Remove System.Text.Json's DynamicDependencies on Collections.Immutable (#53317)

This saves roughly 28 KB compressed in a default blazor wasm app.

Fix #53256

Author: eerhardt

src/libraries/System.Text.Json/src/System/Text/Json/Serialization/Converters/Collection/IEnumerableConverterFactoryHelpers.cs

@@ -40,10 +40,9 @@ internal static class IEnumerableConverterFactoryHelpers
         private const string ImmutableSortedDictionaryTypeName = "System.Collections.Immutable.ImmutableSortedDictionary";
 
         private const string CreateRangeMethodName = "CreateRange";
-        private const string CreateRangeMethodNameForEnumerable = "CreateRange`1";
-        private const string CreateRangeMethodNameForDictionary = "CreateRange`2";
 
-        private const string ImmutableCollectionsAssembly = "System.Collections.Immutable";
+        // Don't use DynamicDependency attributes to the Immutable Collection types so they can be trimmed in applications that don't use Immutable Collections.
+        internal const string ImmutableConvertersUnreferencedCodeMessage = "System.Collections.Immutable converters use Reflection to find and create Immutable Collection types, which requires unreferenced code.";
 
         internal static Type? GetCompatibleGenericBaseClass(this Type type, Type baseType)
         {
@@ -151,16 +150,7 @@ public static bool IsImmutableEnumerableType(this Type type)
             }
         }
 
-        [DynamicDependency(CreateRangeMethodNameForEnumerable, ImmutableArrayTypeName, ImmutableCollectionsAssembly)]
-        [DynamicDependency(CreateRangeMethodNameForEnumerable, ImmutableListTypeName, ImmutableCollectionsAssembly)]
-        [DynamicDependency(CreateRangeMethodNameForEnumerable, ImmutableStackTypeName, ImmutableCollectionsAssembly)]
-        [DynamicDependency(CreateRangeMethodNameForEnumerable, ImmutableQueueTypeName, ImmutableCollectionsAssembly)]
-        [DynamicDependency(CreateRangeMethodNameForEnumerable, ImmutableSortedSetTypeName, ImmutableCollectionsAssembly)]
-        [DynamicDependency(CreateRangeMethodNameForEnumerable, ImmutableHashSetTypeName, ImmutableCollectionsAssembly)]
-        [UnconditionalSuppressMessage("ReflectionAnalysis", "IL2075:UnrecognizedReflectionPattern",
-            Justification = "The CreateRange method is preserved by the DynamicDependency attribute.")]
-        [UnconditionalSuppressMessage("ReflectionAnalysis", "IL2060:MakeGenericMethod",
-            Justification = "Immutable collections don't have trimming annotations.")]
+        [RequiresUnreferencedCode(ImmutableConvertersUnreferencedCodeMessage)]
         public static MethodInfo GetImmutableEnumerableCreateRangeMethod(this Type type, Type elementType)
         {
             Type? constructingType = GetImmutableEnumerableConstructingType(type);
@@ -183,12 +173,7 @@ public static MethodInfo GetImmutableEnumerableCreateRangeMethod(this Type type,
             return null!;
         }
 
-        [DynamicDependency(CreateRangeMethodNameForDictionary, ImmutableDictionaryTypeName, ImmutableCollectionsAssembly)]
-        [DynamicDependency(CreateRangeMethodNameForDictionary, ImmutableSortedDictionaryTypeName, ImmutableCollectionsAssembly)]
-        [UnconditionalSuppressMessage("ReflectionAnalysis", "IL2075:UnrecognizedReflectionPattern",
-            Justification = "The CreateRange method is preserved by the DynamicDependency attribute.")]
-        [UnconditionalSuppressMessage("ReflectionAnalysis", "IL2060:MakeGenericMethod",
-            Justification = "Immutable collections don't have trimming annotations.")]
+        [RequiresUnreferencedCode(ImmutableConvertersUnreferencedCodeMessage)]
         public static MethodInfo GetImmutableDictionaryCreateRangeMethod(this Type type, Type keyType, Type valueType)
         {
             Type? constructingType = GetImmutableDictionaryConstructingType(type);
@@ -211,9 +196,7 @@ public static MethodInfo GetImmutableDictionaryCreateRangeMethod(this Type type,
             return null!;
         }
 
-        [UnconditionalSuppressMessage("ReflectionAnalysis", "IL2026:RequiresUnreferencedCode",
-            Justification = "Json can't take a direct dependency on Collections.Immutable." +
-            "The types used here will be preserved by the DynamicDependency attributes on the only caller - GetImmutableEnumerableCreateRangeMethod.")]
+        [RequiresUnreferencedCode(ImmutableConvertersUnreferencedCodeMessage)]
         private static Type? GetImmutableEnumerableConstructingType(Type type)
         {
             Debug.Assert(type.IsImmutableEnumerableType());
@@ -257,9 +240,7 @@ public static MethodInfo GetImmutableDictionaryCreateRangeMethod(this Type type,
             return underlyingType.Assembly.GetType(constructingTypeName);
         }
 
-        [UnconditionalSuppressMessage("ReflectionAnalysis", "IL2026:RequiresUnreferencedCode",
-            Justification = "Json can't take a direct dependency on Collections.Immutable." +
-            "The types used here will be preserved by the DynamicDependency attributes on the only caller - GetImmutableDictionaryCreateRangeMethod.")]
+        [RequiresUnreferencedCode(ImmutableConvertersUnreferencedCodeMessage)]
         private static Type? GetImmutableDictionaryConstructingType(Type type)
         {
             Debug.Assert(type.IsImmutableDictionaryType());

src/libraries/System.Text.Json/src/System/Text/Json/Serialization/Converters/Collection/ImmutableDictionaryOfTKeyTValueConverter.cs

@@ -2,6 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 
 using System.Collections.Generic;
+using System.Diagnostics.CodeAnalysis;
 using System.Text.Json.Serialization.Metadata;
 
 namespace System.Text.Json.Serialization.Converters
@@ -11,6 +12,11 @@ internal sealed class ImmutableDictionaryOfTKeyTValueConverter<TCollection, TKey
         where TCollection : IReadOnlyDictionary<TKey, TValue>
         where TKey : notnull
     {
+        [RequiresUnreferencedCode(IEnumerableConverterFactoryHelpers.ImmutableConvertersUnreferencedCodeMessage)]
+        public ImmutableDictionaryOfTKeyTValueConverter()
+        {
+        }
+
         protected override void Add(TKey key, in TValue value, JsonSerializerOptions options, ref ReadStack state)
         {
             ((Dictionary<TKey, TValue>)state.Current.ReturnValue!)[key] = value;
@@ -23,6 +29,8 @@ protected override void CreateCollection(ref Utf8JsonReader reader, ref ReadStac
             state.Current.ReturnValue = new Dictionary<TKey, TValue>();
         }
 
+        [UnconditionalSuppressMessage("ReflectionAnalysis", "IL2026:RequiresUnreferencedCode",
+            Justification = "The ctor is marked RequiresUnreferencedCode.")]
         protected override void ConvertCollection(ref ReadStack state, JsonSerializerOptions options)
         {
             JsonTypeInfo typeInfo = state.Current.JsonTypeInfo;

src/libraries/System.Text.Json/src/System/Text/Json/Serialization/Converters/Collection/ImmutableEnumerableOfTConverter.cs

@@ -2,6 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 
 using System.Collections.Generic;
+using System.Diagnostics.CodeAnalysis;
 using System.Text.Json.Serialization.Metadata;
 
 namespace System.Text.Json.Serialization.Converters
@@ -10,6 +11,11 @@ internal sealed class ImmutableEnumerableOfTConverter<TCollection, TElement>
         : IEnumerableDefaultConverter<TCollection, TElement>
         where TCollection : IEnumerable<TElement>
     {
+        [RequiresUnreferencedCode(IEnumerableConverterFactoryHelpers.ImmutableConvertersUnreferencedCodeMessage)]
+        public ImmutableEnumerableOfTConverter()
+        {
+        }
+
         protected override void Add(in TElement value, ref ReadStack state)
         {
             ((List<TElement>)state.Current.ReturnValue!).Add(value);
@@ -22,6 +28,8 @@ protected override void CreateCollection(ref Utf8JsonReader reader, ref ReadStac
             state.Current.ReturnValue = new List<TElement>();
         }
 
+        [UnconditionalSuppressMessage("ReflectionAnalysis", "IL2026:RequiresUnreferencedCode",
+            Justification = "The ctor is marked RequiresUnreferencedCode.")]
         protected override void ConvertCollection(ref ReadStack state, JsonSerializerOptions options)
         {
             JsonTypeInfo typeInfo = state.Current.JsonTypeInfo;

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

@@ -19,8 +19,10 @@ public abstract JsonTypeInfo.ParameterizedConstructorDelegate<T, TArg0, TArg1, T
 
         public abstract Action<TCollection, object?> CreateAddMethodDelegate<[DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.PublicMethods)] TCollection>();
 
+        [RequiresUnreferencedCode(IEnumerableConverterFactoryHelpers.ImmutableConvertersUnreferencedCodeMessage)]
         public abstract Func<IEnumerable<TElement>, TCollection> CreateImmutableEnumerableCreateRangeDelegate<TCollection, TElement>();
 
+        [RequiresUnreferencedCode(IEnumerableConverterFactoryHelpers.ImmutableConvertersUnreferencedCodeMessage)]
         public abstract Func<IEnumerable<KeyValuePair<TKey, TValue>>, TCollection> CreateImmutableDictionaryCreateRangeDelegate<TCollection, TKey, TValue>();
 
         public abstract Func<object, TProperty> CreatePropertyGetter<TProperty>(PropertyInfo propertyInfo);

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

@@ -172,10 +172,12 @@ private static DynamicMethod CreateAddMethodDelegate(
             return dynamicMethod;
         }
 
+        [RequiresUnreferencedCode(IEnumerableConverterFactoryHelpers.ImmutableConvertersUnreferencedCodeMessage)]
         public override Func<IEnumerable<TElement>, TCollection> CreateImmutableEnumerableCreateRangeDelegate<TCollection, TElement>() =>
             CreateDelegate<Func<IEnumerable<TElement>, TCollection>>(
                 CreateImmutableEnumerableCreateRangeDelegate(typeof(TCollection), typeof(TElement), typeof(IEnumerable<TElement>)));
 
+        [RequiresUnreferencedCode(IEnumerableConverterFactoryHelpers.ImmutableConvertersUnreferencedCodeMessage)]
         private static DynamicMethod CreateImmutableEnumerableCreateRangeDelegate(Type collectionType, Type elementType, Type enumerableType)
         {
             MethodInfo realMethod = collectionType.GetImmutableEnumerableCreateRangeMethod(elementType);
@@ -196,10 +198,12 @@ private static DynamicMethod CreateImmutableEnumerableCreateRangeDelegate(Type c
             return dynamicMethod;
         }
 
+        [RequiresUnreferencedCode(IEnumerableConverterFactoryHelpers.ImmutableConvertersUnreferencedCodeMessage)]
         public override Func<IEnumerable<KeyValuePair<TKey, TValue>>, TCollection> CreateImmutableDictionaryCreateRangeDelegate<TCollection, TKey, TValue>() =>
             CreateDelegate<Func<IEnumerable<KeyValuePair<TKey, TValue>>, TCollection>>(
                 CreateImmutableDictionaryCreateRangeDelegate(typeof(TCollection), typeof(TKey), typeof(TValue), typeof(IEnumerable<KeyValuePair<TKey, TValue>>)));
 
+        [RequiresUnreferencedCode(IEnumerableConverterFactoryHelpers.ImmutableConvertersUnreferencedCodeMessage)]
         private static DynamicMethod CreateImmutableDictionaryCreateRangeDelegate(Type collectionType, Type keyType, Type valueType, Type enumerableType)
         {
             MethodInfo realMethod = collectionType.GetImmutableDictionaryCreateRangeMethod(keyType, valueType);

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

@@ -124,13 +124,15 @@ public override JsonTypeInfo.ParameterizedConstructorDelegate<T, TArg0, TArg1, T
             };
         }
 
+        [RequiresUnreferencedCode(IEnumerableConverterFactoryHelpers.ImmutableConvertersUnreferencedCodeMessage)]
         public override Func<IEnumerable<TElement>, TCollection> CreateImmutableEnumerableCreateRangeDelegate<TCollection, TElement>()
         {
             MethodInfo createRange = typeof(TCollection).GetImmutableEnumerableCreateRangeMethod(typeof(TElement));
             return (Func<IEnumerable<TElement>, TCollection>)createRange.CreateDelegate(
                 typeof(Func<IEnumerable<TElement>, TCollection>));
         }
 
+        [RequiresUnreferencedCode(IEnumerableConverterFactoryHelpers.ImmutableConvertersUnreferencedCodeMessage)]
         public override Func<IEnumerable<KeyValuePair<TKey, TValue>>, TCollection> CreateImmutableDictionaryCreateRangeDelegate<TCollection, TKey, TValue>()
         {
             MethodInfo createRange = typeof(TCollection).GetImmutableDictionaryCreateRangeMethod(typeof(TKey), typeof(TValue));