Removing RUC from Default and Ambient attributes (dotnet#100821)

* Removing RUC from Default and Ambient attributes

* FB

* FB2

docs/workflow/trimming/feature-switches.md

@@ -36,6 +36,8 @@ configurations but their defaults might vary as any SDK can set the defaults dif
 | EnableGeneratedComInterfaceComImportInterop | System.Runtime.InteropServices.Marshalling.EnableGeneratedComInterfaceComImportInterop | When set to true, enables casting source-generated COM object wrappers to built-in COM-based COM interfaces. |
 | _UseManagedNtlm | System.Net.Security.UseManagedNtlm | When set to true, uses built-in managed implementation of NTLM and SPNEGO algorithm for HTTP, SMTP authentication, and NegotiateAuthentication API instead of system provided GSSAPI implementation. |
 | _ComObjectDescriptorSupport | System.ComponentModel.TypeDescriptor.IsComObjectDescriptorSupported | When set to true, supports creating a TypeDescriptor based view of COM objects. |
+| _DesignerHostSupport | System.ComponentModel.Design.IDesignerHost.IsSupported | When set to true, supports creating design components at runtime. |
+| _DefaultValueAttributeSupport | System.ComponentModel.DefaultValueAttribute.IsSupported | When set to true, supports creating a DefaultValueAttribute at runtime. |
 
 Any feature-switch which defines property can be set in csproj file or
 on the command line as any other MSBuild property. Those without predefined property name

src/libraries/System.ComponentModel.TypeConverter/ref/System.ComponentModel.TypeConverter.cs

@@ -38,7 +38,6 @@ public AmbientValueAttribute(long value) { }
         public AmbientValueAttribute(object? value) { }
         public AmbientValueAttribute(float value) { }
         public AmbientValueAttribute(string? value) { }
-        [System.Diagnostics.CodeAnalysis.RequiresUnreferencedCodeAttribute("Generic TypeConverters may require the generic types to be annotated. For example, NullableConverter requires the underlying type to be DynamicallyAccessedMembers All.")]
         public AmbientValueAttribute([System.Diagnostics.CodeAnalysis.DynamicallyAccessedMembersAttribute(System.Diagnostics.CodeAnalysis.DynamicallyAccessedMemberTypes.All)] System.Type type, string value) { }
         public object? Value { get { throw null; } }
         public override bool Equals([System.Diagnostics.CodeAnalysis.NotNullWhenAttribute(true)] object? obj) { throw null; }

src/libraries/System.ComponentModel.TypeConverter/src/ILLink/ILLink.Suppressions.LibraryBuild.xml

@@ -22,5 +22,12 @@
         <property name="Target">M:System.ComponentModel.TypeDescriptor.NodeFor(System.Object,System.Boolean)</property>
         <property name="Justification">This warning is left in the product so developers get an ILLink warning when trimming an app with System.ComponentModel.TypeDescriptor.IsComObjectDescriptorSupported=true.</property>
     </attribute>
+    <attribute fullname="System.Diagnostics.CodeAnalysis.UnconditionalSuppressMessageAttribute">
+      <argument>ILLink</argument>
+      <argument>IL2026</argument>
+      <property name="Scope">member</property>
+      <property name="Target">M:System.ComponentModel.AmbientValueAttribute.#ctor(System.Type,System.String)</property>
+      <property name="Justification">This warning is left in the product so developers get an ILLink warning when trimming an app with System.ComponentModel.Design.IDesignerHost.IsSupported=true.</property>
+    </attribute>
   </assembly>
 </linker>

src/libraries/System.ComponentModel.TypeConverter/src/System/ComponentModel/AmbientValueAttribute.cs

@@ -24,20 +24,23 @@ public sealed class AmbientValueAttribute : Attribute
         /// specified value to the specified type, and using the U.S. English culture as the
         /// translation context.
         /// </summary>
-        [RequiresUnreferencedCode(TypeConverter.RequiresUnreferencedCodeMessage)]
         public AmbientValueAttribute([DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.All)] Type type, string value)
         {
             // The try/catch here is because attributes should never throw exceptions. We would fail to
             // load an otherwise normal class.
 
+            Debug.Assert(IDesignerHost.IsSupported, "Runtime instantiation of this attribute is not allowed with trimming.");
             if (!IDesignerHost.IsSupported)
             {
                 return;
             }
 
             try
             {
-                _value = TypeDescriptor.GetConverter(type).ConvertFromInvariantString(value);
+                _value = TypeDescriptorGetConverter(type).ConvertFromInvariantString(value);
+
+                [RequiresUnreferencedCode("AmbientValueAttribute usage of TypeConverter is not compatible with trimming.")]
+                static TypeConverter TypeDescriptorGetConverter([DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.All)] Type type) => TypeDescriptor.GetConverter(type);
             }
             catch
             {

src/libraries/System.ComponentModel.TypeConverter/src/System/ComponentModel/Design/IDesignerHost.cs

@@ -12,7 +12,10 @@ namespace System.ComponentModel.Design
     public interface IDesignerHost : IServiceContainer
     {
         [FeatureSwitchDefinition("System.ComponentModel.Design.IDesignerHost.IsSupported")]
+        [FeatureGuard(typeof(RequiresUnreferencedCodeAttribute))]
+#pragma warning disable IL4000
         internal static bool IsSupported => AppContext.TryGetSwitch("System.ComponentModel.Design.IDesignerHost.IsSupported", out bool isSupported) ? isSupported : true;
+#pragma warning restore IL4000
 
         /// <summary>
         /// Gets or sets a value indicating whether the designer host

src/libraries/System.Private.CoreLib/src/ILLink/ILLink.Suppressions.LibraryBuild.xml

@@ -22,5 +22,12 @@
       <property name="Target">M:System.StartupHookProvider.ProcessStartupHooks(System.String)</property>
       <property name="Justification">This warning is left in the product so developers get an ILLink warning when trimming an app with System.StartupHookProvider.IsSupported=true.</property>
     </attribute>
+    <attribute fullname="System.Diagnostics.CodeAnalysis.UnconditionalSuppressMessageAttribute">
+      <argument>ILLink</argument>
+      <argument>IL2026</argument>
+      <property name="Scope">member</property>
+      <property name="Target">M:System.ComponentModel.DefaultValueAttribute.#ctor(System.Type,System.String)</property>
+      <property name="Justification">This warning is left in the product so developers get an ILLink warning when trimming an app with System.ComponentModel.DefaultValueAttribute.IsSupported=true.</property>
+    </attribute>
   </assembly>
 </linker>

src/libraries/System.Private.CoreLib/src/System/ComponentModel/DefaultValueAttribute.cs

@@ -24,24 +24,26 @@ public class DefaultValueAttribute : Attribute
         private static object? s_convertFromInvariantString;
 
         [FeatureSwitchDefinition("System.ComponentModel.DefaultValueAttribute.IsSupported")]
+        [FeatureGuard(typeof(RequiresUnreferencedCodeAttribute))]
+#pragma warning disable IL4000
         internal static bool IsSupported => AppContext.TryGetSwitch("System.ComponentModel.DefaultValueAttribute.IsSupported", out bool isSupported) ? isSupported : true;
+#pragma warning restore IL4000
 
         /// <summary>
         /// Initializes a new instance of the <see cref='DefaultValueAttribute'/>
         /// class, converting the specified value to the specified type, and using the U.S. English
         /// culture as the translation context.
         /// </summary>
-        [RequiresUnreferencedCode("Generic TypeConverters may require the generic types to be annotated. For example, NullableConverter requires the underlying type to be DynamicallyAccessedMembers All.")]
         public DefaultValueAttribute(
             [DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.All)] Type type,
             string? value)
         {
             // The null check and try/catch here are because attributes should never throw exceptions.
             // We would fail to load an otherwise normal class.
 
+            Debug.Assert(IsSupported, "Runtime instantiation of this attribute is not allowed with trimming.");
             if (!IsSupported)
             {
-                Debug.Assert(!IsSupported, "Runtime instantiation of this attribute is not allowed.");
                 return;
             }
 
@@ -69,7 +71,7 @@ public DefaultValueAttribute(
                     _value = Convert.ChangeType(value, type, CultureInfo.InvariantCulture);
                 }
 
-                [RequiresUnreferencedCode("Generic TypeConverters may require the generic types to be annotated. For example, NullableConverter requires the underlying type to be DynamicallyAccessedMembers All.")]
+                [RequiresUnreferencedCode("DefaultValueAttribute usage of TypeConverter is not compatible with trimming.")]
                 // Looking for ad hoc created TypeDescriptor.ConvertFromInvariantString(Type, string)
                 static bool TryConvertFromInvariantString(
                     [DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.All)] Type typeToConvert,

src/libraries/System.Runtime/ref/System.Runtime.cs

@@ -8047,7 +8047,6 @@ public DefaultValueAttribute(object? value) { }
         public DefaultValueAttribute(sbyte value) { }
         public DefaultValueAttribute(float value) { }
         public DefaultValueAttribute(string? value) { }
-        [System.Diagnostics.CodeAnalysis.RequiresUnreferencedCodeAttribute("Generic TypeConverters may require the generic types to be annotated. For example, NullableConverter requires the underlying type to be DynamicallyAccessedMembers All.")]
         public DefaultValueAttribute([System.Diagnostics.CodeAnalysis.DynamicallyAccessedMembersAttribute(System.Diagnostics.CodeAnalysis.DynamicallyAccessedMemberTypes.All)] System.Type type, string? value) { }
         [System.CLSCompliantAttribute(false)]
         public DefaultValueAttribute(ushort value) { }

src/tools/illink/src/ILLink.Tasks/build/Microsoft.NET.ILLink.targets

@@ -53,6 +53,8 @@ Copyright (c) .NET Foundation. All rights reserved.
     <!-- Trim managed NTLM on Linux when it's not explicitly requested -->
     <_UseManagedNtlm Condition="'$(_UseManagedNtlm)' == '' and $(RuntimeIdentifier.StartsWith('linux'))">false</_UseManagedNtlm>
     <_ComObjectDescriptorSupport Condition="'$(_ComObjectDescriptorSupport)' == ''">false</_ComObjectDescriptorSupport>
+    <_DesignerHostSupport Condition="'$(_DesignerHostSupport)' == ''">false</_DesignerHostSupport>
+    <_DefaultValueAttributeSupport Condition="'$(_DefaultValueAttributeSupport)' == ''">false</_DefaultValueAttributeSupport>
   </PropertyGroup>