Add back Serialization

Src/IronPython/Runtime/CommonDictionaryStorage.cs

@@ -7,6 +7,7 @@
 using System.Collections.Generic;
 using System.Diagnostics;
 using System.Runtime.CompilerServices;
+using System.Runtime.Serialization;
 using System.Threading;
 
 using IronPython.Runtime.Operations;
@@ -33,7 +34,8 @@ namespace IronPython.Runtime {
     /// the buckets and then calls a static helper function to do the read from the bucket
     /// array to ensure that readers are not seeing multiple bucket arrays.
     /// </summary>
-    internal sealed class CommonDictionaryStorage : DictionaryStorage {
+    [Serializable]
+    internal sealed class CommonDictionaryStorage : DictionaryStorage, ISerializable, IDeserializationCallback {
         private int[] _indices;
         private List<Bucket> _buckets;
         private int _count;
@@ -117,6 +119,16 @@ private CommonDictionaryStorage(int[] indices, List<Bucket> buckets, int count,
             _eqFunc = eqFunc;
         }
 
+#if FEATURE_SERIALIZATION
+        private CommonDictionaryStorage(SerializationInfo info, StreamingContext context) {
+            // Remember the serialization info, we'll deserialize when we get the callback.  This
+            // enables special types like DBNull.Value to successfully be deserialized inside of us.  We
+            // store the serialization info in a special bucket so we don't have an extra field just for
+            // serialization.
+            _buckets = new List<Bucket> { new Bucket(null, info, 0) };
+        }
+#endif
+
         public override void Add(ref DictionaryStorage storage, object key, object value)
             => Add(key, value);
 
@@ -651,5 +663,31 @@ private static bool TupleEquals(object o1, object o2)
         private static bool GenericEquals(object o1, object o2) => PythonOps.EqualRetBool(o1, o2);
 
         #endregion
+
+#if FEATURE_SERIALIZATION
+        #region ISerializable Members
+
+        public void GetObjectData(SerializationInfo info, StreamingContext context) {
+            info.AddValue("buckets", GetItems());
+        }
+
+        void IDeserializationCallback.OnDeserialization(object sender) {
+            if (_indices is not null) {
+                // we've received multiple OnDeserialization callbacks, only
+                // deserialize after the 1st one
+                return;
+            }
+
+            var info = (SerializationInfo)_buckets[0].Value;
+            _buckets.Clear();
+
+            var buckets = (List<KeyValuePair<object, object>>)info.GetValue("buckets", typeof(List<KeyValuePair<object, object>>));
+            foreach (KeyValuePair<object, object> kvp in buckets) {
+                AddNoLock(kvp.Key, kvp.Value);
+            }
+        }
+
+        #endregion
+#endif
     }
 }

Tests/test_ordered_dict_stdlib.py

@@ -30,6 +30,7 @@ def load_tests(loader, standard_tests, pattern):
         ]
 
         skip_tests = [
+            test.test_ordered_dict.CPythonBuiltinDictTests('test_highly_nested_subclass'), # intermittent AssertionError - GC related?
             test.test_ordered_dict.CPythonOrderedDictSubclassTests('test_highly_nested_subclass'), # intermittent AssertionError - GC related?
             test.test_ordered_dict.CPythonOrderedDictTests('test_highly_nested_subclass'), # intermittent AssertionError - GC related?
             test.test_ordered_dict.PurePythonOrderedDictSubclassTests('test_highly_nested_subclass'), # intermittent AssertionError - GC related?