IL scanner VTable error

[vyacheslav-volkov]

Description

I tried experimental NativeAOT for Android with my framework and hit this problem.

When building I 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;
    }
}

I have attached zip files from <IlcArg Include="--make-repro-path: as suggested here dotnet/android#10546

935452972_NativeAOT.Android.zip

2113164319_NativeAOT.Android.zip

Reproduction Steps

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

Expected behavior

No errors

Actual behavior

Build fails with the error

Regression?

No response

Known Workarounds

No response

Configuration

No response

Other information

No response

[dotnet-policy-service]

Tagging subscribers to this area: @agocke, @MichalStrehovsky, @jkotas
See info in area-owners.md if you want to be subscribed.

[agocke]

Cc @sbomer

[agocke]

Also @MichalStrehovsky

[MichalStrehovsky]

Also @MichalStrehovsky

I see Sven self-assigned this. Happy to help. The general troubleshooting strategy is at the exception throw site:

runtime/src/coreclr/tools/aot/ILCompiler.Compiler/Compiler/ILScanner.cs

Lines 326 to 335 in 119baa9

	// If we couldn't find the vtable slice information for this type, it's because the scanner
	// didn't correctly predict what will be needed.
	// To troubleshoot, compare the dependency graph of the scanner and the compiler.
	// Follow the path from the node that requested this node to the root.
	// On the path, you'll find a node that exists in both graphs, but it's predecessor
	// only exists in the compiler's graph. That's the place to focus the investigation on.
	// Use the ILCompiler-DependencyGraph-Viewer tool to investigate.
	Debug.Assert(false);
	string typeName = ExceptionTypeNameFormatter.Instance.FormatName(type);
	throw new ScannerFailedException($"VTable of type '{typeName}' not computed by the IL scanner.");

Basically run the repro with https://github.com/dotnet/runtime/tree/119baa90421c92affa88c7d0160a68f73f9687be/src/coreclr/tools/aot/DependencyGraphViewer listening for ETW events and you'll get the two graphs to investigate.

[MichalStrehovsky]

Broken since .NET 8. Reduced repro:

using System;
using System.Runtime.CompilerServices;
using System.Threading;

ComponentDescriptor.Impl<IViewManager, object, int>.TrackerId = 5;

Get().TryInvoke<int, object>();

[MethodImpl(MethodImplOptions.NoInlining)]
static ApiProviderDecoratorBase<IViewManager> Get() => new ResourceViewMappingDecorator();

public class ComponentDescriptor
{
    public class Impl<T, U, V>
    {
        public static int TrackerId;
    }
}

public abstract class ApiProviderDecoratorBase<T>
{
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public virtual TResponse TryInvoke<TRequest, TResponse>()
    {
        Console.WriteLine(ComponentDescriptor.Impl<T, T, TRequest>.TrackerId);
        return default;
    }
}

public sealed class ResourceViewMappingDecorator : ApiProviderDecoratorBase<IViewManager>
{
    public override TResponse TryInvoke<TRequest, TResponse>()
    {
        return base.TryInvoke<TRequest, TResponse>();
    }
}

public interface IViewManager;