def test_mixing_slot_wrappers(self):
+        class X(dict):
+            __setattr__ = dict.__setitem__
+        x = X()
+        x.y = 42
+        self.assertEqual(x["y"], 42)
 
     def test_cycle_through_dict(self):
         # See bug #1469629

Misc/NEWS

@@ -9,6 +9,12 @@ What's New in Python 2.7.4
 Core and Builtins
 -----------------
 
+- Issue #11603 (again): Setting __repr__ to __str__ now raises a RuntimeError
+  when repr() or str() is called on such an object.
+
+- Issue #14658: Fix binding a special method to a builtin implementation of a
+  special method with a different name.
+
 - Issue #14612: Fix jumping around with blocks by setting f_lineno.
 
 - Issue #13889: Check and (if necessary) set FPU control word before calling

Objects/typeobject.c

@@ -2996,7 +2996,7 @@ object_str(PyObject *self)
     unaryfunc f;
 
     f = Py_TYPE(self)->tp_repr;
-    if (f == NULL || f == object_str)
+    if (f == NULL)
         f = object_repr;
     return f(self);
 }
@@ -6143,7 +6143,8 @@ update_one_slot(PyTypeObject *type, slotdef *p)
             }
             continue;
         }
-        if (Py_TYPE(descr) == &PyWrapperDescr_Type) {
+        if (Py_TYPE(descr) == &PyWrapperDescr_Type &&
+            ((PyWrapperDescrObject *)descr)->d_base->name_strobj == p->name_strobj) {
             void **tptr = resolve_slotdups(type, p->name_strobj);
             if (tptr == NULL || tptr == ptr)
                 generic = p->function;