Remove NullabilityInfoContext.IsSupported feature switch (#103970)

* Remove NullabilityInfoContext.IsSupported feature switch

* Remove trimming tests

docs/workflow/trimming/feature-switches.md

@@ -29,7 +29,6 @@ configurations but their defaults might vary as any SDK can set the defaults dif
 | _EnableConsumingManagedCodeFromNativeHosting | System.Runtime.InteropServices.EnableConsumingManagedCodeFromNativeHosting | Getting a managed function from native hosting is disabled when set to false and related functionality can be trimmed. |
 | VerifyDependencyInjectionOpenGenericServiceTrimmability | Microsoft.Extensions.DependencyInjection.VerifyOpenGenericServiceTrimmability | When set to true, DependencyInjection will verify trimming annotations applied to open generic services are correct |
 | DisableDependencyInjectionDynamicEngine | Microsoft.Extensions.DependencyInjection.DisableDynamicEngine | When set to true, DependencyInjection will avoid using System.Reflection.Emit when realizing services |
-| NullabilityInfoContextSupport | System.Reflection.NullabilityInfoContext.IsSupported | Nullable attributes can be trimmed when set to false |
 | DynamicCodeSupport | System.Runtime.CompilerServices.RuntimeFeature.IsDynamicCodeSupported | Changes RuntimeFeature.IsDynamicCodeSupported to false to allow testing AOT-safe fallback code without publishing for Native AOT. |
 | _AggressiveAttributeTrimming | System.AggressiveAttributeTrimming | When set to true, aggressively trims attributes to allow for the most size savings possible, even if it could result in runtime behavior changes |
 | JsonSerializerIsReflectionEnabledByDefault | System.Text.Json.JsonSerializer.IsReflectionEnabledByDefault | When set to false, disables using reflection as the default contract resolver in System.Text.Json |

src/libraries/System.Private.CoreLib/src/ILLink/ILLink.LinkAttributes.Shared.xml

@@ -57,37 +57,6 @@
     </type>
   </assembly>
 
-  <!--
-    The following attributes are necessary when NullabilityInfoContext is supported.
-    Note these attributes are allowed to be in any assembly.
-     -->
-  <assembly fullname="*" feature="System.Reflection.NullabilityInfoContext.IsSupported" featurevalue="false">
-    <type fullname="System.Diagnostics.CodeAnalysis.AllowNullAttribute">
-      <attribute internal="RemoveAttributeInstances" />
-    </type>
-    <type fullname="System.Diagnostics.CodeAnalysis.DisallowNullAttribute">
-      <attribute internal="RemoveAttributeInstances" />
-    </type>
-    <type fullname="System.Diagnostics.CodeAnalysis.MaybeNullAttribute">
-      <attribute internal="RemoveAttributeInstances" />
-    </type>
-    <type fullname="System.Diagnostics.CodeAnalysis.MaybeNullWhenAttribute">
-      <attribute internal="RemoveAttributeInstances" />
-    </type>
-    <type fullname="System.Diagnostics.CodeAnalysis.NotNullAttribute">
-      <attribute internal="RemoveAttributeInstances" />
-    </type>
-    <type fullname="System.Runtime.CompilerServices.NullableAttribute">
-      <attribute internal="RemoveAttributeInstances" />
-    </type>
-    <type fullname="System.Runtime.CompilerServices.NullableContextAttribute">
-      <attribute internal="RemoveAttributeInstances" />
-    </type>
-    <type fullname="System.Runtime.CompilerServices.NullablePublicOnlyAttribute">
-      <attribute internal="RemoveAttributeInstances" />
-    </type>
-  </assembly>
-
   <!-- The following attributes are only necessary when COM is supported -->
   <assembly fullname="System.Private.CoreLib" feature="System.Runtime.InteropServices.BuiltInComInterop.IsSupported" featurevalue="false">
     <type fullname="System.Runtime.InteropServices.ClassInterfaceAttribute">

src/libraries/System.Private.CoreLib/src/ILLink/ILLink.Substitutions.Shared.xml

@@ -36,9 +36,6 @@
     <type fullname="System.Reflection.Metadata.MetadataUpdater" feature="System.Reflection.Metadata.MetadataUpdater.IsSupported" featurevalue="false">
       <method signature="System.Boolean get_IsSupported()" body="stub" value="false" />
     </type>
-    <type fullname="System.Reflection.NullabilityInfoContext" feature="System.Reflection.NullabilityInfoContext.IsSupported" featurevalue="false">
-      <method signature="System.Boolean get_IsSupported()" body="stub" value="false" />
-    </type>
     <type fullname="Internal.Runtime.InteropServices.ComponentActivator" feature="System.Runtime.InteropServices.EnableConsumingManagedCodeFromNativeHosting" featurevalue="false">
       <method signature="System.Boolean get_IsSupported()" body="stub" value="false" />
     </type>

src/libraries/System.Private.CoreLib/src/Resources/Strings.resx

@@ -4058,9 +4058,6 @@
   <data name="TimeZoneNotFound_ValidTimeZoneFileMissing" xml:space="preserve">
     <value>Unable to properly load any time zone data files.</value>
   </data>
-  <data name="NullabilityInfoContext_NotSupported" xml:space="preserve">
-    <value>NullabilityInfoContext is not supported in the current application because 'System.Reflection.NullabilityInfoContext.IsSupported' is set to false. Set the MSBuild Property 'NullabilityInfoContextSupport' to true in order to enable it.</value>
-  </data>
   <data name="ThreadState_AlreadyStarted" xml:space="preserve">
     <value>Thread is running or terminated; it cannot restart.</value>
   </data>

src/libraries/System.Private.CoreLib/src/System/Reflection/NullabilityInfoContext.cs

@@ -22,9 +22,6 @@ sealed class NullabilityInfoContext
         private readonly Dictionary<Module, NotAnnotatedStatus> _publicOnlyModules = new();
         private readonly Dictionary<MemberInfo, NullabilityState> _context = new();
 
-        internal static bool IsSupported { get; } =
-            AppContext.TryGetSwitch("System.Reflection.NullabilityInfoContext.IsSupported", out bool isSupported) ? isSupported : true;
-
         [Flags]
         private enum NotAnnotatedStatus
         {
@@ -75,9 +72,6 @@ public NullabilityInfo Create(ParameterInfo parameterInfo)
 #else
             NetstandardHelpers.ThrowIfNull(parameterInfo, nameof(parameterInfo));
 #endif
-
-            EnsureIsSupported();
-
             IList<CustomAttributeData> attributes = parameterInfo.GetCustomAttributesData();
             NullableAttributeStateParser parser = parameterInfo.Member is MethodBase method && IsPrivateOrInternalMethodAndAnnotationDisabled(method)
                 ? NullableAttributeStateParser.Unknown
@@ -204,9 +198,6 @@ public NullabilityInfo Create(PropertyInfo propertyInfo)
 #else
             NetstandardHelpers.ThrowIfNull(propertyInfo, nameof(propertyInfo));
 #endif
-
-            EnsureIsSupported();
-
             MethodInfo? getter = propertyInfo.GetGetMethod(true);
             MethodInfo? setter = propertyInfo.GetSetMethod(true);
             bool annotationsDisabled = (getter == null || IsPrivateOrInternalMethodAndAnnotationDisabled(getter))
@@ -263,9 +254,6 @@ public NullabilityInfo Create(EventInfo eventInfo)
 #else
             NetstandardHelpers.ThrowIfNull(eventInfo, nameof(eventInfo));
 #endif
-
-            EnsureIsSupported();
-
             return GetNullabilityInfo(eventInfo, eventInfo.EventHandlerType!, CreateParser(eventInfo.GetCustomAttributesData()));
         }
 
@@ -284,24 +272,13 @@ public NullabilityInfo Create(FieldInfo fieldInfo)
 #else
             NetstandardHelpers.ThrowIfNull(fieldInfo, nameof(fieldInfo));
 #endif
-
-            EnsureIsSupported();
-
             IList<CustomAttributeData> attributes = fieldInfo.GetCustomAttributesData();
             NullableAttributeStateParser parser = IsPrivateOrInternalFieldAndAnnotationDisabled(fieldInfo) ? NullableAttributeStateParser.Unknown : CreateParser(attributes);
             NullabilityInfo nullability = GetNullabilityInfo(fieldInfo, fieldInfo.FieldType, parser);
             CheckNullabilityAttributes(nullability, attributes);
             return nullability;
         }
 
-        private static void EnsureIsSupported()
-        {
-            if (!IsSupported)
-            {
-                throw new InvalidOperationException(SR.NullabilityInfoContext_NotSupported);
-            }
-        }
-
         private bool IsPrivateOrInternalFieldAndAnnotationDisabled(FieldInfo fieldInfo)
         {
             if ((fieldInfo.IsPrivate || fieldInfo.IsFamilyAndAssembly || fieldInfo.IsAssembly) &&

src/libraries/System.Runtime/tests/System.Runtime.Tests/System/Reflection/NullabilityInfoContextTests.cs

@@ -284,43 +284,6 @@ public void GenericDictionaryPropertyTest(string propertyName, NullabilityState
             Assert.Null(nullability.ElementType);
         }
 
-        [ConditionalFact(typeof(RemoteExecutor), nameof(RemoteExecutor.IsSupported))]
-        public void VerifyIsSupportedThrows()
-        {
-            RemoteInvokeOptions options = new RemoteInvokeOptions();
-            options.RuntimeConfigurationOptions.Add("System.Reflection.NullabilityInfoContext.IsSupported", "false");
-
-            using RemoteInvokeHandle remoteHandle = RemoteExecutor.Invoke(() =>
-            {
-                FieldInfo field = testType.GetField("FieldNullable", flags);
-                Assert.Throws<InvalidOperationException>(() => nullabilityContext.Create(field));
-
-                EventInfo @event = testType.GetEvent("EventNullable");
-                Assert.Throws<InvalidOperationException>(() => nullabilityContext.Create(@event));
-
-                PropertyInfo property = testType.GetProperty("PropertyNullable", flags);
-                Assert.Throws<InvalidOperationException>(() => nullabilityContext.Create(property));
-
-                MethodInfo method = testType.GetMethod("MethodNullNonNullNonNon", flags);
-                Assert.Throws<InvalidOperationException>(() => nullabilityContext.Create(method.ReturnParameter));
-            }, options);
-        }
-
-        [ConditionalFact(typeof(RemoteExecutor), nameof(RemoteExecutor.IsSupported))]
-        public void VerifyIsSupportedWorks()
-        {
-            RemoteInvokeOptions options = new RemoteInvokeOptions();
-            options.RuntimeConfigurationOptions.Add("System.Reflection.NullabilityInfoContext.IsSupported", "true");
-
-            using RemoteInvokeHandle remoteHandle = RemoteExecutor.Invoke(() =>
-            {
-                FieldInfo field = testType.GetField("FieldNullable", flags);
-                NullabilityInfo nullability = nullabilityContext.Create(field);
-                Assert.Equal(NullabilityState.Nullable, nullability.ReadState);
-                Assert.Equal(NullabilityState.Nullable, nullability.WriteState);
-            }, options);
-        }
-
         public static IEnumerable<object[]> GenericPropertyReferenceTypeTestData()
         {
             yield return new object[] { "PropertyNullable", NullabilityState.Nullable, NullabilityState.Nullable, typeof(TypeWithNotNullContext) };

src/libraries/System.Runtime/tests/System.Runtime.Tests/TrimmingTests/System.Runtime.TrimmingTests.proj

@@ -56,12 +56,6 @@
       <!-- Reflection.Emit doesn't work with native AOT -->
       <NativeAotIncompatible>true</NativeAotIncompatible>
     </TestConsoleAppSourceFiles>
-    <TestConsoleAppSourceFiles Include="NullabilityInfoContextSupportFalse.cs">
-      <DisabledProperties>NullabilityInfoContextSupport</DisabledProperties>
-    </TestConsoleAppSourceFiles>
-    <TestConsoleAppSourceFiles Include="NullabilityInfoContextSupportTrue.cs">
-      <EnabledProperties>NullabilityInfoContextSupport</EnabledProperties>
-    </TestConsoleAppSourceFiles>
   </ItemGroup>
   <ItemGroup Condition="'$(TargetsWindows)' == 'true'">
     <TestConsoleAppSourceFiles Include="UseWindowsThreadPoolFalse.cs">

src/libraries/System.Text.Json/src/Resources/Strings.resx

@@ -749,9 +749,6 @@
   <data name="ConstructorParameterDisallowNull" xml:space="preserve">
     <value>The constructor parameter '{0}' on type '{1}' doesn't allow null values. Consider updating its nullability annotation.</value>
   </data>
-  <data name="NullabilityInfoContext_NotSupported" xml:space="preserve">
-    <value>NullabilityInfoContext is not supported in the current application because 'System.Reflection.NullabilityInfoContext.IsSupported' is set to false. Set the MSBuild Property 'NullabilityInfoContextSupport' to true in order to enable it.</value>
-  </data>
   <data name="JsonSchemaExporter_ReferenceHandlerPreserve_NotSupported" xml:space="preserve">
     <value>JSON schema generation is not supported for contracts using ReferenceHandler.Preserve.</value>
   </data>

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

@@ -13,9 +13,6 @@ namespace System.Text.Json.Serialization.Metadata
 {
     public partial class DefaultJsonTypeInfoResolver
     {
-        private static readonly bool s_isNullabilityInfoContextSupported =
-            AppContext.TryGetSwitch("System.Reflection.NullabilityInfoContext.IsSupported", out bool isSupported) ? isSupported : true;
-
         internal static MemberAccessor MemberAccessor
         {
             [RequiresUnreferencedCode(JsonSerializer.SerializationRequiresDynamicCodeMessage)]
@@ -74,10 +71,7 @@ private static JsonTypeInfo CreateTypeInfoCore(Type type, JsonConverter converte
 
             if (typeInfo is { Kind: JsonTypeInfoKind.Object, IsNullable: false })
             {
-                // If the System.Reflection.NullabilityInfoContext.IsSupported feature switch has been disabled,
-                // we want to avoid resolving nullability information for properties and parameters unless the
-                // user has explicitly opted into nullability enforcement in which case an exception will be surfaced.
-                NullabilityInfoContext? nullabilityCtx = s_isNullabilityInfoContextSupported || options.RespectNullableAnnotations ? new() : null;
+                NullabilityInfoContext nullabilityCtx = new();
 
                 if (converter.ConstructorIsParameterized)
                 {
@@ -99,7 +93,7 @@ private static JsonTypeInfo CreateTypeInfoCore(Type type, JsonConverter converte
 
         [RequiresUnreferencedCode(JsonSerializer.SerializationUnreferencedCodeMessage)]
         [RequiresDynamicCode(JsonSerializer.SerializationRequiresDynamicCodeMessage)]
-        private static void PopulateProperties(JsonTypeInfo typeInfo, NullabilityInfoContext? nullabilityCtx)
+        private static void PopulateProperties(JsonTypeInfo typeInfo, NullabilityInfoContext nullabilityCtx)
         {
             Debug.Assert(!typeInfo.IsReadOnly);
             Debug.Assert(typeInfo.Kind is JsonTypeInfoKind.Object);
@@ -146,7 +140,7 @@ private static void PopulateProperties(JsonTypeInfo typeInfo, NullabilityInfoCon
         private static void AddMembersDeclaredBySuperType(
             JsonTypeInfo typeInfo,
             Type currentType,
-            NullabilityInfoContext? nullabilityCtx,
+            NullabilityInfoContext nullabilityCtx,
             bool constructorHasSetsRequiredMembersAttribute,
             ref JsonTypeInfo.PropertyHierarchyResolutionState state)
         {
@@ -207,7 +201,7 @@ private static void AddMember(
             JsonTypeInfo typeInfo,
             Type typeToConvert,
             MemberInfo memberInfo,
-            NullabilityInfoContext? nullabilityCtx,
+            NullabilityInfoContext nullabilityCtx,
             bool shouldCheckForRequiredKeyword,
             bool hasJsonIncludeAttribute,
             ref JsonTypeInfo.PropertyHierarchyResolutionState state)
@@ -229,7 +223,7 @@ private static void AddMember(
             JsonTypeInfo typeInfo,
             Type typeToConvert,
             MemberInfo memberInfo,
-            NullabilityInfoContext? nullabilityCtx,
+            NullabilityInfoContext nullabilityCtx,
             JsonSerializerOptions options,
             bool shouldCheckForRequiredKeyword,
             bool hasJsonIncludeAttribute)
@@ -289,7 +283,7 @@ private static bool PropertyIsOverriddenAndIgnored(PropertyInfo propertyInfo, Di
 
         [RequiresUnreferencedCode(JsonSerializer.SerializationUnreferencedCodeMessage)]
         [RequiresDynamicCode(JsonSerializer.SerializationRequiresDynamicCodeMessage)]
-        private static void PopulateParameterInfoValues(JsonTypeInfo typeInfo, NullabilityInfoContext? nullabilityCtx)
+        private static void PopulateParameterInfoValues(JsonTypeInfo typeInfo, NullabilityInfoContext nullabilityCtx)
         {
             Debug.Assert(typeInfo.Converter.ConstructorInfo != null);
             ParameterInfo[] parameters = typeInfo.Converter.ConstructorInfo.GetParameters();
@@ -330,7 +324,7 @@ private static void PopulatePropertyInfo(
             MemberInfo memberInfo,
             JsonConverter? customConverter,
             JsonIgnoreCondition? ignoreCondition,
-            NullabilityInfoContext? nullabilityCtx,
+            NullabilityInfoContext nullabilityCtx,
             bool shouldCheckForRequiredKeyword,
             bool hasJsonIncludeAttribute)
         {
@@ -473,9 +467,9 @@ internal static void DeterminePropertyAccessors<T>(JsonPropertyInfo<T> jsonPrope
 
         [RequiresUnreferencedCode(JsonSerializer.SerializationUnreferencedCodeMessage)]
         [RequiresDynamicCode(JsonSerializer.SerializationRequiresDynamicCodeMessage)]
-        private static void DeterminePropertyNullability(JsonPropertyInfo propertyInfo, MemberInfo memberInfo, NullabilityInfoContext? nullabilityCtx)
+        private static void DeterminePropertyNullability(JsonPropertyInfo propertyInfo, MemberInfo memberInfo, NullabilityInfoContext nullabilityCtx)
         {
-            if (!propertyInfo.PropertyTypeCanBeNull || nullabilityCtx is null)
+            if (!propertyInfo.PropertyTypeCanBeNull)
             {
                 return;
             }
@@ -497,17 +491,12 @@ private static void DeterminePropertyNullability(JsonPropertyInfo propertyInfo,
 
         [RequiresUnreferencedCode(JsonSerializer.SerializationUnreferencedCodeMessage)]
         [RequiresDynamicCode(JsonSerializer.SerializationRequiresDynamicCodeMessage)]
-        private static NullabilityState DetermineParameterNullability(ParameterInfo parameterInfo, NullabilityInfoContext? nullabilityCtx)
+        private static NullabilityState DetermineParameterNullability(ParameterInfo parameterInfo, NullabilityInfoContext nullabilityCtx)
         {
             if (!parameterInfo.ParameterType.IsNullableType())
             {
                 return NullabilityState.NotNull;
             }
-
-            if (nullabilityCtx is null)
-            {
-                return NullabilityState.Unknown;
-            }
 #if NET8_0
             // Workaround for https://github.com/dotnet/runtime/issues/92487
             // The fix has been incorporated into .NET 9 (and the polyfilled implementations in netfx).