Implement compact dict

Issue #27350: `dict` implementation is changed like PyPy. It is more compact
and preserves insertion order.

_PyDict_Dummy() function has been removed.

Disable test_gdb: python-gdb.py is not updated yet to the new structure of
compact dictionaries (issue #28023).

Patch written by INADA Naoki.

1 files changed, 5 insertions, 2 deletions

diff --git a/Lib/test/test_weakref.py b/Lib/test/test_weakref.py
index b1476d0a1a6..6e6990cd58f 100644
--- a/Lib/test/test_weakref.py
+++ b/Lib/test/test_weakref.py
@@ -1325,13 +1325,16 @@ class MappingTestCase(TestBase):
         o = Object(123456)
         with testcontext():
             n = len(dict)
-            dict.popitem()
+            # Since underlaying dict is ordered, first item is popped
+            dict.pop(next(dict.keys()))
             self.assertEqual(len(dict), n - 1)
             dict[o] = o
             self.assertEqual(len(dict), n)
+        # last item in objects is removed from dict in context shutdown
         with testcontext():
             self.assertEqual(len(dict), n - 1)
-            dict.pop(next(dict.keys()))
+            # Then, (o, o) is popped
+            dict.popitem()
             self.assertEqual(len(dict), n - 2)
         with testcontext():
             self.assertEqual(len(dict), n - 3)