[NativeAOT] Use XAJavaInterop1 codegen target and unify GC bridge

Documentation/docs-mobile/building-apps/build-properties.md

@@ -273,8 +273,7 @@ Possible values include:
   Xamarin.Android 6.1 or later. Xamarin.Android 6.1 and later bind
   `Mono.Android.dll` with this value.
 
-- **JavaInterop1**: experimental value, currently the default for the
-  NativeAOT runtime.
+- **JavaInterop1**: this value is obsolete and is no longer supported.
 
 The default value is `XAJavaInterop1`.
 

Documentation/docs-mobile/messages/index.md

@@ -203,7 +203,7 @@ Either change the value in the AndroidManifest.xml to match the $(SupportedOSPla
 + XA4229: Unrecognized \`TransformFile\` root element: {element}.
 + XA4230: Error parsing XML: {exception}
 + [XA4231](xa4231.md): The Android class parser value 'jar2xml' is deprecated and will be removed in a future version of .NET for Android. Update the project properties to use 'class-parse'.
-+ [XA4232](xa4232.md): The Android code generation target 'XamarinAndroid' is deprecated and will be removed in a future version of .NET for Android. Update the project properties to use 'XAJavaInterop1'.
++ [XA4232](xa4232.md): The Android code generation target '{0}' is no longer supported. The '_AndroidJcwCodegenTarget' property only supports 'XAJavaInterop1'; 'XamarinAndroid' and 'JavaInterop1' are not supported.
 + [XA4234](xa4234.md): '<{item}>' item '{itemspec}' is missing required attribute '{name}'.
 + [XA4235](xa4235.md): Maven artifact specification '{artifact}' is invalid. The correct format is 'group_id:artifact_id'.
 + [XA4236](xa4236.md): Cannot download Maven artifact '{group}:{artifact}'. - {jar}: {exception} - {aar}: {exception}

Documentation/docs-mobile/messages/xa4232.md

@@ -1,33 +1,34 @@
 ---
-title: .NET for Android warning XA4232
-description: XA4232 warning code
-ms.date: 04/11/2024
+title: .NET for Android error XA4232
+description: XA4232 error code
+ms.date: 07/17/2026
 f1_keywords:
   - "XA4232"
 ---
 
-# .NET for Android warning XA4232
+# .NET for Android error XA4232
 
 ## Example messages
 
 ```
-warning XA4232: The Android code generation target 'XamarinAndroid' is deprecated and will be removed in a future version of .NET for Android. Update the project properties to use 'XAJavaInterop1'.
+error XA4232: The Android code generation target 'XamarinAndroid' is no longer supported. The '_AndroidJcwCodegenTarget' property only supports 'XAJavaInterop1'; 'XamarinAndroid' and 'JavaInterop1' are not supported.
+error XA4232: The Android code generation target 'JavaInterop1' is no longer supported. The '_AndroidJcwCodegenTarget' property only supports 'XAJavaInterop1'; 'XamarinAndroid' and 'JavaInterop1' are not supported.
 ```
 
 ## Issue
 
-The Android code generation target `XamarinAndroid` has been deprecated.
+The project sets the internal `_AndroidJcwCodegenTarget` MSBuild property to
+`XamarinAndroid` or `JavaInterop1`. These code generation targets are no longer
+supported for any .NET for Android runtime.
 
 ## Solution
 
-To resolve this warning, update the **Android Codegen target** setting in the
-Visual Studio project property pages or the **Code generation target** setting
-in Visual Studio for Mac to **XAJavaInterop1**.  This corresponds to the
-`XAJavaInterop1` value for the `AndroidCodegenTarget` MSBuild property in the
-_.csproj_ file:
+Remove any `_AndroidJcwCodegenTarget` assignment that uses `XamarinAndroid` or
+`JavaInterop1`, for example:
 
 ```xml
-<PropertyGroup>
-  <AndroidCodegenTarget>XAJavaInterop1</AndroidCodegenTarget>
-</PropertyGroup>
+<_AndroidJcwCodegenTarget>JavaInterop1</_AndroidJcwCodegenTarget>
 ```
+
+The property defaults to `XAJavaInterop1`. If a build customization must set
+it explicitly, update the value to `XAJavaInterop1`.

Documentation/guides/OneDotNet.md

@@ -88,7 +88,7 @@ will not be supported.
 supported.
 
 `$(AndroidCodegenTarget)` will be `XAJavaInterop1` by default.
-`XamarinAndroid` will not be supported.
+`XamarinAndroid` and `JavaInterop1` will not be supported.
 
 `$(AndroidManifest)` will default to `AndroidManifest.xml` in the root
 of projects as `Properties\AssemblyInfo.cs` is no longer used in

Documentation/guides/OneDotNetBindingProjects.md

@@ -43,8 +43,9 @@ will always be used.
 
 ### `<AndroidCodegenTarget>`
 
-`XamarinAndroid` is no longer a valid option for `<AndroidCodegenTarget>`.  `XAJavaInterop1`
-is now the default and only supported option.
+`XamarinAndroid` and `JavaInterop1` are no longer valid options for
+`<AndroidCodegenTarget>`. `XAJavaInterop1` is now the default and only
+supported option.
 
 If you have hand-bound code in your `Additions` files that interacts with the generated binding 
 plumbing (which is rare), it may need to be updated to be compatible with `XAJavaInterop1`.

src/Xamarin.Android.Build.Tasks/Microsoft.Android.Sdk/targets/Microsoft.Android.Sdk.DefaultProperties.targets

@@ -37,7 +37,7 @@
     <!-- jar2xml is not supported -->
     <AndroidClassParser>class-parse</AndroidClassParser>
     <AndroidCodegenTarget Condition=" '$(AndroidCodegenTarget)' == '' ">XAJavaInterop1</AndroidCodegenTarget>
-    <_AndroidJcwCodegenTarget Condition=" '$(_AndroidJcwCodegenTarget)' == '' and '$(_AndroidRuntime)' != 'NativeAOT' ">XAJavaInterop1</_AndroidJcwCodegenTarget>
+    <_AndroidJcwCodegenTarget Condition=" '$(_AndroidJcwCodegenTarget)' == '' ">XAJavaInterop1</_AndroidJcwCodegenTarget>
     <_AndroidTypeMapImplementation Condition=" '$(_AndroidTypeMapImplementation)' == '' and '$(_AndroidRuntime)' != 'NativeAOT' ">llvm-ir</_AndroidTypeMapImplementation>
     <AndroidBoundInterfacesContainStaticAndDefaultInterfaceMethods Condition=" '$(AndroidBoundInterfacesContainStaticAndDefaultInterfaceMethods)' == '' ">true</AndroidBoundInterfacesContainStaticAndDefaultInterfaceMethods>
     <AndroidBoundInterfacesContainTypes Condition=" '$(AndroidBoundInterfacesContainTypes)' == '' ">true</AndroidBoundInterfacesContainTypes>

src/Xamarin.Android.Build.Tasks/Microsoft.Android.Sdk/targets/Microsoft.Android.Sdk.NativeAOT.targets

@@ -16,7 +16,6 @@ This file contains the NativeAOT-specific MSBuild logic for .NET for Android.
   <PropertyGroup>
     <_AndroidRuntimePackRuntime>NativeAOT</_AndroidRuntimePackRuntime>
     <_AndroidUseWorkloadNativeLinker Condition=" '$(_AndroidUseWorkloadNativeLinker)' == '' ">true</_AndroidUseWorkloadNativeLinker>
-    <_AndroidJcwCodegenTarget Condition=" '$(_AndroidJcwCodegenTarget)' == '' ">JavaInterop1</_AndroidJcwCodegenTarget>
     <_AndroidTypeMapImplementation Condition=" '$(_AndroidTypeMapImplementation)' == '' ">trimmable</_AndroidTypeMapImplementation>
     <!-- .NET SDK gives: error NETSDK1191: A runtime identifier for the property 'PublishAot' couldn't be inferred. Specify a rid explicitly. -->
     <AllowPublishAotWithoutRuntimeIdentifier Condition=" '$(AllowPublishAotWithoutRuntimeIdentifier)' == '' ">true</AllowPublishAotWithoutRuntimeIdentifier>

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

@@ -725,8 +725,8 @@ In this message, "root element" refers to the root element of an XML file.
 {0} - The name of the current class parser value</comment>
   </data>
   <data name="XA4232" xml:space="preserve">
-    <value>The Android code generation target '{0}' is deprecated and will be removed in a future version of .NET for Android. Update the project properties to use 'XAJavaInterop1'.</value>
-    <comment>The following are literal names and should not be translated: XAJavaInterop1
+    <value>The Android code generation target '{0}' is no longer supported. The '_AndroidJcwCodegenTarget' property only supports 'XAJavaInterop1'; 'XamarinAndroid' and 'JavaInterop1' are not supported.</value>
+    <comment>The following are literal names and should not be translated: _AndroidJcwCodegenTarget, XAJavaInterop1, XamarinAndroid, JavaInterop1
 {0} - The name of the current code generation target</comment>
   </data>
   <data name="XA4300" xml:space="preserve">

src/Xamarin.Android.Build.Tasks/Tests/Xamarin.Android.Build.Tests/InvalidConfigTests.cs

@@ -44,5 +44,27 @@ public void XA0119AAB ()
 			}
 		}
 
+		[Test]
+		public void UnsupportedJcwCodegenTargetIsRejected (
+			[Values ("XamarinAndroid", "JavaInterop1")] string codegenTarget,
+			[Values (AndroidRuntime.MonoVM, AndroidRuntime.CoreCLR, AndroidRuntime.NativeAOT)] AndroidRuntime runtime)
+		{
+			var project = new XamarinAndroidApplicationProject {
+				IsRelease = runtime == AndroidRuntime.NativeAOT,
+			};
+			if (runtime == AndroidRuntime.MonoVM) {
+				project.SetProperty ("_DisableCheckForUnsupportedMonoMobileRuntime", "true");
+			}
+			project.SetRuntime (runtime);
+			project.SetProperty ("_AndroidJcwCodegenTarget", codegenTarget);
+			using (var builder = CreateApkBuilder ()) {
+				builder.Target = "_CheckForInvalidConfigurationAndPlatform";
+				builder.ThrowOnBuildFailure = false;
+				Assert.IsFalse (builder.Build (project), "Build should have failed.");
+				StringAssertEx.Contains ("error XA4232:", builder.LastBuildOutput, "Build should fail with XA4232.");
+				StringAssertEx.Contains (codegenTarget, builder.LastBuildOutput, "Error should identify the unsupported code generation target.");
+			}
+		}
+
 	}
 }

src/Xamarin.Android.Build.Tasks/Tests/Xamarin.ProjectTools/Resources/Base/BuildReleaseArm64SimpleDotNet.NativeAOT.apkdesc

@@ -5,10 +5,10 @@
       "Size": 3124
     },
     "classes.dex": {
-      "Size": 22804
+      "Size": 404664
     },
     "lib/arm64-v8a/libUnnamedProject.so": {
-      "Size": 5747648
+      "Size": 5731688
     },
     "res/drawable-hdpi-v4/icon.png": {
       "Size": 2178
@@ -35,5 +35,5 @@
       "Size": 1904
     }
   },
-  "PackageSize": 2401051
+  "PackageSize": 2474779
 }

src/Xamarin.Android.Build.Tasks/Xamarin.Android.Common.targets

@@ -3003,6 +3003,14 @@ because xbuild doesn't support framework reference assemblies.
 
 <Import Project="$(MSBuildThisFileDirectory)Xamarin.Installer.Common.targets"
         Condition=" '$(DesignTimeBuild)' != 'true' "/>
+  <Target Name="_ValidateAndroidJcwCodegenTarget"
+      BeforeTargets="_CheckForInvalidConfigurationAndPlatform">
+    <AndroidError Code="XA4232"
+        ResourceName="XA4232"
+        FormatArguments="$(_AndroidJcwCodegenTarget)"
+        Condition=" '$(_AndroidJcwCodegenTarget)' == 'XamarinAndroid' or '$(_AndroidJcwCodegenTarget)' == 'JavaInterop1' " />
+  </Target>
+
   <Target Name="_ValidateAndroidTypeMapImplementation"
       BeforeTargets="_CheckForInvalidConfigurationAndPlatform">
     <Error Condition=" '$(_AndroidTypeMapImplementation)' != '' and '$(_AndroidTypeMapImplementation)' != 'llvm-ir' and '$(_AndroidTypeMapImplementation)' != 'managed' and '$(_AndroidTypeMapImplementation)' != 'trimmable' "