NativeAOT: crash at startup in JNINativeWrapper.CreateDelegate (Reflection.Emit)

[vyacheslav-volkov]

Android framework version

net10.0-android (Preview)

Affected platform version

NET 10 RC2

Description

Hi team — thanks a lot for adding initial NativeAOT support for Android! I tried it with my framework and hit two problems.

1) Crash on startup (Reflection.Emit)

The app crashes immediately with:

System.PlatformNotSupportedException: PlatformNotSupported_ReflectionEmit
   at System.Reflection.Emit.ReflectionEmitThrower.ThrowPlatformNotSupportedException() + 0x34
   at Android.Runtime.JNINativeWrapper.CreateDelegate(Delegate dlg) + 0x308
   at MugenMvvm.Android.Native.Interfaces.INativeLifecycleDispatcherInvoker.GetOnLifecycleChanged_Ljava_lang_Object_ILjava_lang_Object_Handler() + 0x60
   at Microsoft.Android.Runtime.ManagedTypeManager.RegisterNativeMembers(JniType, Type, ReadOnlySpan`1) + 0x1c0
   at Java.Interop.ManagedPeer.RegisterNativeMembers(IntPtr jnienv, IntPtr klass, IntPtr n_nativeClass, IntPtr n_methods) + 0x19c
--- End of stack trace from previous location ---
   at Java.Interop.JniEnvironment.Object.AllocObject(JniObjectReference) + 0x18c
   at Java.Interop.JniPeerMembers.JniInstanceMethods.StartCreateInstance(String, Type, JniArgumentValue*) + 0x2c
   at Java.Lang.Object..ctor() + 0x108
   at MugenMvvm.Android.AndroidMugenExtensions.AddAndroidCore(MugenApplicationConfiguration, IBindVie

Is Android.Runtime.JNINativeWrapper.CreateDelegate expected to use Reflection.Emit under Android NativeAOT?

2) IL scanner VTable error (linker)

When building for Android AOT I also get:

EXEC : error VTable of type 'Impl`3<MugenMvvm.Views.Interfaces.IViewManager,
MugenMvvm.Api.Interfaces.IApiProviderComponent`1<MugenMvvm.Views.Interfaces.IViewManager>,
MugenMvvm.Bindings.Api.BindingBuilderRequest`1<MugenMvvm.Common.InlineObjectTuple>>'
not computed by the IL scanner. You can work around by running the compilation with scanner disabled.

This generic combination isn’t actually used at runtime. As a workaround I added an explicit reference so the type is kept:

public static class LinkerInclude
{
    public static void Include()
    {
        // Workaround for AOT linking / IL scanner
        _ = ComponentDescriptor.Impl<
                IViewManager,
                IApiProviderComponent<IViewManager>,
                BindingBuilderRequest<InlineObjectTuple>
            >.EmptyInstance;
    }
}

Repro repository

Minimal repro (Android + iOS projects): https://github.com/vyacheslav-volkov/NativeAot.Test

Notes:

• The iOS app works fine under NativeAOT with the same framework code.
• The Android app demonstrates the crash.

How I build (Android)

I used the following command to reproduce:

dotnet publish -f net10.0-android -c Release /t:Run   -p:AndroidNdkDirectory="pathToRoot/Developer/Xamarin/android-sdk-macosx/ndk/27.2.12479018"

(Explicit NDK is r27.2.12479018.)

---

Thanks again for the NativeAOT work — happy to test any fixes or try suggested changes to the sample.

Steps to Reproduce

Build and run the android app from the link https://github.com/vyacheslav-volkov/NativeAot.Test

Did you find any workaround?

No response

Relevant log output

[hez2010]

Is Android.Runtime.JNINativeWrapper.CreateDelegate expected to use Reflection.Emit under Android NativeAOT?

You should not use JNINativeWrapper.CreateDelegate with NativeAOT, it won't work.

This generic combination isn’t actually used at runtime. As a workaround I added an explicit reference so the type is kept:

This looks like a bug in NativeAOT ilc, better to report it in dotnet/runtime as well. You can add this line to your csproj to get an ilc repro:

<ItemGroup>
    <!-- Replace /some/path/where/to/store/zip with an actual path -->
    <IlcArg Include="--make-repro-path:/some/path/where/to/store/zip">
</ItemGroup>

then attach the zip file in your issue.

[vyacheslav-volkov]

You should not use JNINativeWrapper.CreateDelegate with NativeAOT, it won't work.

@hez2010 Thanks to clarify, I’m not calling/using JNINativeWrapper.CreateDelegate in my code. It’s coming from the generated bindings for an .aar (Android binding project). The crash happens during JNI registration inside the Android runtime path used by those bindings.

		static Delegate GetOnLifecycleChanged_Ljava_lang_Object_ILjava_lang_Object_Handler ()
		{
			if (cb_onLifecycleChanged_OnLifecycleChanged_Ljava_lang_Object_ILjava_lang_Object__V == null)
				cb_onLifecycleChanged_OnLifecycleChanged_Ljava_lang_Object_ILjava_lang_Object__V = JNINativeWrapper.CreateDelegate (new _JniMarshal_PPLIL_V (n_OnLifecycleChanged_Ljava_lang_Object_ILjava_lang_Object_));
			return cb_onLifecycleChanged_OnLifecycleChanged_Ljava_lang_Object_ILjava_lang_Object__V;
		}

[hez2010]

It’s coming from the generated bindings for an .aar (Android binding project).

You may need to regenerate the bindings with the latest SDK.

[jonathanpeppers]

Yes, net10.0-android binding projects have changes to support NativeAOT inside.

[vyacheslav-volkov]

Thank you so much! I rebuilt for .NET 10 previously I was on the latest .NET 9 for android bindings and didn’t realize they’re not compatible. Everything works now: the app launches, and the startup time is fantastic 271–331ms for heavy initialization. For comparison, I built with the old MonoAOT and the startup time is terrible 1s27-1s41ms.
Thanks again, no more worrying about slow startup!