From 304f0f952da3c2f1d354b1701aa5ad61b53ff179 Mon Sep 17 00:00:00 2001
From: Antoine Pitrou <solipsis@pitrou.net>
Date: Fri, 15 Jul 2011 21:22:50 +0200
Subject: [PATCH] =?UTF-8?q?Issue=20#11603:=20Fix=20a=20crash=20when=20=5F?=
 =?UTF-8?q?=5Fstr=5F=5F=20is=20rebound=20as=20=5F=5Frepr=5F=5F.=20Patch=20?=
 =?UTF-8?q?by=20Andreas=20St=C3=BChrk.?=
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---
 Lib/test/test_descr.py | 8 ++++++++
 Misc/NEWS              | 3 +++
 Objects/typeobject.c   | 2 +-
 3 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/Lib/test/test_descr.py b/Lib/test/test_descr.py
index b5d98900e23..964cc5cf564 100644
--- a/Lib/test/test_descr.py
+++ b/Lib/test/test_descr.py
@@ -4581,6 +4581,14 @@ order (MRO) for bases """
         with self.assertRaises(TypeError):
             str.__add__(fake_str, "abc")
 
+    def test_repr_as_str(self):
+        # Issue #11603: crash or infinite loop when rebinding __str__ as
+        # __repr__.
+        class Foo(object):
+            pass
+        Foo.__repr__ = Foo.__str__
+        foo = Foo()
+        str(foo)
 
 class DictProxyTests(unittest.TestCase):
     def setUp(self):
diff --git a/Misc/NEWS b/Misc/NEWS
index 867ef9ce6cc..2ec44d9a6a7 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -33,6 +33,9 @@ Core and Builtins
 Library
 -------
 
+- Issue #11603: Fix a crash when __str__ is rebound as __repr__.  Patch by
+  Andreas Stührk.
+
 - Issue #12502: asyncore: fix polling loop with AF_UNIX sockets.
 
 - Issue #4376: ctypes now supports nested structures in a endian different than
diff --git a/Objects/typeobject.c b/Objects/typeobject.c
index 8326d073f10..3864b48b4bb 100644
--- a/Objects/typeobject.c
+++ b/Objects/typeobject.c
@@ -2980,7 +2980,7 @@ object_str(PyObject *self)
     unaryfunc f;
 
     f = Py_TYPE(self)->tp_repr;
-    if (f == NULL)
+    if (f == NULL || f == object_str)
         f = object_repr;
     return f(self);
 }