Merge 9aaf916dbf into 61dd9fdad7

Lib/copy.py

@@ -235,6 +235,33 @@ def _reconstruct(x, memo, func, args,
     if deep:
         memo[id(x)] = y
 
+    if isinstance(state, list):
+        if listiter is not None:
+            if deep:
+                for item in listiter:
+                    item = deepcopy(item, memo)
+                    y.append(item)
+            else:
+                for item in listiter:
+                    y.append(item)
+
+        if state is not None:
+            if deep:
+                state = deepcopy(state, memo)
+            if hasattr(y, '__setstate__'):
+                y.__setstate__(state)
+            else:
+                if isinstance(state, tuple) and len(state) == 2:
+                    state, slotstate = state
+                else:
+                    slotstate = None
+                if state is not None:
+                    y.__dict__.update(state)
+                if slotstate is not None:
+                    for key, value in slotstate.items():
+                        setattr(y, key, value)
+        return y
+
     if state is not None:
         if deep:
             state = deepcopy(state, memo)

Lib/test/test_copy.py

@@ -767,6 +767,18 @@ class TestCopy(unittest.TestCase):
         self.assertIsNot(x[0], y[0])
         self.assertIsNot(x.foo, y.foo)
 
+        class L(list):
+            def __getstate__(self):
+                return list(self)
+
+            def __setstate__(self, state):
+                self[:] = state
+
+        l1 = L([1, 2])
+        l2 = copy.deepcopy(l1)
+        self.assertEqual(l1, l2)
+        self.assertEqual(len(l1), len(l2))
+
     def test_copy_tuple_subclass(self):
         class C(tuple):
             pass

Misc/NEWS.d/next/Library/2023-01-31-16-48-54.gh-issue-48962.RvwDsB.rst

@@ -0,0 +1 @@
+Fix duplicate values in the list when deepcopying a subclass list in the copy module.