Enable nullability in TypeCodeDomSerializer

src/System.Windows.Forms.Design/src/PublicAPI.Shipped.txt

@@ -343,10 +343,10 @@ virtual System.ComponentModel.Design.Serialization.BasicDesignerLoader.OnEndLoad
 virtual System.ComponentModel.Design.Serialization.BasicDesignerLoader.ReportFlushErrors(System.Collections.ICollection! errors) -> void
 virtual System.ComponentModel.Design.Serialization.CodeDomDesignerLoader.OnComponentRename(object! component, string? oldName, string? newName) -> void
 virtual System.ComponentModel.Design.Serialization.CollectionCodeDomSerializer.SerializeCollection(System.ComponentModel.Design.Serialization.IDesignerSerializationManager! manager, System.CodeDom.CodeExpression? targetExpression, System.Type! targetType, System.Collections.ICollection! originalCollection, System.Collections.ICollection! valuesToSerialize) -> object?
-~virtual System.ComponentModel.Design.Serialization.TypeCodeDomSerializer.Deserialize(System.ComponentModel.Design.Serialization.IDesignerSerializationManager manager, System.CodeDom.CodeTypeDeclaration declaration) -> object
-~virtual System.ComponentModel.Design.Serialization.TypeCodeDomSerializer.GetInitializeMethod(System.ComponentModel.Design.Serialization.IDesignerSerializationManager manager, System.CodeDom.CodeTypeDeclaration declaration, object value) -> System.CodeDom.CodeMemberMethod
-~virtual System.ComponentModel.Design.Serialization.TypeCodeDomSerializer.GetInitializeMethods(System.ComponentModel.Design.Serialization.IDesignerSerializationManager manager, System.CodeDom.CodeTypeDeclaration declaration) -> System.CodeDom.CodeMemberMethod[]
-~virtual System.ComponentModel.Design.Serialization.TypeCodeDomSerializer.Serialize(System.ComponentModel.Design.Serialization.IDesignerSerializationManager manager, object root, System.Collections.ICollection members) -> System.CodeDom.CodeTypeDeclaration
+virtual System.ComponentModel.Design.Serialization.TypeCodeDomSerializer.Deserialize(System.ComponentModel.Design.Serialization.IDesignerSerializationManager! manager, System.CodeDom.CodeTypeDeclaration! declaration) -> object!
+virtual System.ComponentModel.Design.Serialization.TypeCodeDomSerializer.GetInitializeMethod(System.ComponentModel.Design.Serialization.IDesignerSerializationManager! manager, System.CodeDom.CodeTypeDeclaration! declaration, object! value) -> System.CodeDom.CodeMemberMethod!
+virtual System.ComponentModel.Design.Serialization.TypeCodeDomSerializer.GetInitializeMethods(System.ComponentModel.Design.Serialization.IDesignerSerializationManager! manager, System.CodeDom.CodeTypeDeclaration! declaration) -> System.CodeDom.CodeMemberMethod![]!
+virtual System.ComponentModel.Design.Serialization.TypeCodeDomSerializer.Serialize(System.ComponentModel.Design.Serialization.IDesignerSerializationManager! manager, object! root, System.Collections.ICollection? members) -> System.CodeDom.CodeTypeDeclaration!
 virtual System.Drawing.Design.ToolboxItem.ComponentType.get -> string!
 virtual System.Drawing.Design.ToolboxItem.CreateComponentsCore(System.ComponentModel.Design.IDesignerHost? host) -> System.ComponentModel.IComponent![]?
 virtual System.Drawing.Design.ToolboxItem.CreateComponentsCore(System.ComponentModel.Design.IDesignerHost? host, System.Collections.IDictionary? defaultValues) -> System.ComponentModel.IComponent![]?

src/System.Windows.Forms.Design/src/System/ComponentModel/Design/Serialization/CodeDomSerializationProvider.cs

@@ -1,8 +1,6 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
-#nullable disable
-
 using System.Collections;
 using System.Resources;
 
@@ -20,19 +18,25 @@ internal sealed class CodeDomSerializationProvider : IDesignerSerializationProvi
     ///  that is of the correct type, it should return it.
     ///  Otherwise, it should return null.
     /// </summary>
-    object IDesignerSerializationProvider.GetSerializer(IDesignerSerializationManager manager, object currentSerializer, Type objectType, Type serializerType)
+    object? IDesignerSerializationProvider.GetSerializer(IDesignerSerializationManager manager, object? currentSerializer, Type? objectType, Type serializerType)
     {
+        // Don't provide our serializer if someone else already had one
+        if (currentSerializer is not null)
+        {
+            return null;
+        }
+
         if (serializerType == typeof(CodeDomSerializer))
         {
-            return GetCodeDomSerializer(manager, currentSerializer, objectType, serializerType);
+            return GetCodeDomSerializer(objectType);
         }
         else if (serializerType == typeof(MemberCodeDomSerializer))
         {
-            return GetMemberCodeDomSerializer(manager, currentSerializer, objectType, serializerType);
+            return GetMemberCodeDomSerializer(objectType);
         }
         else if (serializerType == typeof(TypeCodeDomSerializer))
         {
-            return GetTypeCodeDomSerializer(manager, currentSerializer, objectType, serializerType);
+            return GetTypeCodeDomSerializer(objectType);
         }
 
         return null; // don't understand this type of serializer.
@@ -41,15 +45,8 @@ object IDesignerSerializationProvider.GetSerializer(IDesignerSerializationManage
     /// <summary>
     ///  Returns a code dom serializer
     /// </summary>
-    private static object GetCodeDomSerializer(IDesignerSerializationManager manager, object currentSerializer, Type objectType, Type serializerType)
+    private static object? GetCodeDomSerializer(Type? objectType)
     {
-        // If this isn't a serializer type we recognize, do nothing.  Also, if metadata specified
-        // a custom serializer, then use it.
-        if (currentSerializer is not null)
-        {
-            return null;
-        }
-
         // Null is a valid value that can be passed into GetSerializer.  It indicates
         // that the value we need to serialize is null, in which case we handle it
         // through the PrimitiveCodeDomSerializer.
@@ -104,14 +101,8 @@ private static object GetCodeDomSerializer(IDesignerSerializationManager manager
     /// <summary>
     ///  Returns a code dom serializer for members
     /// </summary>
-    private static object GetMemberCodeDomSerializer(IDesignerSerializationManager manager, object currentSerializer, Type objectType, Type serializerType)
+    private static object? GetMemberCodeDomSerializer(Type? objectType)
     {
-        // Don't provide our serializer if someone else already had one
-        if (currentSerializer is not null)
-        {
-            return null;
-        }
-
         if (typeof(PropertyDescriptor).IsAssignableFrom(objectType))
         {
             return PropertyMemberCodeDomSerializer.Default;
@@ -128,14 +119,8 @@ private static object GetMemberCodeDomSerializer(IDesignerSerializationManager m
     /// <summary>
     ///  Returns a code dom serializer for types
     /// </summary>
-    private static object GetTypeCodeDomSerializer(IDesignerSerializationManager manager, object currentSerializer, Type objectType, Type serializerType)
+    private static object? GetTypeCodeDomSerializer(Type? objectType)
     {
-        // Don't provide our serializer if someone else already had one
-        if (currentSerializer is not null)
-        {
-            return null;
-        }
-
         if (typeof(IComponent).IsAssignableFrom(objectType))
         {
             return ComponentTypeCodeDomSerializer.Default;

src/System.Windows.Forms.Design/src/System/ComponentModel/Design/Serialization/ComponentTypeCodeDomSerializer.cs

@@ -1,8 +1,6 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
-#nullable disable
-
 using System.CodeDom;
 
 namespace System.ComponentModel.Design.Serialization;
@@ -14,17 +12,9 @@ internal class ComponentTypeCodeDomSerializer : TypeCodeDomSerializer
 {
     private static readonly object _initMethodKey = new();
     private const string _initMethodName = "InitializeComponent";
-    private static ComponentTypeCodeDomSerializer s_default;
-
-    internal static new ComponentTypeCodeDomSerializer Default
-    {
-        get
-        {
-            s_default ??= new ComponentTypeCodeDomSerializer();
+    private static ComponentTypeCodeDomSerializer? s_default;
 
-            return s_default;
-        }
-    }
+    internal static new ComponentTypeCodeDomSerializer Default => s_default ??= new ComponentTypeCodeDomSerializer();
 
     /// <summary>
     ///  This method returns the method to emit all of the initialization code to for the given member.
@@ -36,7 +26,7 @@ protected override CodeMemberMethod GetInitializeMethod(IDesignerSerializationMa
         ArgumentNullException.ThrowIfNull(typeDecl);
         ArgumentNullException.ThrowIfNull(value);
 
-        if (!(typeDecl.UserData[_initMethodKey] is CodeMemberMethod method))
+        if (typeDecl.UserData[_initMethodKey] is not CodeMemberMethod method)
         {
             method = new CodeMemberMethod
             {

src/System.Windows.Forms.Design/src/System/ComponentModel/Design/Serialization/TypeCodeDomSerializer.StatementOrderComparer.cs

@@ -0,0 +1,34 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+namespace System.ComponentModel.Design.Serialization;
+
+public partial class TypeCodeDomSerializer
+{
+    private class StatementOrderComparer : IComparer<OrderedCodeStatementCollection>
+    {
+        public static readonly StatementOrderComparer s_default = new();
+
+        private StatementOrderComparer()
+        {
+        }
+
+        public int Compare(OrderedCodeStatementCollection? left, OrderedCodeStatementCollection? right)
+        {
+            if (left is null)
+            {
+                return 1;
+            }
+            else if (right is null)
+            {
+                return -1;
+            }
+            else if (right == left)
+            {
+                return 0;
+            }
+
+            return left.Order - right.Order;
+        }
+    }
+}