[TrimmableTypeMap] Pre-generate Mono.Android/Java.Interop typemaps at SDK build time

build-tools/create-packs/Microsoft.Android.Sdk.TrimmableTypeMap.targets

@@ -0,0 +1,155 @@
+<!--
+  Pre-generates the trimmable type map for Mono.Android at SDK build time (issue #10792).
+
+  App builds otherwise rescan the ~8000 Mono.Android types on every (Debug) build. Instead we
+  scan Mono.Android once here and ship the resulting typemap assemblies and Java Callable Wrappers
+  in the SDK pack. The typemap anchors on Java.Lang.Object (ForceSharedTypemapUniverse=true) to
+  coordinate aliases across Mono.Android and Java.Interop. Debug app builds can consume it because
+  their remaining typemaps use separate per-assembly universes. Release builds must instead scan the
+  complete app closure so shared-universe alias ownership includes application types. The root
+  _Microsoft.Android.TypeMaps assembly is NOT generated here (GenerateRootAssembly=false) — the
+  Debug app build emits it and references this pre-generated typemap under Java.Lang.Object.
+-->
+<Project>
+
+  <UsingTask TaskName="Xamarin.Android.Tasks.GenerateTrimmableTypeMap" AssemblyFile="$(MicrosoftAndroidSdkOutDir)Xamarin.Android.Build.Tasks.dll" />
+
+  <PropertyGroup>
+    <_PreBuiltTypeMapPackSubDir>data\prebuilt-typemap</_PreBuiltTypeMapPackSubDir>
+    <_PreBuiltTypeMapOutputDir>$(MicrosoftAndroidSdkPackDir)$(_PreBuiltTypeMapPackSubDir)\</_PreBuiltTypeMapOutputDir>
+    <!-- These DLLs are SDK runtime inputs consumed explicitly by the Android targets, not
+         compile-time references. NuGet otherwise warns that assemblies under data/ are outside
+         lib/, and this repository treats pack warnings as errors. -->
+    <NoWarn>$(NoWarn);NU5100</NoWarn>
+    <!-- Intermediate (not packaged): generated JCW .java and compiled .class files. -->
+    <_PreBuiltTypeMapIntDir>$([MSBuild]::NormalizeDirectory('$(MSBuildProjectDirectory)', 'obj', 'prebuilt-typemap'))</_PreBuiltTypeMapIntDir>
+    <_PreBuiltTypeMapJavaDir>$(_PreBuiltTypeMapIntDir)java\</_PreBuiltTypeMapJavaDir>
+    <_PreBuiltTypeMapAssembly>$(_PreBuiltTypeMapOutputDir)_Mono.Android.TypeMap.dll</_PreBuiltTypeMapAssembly>
+    <_PreBuiltTypeMapJavaInteropAssembly>$(_PreBuiltTypeMapOutputDir)_Java.Interop.TypeMap.dll</_PreBuiltTypeMapJavaInteropAssembly>
+    <_PreBuiltTypeMapAcwMap>$(_PreBuiltTypeMapOutputDir)mono.android-acw-map.txt</_PreBuiltTypeMapAcwMap>
+    <_PreBuiltTypeMapJavaFilesList>$(_PreBuiltTypeMapIntDir)java-files.txt</_PreBuiltTypeMapJavaFilesList>
+    <_PreBuiltTypeMapGenerationStamp>$(_PreBuiltTypeMapIntDir)_GeneratePreBuiltMonoAndroidTypeMap.stamp</_PreBuiltTypeMapGenerationStamp>
+  </PropertyGroup>
+
+  <!-- Generated files use content-based writes and can legitimately be older than the generator
+       inputs. Use a stamp for timestamp incrementality, but invalidate it whenever any real output
+       recorded by the previous generation pass is missing. -->
+  <Target Name="_InvalidatePreBuiltMonoAndroidTypeMapStampIfOutputsMissing">
+    <ItemGroup>
+      <_ExpectedPreBuiltTypeMapJavaFile Remove="@(_ExpectedPreBuiltTypeMapJavaFile)" />
+      <_ActualPreBuiltTypeMapJavaFile Remove="@(_ActualPreBuiltTypeMapJavaFile)" />
+      <_MissingPreBuiltTypeMapJavaFile Remove="@(_MissingPreBuiltTypeMapJavaFile)" />
+      <_UnexpectedPreBuiltTypeMapJavaFile Remove="@(_UnexpectedPreBuiltTypeMapJavaFile)" />
+    </ItemGroup>
+    <ReadLinesFromFile
+        File="$(_PreBuiltTypeMapJavaFilesList)"
+        Condition="Exists('$(_PreBuiltTypeMapJavaFilesList)')">
+      <Output TaskParameter="Lines" ItemName="_ExpectedPreBuiltTypeMapJavaFile" />
+    </ReadLinesFromFile>
+    <ItemGroup>
+      <_ActualPreBuiltTypeMapJavaFile Include="$(_PreBuiltTypeMapJavaDir)**\*.java" />
+      <_MissingPreBuiltTypeMapJavaFile Include="@(_ExpectedPreBuiltTypeMapJavaFile)"
+          Condition="!Exists('%(_ExpectedPreBuiltTypeMapJavaFile.Identity)')" />
+      <_UnexpectedPreBuiltTypeMapJavaFile Include="@(_ActualPreBuiltTypeMapJavaFile->'%(FullPath)')"
+          Exclude="@(_ExpectedPreBuiltTypeMapJavaFile)" />
+    </ItemGroup>
+    <Delete
+        Files="$(_PreBuiltTypeMapGenerationStamp)"
+        Condition="Exists('$(_PreBuiltTypeMapGenerationStamp)') and (!Exists('$(_PreBuiltTypeMapAssembly)') or !Exists('$(_PreBuiltTypeMapJavaInteropAssembly)') or !Exists('$(_PreBuiltTypeMapAcwMap)') or !Exists('$(_PreBuiltTypeMapJavaFilesList)') or '@(_MissingPreBuiltTypeMapJavaFile->Count())' != '0' or '@(_UnexpectedPreBuiltTypeMapJavaFile->Count())' != '0')" />
+    <ItemGroup>
+      <_ExpectedPreBuiltTypeMapJavaFile Remove="@(_ExpectedPreBuiltTypeMapJavaFile)" />
+      <_ActualPreBuiltTypeMapJavaFile Remove="@(_ActualPreBuiltTypeMapJavaFile)" />
+      <_MissingPreBuiltTypeMapJavaFile Remove="@(_MissingPreBuiltTypeMapJavaFile)" />
+      <_UnexpectedPreBuiltTypeMapJavaFile Remove="@(_UnexpectedPreBuiltTypeMapJavaFile)" />
+    </ItemGroup>
+  </Target>
+
+  <Target Name="_GeneratePreBuiltMonoAndroidTypeMap"
+      BeforeTargets="ConfigureLocalWorkload;_GenerateXASdkContent"
+      DependsOnTargets="_InvalidatePreBuiltMonoAndroidTypeMapStampIfOutputsMissing"
+      Inputs="$(_MonoAndroidNETDefaultOutDir)Mono.Android.dll;$(_MonoAndroidNETDefaultOutDir)Java.Interop.dll;$(MicrosoftAndroidSdkOutDir)Xamarin.Android.Build.Tasks.dll"
+      Outputs="$(_PreBuiltTypeMapGenerationStamp)">
+    <ItemGroup>
+      <!-- Scan Mono.Android and Java.Interop TOGETHER so their cross-assembly aliases (e.g.
+           java/lang/Object mapped by both Java.Lang.Object and Java.Interop.JavaObject) are
+           coordinated into a single primary + aliases, instead of colliding as duplicate keys in
+           the merged Java.Lang.Object universe at runtime. -->
+      <_PreBuiltTypeMapInput Include="$(_MonoAndroidNETDefaultOutDir)Mono.Android.dll" />
+      <_PreBuiltTypeMapInput Include="$(_MonoAndroidNETDefaultOutDir)Java.Interop.dll" />
+      <!-- Reference-only framework assemblies needed to resolve base types.
+           These are NOT scanned for peers; only @(_PreBuiltTypeMapInput) is. -->
+      <_PreBuiltTypeMapFramework Include="$(_MonoAndroidNETDefaultOutDir)*.dll"
+          Exclude="@(_PreBuiltTypeMapInput)" />
+    </ItemGroup>
+    <MakeDir Directories="$(_PreBuiltTypeMapOutputDir);$(_PreBuiltTypeMapJavaDir)" />
+    <GenerateTrimmableTypeMap
+        ResolvedAssemblies="@(_PreBuiltTypeMapInput)"
+        ResolvedFrameworkAssemblies="@(_PreBuiltTypeMapFramework)"
+        FrameworkAssemblyNames="@(_PreBuiltTypeMapFramework->'%(Filename)')"
+        OutputDirectory="$(_PreBuiltTypeMapOutputDir)"
+        JavaSourceOutputDirectory="$(_PreBuiltTypeMapJavaDir)"
+        AcwMapOutputFile="$(_PreBuiltTypeMapAcwMap)"
+        TargetFrameworkVersion="v$(DotNetTargetFrameworkVersion)"
+        ForceSharedTypemapUniverse="true"
+        GenerateRootAssembly="false">
+      <Output TaskParameter="GeneratedJavaFiles" ItemName="_GeneratedPreBuiltTypeMapJavaFile" />
+    </GenerateTrimmableTypeMap>
+    <WriteLinesToFile
+        File="$(_PreBuiltTypeMapJavaFilesList)"
+        Lines="@(_GeneratedPreBuiltTypeMapJavaFile->'%(FullPath)')"
+        Overwrite="true"
+        WriteOnlyWhenDifferent="true" />
+    <Touch Files="$(_PreBuiltTypeMapGenerationStamp)" AlwaysCreate="true" />
+    <ItemGroup>
+      <FileWrites Include="@(_GeneratedPreBuiltTypeMapJavaFile)" />
+      <FileWrites Include="$(_PreBuiltTypeMapJavaFilesList)" />
+      <FileWrites Include="$(_PreBuiltTypeMapGenerationStamp)" />
+    </ItemGroup>
+  </Target>
+
+  <PropertyGroup>
+    <_PreBuiltTypeMapJcwJar>$(_PreBuiltTypeMapOutputDir)mono.android-typemaps.jar</_PreBuiltTypeMapJcwJar>
+    <_PreBuiltTypeMapJcwClassesDir>$(_PreBuiltTypeMapIntDir)jcw-classes\</_PreBuiltTypeMapJcwClassesDir>
+    <_PreBuiltTypeMapJcwSourceList>$(_PreBuiltTypeMapIntDir)jcw-sources.txt</_PreBuiltTypeMapJcwSourceList>
+    <_PreBuiltTypeMapAndroidJar>$(AndroidSdkDirectory)\platforms\android-$(AndroidPlatformId)\android.jar</_PreBuiltTypeMapAndroidJar>
+    <_PreBuiltTypeMapMonoAndroidJar>$(_MonoAndroidNETDefaultOutDir)mono.android.jar</_PreBuiltTypeMapMonoAndroidJar>
+    <_PreBuiltTypeMapRuntimeJar>$(MicrosoftAndroidSdkOutDir)java_runtime.jar</_PreBuiltTypeMapRuntimeJar>
+  </PropertyGroup>
+
+  <!-- Compile the generated Java Callable Wrappers into a jar shipped in the SDK pack. These
+       wrappers use the trimmable runtime registration path and cannot be replaced by the legacy
+       wrappers from mono.android.jar, which call TypeManager.n_activate. -->
+  <Target Name="_CompilePreBuiltMonoAndroidTypeMapJcwJarInputs"
+      DependsOnTargets="_GeneratePreBuiltMonoAndroidTypeMap">
+    <ItemGroup>
+      <_PreBuiltTypeMapJavaFile Remove="@(_PreBuiltTypeMapJavaFile)" />
+    </ItemGroup>
+    <ReadLinesFromFile File="$(_PreBuiltTypeMapJavaFilesList)">
+      <Output TaskParameter="Lines" ItemName="_PreBuiltTypeMapJavaFile" />
+    </ReadLinesFromFile>
+  </Target>
+
+  <Target Name="_CompilePreBuiltMonoAndroidTypeMapJcwJar"
+      BeforeTargets="ConfigureLocalWorkload;_GenerateXASdkContent"
+      DependsOnTargets="_CompilePreBuiltMonoAndroidTypeMapJcwJarInputs"
+      Inputs="$(_PreBuiltTypeMapGenerationStamp);$(_PreBuiltTypeMapJavaFilesList);@(_PreBuiltTypeMapJavaFile);$(_PreBuiltTypeMapAndroidJar);$(_PreBuiltTypeMapMonoAndroidJar);$(_PreBuiltTypeMapRuntimeJar)"
+      Outputs="$(_PreBuiltTypeMapJcwJar)">
+    <RemoveDir Directories="$(_PreBuiltTypeMapJcwClassesDir)" />
+    <MakeDir Directories="$(_PreBuiltTypeMapJcwClassesDir)" />
+    <WriteLinesToFile File="$(_PreBuiltTypeMapJcwSourceList)" Lines="@(_PreBuiltTypeMapJavaFile)" Overwrite="true" />
+    <Exec Command="&quot;$(JavaCPath)&quot; -source $(JavacSourceVersion) -target $(JavacTargetVersion) -nowarn -d &quot;$(_PreBuiltTypeMapJcwClassesDir.TrimEnd('\'))&quot; -classpath &quot;$(_PreBuiltTypeMapAndroidJar)&quot;$(PathSeparator)&quot;$(_PreBuiltTypeMapMonoAndroidJar)&quot;$(PathSeparator)&quot;$(_PreBuiltTypeMapRuntimeJar)&quot; @&quot;$(_PreBuiltTypeMapJcwSourceList)&quot;" />
+    <Exec Command="&quot;$(JarPath)&quot; cf &quot;$(_PreBuiltTypeMapJcwJar)&quot; -C &quot;$(_PreBuiltTypeMapJcwClassesDir.TrimEnd('\'))&quot; ." />
+  </Target>
+
+  <Target Name="_AddPreBuiltMonoAndroidTypeMapToPackage"
+      BeforeTargets="_GenerateXASdkContent"
+      DependsOnTargets="_GeneratePreBuiltMonoAndroidTypeMap;_CompilePreBuiltMonoAndroidTypeMapJcwJar">
+    <ItemGroup>
+      <_PreBuiltTypeMapAllAssemblies Include="$(_PreBuiltTypeMapOutputDir)*.TypeMap.dll" />
+      <FilesToPackage Include="@(_PreBuiltTypeMapAllAssemblies)" TargetPath="$(_PreBuiltTypeMapPackSubDir)" />
+      <FilesToPackage Include="$(_PreBuiltTypeMapJcwJar)" TargetPath="$(_PreBuiltTypeMapPackSubDir)" />
+      <FilesToPackage Include="$(_PreBuiltTypeMapAcwMap)" TargetPath="$(_PreBuiltTypeMapPackSubDir)" />
+    </ItemGroup>
+  </Target>
+
+</Project>

build-tools/create-packs/Microsoft.Android.Sdk.proj

@@ -12,6 +12,8 @@ core workload SDK packs imported by WorkloadManifest.targets.
   <Sdk Name="Microsoft.DotNet.SharedFramework.Sdk" Version="$(MicrosoftDotNetBuildTasksFeedPackageVersionNet10)" />
   <UsingTask AssemblyFile="$(BootstrapTasksAssembly)" TaskName="Xamarin.Android.Tools.BootstrapTasks.GenerateUnixFilePermissions" TaskFactory="TaskHostFactory" Runtime="NET" />
 
+  <Import Project="Microsoft.Android.Sdk.TrimmableTypeMap.targets" />
+
   <PropertyGroup>
     <!-- Use stable TFM since CI only has the stable .NET SDK installed -->
     <TargetFramework>$(DotNetStableTargetFramework)</TargetFramework>

src/Microsoft.Android.Sdk.TrimmableTypeMap/AssemblyInput.cs

@@ -2,4 +2,9 @@
 
 namespace Microsoft.Android.Sdk.TrimmableTypeMap;
 
-public readonly record struct AssemblyInput (string Name, string Path, PEReader Reader);
+/// <param name="ScanForPeers">
+/// When true (default) the assembly is scanned and its Java peers are emitted into a typemap.
+/// When false the assembly is only indexed for base-type resolution (e.g. Mono.Android on the app
+/// build, whose typemap is pre-generated at SDK build time, issue #10792) and no peers are emitted.
+/// </param>
+public readonly record struct AssemblyInput (string Name, string Path, PEReader Reader, bool ScanForPeers = true);

src/Microsoft.Android.Sdk.TrimmableTypeMap/Generator/RootTypeMapAssemblyGenerator.cs

@@ -74,7 +74,16 @@ public RootTypeMapAssemblyGenerator (Version systemRuntimeVersion)
 	/// <param name="stream">Stream to write the output PE to.</param>
 	/// <param name="assemblyName">Optional assembly name (defaults to _Microsoft.Android.TypeMaps).</param>
 	/// <param name="moduleName">Optional module name for the PE metadata.</param>
-	public void Generate (IReadOnlyList<string> perAssemblyTypeMapNames, bool useSharedTypemapUniverse, Stream stream, string? assemblyName = null, string? moduleName = null)
+	/// <param name="sharedFrameworkTypeMapNames">
+	/// Names of pre-generated framework per-assembly typemaps (e.g. <c>_Mono.Android.TypeMap</c>,
+	/// produced at SDK build time, issue #10792) that always use <c>Java.Lang.Object</c> as their
+	/// universe anchor regardless of <paramref name="useSharedTypemapUniverse"/>. They are emitted as
+	/// <c>[assembly: TypeMapAssemblyTarget&lt;Java.Lang.Object&gt;("name")]</c> so the runtime loads
+	/// them into the <c>Java.Lang.Object</c> universe: in shared mode they merge into the single
+	/// app universe; in aggregate mode the loader adds the <c>Java.Lang.Object</c> universe alongside
+	/// the app's per-assembly universes.
+	/// </param>
+	public void Generate (IReadOnlyList<string> perAssemblyTypeMapNames, bool useSharedTypemapUniverse, Stream stream, string? assemblyName = null, string? moduleName = null, IReadOnlyList<string>? sharedFrameworkTypeMapNames = null)
 	{
 		if (perAssemblyTypeMapNames is null) {
 			throw new ArgumentNullException (nameof (perAssemblyTypeMapNames));
@@ -118,17 +127,28 @@ public void Generate (IReadOnlyList<string> perAssemblyTypeMapNames, bool useSha
 			EmitPerAssemblyUniverseAssemblyTargetAttributes (pe, perAssemblyTypeMapNames);
 		}
 
+		// Pre-generated framework typemaps (e.g. _Mono.Android.TypeMap) always live in the
+		// Java.Lang.Object universe, so reference them under that anchor regardless of mode.
+		var sharedFrameworkNames = sharedFrameworkTypeMapNames;
+		bool hasSharedFrameworkUniverse = sharedFrameworkNames is { Count: > 0 };
+		if (sharedFrameworkNames is { Count: > 0 }) {
+			var javaLangObjectHandle = pe.Metadata.AddTypeReference (pe.MonoAndroidRef,
+				pe.Metadata.GetOrAddString ("Java.Lang"),
+				pe.Metadata.GetOrAddString ("Object"));
+			EmitSharedUniverseAssemblyTargetAttributes (pe, javaLangObjectHandle, sharedFrameworkNames);
+		}
+
 		// Emit [assembly: IgnoresAccessChecksTo("...")] so TypeMapLoader.Initialize() can access
 		// internal types (TrimmableTypeMap and friends in Mono.Android, and private anchors
-		// in each per-assembly typemap DLL when aggregate universes or array maps are used).
+		// in each per-assembly typemap DLL when aggregate universes are used).
 		var accessTargets = new List<string> { "Mono.Android" };
 		if (!useSharedTypemapUniverse) {
 			accessTargets.AddRange (perAssemblyTypeMapNames);
 		}
 		pe.EmitIgnoresAccessChecksToAttribute (accessTargets);
 
 		// Emit TypeMapLoader class with Initialize() method
-		EmitTypeMapLoader (pe, anchorTypeHandle, perAssemblyTypeMapNames, useSharedTypemapUniverse, assemblyName);
+		EmitTypeMapLoader (pe, anchorTypeHandle, perAssemblyTypeMapNames, useSharedTypemapUniverse, assemblyName, hasSharedFrameworkUniverse);
 
 		pe.WritePE (stream);
 	}
@@ -176,7 +196,7 @@ static void EmitAssemblyTargetAttribute (PEAssemblyBuilder pe, MemberReferenceHa
 		pe.Metadata.AddCustomAttribute (EntityHandle.AssemblyDefinition, ctorRef, blobHandle);
 	}
 
-	static void EmitTypeMapLoader (PEAssemblyBuilder pe, EntityHandle anchorTypeHandle, IReadOnlyList<string> perAssemblyTypeMapNames, bool useSharedTypemapUniverse, string assemblyName)
+	static void EmitTypeMapLoader (PEAssemblyBuilder pe, EntityHandle anchorTypeHandle, IReadOnlyList<string> perAssemblyTypeMapNames, bool useSharedTypemapUniverse, string assemblyName, bool hasSharedFrameworkUniverse = false)
 	{
 		var metadata = pe.Metadata;
 
@@ -214,13 +234,16 @@ static void EmitTypeMapLoader (PEAssemblyBuilder pe, EntityHandle anchorTypeHand
 		var externalDictTypeSpec = MakeIReadOnlyDictTypeSpec (pe, iReadOnlyDictOpenRef, systemTypeRef, keyIsString: true);
 
 		if (useSharedTypemapUniverse) {
+			// Single Java.Lang.Object universe. Pre-generated framework typemaps (if any) also
+			// anchor on Java.Lang.Object, so GetOrCreateExternalTypeMapping<Java.Lang.Object>()
+			// already merges them in via their TypeMapAssemblyTarget attributes — no extra universe.
 			var initializeRef = AddInitializeSingleNoArraysRef (pe, trimmableTypeMapRef, iReadOnlyDictOpenRef, systemTypeRef);
 			EmitInitializeWithSingleTypeMapNoArrays (pe, anchorTypeHandle, getExternalMemberRef, getProxyMemberRef, initializeRef, assemblyName);
 		} else {
 			var proxyDictTypeSpec = MakeIReadOnlyDictTypeSpec (pe, iReadOnlyDictOpenRef, systemTypeRef, keyIsString: false);
 			var initializeRef = AddInitializeAggregateNoArraysRef (pe, trimmableTypeMapRef, iReadOnlyDictOpenRef, systemTypeRef);
 			EmitInitializeWithAggregateTypeMapNoArrays (pe, perAssemblyTypeMapNames, getExternalMemberRef, getProxyMemberRef,
-				initializeRef, externalDictTypeSpec, proxyDictTypeSpec, iReadOnlyDictOpenRef, systemTypeRef, assemblyName);
+				initializeRef, externalDictTypeSpec, proxyDictTypeSpec, iReadOnlyDictOpenRef, systemTypeRef, assemblyName, hasSharedFrameworkUniverse);
 		}
 	}
 
@@ -251,18 +274,30 @@ static void EmitInitializeWithAggregateTypeMapNoArrays (PEAssemblyBuilder pe,
 		MemberReferenceHandle initializeRef,
 		TypeSpecificationHandle externalDictTypeSpec, TypeSpecificationHandle proxyDictTypeSpec,
 		TypeReferenceHandle iReadOnlyDictOpenRef, TypeReferenceHandle systemTypeRef,
-		string assemblyName)
+		string assemblyName,
+		bool hasSharedFrameworkUniverse = false)
 	{
-		var count = perAssemblyTypeMapNames.Count;
+		// When a pre-generated framework typemap is present (e.g. _Mono.Android.TypeMap), it lives in
+		// the Java.Lang.Object universe. Emit it as universe [0] (via
+		// GetOrCreate*TypeMapping<Java.Lang.Object>()), followed by the app's per-assembly universes.
+		var count = perAssemblyTypeMapNames.Count + (hasSharedFrameworkUniverse ? 1 : 0);
 
 		var getExternalSpecs = new EntityHandle [count];
 		var getProxySpecs = new EntityHandle [count];
-		for (int i = 0; i < count; i++) {
+		int offset = 0;
+		if (hasSharedFrameworkUniverse) {
+			var javaLangObjectRef = pe.Metadata.AddTypeReference (pe.MonoAndroidRef,
+				pe.Metadata.GetOrAddString ("Java.Lang"), pe.Metadata.GetOrAddString ("Object"));
+			getExternalSpecs [0] = MakeGenericMethodSpec (pe, getExternalMemberRef, javaLangObjectRef);
+			getProxySpecs [0] = MakeGenericMethodSpec (pe, getProxyMemberRef, javaLangObjectRef);
+			offset = 1;
+		}
+		for (int i = 0; i < perAssemblyTypeMapNames.Count; i++) {
 			var asmRef = pe.FindOrAddAssemblyRef (perAssemblyTypeMapNames [i]);
 			var perAsmAnchorRef = pe.Metadata.AddTypeReference (asmRef,
 				default, pe.Metadata.GetOrAddString ("__TypeMapAnchor"));
-			getExternalSpecs [i] = MakeGenericMethodSpec (pe, getExternalMemberRef, perAsmAnchorRef);
-			getProxySpecs [i] = MakeGenericMethodSpec (pe, getProxyMemberRef, perAsmAnchorRef);
+			getExternalSpecs [offset + i] = MakeGenericMethodSpec (pe, getExternalMemberRef, perAsmAnchorRef);
+			getProxySpecs [offset + i] = MakeGenericMethodSpec (pe, getProxyMemberRef, perAsmAnchorRef);
 		}
 
 		pe.EmitBody ("Initialize",