Fix a linker warning with the JsonSerializerOptionsUpdateHandler (#100362)

* * Fixes a linker warning with JsonSerializerOptionsUpdateHandler.
* Makes a few cleanups in the MemberAccessor clases.
* Ensures that the MemberAccessor being used is a singleton.

* Fix a number of trimmability warnings.

Author: eiriktsarpalis

src/libraries/System.Text.Json/src/System/Text/Json/Serialization/JsonSerializerOptionsUpdateHandler.cs

@@ -2,9 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 
 using System.Collections.Generic;
-using System.Diagnostics.CodeAnalysis;
 using System.Reflection.Metadata;
-using System.Runtime.CompilerServices;
 using System.Text.Json;
 using System.Text.Json.Serialization.Metadata;
 
@@ -25,11 +23,7 @@ public static void ClearCache(Type[]? types)
                 options.Key.ClearCaches();
             }
 
-            if (RuntimeFeature.IsDynamicCodeSupported)
-            {
-                // Flush the dynamic method cache
-                ReflectionEmitCachingMemberAccessor.Clear();
-            }
+            DefaultJsonTypeInfoResolver.ClearMemberAccessorCaches();
         }
     }
 }

src/libraries/System.Text.Json/src/System/Text/Json/Serialization/Metadata/DefaultJsonTypeInfoResolver.Helpers.cs

@@ -7,30 +7,38 @@
 using System.Reflection;
 using System.Runtime.CompilerServices;
 using System.Text.Json.Reflection;
+using System.Threading;
 
 namespace System.Text.Json.Serialization.Metadata
 {
     public partial class DefaultJsonTypeInfoResolver
     {
         internal static MemberAccessor MemberAccessor
         {
+            [RequiresUnreferencedCode(JsonSerializer.SerializationRequiresDynamicCodeMessage)]
             [RequiresDynamicCode(JsonSerializer.SerializationRequiresDynamicCodeMessage)]
             get
             {
-                return s_memberAccessor ??=
+                return s_memberAccessor ?? Initialize();
+                static MemberAccessor Initialize()
+                {
+                    MemberAccessor value =
 #if NETCOREAPP
-                // if dynamic code isn't supported, fallback to reflection
-                RuntimeFeature.IsDynamicCodeSupported ?
-                    new ReflectionEmitCachingMemberAccessor() :
-                    new ReflectionMemberAccessor();
+                        // if dynamic code isn't supported, fallback to reflection
+                        RuntimeFeature.IsDynamicCodeSupported ?
+                            new ReflectionEmitCachingMemberAccessor() :
+                            new ReflectionMemberAccessor();
 #elif NETFRAMEWORK
-                    new ReflectionEmitCachingMemberAccessor();
+                            new ReflectionEmitCachingMemberAccessor();
 #else
-                    new ReflectionMemberAccessor();
+                            new ReflectionMemberAccessor();
 #endif
+                    return Interlocked.CompareExchange(ref s_memberAccessor, value, null) ?? value;
+                }
             }
         }
 
+        internal static void ClearMemberAccessorCaches() => s_memberAccessor?.Clear();
         private static MemberAccessor? s_memberAccessor;
 
         [RequiresUnreferencedCode(JsonSerializer.SerializationUnreferencedCodeMessage)]

src/libraries/System.Text.Json/src/System/Text/Json/Serialization/Metadata/MemberAccessor.cs

@@ -9,23 +9,16 @@ namespace System.Text.Json.Serialization.Metadata
 {
     internal abstract class MemberAccessor
     {
-        public abstract Func<object>? CreateParameterlessConstructor(
-             [DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.PublicConstructors)] Type type,
-             ConstructorInfo? constructorInfo);
+        public abstract Func<object>? CreateParameterlessConstructor(Type type, ConstructorInfo? constructorInfo);
 
         public abstract Func<object[], T> CreateParameterizedConstructor<T>(ConstructorInfo constructor);
 
-        public abstract JsonTypeInfo.ParameterizedConstructorDelegate<T, TArg0, TArg1, TArg2, TArg3>?
-            CreateParameterizedConstructor<T, TArg0, TArg1, TArg2, TArg3>(ConstructorInfo constructor);
+        public abstract JsonTypeInfo.ParameterizedConstructorDelegate<T, TArg0, TArg1, TArg2, TArg3>? CreateParameterizedConstructor<T, TArg0, TArg1, TArg2, TArg3>(ConstructorInfo constructor);
 
         public abstract Action<TCollection, object?> CreateAddMethodDelegate<[DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.PublicMethods)] TCollection>();
 
-        [RequiresUnreferencedCode(IEnumerableConverterFactoryHelpers.ImmutableConvertersUnreferencedCodeMessage)]
-        [RequiresDynamicCode(IEnumerableConverterFactoryHelpers.ImmutableConvertersUnreferencedCodeMessage)]
         public abstract Func<IEnumerable<TElement>, TCollection> CreateImmutableEnumerableCreateRangeDelegate<TCollection, TElement>();
 
-        [RequiresUnreferencedCode(IEnumerableConverterFactoryHelpers.ImmutableConvertersUnreferencedCodeMessage)]
-        [RequiresDynamicCode(IEnumerableConverterFactoryHelpers.ImmutableConvertersUnreferencedCodeMessage)]
         public abstract Func<IEnumerable<KeyValuePair<TKey, TValue>>, TCollection> CreateImmutableDictionaryCreateRangeDelegate<TCollection, TKey, TValue>();
 
         public abstract Func<object, TProperty> CreatePropertyGetter<TProperty>(PropertyInfo propertyInfo);
@@ -35,5 +28,7 @@ public abstract JsonTypeInfo.ParameterizedConstructorDelegate<T, TArg0, TArg1, T
         public abstract Func<object, TProperty> CreateFieldGetter<TProperty>(FieldInfo fieldInfo);
 
         public abstract Action<object, TProperty> CreateFieldSetter<TProperty>(FieldInfo fieldInfo);
+
+        public virtual void Clear() { }
     }
 }

src/libraries/System.Text.Json/src/System/Text/Json/Serialization/Metadata/ReflectionEmitCachingMemberAccessor.cs

@@ -8,54 +8,70 @@
 
 namespace System.Text.Json.Serialization.Metadata
 {
-    [RequiresDynamicCode(JsonSerializer.SerializationRequiresDynamicCodeMessage)]
     internal sealed partial class ReflectionEmitCachingMemberAccessor : MemberAccessor
     {
-        private static readonly ReflectionEmitMemberAccessor s_sourceAccessor = new();
-        private static readonly Cache<(string id, Type declaringType, MemberInfo? member)> s_cache =
-            new(slidingExpiration: TimeSpan.FromMilliseconds(1000), evictionInterval: TimeSpan.FromMilliseconds(200));
+        private readonly ReflectionEmitMemberAccessor _sourceAccessor;
+        private readonly Cache<(string id, Type declaringType, MemberInfo? member)> _cache;
 
-        public static void Clear() => s_cache.Clear();
+        [RequiresDynamicCode(JsonSerializer.SerializationRequiresDynamicCodeMessage)]
+        [RequiresUnreferencedCode(JsonSerializer.SerializationRequiresDynamicCodeMessage)]
+        public ReflectionEmitCachingMemberAccessor()
+        {
+            _sourceAccessor = new ReflectionEmitMemberAccessor();
+            _cache = new(slidingExpiration: TimeSpan.FromMilliseconds(1000), evictionInterval: TimeSpan.FromMilliseconds(200));
+        }
 
-        public override Action<TCollection, object?> CreateAddMethodDelegate<[DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.PublicMethods)] TCollection>()
-            => s_cache.GetOrAdd((nameof(CreateAddMethodDelegate), typeof(TCollection), null),
-                static (_) => s_sourceAccessor.CreateAddMethodDelegate<TCollection>());
+        public override void Clear() => _cache.Clear();
 
-        public override Func<object>? CreateParameterlessConstructor([DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.PublicConstructors)] Type type, ConstructorInfo? ctorInfo)
-            => s_cache.GetOrAdd((nameof(CreateParameterlessConstructor), type, ctorInfo),
-                [UnconditionalSuppressMessage("ReflectionAnalysis", "IL2077:UnrecognizedReflectionPattern",
-                    Justification = "Cannot apply DynamicallyAccessedMembersAttribute to tuple properties.")]
-#pragma warning disable IL2077 // The suppression doesn't work for the trim analyzer: https://github.com/dotnet/roslyn/issues/59746
-                static (key) => s_sourceAccessor.CreateParameterlessConstructor(key.declaringType, (ConstructorInfo?)key.member));
-#pragma warning restore IL2077
+        public override Action<TCollection, object?> CreateAddMethodDelegate<[DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.PublicMethods)] TCollection>() =>
+            _cache.GetOrAdd(
+                key: (nameof(CreateAddMethodDelegate), typeof(TCollection), null),
+                _ => _sourceAccessor.CreateAddMethodDelegate<TCollection>());
 
-        public override Func<object, TProperty> CreateFieldGetter<TProperty>(FieldInfo fieldInfo)
-            => s_cache.GetOrAdd((nameof(CreateFieldGetter), typeof(TProperty), fieldInfo), static key => s_sourceAccessor.CreateFieldGetter<TProperty>((FieldInfo)key.member!));
+        public override Func<object>? CreateParameterlessConstructor(Type type, ConstructorInfo? ctorInfo) =>
+            _cache.GetOrAdd(
+                key: (nameof(CreateParameterlessConstructor), type, ctorInfo),
+                valueFactory: key => _sourceAccessor.CreateParameterlessConstructor(key.declaringType, (ConstructorInfo?)key.member));
 
-        public override Action<object, TProperty> CreateFieldSetter<TProperty>(FieldInfo fieldInfo)
-            => s_cache.GetOrAdd((nameof(CreateFieldSetter), typeof(TProperty), fieldInfo), static key => s_sourceAccessor.CreateFieldSetter<TProperty>((FieldInfo)key.member!));
+        public override Func<object, TProperty> CreateFieldGetter<TProperty>(FieldInfo fieldInfo) =>
+            _cache.GetOrAdd(
+                key: (nameof(CreateFieldGetter), typeof(TProperty), fieldInfo),
+                valueFactory: key => _sourceAccessor.CreateFieldGetter<TProperty>((FieldInfo)key.member!));
 
-        [RequiresUnreferencedCode(IEnumerableConverterFactoryHelpers.ImmutableConvertersUnreferencedCodeMessage)]
-        public override Func<IEnumerable<KeyValuePair<TKey, TValue>>, TCollection> CreateImmutableDictionaryCreateRangeDelegate<TCollection, TKey, TValue>()
-            => s_cache.GetOrAdd((nameof(CreateImmutableDictionaryCreateRangeDelegate), typeof((TCollection, TKey, TValue)), null),
-                static (_) => s_sourceAccessor.CreateImmutableDictionaryCreateRangeDelegate<TCollection, TKey, TValue>());
+        public override Action<object, TProperty> CreateFieldSetter<TProperty>(FieldInfo fieldInfo) =>
+            _cache.GetOrAdd(
+                key: (nameof(CreateFieldSetter), typeof(TProperty), fieldInfo),
+                valueFactory: key => _sourceAccessor.CreateFieldSetter<TProperty>((FieldInfo)key.member!));
 
-        [RequiresUnreferencedCode(IEnumerableConverterFactoryHelpers.ImmutableConvertersUnreferencedCodeMessage)]
-        public override Func<IEnumerable<TElement>, TCollection> CreateImmutableEnumerableCreateRangeDelegate<TCollection, TElement>()
-            => s_cache.GetOrAdd((nameof(CreateImmutableEnumerableCreateRangeDelegate), typeof((TCollection, TElement)), null),
-                static (_) => s_sourceAccessor.CreateImmutableEnumerableCreateRangeDelegate<TCollection, TElement>());
+        public override Func<IEnumerable<KeyValuePair<TKey, TValue>>, TCollection> CreateImmutableDictionaryCreateRangeDelegate<TCollection, TKey, TValue>() =>
+            _cache.GetOrAdd(
+                key: (nameof(CreateImmutableDictionaryCreateRangeDelegate), typeof((TCollection, TKey, TValue)), null),
+                valueFactory: _ => _sourceAccessor.CreateImmutableDictionaryCreateRangeDelegate<TCollection, TKey, TValue>());
 
-        public override Func<object[], T> CreateParameterizedConstructor<T>(ConstructorInfo constructor)
-            => s_cache.GetOrAdd((nameof(CreateParameterizedConstructor), typeof(T), constructor), static key => s_sourceAccessor.CreateParameterizedConstructor<T>((ConstructorInfo)key.member!));
+        public override Func<IEnumerable<TElement>, TCollection> CreateImmutableEnumerableCreateRangeDelegate<TCollection, TElement>() =>
+            _cache.GetOrAdd(
+                key: (nameof(CreateImmutableEnumerableCreateRangeDelegate), typeof((TCollection, TElement)), null),
+                valueFactory: _ => _sourceAccessor.CreateImmutableEnumerableCreateRangeDelegate<TCollection, TElement>());
 
-        public override JsonTypeInfo.ParameterizedConstructorDelegate<T, TArg0, TArg1, TArg2, TArg3>? CreateParameterizedConstructor<T, TArg0, TArg1, TArg2, TArg3>(ConstructorInfo constructor)
-            => s_cache.GetOrAdd((nameof(CreateParameterizedConstructor), typeof(T), constructor), static key => s_sourceAccessor.CreateParameterizedConstructor<T, TArg0, TArg1, TArg2, TArg3>((ConstructorInfo)key.member!));
+        public override Func<object[], T> CreateParameterizedConstructor<T>(ConstructorInfo constructor) =>
+            _cache.GetOrAdd(
+                key: (nameof(CreateParameterizedConstructor), typeof(T), constructor),
+                valueFactory: key => _sourceAccessor.CreateParameterizedConstructor<T>((ConstructorInfo)key.member!));
 
-        public override Func<object, TProperty> CreatePropertyGetter<TProperty>(PropertyInfo propertyInfo)
-            => s_cache.GetOrAdd((nameof(CreatePropertyGetter), typeof(TProperty), propertyInfo), static key => s_sourceAccessor.CreatePropertyGetter<TProperty>((PropertyInfo)key.member!));
+        public override JsonTypeInfo.ParameterizedConstructorDelegate<T, TArg0, TArg1, TArg2, TArg3>? CreateParameterizedConstructor<T, TArg0, TArg1, TArg2, TArg3>(ConstructorInfo constructor) =>
+            _cache.GetOrAdd(
+                key: (nameof(CreateParameterizedConstructor), typeof(T), constructor),
+                valueFactory: key => _sourceAccessor.CreateParameterizedConstructor<T, TArg0, TArg1, TArg2, TArg3>((ConstructorInfo)key.member!));
 
-        public override Action<object, TProperty> CreatePropertySetter<TProperty>(PropertyInfo propertyInfo)
-            => s_cache.GetOrAdd((nameof(CreatePropertySetter), typeof(TProperty), propertyInfo), static key => s_sourceAccessor.CreatePropertySetter<TProperty>((PropertyInfo)key.member!));
+        public override Func<object, TProperty> CreatePropertyGetter<TProperty>(PropertyInfo propertyInfo) =>
+            _cache.GetOrAdd(
+                key: (nameof(CreatePropertyGetter), typeof(TProperty), propertyInfo),
+                valueFactory: key => _sourceAccessor.CreatePropertyGetter<TProperty>((PropertyInfo)key.member!));
+
+        public override Action<object, TProperty> CreatePropertySetter<TProperty>(PropertyInfo propertyInfo) =>
+            _cache.GetOrAdd(
+                key: (nameof(CreatePropertySetter), typeof(TProperty), propertyInfo),
+                valueFactory: key => _sourceAccessor.CreatePropertySetter<TProperty>((PropertyInfo)key.member!));
     }
 }
 #endif