ReactiveUI.Fody ToPropertyEx throws Ambiguous match found

[toverux]

Describe the bug

With Fody 6.1.1 and ReactiveUI.Fody 11.4.1, I have no problems. After upgrading to Fody 6.2.0 and ReactiveUI 11.4.17, every ToPropertyEx binding in my viewmodels fail, throwing an "Ambiguous match found" exception:

System.Reflection.AmbiguousMatchException: Ambiguous match found.
  at System.RuntimeType.GetField (System.String name, System.Reflection.BindingFlags bindingAttr) [0x0006c] in <b3870d1cc8a043b9b772bb481ef361c8>:0 
  at System.Reflection.TypeInfo.GetDeclaredField (System.String name) [0x00000] in <b3870d1cc8a043b9b772bb481ef361c8>:0 
  at ReactiveUI.Fody.Helpers.ObservableAsPropertyExtensions.ToPropertyEx[TObj,TRet] (System.IObservable`1[T] item, TObj source, System.Linq.Expressions.Expression`1[TDelegate] property, TRet initialValue, System.Boolean deferSubscription, System.Reactive.Concurrency.IScheduler scheduler) [0x0005c] in d:\a\1\s\src\ReactiveUI.Fody.Helpers\ObservableAsPropertyExtensions.cs:57 
  at Redacted.ViewModels.Heating.RoomHeatingViewModel..ctor (System.String roomId) [0x00444] in /redacted-mobile/ViewModels/Heating/RoomHeatingViewModel.cs:243 
  ...

Steps To Reproduce

The failing property binding here is declared as such:

The view model property:

public extern InferredRoomHeatingState HeatingState { [ObservableAsProperty] get; }

In the view model constructor:

heatingStateObs.ToPropertyEx(this, vm => vm.HeatingState, scheduler: RxApp.MainThreadScheduler);

I couldn't find any issue talking about this which surprised me, so let me know if I can provide more information.

Environment

• OS: Linux Ubuntu 20.04
• Mono version: 6.8.0.123
• Version: 11.4.17
• Device: Android 10

[open-collective-bot[bot]]

Hey @toverux :wave:,

Thank you for opening an issue. We will get back to you as soon as we can. Also, check out our Open Collective and consider contributing financially.

https://opencollective.com/reactiveui

PS.: We offer priority support for all financial contributors. Don't forget to add priority label once you start contributing :smile:

ReactiveUI - Open Collective

An advanced, composable, functional reactive model-view-viewmodel framework for all .NET platforms!

[glennawatson]

Hmm...

Thanks for reporting, will have to play around and see what changed for us in Fody 6.2.0

[EvanMulawski]

I'm seeing this as well, but it is intermittent.

iOS Simulator 13.6

The exception occurs on the first-ever call to ToPropertyEx. Rebuilding the Xamarin iOS project resolves the issue.

  at System.RuntimeType.GetField (System.String name, System.Reflection.BindingFlags bindingAttr) [0x00062] in /Library/Frameworks/Xamarin.iOS.framework/Versions/Current/src/Xamarin.iOS/mcs/class/referencesource/mscorlib/system/rttype.cs:3417 
  at System.Reflection.TypeInfo.GetDeclaredField (System.String name) [0x00000] in /Library/Frameworks/Xamarin.iOS.framework/Versions/Current/src/Xamarin.iOS/external/corefx/src/Common/src/CoreLib/System/Reflection/TypeInfo.cs:19 
  at ReactiveUI.Fody.Helpers.ObservableAsPropertyExtensions.ToPropertyEx[TObj,TRet] (System.IObservable`1[T] item, TObj source, System.Linq.Expressions.Expression`1[TDelegate] property, TRet initialValue, System.Boolean deferSubscription, System.Reactive.Concurrency.IScheduler scheduler) [0x0005c] in d:\a\1\s\src\ReactiveUI.Fody.Helpers\ObservableAsPropertyExtensions.cs:57
...

[toverux]

A few fixes have been published to both ReactiveUI and Fody and my Mono installation got an upgrade too, so I tried upgrading again.
Everything works with the latest releases of those libraries.