Issue 11875: Keep OrderedDict's __reduce__ from temporarily mutating the object.

rhettinger · rhettinger · commit 98c850a39856 · 2011-04-19T11:04:44.000-07:00
diff --git a/Lib/collections/__init__.py b/Lib/collections/__init__.py
@@ -155,10 +155,9 @@ def move_to_end(self, key, last=True):
     def __reduce__(self):
         'Return state information for pickling'
         items = [[k, self[k]] for k in self]
-        tmp = self.__map, self.__root, self.__hardroot
-        del self.__map, self.__root, self.__hardroot
         inst_dict = vars(self).copy()
-        self.__map, self.__root, self.__hardroot = tmp
+        for k in vars(self.__class__()):
+            inst_dict.pop(k, None)
         if inst_dict:
             return (self.__class__, (items,), inst_dict)
         return self.__class__, (items,)
diff --git a/Misc/NEWS b/Misc/NEWS
@@ -121,6 +121,9 @@ Library
 
 - Issue #11852: Add missing imports and update tests.
 
+- Issue #11875: collections.OrderedDict's __reduce__ was temporarily
+  mutating the object instead of just working on a copy.
+
 - Issue #11467: Fix urlparse behavior when handling urls which contains scheme
   specific part only digits. Patch by Santoso Wijaya.
 
