Annotate reflection fallback for S.P.DataContractSerialization (#31533)

This adds [removable feature annotation](dotnet/designs#42) to data
contract serialization.

If the user specifies that they would like to remove support for this
at publish/native compilation time, the linker/compiler is going to
replace the annotated method bodies with a throwing method body.
The exception message is going to inform the user that the feature
has been removed because they opted into the removal. The throwing
method body is significantly smaller than the transitive closure
of code reachable from the original method body.

Contributes to #30597. Turning this feature off in the UWP People app
saves 4% of size. This is a size on disk regression that came with
the new version of CoreFX and blocks the Windows team in picking up
the latest framework. There is a zero size growth goal.

src/System.Private.DataContractSerialization/src/System.Private.DataContractSerialization.csproj

@@ -27,6 +27,9 @@
     <Compile Include="$(CommonPath)\System\NotImplemented.cs">
       <Link>Common\System\NotImplemented.cs</Link>
     </Compile>
+    <Compile Include="$(CommonPath)\System\Runtime\CompilerServices\RemovableFeatureAttribute.cs">
+      <Link>System\Runtime\CompilerServices\RemovableFeatureAttribute</Link>
+    </Compile>
     <Compile Include="$(RuntimeSerializationSources)\Attributes.cs" />
     <Compile Include="$(RuntimeSerializationSources)\CodeGenerator.cs" />
     <Compile Include="$(RuntimeSerializationSources)\ClassDataContract.cs" />
@@ -144,6 +147,7 @@
     <Compile Include="System\Runtime\Serialization\IExtensibleDataObject.cs" />
     <Compile Include="System\Runtime\Serialization\Json\ReflectionJsonFormatReader.cs" />
     <Compile Include="System\Runtime\Serialization\Json\ReflectionJsonFormatWriter.cs" />
+    <Compile Include="System\Runtime\Serialization\ReflectionFeature.cs" />
     <Compile Include="System\Runtime\Serialization\ReflectionReader.cs" />
     <Compile Include="System\Runtime\Serialization\ReflectionClassWriter.cs" />
     <Compile Include="System\Runtime\Serialization\ReflectionXmlFormatReader.cs" />

src/System.Private.DataContractSerialization/src/System/Runtime/Serialization/ClassDataContract.cs

@@ -13,6 +13,7 @@ namespace System.Runtime.Serialization
     using System.IO;
     using System.Globalization;
     using System.Reflection;
+    using System.Runtime.CompilerServices;
     using System.Threading;
     using System.Xml;
     using DataContractDictionary = System.Collections.Generic.Dictionary<System.Xml.XmlQualifiedName, DataContract>;
@@ -242,6 +243,14 @@ internal bool CreateNewInstanceViaDefaultConstructor(out object obj)
             return true;
         }
 
+#if uapaot
+        [RemovableFeature(ReflectionBasedSerializationFeature.Name)]
+#endif
+        private XmlFormatClassWriterDelegate CreateXmlFormatWriterDelegate()
+        {
+            return new XmlFormatWriterGenerator().GenerateClassWriter(this);
+        }
+
 #if uapaot
         private XmlFormatClassWriterDelegate _xmlFormatWriterDelegate;
         public XmlFormatClassWriterDelegate XmlFormatWriterDelegate
@@ -264,7 +273,7 @@ internal XmlFormatClassWriterDelegate XmlFormatWriterDelegate
                     {
                         if (_helper.XmlFormatWriterDelegate == null)
                         {
-                            XmlFormatClassWriterDelegate tempDelegate = new XmlFormatWriterGenerator().GenerateClassWriter(this);
+                            XmlFormatClassWriterDelegate tempDelegate = CreateXmlFormatWriterDelegate();
                             Interlocked.MemoryBarrier();
                             _helper.XmlFormatWriterDelegate = tempDelegate;
                         }
@@ -280,6 +289,14 @@ internal XmlFormatClassWriterDelegate XmlFormatWriterDelegate
             }
         }
 
+#if uapaot
+        [RemovableFeature(ReflectionBasedSerializationFeature.Name)]
+#endif
+        private XmlFormatClassReaderDelegate CreateXmlFormatReaderDelegate()
+        {
+            return new XmlFormatReaderGenerator().GenerateClassReader(this);
+        }
+
 #if uapaot
         private XmlFormatClassReaderDelegate _xmlFormatReaderDelegate;
         public XmlFormatClassReaderDelegate XmlFormatReaderDelegate
@@ -302,7 +319,7 @@ internal XmlFormatClassReaderDelegate XmlFormatReaderDelegate
                     {
                         if (_helper.XmlFormatReaderDelegate == null)
                         {
-                            XmlFormatClassReaderDelegate tempDelegate = new XmlFormatReaderGenerator().GenerateClassReader(this);
+                            XmlFormatClassReaderDelegate tempDelegate = CreateXmlFormatReaderDelegate();
                             Interlocked.MemoryBarrier();
                             _helper.XmlFormatReaderDelegate = tempDelegate;
                         }

src/System.Private.DataContractSerialization/src/System/Runtime/Serialization/CollectionDataContract.cs

@@ -10,6 +10,7 @@ namespace System.Runtime.Serialization
     using System.Collections;
     using System.Collections.Generic;
     using System.Reflection;
+    using System.Runtime.CompilerServices;
     using System.Threading;
     using System.Xml;
     using System.Linq;
@@ -336,6 +337,14 @@ internal string InvalidCollectionInSharedContractMessage
             { return _helper.InvalidCollectionInSharedContractMessage; }
         }
 
+#if uapaot
+        [RemovableFeature(ReflectionBasedSerializationFeature.Name)]
+#endif
+        private XmlFormatCollectionWriterDelegate CreateXmlFormatWriterDelegate()
+        {
+            return new XmlFormatWriterGenerator().GenerateCollectionWriter(this);
+        }
+
 #if uapaot
         private XmlFormatCollectionWriterDelegate _xmlFormatWriterDelegate;
         public XmlFormatCollectionWriterDelegate XmlFormatWriterDelegate
@@ -358,7 +367,7 @@ internal XmlFormatCollectionWriterDelegate XmlFormatWriterDelegate
                     {
                         if (_helper.XmlFormatWriterDelegate == null)
                         {
-                            XmlFormatCollectionWriterDelegate tempDelegate = new XmlFormatWriterGenerator().GenerateCollectionWriter(this);
+                            XmlFormatCollectionWriterDelegate tempDelegate = CreateXmlFormatWriterDelegate();
                             Interlocked.MemoryBarrier();
                             _helper.XmlFormatWriterDelegate = tempDelegate;
                         }
@@ -374,6 +383,14 @@ internal XmlFormatCollectionWriterDelegate XmlFormatWriterDelegate
             }
         }
 
+#if uapaot
+        [RemovableFeature(ReflectionBasedSerializationFeature.Name)]
+#endif
+        private XmlFormatCollectionReaderDelegate CreateXmlFormatReaderDelegate()
+        {
+            return new XmlFormatReaderGenerator().GenerateCollectionReader(this);
+        }
+
 #if uapaot
         private XmlFormatCollectionReaderDelegate _xmlFormatReaderDelegate;
         public XmlFormatCollectionReaderDelegate XmlFormatReaderDelegate
@@ -396,7 +413,7 @@ internal XmlFormatCollectionReaderDelegate XmlFormatReaderDelegate
                     {
                         if (_helper.XmlFormatReaderDelegate == null)
                         {
-                            XmlFormatCollectionReaderDelegate tempDelegate = new XmlFormatReaderGenerator().GenerateCollectionReader(this);
+                            XmlFormatCollectionReaderDelegate tempDelegate = CreateXmlFormatReaderDelegate();
                             Interlocked.MemoryBarrier();
                             _helper.XmlFormatReaderDelegate = tempDelegate;
                         }
@@ -412,6 +429,15 @@ internal XmlFormatCollectionReaderDelegate XmlFormatReaderDelegate
             }
         }
 
+#if uapaot
+        [RemovableFeature(ReflectionBasedSerializationFeature.Name)]
+#endif
+        private XmlFormatGetOnlyCollectionReaderDelegate CreateXmlFormatGetOnlyCollectionReaderDelegate()
+        {
+            return new XmlFormatReaderGenerator().GenerateGetOnlyCollectionReader(this);
+        }
+
+
 #if uapaot
         private XmlFormatGetOnlyCollectionReaderDelegate _xmlFormatGetOnlyCollectionReaderDelegate;
         public XmlFormatGetOnlyCollectionReaderDelegate XmlFormatGetOnlyCollectionReaderDelegate
@@ -444,7 +470,7 @@ internal XmlFormatGetOnlyCollectionReaderDelegate XmlFormatGetOnlyCollectionRead
                                 throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(new InvalidDataContractException(SR.Format(SR.GetOnlyCollectionMustHaveAddMethod, GetClrTypeFullName(UnderlyingType))));
                             }
 
-                            XmlFormatGetOnlyCollectionReaderDelegate tempDelegate = new XmlFormatReaderGenerator().GenerateGetOnlyCollectionReader(this);
+                            XmlFormatGetOnlyCollectionReaderDelegate tempDelegate = CreateXmlFormatGetOnlyCollectionReaderDelegate();
                             Interlocked.MemoryBarrier();
                             _helper.XmlFormatGetOnlyCollectionReaderDelegate = tempDelegate;
                         }

src/System.Private.DataContractSerialization/src/System/Runtime/Serialization/DataContractSerializer.cs

@@ -34,7 +34,7 @@ public sealed class DataContractSerializer : XmlObjectSerializer
         private ISerializationSurrogateProvider _serializationSurrogateProvider;
         private bool _serializeReadOnlyTypes;
 
-        private static SerializationOption _option = SerializationOption.ReflectionAsBackup;
+        private static SerializationOption _option = IsReflectionBackupAllowed() ? SerializationOption.ReflectionAsBackup : SerializationOption.CodeGenOnly;
         private static bool _optionAlreadySet;
         internal static SerializationOption Option
         {
@@ -50,6 +50,17 @@ internal static SerializationOption Option
             }
         }
 
+#if uapaot
+        [RemovableFeature(ReflectionBasedSerializationFeature.Name, UseNopBody = true)]
+#endif
+        private static bool IsReflectionBackupAllowed()
+        {
+            // The RemovableFeature annotation above is going to replace this with
+            // "return false" if reflection based serialization feature was removed
+            // at publishing time.
+            return true;
+        }
+
         public DataContractSerializer(Type type)
             : this(type, (IEnumerable<Type>)null)
         {

src/System.Private.DataContractSerialization/src/System/Runtime/Serialization/Json/JsonClassDataContract.cs

@@ -6,6 +6,7 @@
 using System.Xml;
 using System.Diagnostics;
 using System.Collections.Generic;
+using System.Runtime.CompilerServices;
 
 namespace System.Runtime.Serialization.Json
 {
@@ -19,6 +20,14 @@ public JsonClassDataContract(ClassDataContract traditionalDataContract)
             _helper = base.Helper as JsonClassDataContractCriticalHelper;
         }
 
+#if uapaot
+        [RemovableFeature(ReflectionBasedSerializationFeature.Name)]
+#endif
+        private JsonFormatClassReaderDelegate CreateJsonFormatReaderDelegate()
+        {
+            return new ReflectionJsonClassReader(TraditionalClassDataContract).ReflectionReadClass;
+        }
+
         internal JsonFormatClassReaderDelegate JsonFormatReaderDelegate
         {
             get
@@ -32,13 +41,13 @@ internal JsonFormatClassReaderDelegate JsonFormatReaderDelegate
                             JsonFormatClassReaderDelegate tempDelegate;
                             if (DataContractSerializer.Option == SerializationOption.ReflectionOnly)
                             {
-                                tempDelegate = new ReflectionJsonClassReader(TraditionalClassDataContract).ReflectionReadClass;
+                                tempDelegate = CreateJsonFormatReaderDelegate();
                             }
 #if uapaot
                             else if (DataContractSerializer.Option == SerializationOption.ReflectionAsBackup)
                             {
                                 tempDelegate = JsonDataContract.TryGetReadWriteDelegatesFromGeneratedAssembly(TraditionalClassDataContract)?.ClassReaderDelegate;
-                                tempDelegate = tempDelegate ?? new ReflectionJsonClassReader(TraditionalClassDataContract).ReflectionReadClass;
+                                tempDelegate = tempDelegate ?? CreateJsonFormatReaderDelegate();
 
                                 if (tempDelegate == null)
                                     throw new InvalidDataContractException(SR.Format(SR.SerializationCodeIsMissingForType, TraditionalClassDataContract.UnderlyingType.ToString()));
@@ -62,6 +71,14 @@ internal JsonFormatClassReaderDelegate JsonFormatReaderDelegate
             }
         }
 
+#if uapaot
+        [RemovableFeature(ReflectionBasedSerializationFeature.Name)]
+#endif
+        private JsonFormatClassWriterDelegate CreateJsonFormatWriterDelegate()
+        {
+            return new ReflectionJsonFormatWriter().ReflectionWriteClass;
+        }
+
         internal JsonFormatClassWriterDelegate JsonFormatWriterDelegate
         {
             get
@@ -75,13 +92,13 @@ internal JsonFormatClassWriterDelegate JsonFormatWriterDelegate
                             JsonFormatClassWriterDelegate tempDelegate;
                             if (DataContractSerializer.Option == SerializationOption.ReflectionOnly)
                             {
-                                tempDelegate = new ReflectionJsonFormatWriter().ReflectionWriteClass;
+                                tempDelegate = CreateJsonFormatWriterDelegate();
                             }
 #if uapaot
                             else if (DataContractSerializer.Option == SerializationOption.ReflectionAsBackup)
                             {
                                 tempDelegate = JsonDataContract.TryGetReadWriteDelegatesFromGeneratedAssembly(TraditionalClassDataContract)?.ClassWriterDelegate;
-                                tempDelegate = tempDelegate ?? new ReflectionJsonFormatWriter().ReflectionWriteClass;
+                                tempDelegate = tempDelegate ?? CreateJsonFormatWriterDelegate();
 
                                 if (tempDelegate == null)
                                     throw new InvalidDataContractException(SR.Format(SR.SerializationCodeIsMissingForType, TraditionalClassDataContract.UnderlyingType.ToString()));

src/System.Private.DataContractSerialization/src/System/Runtime/Serialization/Json/JsonCollectionDataContract.cs

@@ -3,6 +3,7 @@
 // See the LICENSE file in the project root for more information.
 
 using System.Reflection;
+using System.Runtime.CompilerServices;
 using System.Threading;
 using System.Xml;
 
@@ -18,6 +19,14 @@ public JsonCollectionDataContract(CollectionDataContract traditionalDataContract
             _helper = base.Helper as JsonCollectionDataContractCriticalHelper;
         }
 
+#if uapaot
+        [RemovableFeature(ReflectionBasedSerializationFeature.Name)]
+#endif
+        private JsonFormatCollectionReaderDelegate CreateJsonFormatReaderDelegate()
+        {
+            return new ReflectionJsonCollectionReader().ReflectionReadCollection;
+        }
+
         internal JsonFormatCollectionReaderDelegate JsonFormatReaderDelegate
         {
             get
@@ -31,13 +40,13 @@ internal JsonFormatCollectionReaderDelegate JsonFormatReaderDelegate
                             JsonFormatCollectionReaderDelegate tempDelegate;
                             if (DataContractSerializer.Option == SerializationOption.ReflectionOnly)
                             {
-                                tempDelegate = new ReflectionJsonCollectionReader().ReflectionReadCollection;
+                                tempDelegate = CreateJsonFormatReaderDelegate();
                             }
 #if uapaot
                             else if (DataContractSerializer.Option == SerializationOption.ReflectionAsBackup)
                             {
                                 tempDelegate = JsonDataContract.TryGetReadWriteDelegatesFromGeneratedAssembly(TraditionalCollectionDataContract)?.CollectionReaderDelegate;
-                                tempDelegate = tempDelegate ?? new ReflectionJsonCollectionReader().ReflectionReadCollection;
+                                tempDelegate = tempDelegate ?? CreateJsonFormatReaderDelegate();
 
                                 if (tempDelegate == null)
                                     throw new InvalidDataContractException(SR.Format(SR.SerializationCodeIsMissingForType, TraditionalCollectionDataContract.UnderlyingType.ToString()));
@@ -61,6 +70,14 @@ internal JsonFormatCollectionReaderDelegate JsonFormatReaderDelegate
             }
         }
 
+#if uapaot
+        [RemovableFeature(ReflectionBasedSerializationFeature.Name)]
+#endif
+        private JsonFormatGetOnlyCollectionReaderDelegate CreateJsonFormatGetOnlyReaderDelegate()
+        {
+            return new ReflectionJsonCollectionReader().ReflectionReadGetOnlyCollection;
+        }
+
         internal JsonFormatGetOnlyCollectionReaderDelegate JsonFormatGetOnlyReaderDelegate
         {
             get
@@ -80,13 +97,13 @@ internal JsonFormatGetOnlyCollectionReaderDelegate JsonFormatGetOnlyReaderDelega
                             JsonFormatGetOnlyCollectionReaderDelegate tempDelegate;
                             if (DataContractSerializer.Option == SerializationOption.ReflectionOnly)
                             {
-                                tempDelegate = new ReflectionJsonCollectionReader().ReflectionReadGetOnlyCollection;
+                                tempDelegate = CreateJsonFormatGetOnlyReaderDelegate();
                             }
 #if uapaot
                             else if (DataContractSerializer.Option == SerializationOption.ReflectionAsBackup)
                             {
                                 tempDelegate = JsonDataContract.TryGetReadWriteDelegatesFromGeneratedAssembly(TraditionalCollectionDataContract)?.GetOnlyCollectionReaderDelegate;
-                                tempDelegate = tempDelegate ?? new ReflectionJsonCollectionReader().ReflectionReadGetOnlyCollection;
+                                tempDelegate = tempDelegate ?? CreateJsonFormatGetOnlyReaderDelegate();
 
                                 if (tempDelegate == null)
                                     throw new InvalidDataContractException(SR.Format(SR.SerializationCodeIsMissingForType, TraditionalCollectionDataContract.UnderlyingType.ToString()));
@@ -97,7 +114,7 @@ internal JsonFormatGetOnlyCollectionReaderDelegate JsonFormatGetOnlyReaderDelega
 #if uapaot
                                 tempDelegate = JsonDataContract.GetReadWriteDelegatesFromGeneratedAssembly(TraditionalCollectionDataContract).GetOnlyCollectionReaderDelegate;
 #else   
-                                tempDelegate = new JsonFormatReaderGenerator().GenerateGetOnlyCollectionReader(TraditionalCollectionDataContract);
+                                tempDelegate =  new JsonFormatReaderGenerator().GenerateGetOnlyCollectionReader(TraditionalCollectionDataContract);
 #endif
                             }
 
@@ -110,6 +127,15 @@ internal JsonFormatGetOnlyCollectionReaderDelegate JsonFormatGetOnlyReaderDelega
             }
         }
 
+#if uapaot
+        [RemovableFeature(ReflectionBasedSerializationFeature.Name)]
+#endif
+        private JsonFormatCollectionWriterDelegate CreateJsonFormatWriterDelegate()
+        {
+            return new ReflectionJsonFormatWriter().ReflectionWriteCollection;
+        }
+
+
         internal JsonFormatCollectionWriterDelegate JsonFormatWriterDelegate
         {
             get
@@ -123,13 +149,13 @@ internal JsonFormatCollectionWriterDelegate JsonFormatWriterDelegate
                             JsonFormatCollectionWriterDelegate tempDelegate;
                             if (DataContractSerializer.Option == SerializationOption.ReflectionOnly)
                             {
-                                tempDelegate = new ReflectionJsonFormatWriter().ReflectionWriteCollection;
+                                tempDelegate = CreateJsonFormatWriterDelegate();
                             }
 #if uapaot
                             else if (DataContractSerializer.Option == SerializationOption.ReflectionAsBackup)
                             {
                                 tempDelegate = JsonDataContract.TryGetReadWriteDelegatesFromGeneratedAssembly(TraditionalCollectionDataContract)?.CollectionWriterDelegate;
-                                tempDelegate = tempDelegate ?? new ReflectionJsonFormatWriter().ReflectionWriteCollection;
+                                tempDelegate = tempDelegate ?? CreateJsonFormatWriterDelegate();
 
                                 if (tempDelegate == null)
                                     throw new InvalidDataContractException(SR.Format(SR.SerializationCodeIsMissingForType, TraditionalCollectionDataContract.UnderlyingType.ToString()));
@@ -217,4 +243,4 @@ internal CollectionDataContract TraditionalCollectionDataContract
             }
         }
     }
-}
+}

src/System.Private.DataContractSerialization/src/System/Runtime/Serialization/ReflectionFeature.cs

@@ -0,0 +1,11 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+namespace System.Runtime.Serialization
+{
+    class ReflectionBasedSerializationFeature
+    {
+        public const string Name = "System.Runtime.Serialization.ReflectionBasedSerialization";
+    }
+}