From 7a9bdbc1c2214bec2133139dd8830f17e0383eed Mon Sep 17 00:00:00 2001
From: Alexander Belopolsky <alexander.belopolsky@gmail.com>
Date: Mon, 16 Aug 2010 19:46:32 +0000
Subject: [PATCH] Merged revisions 84098 via svnmerge from
 svn+ssh://pythondev@svn.python.org/python/branches/py3k

........
  r84098 | alexander.belopolsky | 2010-08-16 14:55:46 -0400 (Mon, 16 Aug 2010) | 4 lines

  Issue #665761: functools.reduce() will no longer mask exceptions other
  than TypeError raised by the iterator argument.  Also added a test to
  check that zip() already behaves similarly.
........
---
 Lib/test/test_builtin.py   |  1 +
 Lib/test/test_functools.py | 25 +++++++++++++++++++------
 Misc/NEWS                  |  3 +++
 Modules/_functoolsmodule.c |  5 +++--
 4 files changed, 26 insertions(+), 8 deletions(-)

diff --git a/Lib/test/test_builtin.py b/Lib/test/test_builtin.py
index 34c2bb18a8..2a08337c79 100644
--- a/Lib/test/test_builtin.py
+++ b/Lib/test/test_builtin.py
@@ -1221,6 +1221,7 @@ class BuiltinTest(unittest.TestCase):
         class G:
             pass
         self.assertRaises(TypeError, zip, a, G())
+        self.assertRaises(RuntimeError, zip, a, TestFailingIter())
 
         # Make sure zip doesn't try to allocate a billion elements for the
         # result list when one of its arguments doesn't say how long it is.
diff --git a/Lib/test/test_functools.py b/Lib/test/test_functools.py
index 7b79f28369..d20bafe7dc 100644
--- a/Lib/test/test_functools.py
+++ b/Lib/test/test_functools.py
@@ -302,10 +302,11 @@ class TestReduce(unittest.TestCase):
                     self.sofar.append(n*n)
                     n += 1
                 return self.sofar[i]
-
-        self.assertEqual(self.func(lambda x, y: x+y, ['a', 'b', 'c'], ''), 'abc')
+        def add(x, y):
+            return x + y
+        self.assertEqual(self.func(add, ['a', 'b', 'c'], ''), 'abc')
         self.assertEqual(
-            self.func(lambda x, y: x+y, [['a', 'c'], [], ['d', 'w']], []),
+            self.func(add, [['a', 'c'], [], ['d', 'w']], []),
             ['a','c','d','w']
         )
         self.assertEqual(self.func(lambda x, y: x*y, range(2,8), 1), 5040)
@@ -313,15 +314,27 @@ class TestReduce(unittest.TestCase):
             self.func(lambda x, y: x*y, range(2,21), 1),
             2432902008176640000
         )
-        self.assertEqual(self.func(lambda x, y: x+y, Squares(10)), 285)
-        self.assertEqual(self.func(lambda x, y: x+y, Squares(10), 0), 285)
-        self.assertEqual(self.func(lambda x, y: x+y, Squares(0), 0), 0)
+        self.assertEqual(self.func(add, Squares(10)), 285)
+        self.assertEqual(self.func(add, Squares(10), 0), 285)
+        self.assertEqual(self.func(add, Squares(0), 0), 0)
         self.assertRaises(TypeError, self.func)
         self.assertRaises(TypeError, self.func, 42, 42)
         self.assertRaises(TypeError, self.func, 42, 42, 42)
         self.assertEqual(self.func(42, "1"), "1") # func is never called with one item
         self.assertEqual(self.func(42, "", "1"), "1") # func is never called with one item
         self.assertRaises(TypeError, self.func, 42, (42, 42))
+        self.assertRaises(TypeError, self.func, add, []) # arg 2 must not be empty sequence with no initial value
+        self.assertRaises(TypeError, self.func, add, "")
+        self.assertRaises(TypeError, self.func, add, ())
+        self.assertRaises(TypeError, self.func, add, object())
+
+        class TestFailingIter:
+            def __iter__(self):
+                raise RuntimeError
+        self.assertRaises(RuntimeError, self.func, add, TestFailingIter())
+
+        self.assertEqual(self.func(add, [], None), None)
+        self.assertEqual(self.func(add, [], 42), 42)
 
         class BadSeq:
             def __getitem__(self, index):
diff --git a/Misc/NEWS b/Misc/NEWS
index 83ddaaa950..d035ff10bd 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -435,6 +435,9 @@ Library
 Extension Modules
 -----------------
 
+- Issue #665761: ``functools.reduce()`` will no longer mask exceptions
+  other than ``TypeError`` raised by the iterator argument.
+
 - Issue #9570: Use PEP 383 decoding in os.mknod and os.mkfifo.
 
 - Issue #9324: Add parameter validation to signal.signal on Windows in order
diff --git a/Modules/_functoolsmodule.c b/Modules/_functoolsmodule.c
index bf2ea3b2af..3437353933 100644
--- a/Modules/_functoolsmodule.c
+++ b/Modules/_functoolsmodule.c
@@ -302,8 +302,9 @@ functools_reduce(PyObject *self, PyObject *args)
 
     it = PyObject_GetIter(seq);
     if (it == NULL) {
-        PyErr_SetString(PyExc_TypeError,
-            "reduce() arg 2 must support iteration");
+        if (PyErr_ExceptionMatches(PyExc_TypeError))
+            PyErr_SetString(PyExc_TypeError,
+                            "reduce() arg 2 must support iteration");
         Py_XDECREF(result);
         return NULL;
     }
-- 
2.40.0