[TrimmableTypeMap] Fix trimmable typemap single-RID release builds

Documentation/docs-mobile/messages/index.md

@@ -219,6 +219,8 @@ Either change the value in the AndroidManifest.xml to match the $(SupportedOSPla
 + [XA4250](xa4250.md): Manifest-referenced type '{type}' was not found in any scanned assembly. It may be a framework type.
 + [XA4252](xa4252.md): Insecure HTTP Maven repository URL '{url}' is not allowed. Use an HTTPS URL, or set AllowInsecureHttp="true" metadata on the item to override this check.
 + [XA4253](xa4253.md): Generated Java callable wrapper code changed: '{path}'
++ [XA4254](xa4254.md): Trimmable type map Java source input directory '{input}' and output directory '{output}' must be different.
++ [XA4255](xa4255.md): Generated trimmable type map Java source '{path}' was not found.
 + XA4300: Native library '{library}' will not be bundled because it has an unsupported ABI.
 + [XA4301](xa4301.md): Apk already contains the item `xxx`.
 + [XA4302](xa4302.md): Unhandled exception merging \`AndroidManifest.xml\`: {ex}

Documentation/docs-mobile/messages/xa4253.md

@@ -10,7 +10,7 @@ f1_keywords:
 
 ## Example messages
 
-```
+```text
 error XA4253: Generated Java callable wrapper code changed: 'obj/Release/android/src/mono/MonoRuntimeProvider.java'
 ```
 

Documentation/docs-mobile/messages/xa4254.md

@@ -0,0 +1,25 @@
+---
+title: .NET for Android error XA4254
+description: XA4254 error code
+ms.date: 05/20/2026
+f1_keywords:
+  - "XA4254"
+---
+
+# .NET for Android error XA4254
+
+## Example message
+
+```text
+error XA4254: Trimmable type map Java source input directory 'obj/Release/net11.0-android/typemap/java' and output directory 'obj/Release/net11.0-android/typemap/java' must be different.
+```
+
+## Issue
+
+The trimmable type map build tried to clean the Java source output directory, but the configured input and output directories resolved to the same path.
+
+Cleaning the output directory in this configuration would delete the input Java sources before they can be copied.
+
+## Solution
+
+This error indicates an internal build configuration problem. File an issue at <https://github.com/dotnet/android/issues> and include the full build log.

Documentation/docs-mobile/messages/xa4255.md

@@ -0,0 +1,27 @@
+---
+title: .NET for Android error XA4255
+description: XA4255 error code
+ms.date: 05/20/2026
+f1_keywords:
+  - "XA4255"
+---
+
+# .NET for Android error XA4255
+
+## Example message
+
+```text
+error XA4255: Generated trimmable type map Java source 'obj/Release/net11.0-android/typemap/java/my/app/MainActivity.java' was not found.
+```
+
+## Issue
+
+The post-trim trimmable type map scan expected to copy a generated Java source file from the pre-trim Java source directory, but the file was missing.
+
+This can happen if intermediate build outputs are stale or if the generated Java source list no longer matches the files on disk.
+
+## Solution
+
+Delete the project's `obj` and `bin` directories, then rebuild.
+
+If the error persists after a clean rebuild, file an issue at <https://github.com/dotnet/android/issues> and include the full build log.

src/Microsoft.Android.Sdk.TrimmableTypeMap/Scanner/JavaPeerInfo.cs

@@ -48,7 +48,7 @@ public sealed record JavaPeerInfo
 	/// Framework ACWs are generated by the SDK and can be trimmed like bindings unless
 	/// another rule explicitly roots them.
 	/// </summary>
-	public bool IsFrameworkAssembly { get; init; }
+	public bool IsFrameworkAssembly { get; set; }
 
 	/// <summary>
 	/// True when per-rank array typemap entries should be generated for this peer.

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

@@ -34,7 +34,8 @@ public TrimmableTypeMapResult Execute (
 		ManifestConfig? manifestConfig = null,
 		XDocument? manifestTemplate = null,
 		string? packageNamingPolicy = null,
-		int maxArrayRank = 0)
+		int maxArrayRank = 0,
+		bool generateTypeMapAssemblies = true)
 	{
 		_ = assemblies ?? throw new ArgumentNullException (nameof (assemblies));
 		_ = systemRuntimeVersion ?? throw new ArgumentNullException (nameof (systemRuntimeVersion));
@@ -48,16 +49,15 @@ public TrimmableTypeMapResult Execute (
 			logger.LogNoJavaPeerTypesFound ();
 			return new TrimmableTypeMapResult ([], [], allPeers);
 		}
+		MarkFrameworkAssemblyPeers (allPeers, frameworkAssemblyNames);
 
 		RootManifestReferencedTypes (allPeers, PrepareManifestForRooting (manifestTemplate, manifestConfig));
 		PropagateDeferredRegistrationToBaseClasses (allPeers);
 		PropagateCannotRegisterToDescendants (allPeers);
 
-		var generatedAssemblies = GenerateTypeMapAssemblies (
-			allPeers,
-			systemRuntimeVersion,
-			useSharedTypemapUniverse,
-			maxArrayRank);
+		var generatedAssemblies = generateTypeMapAssemblies
+			? GenerateTypeMapAssemblies (allPeers, systemRuntimeVersion, useSharedTypemapUniverse, maxArrayRank)
+			: [];
 		var jcwPeers = allPeers.Where (ShouldGenerateJcw).ToList ();
 		logger.LogGeneratingJcwFilesInfo (jcwPeers.Count, allPeers.Count);
 		var generatedJavaSources = GenerateJcwJavaSources (jcwPeers);
@@ -212,6 +212,15 @@ List<GeneratedAssembly> GenerateTypeMapAssemblies (
 		return generatedAssemblies;
 	}
 
+	static void MarkFrameworkAssemblyPeers (List<JavaPeerInfo> allPeers, HashSet<string> frameworkAssemblyNames)
+	{
+		foreach (var peer in allPeers) {
+			if (frameworkAssemblyNames.Contains (peer.AssemblyName)) {
+				peer.IsFrameworkAssembly = true;
+			}
+		}
+	}
+
 	/// <summary>
 	/// Groups peers by assembly, merging cross-assembly aliases into a single group.
 	/// When the same JNI name appears in multiple assemblies (e.g. <c>Java.Lang.Object</c>

src/Xamarin.Android.Build.Tasks/Microsoft.Android.Sdk/targets/Microsoft.Android.Sdk.TypeMap.Trimmable.CoreCLR.targets

@@ -48,6 +48,45 @@
         OutputFile="$(_ProguardProjectConfiguration)" />
   </Target>
 
+  <Target Name="_GeneratePostTrimTrimmableTypeMapJavaSources"
+      Condition=" '$(_AndroidTypeMapImplementation)' == 'trimmable' and '$(PublishTrimmed)' == 'true' and Exists('$(IntermediateOutputPath)linked/Link.semaphore') "
+      AfterTargets="ILLink"
+      BeforeTargets="_GenerateJavaStubs;_CompileJava;_CompileToDalvik"
+      Inputs="$(IntermediateOutputPath)linked/Link.semaphore"
+      Outputs="$(_PostTrimTrimmableTypeMapJavaStamp)">
+    <ItemGroup>
+      <_PostTrimTrimmableTypeMapInputAssemblies Include="@(ResolvedFileToPublish)"
+          Condition=" '%(Extension)' == '.dll' " />
+    </ItemGroup>
+
+    <GenerateTrimmableTypeMap
+        ResolvedAssemblies="@(_PostTrimTrimmableTypeMapInputAssemblies)"
+        FrameworkAssemblyNames="@(ResolvedFrameworkAssemblies->'%(Filename)')"
+        OutputDirectory="$(_TypeMapOutputDirectory)"
+        JavaSourceOutputDirectory="$(_PostTrimTypeMapJavaOutputDirectory)"
+        JavaSourceInputDirectory="$(_TypeMapJavaOutputDirectory)"
+        TargetFrameworkVersion="$(TargetFrameworkVersion)"
+        PackageNamingPolicy="$(_TrimmableTypeMapPackageNamingPolicy)"
+        MaxArrayRank="$(_AndroidTrimmableTypeMapMaxArrayRank)"
+        GenerateTypeMapAssemblies="false"
+        CleanJavaSourceOutputDirectory="true"
+        AcwMapOutputFile="$(IntermediateOutputPath)acw-map.txt"
+        ApplicationRegistrationOutputFile="$(IntermediateOutputPath)android/src/net/dot/android/ApplicationRegistration.java">
+      <Output TaskParameter="GeneratedJavaFiles" ItemName="_PostTrimGeneratedJavaFiles" />
+    </GenerateTrimmableTypeMap>
+
+    <MakeDir Directories="$([System.IO.Path]::GetDirectoryName('$(_PostTrimTrimmableTypeMapJavaStamp)'))" />
+    <Touch Files="$(_PostTrimTrimmableTypeMapJavaStamp)" AlwaysCreate="true" />
+
+    <ItemGroup>
+      <FileWrites Include="@(_PostTrimGeneratedJavaFiles)" />
+      <FileWrites Include="$(IntermediateOutputPath)acw-map.txt" />
+      <FileWrites Include="$(IntermediateOutputPath)android/src/net/dot/android/ApplicationRegistration.java" />
+      <FileWrites Include="$(_PostTrimTrimmableTypeMapJavaStamp)" />
+      <_PostTrimTrimmableTypeMapInputAssemblies Remove="@(_PostTrimTrimmableTypeMapInputAssemblies)" />
+      <_PostTrimGeneratedJavaFiles Remove="@(_PostTrimGeneratedJavaFiles)" />
+    </ItemGroup>
+  </Target>
   <!-- Add linked TypeMap DLLs to the normal publish assembly pipeline.  The SDK R2R
        target only compiles ResolvedFileToPublish items with PostprocessAssembly=true. -->
   <Target Name="_AddTrimmableTypeMapToResolvedFileToPublish"

src/Xamarin.Android.Build.Tasks/Microsoft.Android.Sdk/targets/Microsoft.Android.Sdk.TypeMap.Trimmable.targets

@@ -24,6 +24,12 @@
     <_TypeMapOutputDirectory>$(_TypeMapBaseOutputDir)typemap/</_TypeMapOutputDirectory>
     <_TypeMapJavaOutputDirectory>$(_TypeMapBaseOutputDir)typemap/java</_TypeMapJavaOutputDirectory>
     <_TypeMapAssembliesListFile>$(_TypeMapOutputDirectory)typemap-assemblies.txt</_TypeMapAssembliesListFile>
+    <_PostTrimTypeMapJavaOutputDirectory>$(_TypeMapBaseOutputDir)typemap/linked-java</_PostTrimTypeMapJavaOutputDirectory>
+    <_TypeMapJavaStubsSourceDirectory Condition=" '$(_TypeMapJavaStubsSourceDirectory)' == '' and '$(_AndroidRuntime)' == 'CoreCLR' and '$(PublishTrimmed)' == 'true' ">$(_PostTrimTypeMapJavaOutputDirectory)</_TypeMapJavaStubsSourceDirectory>
+    <_TypeMapJavaStubsSourceDirectory Condition=" '$(_TypeMapJavaStubsSourceDirectory)' == '' ">$(_TypeMapJavaOutputDirectory)</_TypeMapJavaStubsSourceDirectory>
+    <_PostTrimTrimmableTypeMapJavaStamp>$(_TypeMapBaseOutputDir)stamp/_GeneratePostTrimTrimmableTypeMapJavaSources.stamp</_PostTrimTrimmableTypeMapJavaStamp>
+    <_TrimmableJavaSourceStamp Condition=" '$(_TrimmableJavaSourceStamp)' == '' and '$(_AndroidRuntime)' == 'CoreCLR' and '$(PublishTrimmed)' == 'true' ">$(_PostTrimTrimmableTypeMapJavaStamp)</_TrimmableJavaSourceStamp>
+    <_TrimmableJavaSourceStamp Condition=" '$(_TrimmableJavaSourceStamp)' == '' ">$(_TypeMapOutputDirectory)$(_TypeMapAssemblyName).dll</_TrimmableJavaSourceStamp>
     <!-- Max array rank for __ArrayMapRank{N} sentinel emission. Defaults to 3 when
          dynamic code is unavailable, so array creation uses the typemap path;
          defaults to 0 otherwise, where dynamic code can use Array.CreateInstance directly. -->
@@ -251,7 +257,7 @@
       Outputs="$(_AndroidStampDirectory)_GenerateJavaStubs.stamp">
 
     <ItemGroup>
-      <_TypeMapJavaFiles Include="$(_TypeMapJavaOutputDirectory)/**/*.java" />
+      <_TypeMapJavaFiles Include="$(_TypeMapJavaStubsSourceDirectory)/**/*.java" />
     </ItemGroup>
     <Copy SourceFiles="@(_TypeMapJavaFiles)" DestinationFolder="$(IntermediateOutputPath)android/src/%(RecursiveDir)" />
 

src/Xamarin.Android.Build.Tasks/Properties/Resources.resx

@@ -1141,6 +1141,17 @@ To use a custom JDK path for a command line build, set the 'JavaSdkDirectory' MS
     <value>Generated Java callable wrapper code changed: '{0}'</value>
     <comment>{0} - The path to the generated Java callable wrapper file</comment>
   </data>
+  <data name="XA4254" xml:space="preserve">
+    <value>Trimmable type map Java source input directory '{0}' and output directory '{1}' must be different.</value>
+    <comment>The following are literal names and should not be translated: Trimmable type map, Java.
+{0} - Full path to the Java source input directory
+{1} - Full path to the Java source output directory</comment>
+  </data>
+  <data name="XA4255" xml:space="preserve">
+    <value>Generated trimmable type map Java source '{0}' was not found.</value>
+    <comment>The following are literal names and should not be translated: trimmable type map, Java.
+{0} - Full path to the generated Java source file</comment>
+  </data>
   <data name="XA0142" xml:space="preserve">
     <value>Command '{0}' failed.\n{1}</value>
     <comment>'{0}' is a failed command name (potentially with path) followed by all the arguments passed to it. {1} is the combined output on the standard error and standard output streams.</comment>

src/Xamarin.Android.Build.Tasks/Tasks/GenerateTrimmableTypeMap.cs

@@ -57,6 +57,7 @@ public void LogJniAddNativeMethodRegistrationAttributeError (string managedTypeN
 	public string OutputDirectory { get; set; } = "";
 	[Required]
 	public string JavaSourceOutputDirectory { get; set; } = "";
+	public string? JavaSourceInputDirectory { get; set; }
 	[Required]
 	public string TargetFrameworkVersion { get; set; } = "";
 
@@ -92,6 +93,8 @@ public void LogJniAddNativeMethodRegistrationAttributeError (string managedTypeN
 	public string? ManifestPlaceholders { get; set; }
 	public string? CheckedBuild { get; set; }
 	public string? ApplicationJavaClass { get; set; }
+	public bool GenerateTypeMapAssemblies { get; set; } = true;
+	public bool CleanJavaSourceOutputDirectory { get; set; }
 
 	[Output]
 	public ITaskItem [] GeneratedAssemblies { get; set; } = [];
@@ -116,8 +119,19 @@ public override bool RunTask ()
 		foreach (var assemblyName in FrameworkAssemblyNames) {
 			frameworkAssemblyNames.Add (assemblyName);
 		}
+		if (CleanJavaSourceOutputDirectory && !JavaSourceInputDirectory.IsNullOrEmpty ()) {
+			var inputDirectory = Path.GetFullPath (JavaSourceInputDirectory);
+			var outputDirectory = Path.GetFullPath (JavaSourceOutputDirectory);
+			if (string.Equals (inputDirectory, outputDirectory, StringComparison.OrdinalIgnoreCase)) {
+				Log.LogCodedError ("XA4254", Properties.Resources.XA4254, inputDirectory, outputDirectory);
+				return false;
+			}
+		}
 
 		Directory.CreateDirectory (OutputDirectory);
+		if (CleanJavaSourceOutputDirectory && Directory.Exists (JavaSourceOutputDirectory)) {
+			Directory.Delete (JavaSourceOutputDirectory, recursive: true);
+		}
 		Directory.CreateDirectory (JavaSourceOutputDirectory);
 
 		var peReaders = new List<PEReader> ();
@@ -168,11 +182,16 @@ public override bool RunTask ()
 				manifestConfig: manifestConfig,
 				manifestTemplate: manifestTemplate,
 				packageNamingPolicy: PackageNamingPolicy,
-				maxArrayRank: MaxArrayRank);
+				maxArrayRank: MaxArrayRank,
+				generateTypeMapAssemblies: GenerateTypeMapAssemblies);
 
-			GeneratedAssemblies = WriteAssembliesToDisk (result.GeneratedAssemblies, assemblyInputs.Select (i => i.Path).ToList ());
-			WriteGeneratedAssembliesListFile (GeneratedAssemblies);
-			GeneratedJavaFiles = WriteJavaSourcesToDisk (result.GeneratedJavaSources);
+			if (GenerateTypeMapAssemblies) {
+				GeneratedAssemblies = WriteAssembliesToDisk (result.GeneratedAssemblies, assemblyInputs.Select (i => i.Path).ToList ());
+				WriteGeneratedAssembliesListFile (GeneratedAssemblies);
+			}
+			GeneratedJavaFiles = JavaSourceInputDirectory.IsNullOrEmpty ()
+				? WriteJavaSourcesToDisk (result.GeneratedJavaSources)
+				: CopyJavaSourcesFromInputDirectory (result.GeneratedJavaSources);
 
 			// Write manifest to disk if generated
 			if (result.Manifest is not null && !MergedAndroidManifestOutput.IsNullOrEmpty ()) {
@@ -247,6 +266,29 @@ void WriteGeneratedAssembliesListFile (IReadOnlyList<ITaskItem> assemblies)
 		Files.CopyIfStringChanged (text, GeneratedAssembliesListFile);
 	}
 
+	ITaskItem [] CopyJavaSourcesFromInputDirectory (IReadOnlyList<GeneratedJavaSource> javaSources)
+	{
+		var items = new List<ITaskItem> ();
+		foreach (var source in javaSources) {
+			string inputPath = Path.Combine (JavaSourceInputDirectory ?? "", source.RelativePath);
+			if (!File.Exists (inputPath)) {
+				Log.LogCodedError ("XA4255", Properties.Resources.XA4255, inputPath);
+				continue;
+			}
+
+			string outputPath = Path.Combine (JavaSourceOutputDirectory, source.RelativePath);
+			string? dir = Path.GetDirectoryName (outputPath);
+			if (!string.IsNullOrEmpty (dir)) {
+				Directory.CreateDirectory (dir);
+			}
+			using (var stream = File.OpenRead (inputPath)) {
+				Files.CopyIfStreamChanged (stream, outputPath);
+			}
+			items.Add (new TaskItem (outputPath));
+		}
+		return items.ToArray ();
+	}
+
 	ITaskItem [] WriteAssembliesToDisk (IReadOnlyList<GeneratedAssembly> assemblies, IReadOnlyList<string> assemblyPaths)
 	{
 		// Build a map from assembly name -> source path for timestamp comparison