Use FeatureSwitchDefinition in a few places (#106564)

This replaces much of our ILLink.Substitutions.xml with nearly
equivalent FeatureSwitchDefinitionAttribute. The minor difference is
that both true and false are substituted (when the feature switch is
set accordingly), whereas some of our substitution xmls only defined a
substitution for the false case.

---------

Co-authored-by: Jackson Schuster <36744439+jtschuster@users.noreply.github.com>

src/coreclr/System.Private.CoreLib/System.Private.CoreLib.csproj

@@ -25,7 +25,6 @@
 
   <ItemGroup>
     <ILLinkSubstitutionsXmls Include="$(ILLinkDirectory)ILLink.Substitutions.xml" />
-    <ILLinkSubstitutionsXmls Condition="'$(TargetsWindows)' == 'true'" Include="$(ILLinkDirectory)ILLink.Substitutions.Windows.xml" />
   </ItemGroup>
 
   <!-- Note that various places in SPCL depend on this resource name i.e. TplEventSource -->

src/coreclr/System.Private.CoreLib/src/Internal/Runtime/InteropServices/InMemoryAssemblyLoader.cs

@@ -15,6 +15,7 @@ namespace Internal.Runtime.InteropServices
     [SupportedOSPlatform("windows")]
     internal static class InMemoryAssemblyLoader
     {
+        [FeatureSwitchDefinition("System.Runtime.InteropServices.EnableCppCLIHostActivation")]
         private static bool IsSupported { get; } = InitializeIsSupported();
         private static bool InitializeIsSupported() => AppContext.TryGetSwitch("System.Runtime.InteropServices.EnableCppCLIHostActivation", out bool isSupported) ? isSupported : true;
 

src/coreclr/System.Private.CoreLib/src/System/Reflection/Metadata/MetadataUpdater.cs

@@ -2,6 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 
 using System.Diagnostics;
+using System.Diagnostics.CodeAnalysis;
 using System.Runtime.CompilerServices;
 using System.Runtime.InteropServices;
 
@@ -59,6 +60,7 @@ public static void ApplyUpdate(Assembly assembly, ReadOnlySpan<byte> metadataDel
         /// <summary>
         /// Returns true if the apply assembly update is enabled and available.
         /// </summary>
+        [FeatureSwitchDefinition("System.Reflection.Metadata.MetadataUpdater.IsSupported")]
         public static bool IsSupported { get; } = IsApplyUpdateSupported();
     }
 }

src/coreclr/System.Private.CoreLib/src/System/Runtime/InteropServices/Marshal.CoreCLR.cs

@@ -330,6 +330,7 @@ internal static unsafe bool IsPinnable(object? obj)
             => (obj == null) || !RuntimeHelpers.GetMethodTable(obj)->ContainsGCPointers;
 
 #if TARGET_WINDOWS
+        [FeatureSwitchDefinition("System.Runtime.InteropServices.BuiltInComInterop.IsSupported")]
         internal static bool IsBuiltInComSupported { get; } = IsBuiltInComSupportedInternal();
 
         [LibraryImport(RuntimeHelpers.QCall, EntryPoint = "MarshalNative_IsBuiltInComSupported")]

src/coreclr/nativeaot/System.Private.CoreLib/src/ILLink/ILLink.Substitutions.xml

@@ -1,22 +1,5 @@
 <linker>
 
-  <type fullname="System.Collections.Generic.Comparer`1" feature="System.Collections.Generic.DefaultComparers" featurevalue="false">
-    <method signature="System.Boolean get_SupportsGenericIComparableInterfaces()" body="stub" />
-  </type>
-  <type fullname="System.Collections.Generic.EqualityComparer`1" feature="System.Collections.Generic.DefaultComparers" featurevalue="false">
-    <method signature="System.Boolean get_SupportsGenericIEquatableInterfaces()" body="stub" />
-  </type>
-  <type fullname="System.Collections.Generic.Comparer`1" feature="System.Collections.Generic.DefaultComparers" featurevalue="true" featuredefault="true">
-    <method signature="System.Boolean get_SupportsGenericIComparableInterfaces()" body="stub" value="true" />
-  </type>
-  <type fullname="System.Collections.Generic.EqualityComparer`1" feature="System.Collections.Generic.DefaultComparers" featurevalue="true" featuredefault="true">
-    <method signature="System.Boolean get_SupportsGenericIEquatableInterfaces()" body="stub"  value="true" />
-  </type>
-
-  <type fullname="System.Reflection.Runtime.General.TypeUnifier" feature="System.Reflection.IsTypeConstructionEagerlyValidated" featurevalue="false">
-    <method signature="System.Boolean get_IsTypeConstructionEagerlyValidated()" body="stub" />
-  </type>
-
   <type fullname="System.RuntimeType" feature="System.Reflection" featurevalue="false">
     <method signature="System.Boolean get_IsReflectionDisabled()" body="stub" value="true" />
   </type>

src/coreclr/nativeaot/System.Private.CoreLib/src/System/Collections/Generic/Comparer.NativeAot.cs

@@ -2,6 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 
 #nullable enable
+using System.Diagnostics.CodeAnalysis;
 using System.Runtime.CompilerServices;
 using System.Threading;
 
@@ -12,7 +13,7 @@ namespace System.Collections.Generic
 {
     public abstract partial class Comparer<T> : IComparer, IComparer<T>
     {
-        // The AOT compiler can flip this to false under certain circumstances.
+        [FeatureSwitchDefinition("System.Collections.Generic.DefaultComparers")]
         private static bool SupportsGenericIComparableInterfaces => true;
 
         [Intrinsic]

src/coreclr/nativeaot/System.Private.CoreLib/src/System/Collections/Generic/EqualityComparer.NativeAot.cs

@@ -2,6 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 
 #nullable enable
+using System.Diagnostics.CodeAnalysis;
 using System.Runtime.CompilerServices;
 using System.Threading;
 
@@ -12,7 +13,7 @@ namespace System.Collections.Generic
 {
     public abstract partial class EqualityComparer<T> : IEqualityComparer, IEqualityComparer<T>
     {
-        // The AOT compiler can flip this to false under certain circumstances.
+        [FeatureSwitchDefinition("System.Collections.Generic.DefaultComparers")]
         private static bool SupportsGenericIEquatableInterfaces => true;
 
         [Intrinsic]

src/coreclr/nativeaot/System.Private.CoreLib/src/System/Reflection/Metadata/MetadataUpdater.cs

@@ -1,6 +1,8 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
+using System.Diagnostics.CodeAnalysis;
+
 namespace System.Reflection.Metadata
 {
     public static class MetadataUpdater
@@ -10,6 +12,7 @@ public static void ApplyUpdate(Assembly assembly, ReadOnlySpan<byte> metadataDel
             throw new PlatformNotSupportedException();
         }
 
+        [FeatureSwitchDefinition("System.Reflection.Metadata.MetadataUpdater.IsSupported")]
         public static bool IsSupported => false;
     }
 }

src/coreclr/nativeaot/System.Private.CoreLib/src/System/Reflection/Runtime/General/TypeUnifier.cs

@@ -4,6 +4,7 @@
 using System;
 using System.Collections.Concurrent;
 using System.Diagnostics;
+using System.Diagnostics.CodeAnalysis;
 using System.Reflection;
 using System.Reflection.Runtime.General;
 using System.Reflection.Runtime.MethodInfos;
@@ -36,6 +37,7 @@ namespace System.Reflection.Runtime.General
 {
     internal static partial class TypeUnifier
     {
+        [FeatureSwitchDefinition("System.Reflection.IsTypeConstructionEagerlyValidated")]
         // This can be replaced at native compile time using a feature switch.
         internal static bool IsTypeConstructionEagerlyValidated => true;
 

src/libraries/Microsoft.Extensions.DependencyInjection/src/Microsoft.Extensions.DependencyInjection.csproj

@@ -18,10 +18,6 @@
                                '$(ILEmitBackendSaveAssemblies)' == 'true'">$(DefineConstants);SAVE_ASSEMBLIES</DefineConstants>
   </PropertyGroup>
 
-  <ItemGroup>
-    <ILLinkSubstitutionsXmls Include="$(ILLinkDirectory)ILLink.Substitutions.xml" />
-  </ItemGroup>
-
   <ItemGroup>
     <Compile Include="**\*.cs" />
     <Compile Remove="ServiceLookup\ILEmit\**\*.cs" />
@@ -47,6 +43,10 @@
     <Compile Include="$(CoreLibSharedDir)System\Diagnostics\CodeAnalysis\UnconditionalSuppressMessageAttribute.cs" />
   </ItemGroup>
 
+  <ItemGroup Condition="'$(TargetFrameworkIdentifier)' != '.NETCoreApp' or $([MSBuild]::VersionLessThan('$(TargetFrameworkVersion)', '9.0'))">
+    <Compile Include="$(CoreLibSharedDir)System\Diagnostics\CodeAnalysis\FeatureSwitchDefinitionAttribute.cs" />
+  </ItemGroup>
+
   <ItemGroup>
     <ProjectReference Include="$(LibrariesProjectRoot)Microsoft.Extensions.DependencyInjection.Abstractions\src\Microsoft.Extensions.DependencyInjection.Abstractions.csproj" />
   </ItemGroup>

src/libraries/Microsoft.Extensions.DependencyInjection/src/ServiceProvider.cs

@@ -34,9 +34,11 @@ public sealed class ServiceProvider : IServiceProvider, IKeyedServiceProvider, I
 
         internal ServiceProviderEngineScope Root { get; }
 
+        [FeatureSwitchDefinition("Microsoft.Extensions.DependencyInjection.VerifyOpenGenericServiceTrimmability")]
         internal static bool VerifyOpenGenericServiceTrimmability { get; } =
             AppContext.TryGetSwitch("Microsoft.Extensions.DependencyInjection.VerifyOpenGenericServiceTrimmability", out bool verifyOpenGenerics) ? verifyOpenGenerics : false;
 
+        [FeatureSwitchDefinition("Microsoft.Extensions.DependencyInjection.DisableDynamicEngine")]
         internal static bool DisableDynamicEngine { get; } =
             AppContext.TryGetSwitch("Microsoft.Extensions.DependencyInjection.DisableDynamicEngine", out bool disableDynamicEngine) ? disableDynamicEngine : false;
 

src/libraries/System.ComponentModel.TypeConverter/src/System.ComponentModel.TypeConverter.csproj

@@ -7,10 +7,6 @@
     <UseCompilerGeneratedDocXmlFile>false</UseCompilerGeneratedDocXmlFile>
   </PropertyGroup>
 
-  <ItemGroup>
-    <ILLinkSubstitutionsXmls Include="$(ILLinkDirectory)ILLink.Substitutions.xml" />
-  </ItemGroup>
-
   <ItemGroup>
     <Compile Include="MS\Internal\Xml\Linq\ComponentModel\XComponentModel.cs" />
     <Compile Include="System\ComponentModel\ArrayConverter.cs" />

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

@@ -17,6 +17,7 @@ public class DesigntimeLicenseContextSerializer
     {
         internal const byte BinaryWriterMagic = 255;
 
+        [FeatureSwitchDefinition("System.ComponentModel.TypeConverter.EnableUnsafeBinaryFormatterInDesigntimeLicenseContextSerialization")]
         private static bool EnableUnsafeBinaryFormatterInDesigntimeLicenseContextSerialization { get; } = AppContext.TryGetSwitch("System.ComponentModel.TypeConverter.EnableUnsafeBinaryFormatterInDesigntimeLicenseContextSerialization", out bool isEnabled) ? isEnabled : false;
 
         // Not creatable.

src/libraries/System.Diagnostics.DiagnosticSource/src/ILLink/ILLink.Substitutions.Shared.xml

@@ -1,8 +1,5 @@
 <linker>
   <assembly fullname="System.Diagnostics.DiagnosticSource" feature="System.Diagnostics.Metrics.Meter.IsSupported" featurevalue="false">
-    <type fullname="System.Diagnostics.Metrics.Meter">
-      <method signature="System.Boolean get_IsSupported()" body="stub" value="false" />
-    </type>
     <type fullname="System.Diagnostics.Metrics.Instrument">
       <method signature="System.Boolean get_Enabled()" body="stub" value="false" />
     </type>

src/libraries/System.Diagnostics.DiagnosticSource/src/System.Diagnostics.DiagnosticSource.csproj

@@ -123,6 +123,10 @@ System.Diagnostics.DiagnosticSource</PackageDescription>
     <Compile Include="$(CoreLibSharedDir)System\Runtime\CompilerServices\IsExternalInit.cs" />
   </ItemGroup>
 
+  <ItemGroup Condition="'$(TargetFrameworkIdentifier)' != '.NETCoreApp' or $([MSBuild]::VersionLessThan('$(TargetFrameworkVersion)', '9.0'))">
+    <Compile Include="$(CoreLibSharedDir)System\Diagnostics\CodeAnalysis\FeatureSwitchDefinitionAttribute.cs" />
+  </ItemGroup>
+
   <ItemGroup Condition="'$(TargetFrameworkIdentifier)' == '.NETCoreApp' or
                         '$(TargetFramework)' == 'netstandard2.0'">
     <Compile Include="System\Diagnostics\Activity.DateTime.corefx.cs" />

src/libraries/System.Diagnostics.DiagnosticSource/src/System/Diagnostics/Metrics/Meter.cs

@@ -4,6 +4,7 @@
 using System.Collections.Generic;
 using System.ComponentModel;
 using System.Diagnostics;
+using System.Diagnostics.CodeAnalysis;
 using System.Threading;
 
 namespace System.Diagnostics.Metrics
@@ -20,6 +21,7 @@ public class Meter : IDisposable
 
         internal bool Disposed { get; private set; }
 
+        [FeatureSwitchDefinition("System.Diagnostics.Metrics.Meter.IsSupported")]
         internal static bool IsSupported { get; } = InitializeIsSupported();
 
         private static bool InitializeIsSupported() =>

src/libraries/System.Linq.Expressions/src/System.Linq.Expressions.csproj

@@ -12,10 +12,6 @@
     <UseCompilerGeneratedDocXmlFile>false</UseCompilerGeneratedDocXmlFile>
   </PropertyGroup>
 
-  <ItemGroup>
-    <ILLinkSubstitutionsXmls Include="$(ILLinkDirectory)ILLink.Substitutions.xml" />
-  </ItemGroup>
-
   <ItemGroup>
     <Compile Include="$(CommonPath)System\Obsoletions.cs"
              Link="Common\System\Obsoletions.cs" />

src/libraries/System.Linq.Expressions/src/System/Dynamic/Utils/DelegateHelpers.cs

@@ -13,7 +13,7 @@ namespace System.Dynamic.Utils
 {
     internal static class DelegateHelpers
     {
-        // This can be flipped to false using feature switches at publishing time
+        [FeatureSwitchDefinition("System.Linq.Expressions.CanEmitObjectArrayDelegate")]
         internal static bool CanEmitObjectArrayDelegate => true;
 
         // Separate class so that the it can be trimmed away and doesn't get conflated

src/libraries/System.Net.Http/src/System.Net.Http.csproj

@@ -28,10 +28,6 @@
     <ILLinkSubstitutionsXmls Include="$(ILLinkDirectory)ILLink.Substitutions.xml" />
   </ItemGroup>
 
-  <ItemGroup Condition="'$(TargetPlatformIdentifier)' == 'android' or '$(TargetPlatformIdentifier)' == 'ios' or '$(TargetPlatformIdentifier)' == 'maccatalyst' or '$(TargetPlatformIdentifier)' == 'tvos' or '$(TargetPlatformIdentifier)' == 'browser' or '$(TargetPlatformIdentifier)' == 'wasi'">
-    <ILLinkSubstitutionsXmls Include="$(ILLinkDirectory)ILLink.Substitutions.mobile.xml" Condition="'$(TargetPlatformIdentifier)' != 'browser' and '$(TargetPlatformIdentifier)' != 'wasi'" />
-  </ItemGroup>
-
   <ItemGroup Condition="'$(TargetPlatformIdentifier)' != ''">
     <Compile Include="System\Net\Http\ByteArrayContent.cs" />
     <Compile Include="System\Net\Http\CancellationHelper.cs" />

src/libraries/System.Net.Http/src/System/Net/Http/HttpClientHandler.AnyMobile.cs

@@ -789,6 +789,7 @@ private void ThrowForModifiedManagedSslOptionsIfStarted()
             _socketHandler!.SslOptions = _socketHandler!.SslOptions;
         }
 
+        [FeatureSwitchDefinition("System.Net.Http.UseNativeHttpHandler")]
         private static bool IsNativeHandlerEnabled => RuntimeSettingParser.QueryRuntimeSettingSwitch(
                 "System.Net.Http.UseNativeHttpHandler",
                 false);

src/libraries/System.Net.Security/src/System.Net.Security.csproj

@@ -295,7 +295,6 @@
   </ItemGroup>
 
   <ItemGroup Condition="'$(TargetPlatformIdentifier)' != '' and '$(TargetPlatformIdentifier)' != 'windows' and '$(UseManagedNtlm)' != 'true'">
-    <ILLinkSubstitutionsXmls Include="$(ILLinkDirectory)ILLink.Substitutions.xml" />
     <Compile Include="System\Net\NegotiateAuthenticationPal.Unix.cs" />
     <Compile Include="$(CommonPath)Microsoft\Win32\SafeHandles\GssSafeHandles.cs"
              Link="Common\Microsoft\Win32\SafeHandles\GssSafeHandles.cs" />

src/libraries/System.Net.Security/src/System/Net/NegotiateAuthenticationPal.Unix.cs

@@ -21,6 +21,8 @@ internal partial class NegotiateAuthenticationPal
     {
         private static readonly Lazy<bool> _hasSystemNetSecurityNative = new Lazy<bool>(CheckHasSystemNetSecurityNative);
         internal static bool HasSystemNetSecurityNative => _hasSystemNetSecurityNative.Value;
+
+        [FeatureSwitchDefinition("System.Net.Security.UseManagedNtlm")]
         private static bool UseManagedNtlm { get; } =
             AppContext.TryGetSwitch("System.Net.Security.UseManagedNtlm", out bool useManagedNtlm) ?
             useManagedNtlm :