From bccee2c46f4b0372f3513b4aac45624a395e656b Mon Sep 17 00:00:00 2001
From: Benedikt Reinartz <filmor@gmail.com>
Date: Wed, 18 Oct 2023 15:14:04 +0200
Subject: [PATCH] Explicitly compare MaybeType objects by name

---
 src/runtime/ClassManager.cs                 |  5 +-
 src/runtime/StateSerialization/MaybeType.cs | 91 +++++++++++----------
 2 files changed, 53 insertions(+), 43 deletions(-)

diff --git a/src/runtime/ClassManager.cs b/src/runtime/ClassManager.cs
index d743bc006..a2692bbeb 100644
--- a/src/runtime/ClassManager.cs
+++ b/src/runtime/ClassManager.cs
@@ -3,7 +3,6 @@
 using System.Diagnostics;
 using System.Linq;
 using System.Reflection;
-using System.Runtime.InteropServices;
 using System.Security;
 
 using Python.Runtime.StateSerialization;
@@ -33,7 +32,9 @@ internal class ClassManager
                                                              BindingFlags.Public |
                                                              BindingFlags.NonPublic;
 
-        internal static Dictionary<MaybeType, ReflectedClrType> cache = new(capacity: 128);
+        internal static Dictionary<MaybeType, ReflectedClrType> cache = new(
+            capacity: 128, comparer: new MaybeTypeComparer()
+        );
         private static readonly Type dtype;
 
         private ClassManager()
diff --git a/src/runtime/StateSerialization/MaybeType.cs b/src/runtime/StateSerialization/MaybeType.cs
index 884b7edb0..b8f20db95 100644
--- a/src/runtime/StateSerialization/MaybeType.cs
+++ b/src/runtime/StateSerialization/MaybeType.cs
@@ -3,62 +3,71 @@
 using System.Runtime.Serialization;
 using System.Runtime.Serialization.Formatters.Binary;
 using System.IO;
+using System.Collections.Generic;
 
-namespace Python.Runtime
+namespace Python.Runtime;
+
+[Serializable]
+internal struct MaybeType : ISerializable
 {
-    [Serializable]
-    internal struct MaybeType : ISerializable
-    {
-        public static implicit operator MaybeType (Type ob) => new(ob);
+    public static implicit operator MaybeType (Type ob) => new(ob);
 
-        // The AssemblyQualifiedName of the serialized Type
-        const string SerializationName = "n";
-        readonly string name;
-        readonly Type type;
+    // The AssemblyQualifiedName of the serialized Type
+    const string SerializationName = "n";
+    readonly string name;
+    readonly Type type;
 
-        public string DeletedMessage
+    public string DeletedMessage
+    {
+        get
         {
-            get
-            {
-                return $"The .NET Type {name} no longer exists";
-            }
+            return $"The .NET Type {name} no longer exists";
         }
+    }
 
-        public Type Value
+    public Type Value
+    {
+        get
         {
-            get
+            if (type == null)
             {
-                if (type == null)
-                {
-                    throw new SerializationException(DeletedMessage);
-                }
-                return type;
+                throw new SerializationException(DeletedMessage);
             }
+            return type;
         }
+    }
 
-        public string Name => name;
-        public bool Valid => type != null;
+    public string Name => name;
+    public bool Valid => type != null;
 
-        public override string ToString()
-        {
-            return (type != null ? type.ToString() : $"missing type: {name}");
-        }
+    public override string ToString()
+    {
+        return (type != null ? type.ToString() : $"missing type: {name}");
+    }
 
-        public MaybeType(Type tp)
-        {
-            type = tp;
-            name = tp.AssemblyQualifiedName;
-        }
+    public MaybeType(Type tp)
+    {
+        type = tp;
+        name = tp.AssemblyQualifiedName;
+    }
 
-        private MaybeType(SerializationInfo serializationInfo, StreamingContext context)
-        {
-            name = (string)serializationInfo.GetValue(SerializationName, typeof(string));
-            type = Type.GetType(name, throwOnError:false);
-        }
+    private MaybeType(SerializationInfo serializationInfo, StreamingContext context)
+    {
+        name = (string)serializationInfo.GetValue(SerializationName, typeof(string));
+        type = Type.GetType(name, throwOnError:false);
+    }
 
-        public void GetObjectData(SerializationInfo serializationInfo, StreamingContext context)
-        {
-            serializationInfo.AddValue(SerializationName, name);
-        }
+    public void GetObjectData(SerializationInfo serializationInfo, StreamingContext context)
+    {
+        serializationInfo.AddValue(SerializationName, name);
     }
 }
+
+[Serializable]
+internal class MaybeTypeComparer : IEqualityComparer<MaybeType>
+{
+    public bool Equals (MaybeType lhs, MaybeType rhs) =>
+        lhs.Name == rhs.Name;
+
+    public int GetHashCode(MaybeType t) => (t.Name ?? "").GetHashCode();
+}