Backed out changeset 9f7505019767 (issue #27275).

Lib/test/test_ordered_dict.py

@@ -730,64 +730,5 @@ class CPythonSubclassMappingTests(mapping_tests.BasicTestMappingProtocol):
         self.assertRaises(KeyError, d.popitem)
 
 
-class SimpleLRUCache:
-
-    def __init__(self, size):
-        super().__init__()
-        self.size = size
-
-    def __getitem__(self, item):
-        value = super().__getitem__(item)
-        self.move_to_end(item)
-        return value
-
-    def __setitem__(self, key, value):
-        while key not in self and len(self) >= self.size:
-            self.popitem(last=False)
-        super().__setitem__(key, value)
-        self.move_to_end(key)
-
-
-class SimpleLRUCacheTests:
-
-    def test_add_after_full(self):
-        c = self.type2test(2)
-        c['t1'] = 1
-        c['t2'] = 2
-        c['t3'] = 3
-        self.assertEqual(list(c), ['t2', 't3'])
-
-    def test_popitem(self):
-        c = self.type2test(3)
-        for i in range(1, 4):
-            c[i] = i
-        self.assertEqual(c.popitem(last=False), (1, 1))
-        self.assertEqual(c.popitem(last=True), (3, 3))
-
-    def test_change_order_on_get(self):
-        c = self.type2test(3)
-        for i in range(1, 4):
-            c[i] = i
-        self.assertEqual(list(c), list(range(1, 4)))
-        self.assertEqual(c[2], 2)
-        self.assertEqual(list(c), [1, 3, 2])
-
-
-class PySimpleLRUCacheTests(SimpleLRUCacheTests, unittest.TestCase):
-
-    class type2test(SimpleLRUCache, py_coll.OrderedDict):
-        pass
-
-
-@unittest.skipUnless(c_coll, 'requires the C version of the collections module')
-class CSimpleLRUCacheTests(SimpleLRUCacheTests, unittest.TestCase):
-
-    @classmethod
-    def setUpClass(cls):
-        class type2test(SimpleLRUCache, c_coll.OrderedDict):
-            pass
-        cls.type2test = type2test
-
-
 if __name__ == "__main__":
     unittest.main()

Misc/NEWS

@@ -113,9 +113,6 @@ Core and Builtins
 Library
 -------
 
-- Issue #27275: Fixed implementation of pop() and popitem() methods in
-  subclasses of accelerated OrderedDict.
-
 - Issue #28255: calendar.TextCalendar().prmonth() no longer prints a space
   at the start of new line after printing a month's calendar.  Patch by
   Xiang Zhang.

Objects/odictobject.c

@@ -1099,6 +1099,7 @@ _odict_popkey_hash(PyObject *od, PyObject *key, PyObject *failobj,
     }
 
     /* Now delete the value from the dict. */
+    if (PyODict_CheckExact(od)) {
         if (node != NULL) {
             value = _PyDict_GetItem_KnownHash(od, key, hash);  /* borrowed */
             if (value != NULL) {
@@ -1109,6 +1110,20 @@ _odict_popkey_hash(PyObject *od, PyObject *key, PyObject *failobj,
                 }
             }
         }
+    }
+    else {
+        int exists = PySequence_Contains(od, key);
+        if (exists < 0)
+            return NULL;
+        if (exists) {
+            value = PyObject_GetItem(od, key);
+            if (value != NULL) {
+                if (PyObject_DelItem(od, key) == -1) {
+                    Py_CLEAR(value);
+                }
+            }
+        }
+    }
 
     /* Apply the fallback value, if necessary. */
     if (value == NULL && !PyErr_Occurred()) {