From cadff70ba5a761e5899d09c918ad6c87cfb07b7d Mon Sep 17 00:00:00 2001
From: Ezio Melotti <ezio.melotti@gmail.com>
Date: Fri, 21 Sep 2012 17:26:35 +0300
Subject: [PATCH] =?utf8?q?=20#15421:=20fix=20an=20OverflowError=20in=20Cal?=
 =?utf8?q?endar.itermonthdates()=20after=20datetime.MAXYEAR.=20=20Patch=20?=
 =?utf8?q?by=20C=C3=A9dric=20Krier.?=
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---
 Lib/calendar.py           | 6 +++++-
 Lib/test/test_calendar.py | 6 ++++++
 Misc/NEWS                 | 3 +++
 3 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/Lib/calendar.py b/Lib/calendar.py
index 3106ef273e86..232957829f09 100644
--- a/Lib/calendar.py
+++ b/Lib/calendar.py
@@ -161,7 +161,11 @@ class Calendar(object):
         oneday = datetime.timedelta(days=1)
         while True:
             yield date
-            date += oneday
+            try:
+                date += oneday
+            except OverflowError:
+                # Adding one day could fail after datetime.MAXYEAR
+                break
             if date.month != month and date.weekday() == self.firstweekday:
                 break
 
diff --git a/Lib/test/test_calendar.py b/Lib/test/test_calendar.py
index 2a562688109f..5d6549c6cd8f 100644
--- a/Lib/test/test_calendar.py
+++ b/Lib/test/test_calendar.py
@@ -3,6 +3,7 @@ import unittest
 
 from test import test_support
 import locale
+import datetime
 
 
 result_2004_text = """
@@ -262,6 +263,11 @@ class CalendarTestCase(unittest.TestCase):
         new_october = calendar.TextCalendar().formatmonthname(2010, 10, 10)
         self.assertEquals(old_october, new_october)
 
+    def test_itermonthdates(self):
+        # ensure itermonthdates doesn't overflow after datetime.MAXYEAR
+        # see #15421
+        list(calendar.Calendar().itermonthdates(datetime.MAXYEAR, 12))
+
 
 class MonthCalendarTestCase(unittest.TestCase):
     def setUp(self):
diff --git a/Misc/NEWS b/Misc/NEWS
index e73499810427..84d4bd1910cc 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -103,6 +103,9 @@ Core and Builtins
 Library
 -------
 
+- Issue #15421: fix an OverflowError in Calendar.itermonthdates() after
+  datetime.MAXYEAR.  Patch by Cédric Krier.
+
 - Issue #15970: xml.etree.ElementTree now serializes correctly the empty HTML
   elements 'meta' and 'param'.
 
-- 
2.47.3