From 2d036025766bab417bb1d946f52918048e0f6589 Mon Sep 17 00:00:00 2001
From: Raymond Hettinger <python@rcn.com>
Date: Tue, 3 Feb 2009 02:28:00 +0000
Subject: [PATCH] Validate that __length_hint__ returns a usable result.

---
 Lib/test/test_iterlen.py | 10 ++++++++++
 Objects/abstract.c       |  2 +-
 2 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/Lib/test/test_iterlen.py b/Lib/test/test_iterlen.py
index 91873c2af4a..ab5466ecf99 100644
--- a/Lib/test/test_iterlen.py
+++ b/Lib/test/test_iterlen.py
@@ -208,6 +208,11 @@ class BadLengthHint(object):
     def __length_hint__(self):
         raise RuntimeError('hello')
 
+class NoneLengthHint(object):
+    def __iter__(self): return iter(range(10))
+    def __length_hint__(self):
+        return None
+
 class TestLengthHintExceptions(unittest.TestCase):
 
     def test_issue1242657(self):
@@ -225,6 +230,11 @@ class TestLengthHintExceptions(unittest.TestCase):
         self.assertRaises(RuntimeError, b.extend, BadLen())
         self.assertRaises(RuntimeError, b.extend, BadLengthHint())
 
+    def test_invalid_hint(self):
+        # Make sure an invalid result doesn't muck-up the works
+        self.assertEqual(list(NoneLengthHint()), list(range(10)))
+
+
 def test_main():
     unittests = [
         TestRepeat,
diff --git a/Objects/abstract.c b/Objects/abstract.c
index c10f4ca4f95..b47b1c9772f 100644
--- a/Objects/abstract.c
+++ b/Objects/abstract.c
@@ -123,7 +123,7 @@ _PyObject_LengthHint(PyObject *o, Py_ssize_t defaultvalue)
 		PyErr_Clear();
 		return defaultvalue;
 	}
-	rv = PyInt_AsLong(ro);
+	rv = rv = PyLong_Check(ro) ? PyLong_AsSsize_t(ro) : defaultvalue;
 	Py_DECREF(ro);
 	return rv;
 }