Unexpected anonymous class registration on a C# closure

Scans of non-public classes result in registrations of compiler-generated classes on C# closures. E.g.:

internal class Foo
{
    public void Bar(int i)
    {
        async Task Baz()
        {
            i = i;
        }
    }
}

And then:

services.Scan(s => s.FromCallingAssembly().AddClasses(false));

This results in the following unexpected registration:

ServiceType = {Name = “<<Bar>g__Baz|0>d” FullName = “MyApp.Foo+<>c__DisplayClass0_0+<<Bar>g__Baz|0>d”}, ImplementationType = {Name = “<<Bar>g__Baz|0>d” FullName = “MyApp.Foo+<>c__DisplayClass0_0+<<Bar>g__Baz|0>d”}

If I derive Foo from a new (empty) interface IFoo and add .AsImplementedInterfaces() to the Scan call, I get the following unexpected registration instead:

ServiceType = {Name = “IAsyncStateMachine” FullName = “System.Runtime.CompilerServices.IAsyncStateMachine”}, ImplementationType = {Name = “<<Bar>g__Baz|0>d” FullName = “MyApp.Foo+<>c__DisplayClass0_0+<<Bar>g__Baz|0>d”}

[khellang]

Ah, I see what’s going on. Roslyn’s generating a private nested state machine class inside the display class. Only the outer class has CompilerGeneratedAttribute on it.

I’m not really sure what the best way to solve this would be.

1. Check outer classes for CompilerGeneratedAttribute if the type is nested
2. Filter out types implementing IAsyncStateMachine
3. Filter out nested private types

Or maybe a combination of them? 🤔

[khellang]

Pushed a new version to NuGet that should hopefully address this. Let me know if it doesn’t 😅