bpo-40116: dict: Add regression test for iteration order. (GH-31550)

Lib/test/test_dict.py

@@ -1077,6 +1077,23 @@ class DictTest(unittest.TestCase):
         self.assertEqual(list(a), ['x', 'y'])
         self.assertEqual(list(b), ['x', 'y', 'z'])
 
+    @support.cpython_only
+    def test_splittable_update(self):
+        """dict.update(other) must preserve order in other."""
+        class C:
+            def __init__(self, order):
+                if order:
+                    self.a, self.b, self.c = 1, 2, 3
+                else:
+                    self.c, self.b, self.a = 1, 2, 3
+        o = C(True)
+        o = C(False)  # o.__dict__ has reversed order.
+        self.assertEqual(list(o.__dict__), ["c", "b", "a"])
+
+        d = {}
+        d.update(o.__dict__)
+        self.assertEqual(list(d), ["c", "b", "a"])
+
     def test_iterator_pickling(self):
         for proto in range(pickle.HIGHEST_PROTOCOL + 1):
             data = {1:"a", 2:"b", 3:"c"}

Misc/NEWS.d/next/Core and Builtins/2022-02-24-16-34-17.bpo-40116.AeVGG2.rst

@@ -0,0 +1,2 @@
+Fix regression that dict.update(other) may don't respect iterate order of
+other when other is key sharing dict.

Misc/NEWS.d/next/Library/2022-02-09-22-40-11.bpo-46643.aBlIx1.rst

@@ -1 +1 @@
-In :func:`typing.get_type_hints`, support evaluating stringified ``ParamSpecArgs`` and ``ParamSpecKwargs`` annotations. Patch by Gregory Beauregard.
+In :func:`typing.get_type_hints`, support evaluating stringified ``ParamSpecArgs`` and ``ParamSpecKwargs`` annotations. Patch by Gregory Beauregard.