Add support for exported types in illink XML formats

src/coreclr/tools/Common/Compiler/ProcessLinkerXmlBase.cs

@@ -217,9 +217,10 @@ protected virtual void ProcessTypes(ModuleDesc assembly, XPathNavigator nav, boo
                         continue;
                 }
 
-                // TODO: Process exported types
+                MetadataType? type = CecilCompatibleTypeParser.GetType(assembly, fullname);
 
-                TypeDesc? type = CecilCompatibleTypeParser.GetType(assembly, fullname);
+                if (type != null && type.Module != assembly)
+                    type = ProcessExportedType(type, assembly, typeNav);
 
                 if (type == null)
                 {
@@ -234,6 +235,8 @@ protected virtual void ProcessTypes(ModuleDesc assembly, XPathNavigator nav, boo
             }
         }
 
+        protected virtual MetadataType? ProcessExportedType(MetadataType exported, ModuleDesc assembly, XPathNavigator nav) => exported;
+
         private void MatchType(TypeDesc type, Regex regex, XPathNavigator nav)
         {
             StringBuilder sb = new StringBuilder();
@@ -759,7 +762,7 @@ public bool TryConvertValue(string value, TypeDesc type, out object? result)
 
     public class CecilCompatibleTypeParser
     {
-        public static TypeDesc? GetType(ModuleDesc assembly, string fullName)
+        public static MetadataType? GetType(ModuleDesc assembly, string fullName)
         {
             Debug.Assert(!string.IsNullOrEmpty(fullName));
             var position = fullName.IndexOf('/');

src/coreclr/tools/aot/ILCompiler.Compiler/Compiler/BodySubstitutionParser.cs

@@ -40,7 +40,7 @@ protected override void ProcessAssembly(ModuleDesc assembly, XPathNavigator nav,
             ProcessTypes(assembly, nav, warnOnUnresolvedTypes);
         }
 
-        // protected override TypeDesc? ProcessExportedType(ExportedType exported, ModuleDesc assembly, XPathNavigator nav) => null;
+        protected override MetadataType ProcessExportedType(MetadataType exported, ModuleDesc assembly, XPathNavigator nav) => null;
 
         protected override bool ProcessTypePattern(string fullname, ModuleDesc assembly, XPathNavigator nav) => false;
 

src/coreclr/tools/aot/ILCompiler.Compiler/Compiler/DescriptorMarker.cs

@@ -162,6 +162,14 @@ private void MarkAndPreserve(TypeDesc type, XPathNavigator nav, TypePreserve pre
         }
 #endif
 
+        protected override MetadataType? ProcessExportedType(MetadataType exported, ModuleDesc assembly, XPathNavigator nav)
+        {
+            // Rooting module metadata roots type forwarder metadata for all types in the module that are reflection visible.
+            // (We don't track individual type forwarders right now.)
+            _dependencies.Add(_factory.ModuleMetadata(assembly), "Type used through forwarder");
+            return base.ProcessExportedType(exported, assembly, nav);
+        }
+
         protected override void ProcessType(TypeDesc type, XPathNavigator nav)
         {
             Debug.Assert(ShouldProcessElement(nav));

src/tests/nativeaot/SmokeTests/TrimmingBehaviors/ILLinkDescriptor.cs

@@ -17,6 +17,7 @@ public static int Run()
         ThrowIfMemberNotPresent(typeof(ILLinkDescriptor), nameof(PropertyKeptViaDescriptor));
         ThrowIfMemberNotPresent(typeof(ILLinkDescriptor), nameof(EventKeptViaDescriptor));
         ThrowIfTypeNotPresent(typeof(ILLinkDescriptor), nameof(NestedTypeKeptViaDescriptor));
+        ThrowIfTypeNotPresent("LibraryClass, ShimLibrary");
         ThrowIfTypePresent(typeof(ILLinkDescriptor), nameof(NestedTypeNonKept));
         return 100;
     }
@@ -51,6 +52,10 @@ class NestedTypeNonKept
         Justification = "That's the point")]
     private static bool IsTypePresent(Type testType, string typeName) => testType.GetNestedType(typeName, BindingFlags.NonPublic | BindingFlags.Public) != null;
 
+    [UnconditionalSuppressMessage("ReflectionAnalysis", "IL2057:UnrecognizedReflectionPattern",
+        Justification = "That's the point")]
+    private static bool IsTypePresent(string typeName) => Type.GetType(typeName) != null;
+
     [UnconditionalSuppressMessage("ReflectionAnalysis", "IL2070:UnrecognizedReflectionPattern",
         Justification = "That's the point")]
     private static bool IsMemberPresent(Type testType, string memberName) {
@@ -70,6 +75,14 @@ private static void ThrowIfTypeNotPresent(Type testType, string typeName)
         }
     }
 
+    private static void ThrowIfTypeNotPresent(string typeName)
+    {
+        if (!IsTypePresent(typeName))
+        {
+            throw new Exception(typeName);
+        }
+    }
+
     private static void ThrowIfTypePresent(Type testType, string typeName)
     {
         if (IsTypePresent(testType, typeName))

src/tests/nativeaot/SmokeTests/TrimmingBehaviors/Library.cs

@@ -0,0 +1,4 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+public class LibraryClass { }

src/tests/nativeaot/SmokeTests/TrimmingBehaviors/Library.csproj

@@ -0,0 +1,8 @@
+<Project Sdk="Microsoft.NET.Sdk">
+  <PropertyGroup>
+    <OutputType>Library</OutputType>
+  </PropertyGroup>
+  <ItemGroup>
+    <Compile Include="Library.cs" />
+  </ItemGroup>
+</Project>

src/tests/nativeaot/SmokeTests/TrimmingBehaviors/NonEmbedded.ILLink.Descriptor.xml

@@ -4,4 +4,8 @@
       <method name="methodKeptViaStandaloneDescriptor"/>
     </type>
   </assembly>
+
+  <assembly fullname="ShimLibrary">
+    <type fullname="LibraryClass" />
+  </assembly>
 </linker>

src/tests/nativeaot/SmokeTests/TrimmingBehaviors/ShimLibrary.cs

@@ -0,0 +1,6 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System.Runtime.CompilerServices;
+
+[assembly: TypeForwardedTo(typeof(LibraryClass))]

src/tests/nativeaot/SmokeTests/TrimmingBehaviors/ShimLibrary.csproj

@@ -0,0 +1,11 @@
+<Project Sdk="Microsoft.NET.Sdk">
+  <PropertyGroup>
+    <OutputType>Library</OutputType>
+  </PropertyGroup>
+  <ItemGroup>
+    <Compile Include="ShimLibrary.cs" />
+  </ItemGroup>
+  <ItemGroup>
+    <ProjectReference Include="Library.csproj" />
+  </ItemGroup>
+</Project>

src/tests/nativeaot/SmokeTests/TrimmingBehaviors/TrimmingBehaviors.csproj

@@ -8,6 +8,11 @@
     <!-- We don't run the scanner in optimized builds -->
     <CLRTestTargetUnsupported Condition="'$(IlcMultiModule)' == 'true'">true</CLRTestTargetUnsupported>
   </PropertyGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="ShimLibrary.csproj" />
+  </ItemGroup>
+
   <ItemGroup>
     <Compile Include="Dataflow.cs" />
     <Compile Include="DeadCodeElimination.cs" />