NativeAOT crash with ConcurrentBag and interfaces

[vaind]

Description

A NativeAOT app crashes on converting a ConcurrentBag to a ReadOnlyCollection and then to array, when interfaces are involved in generic types.

Reproduction Steps

1. dotnet new ios
2. Update .csproj to include <PublishAot>true</PublishAot>
3. Add the following code to FinishedLaunching(), e.g. just before the return true:

   var bag = new System.Collections.Concurrent.ConcurrentBag<MyClass>();
   IReadOnlyCollection<IMyInterface> collection = bag;
   var array = collection.ToArray();

   And define these types, e.g. at the end of the same file:

   public class MyClass : IMyInterface {}
   public interface IMyInterface {}

4. Run the published app on an iPhone:

   dotnet publish -c Release -f net8.0-ios
   ios-deploy -b bin/Release/net8.0-ios/ios-arm64/publish/*.ipa
   

Expected behavior

Don't crash

Actual behavior

App crashes after startup

Regression?

It works fine without NativeAOT.

Known Workarounds

none

Configuration

• .NET 8.0.100
• iPhone X v14.5

Other information

No response

[ghost]

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

Issue Details

---

Description

A NativeAOT app crashes on converting a ConcurrentBag to a ReadOnlyCollection and then to array, when interfaces are involved in generic types.

Reproduction Steps

1. dotnet new ios
2. Update .csproj to include <PublishAot>true</PublishAot>
3. Add the following code to FinishedLaunching(), e.g. just before the return true:

var bag = new System.Collections.Concurrent.ConcurrentBag();
IReadOnlyCollection collection = bag;
var array = collection.ToArray();
And define these types, e.g. at the end of the same file:c#
public class MyClass : IMyInterface {}
public interface IMyInterface {}

4. Run the published app on an iPhone: dotnet publish -c Release -f net8.0-ios ; ios-deploy -b bin/Release/net8.0-ios/ios-arm64/publish/*.ipa

### Expected behavior

Don't crash

### Actual behavior

App crashes after startup

### Regression?

It works fine without NativeAOT.

### Known Workarounds

none

### Configuration

* .NET 8.0.100
* iPhone X v14.5

### Other information

_No response_

<table>
<tr>
 <th align="left">Author:</th>
 <td>vaind</td>
</tr>
<tr>
 <th align="left">Assignees:</th>
 <td>-</td>
</tr>
<tr>
 <th align="left">Labels:</th>
 <td>

`area-NativeAOT-coreclr`

</td>
</tr>
<tr>
 <th align="left">Milestone:</th>
 <td>-</td>
</tr>
</table>
</details>

[vitek-karas]

This reproes on Windows as well - same as above.
It's a "Fail fast" at this callstack:

 	KernelBase.dll!00007ff8f26bc3b2()	Unknown
 	95574.exe!S_P_CoreLib_System_Runtime_CachedInterfaceDispatch__RhpCidResolve_Worker() Line 48	Unknown
 	95574.exe!S_P_CoreLib_System_Runtime_CachedInterfaceDispatch__RhpCidResolve() Line 22	Unknown
 	95574.exe!RhpUniversalTransition_DebugStepTailCall() Line 163	Unknown
 	95574.exe!System_Linq_System_Collections_Generic_LargeArrayBuilder_1<System___Canon>__AddRange() Line 104	Unknown
 	95574.exe!System_Linq_System_Collections_Generic_EnumerableHelpers__ToArray_0<System___Canon>() Line 85	Unknown
>	95574.exe!_95574_Program___Main__() Line 6	Unknown
 	95574.exe!_95574__Module___StartupCodeMain()	Unknown
 	95574.exe!wmain(int argc, wchar_t * * argv) Line 224	C++

The fail fast is here:

runtime/src/coreclr/nativeaot/Runtime.Base/src/System/Runtime/CachedInterfaceDispatch.cs

Line 47 in b69f79c

EH.FallbackFailFast(RhFailFastReason.InternalError, null);

[am11]

Workaround is to add something to the bag:

var bag = new System.Collections.Concurrent.ConcurrentBag<MyClass>();
+ bag.Add(new()); // empty bag will hit the bug https://github.com/dotnet/runtime/issues/95574
IReadOnlyCollection<IMyInterface> collection = bag;
var array = collection.ToArray();

[vaind]

Thanks for trying @am11 but that is not an acceptable workaround because it's a functional change. But I guess it helps to devise one - checking for an empty bag before doing the conversion.

[am11]

@vaind, it is definitely a bug (and labeled as such). My comment was mostly from testing perspective that having a non-null item in the bag does not trigger this bug; so the bag has to be empty or with null items. The tests that will go with the fix need to take this into consideration. :)

[ghost]

Tagging subscribers to 'os-ios': @steveisok, @akoeplinger, @kotlarmilos
See info in area-owners.md if you want to be subscribed.

Issue Details

---

Description

A NativeAOT app crashes on converting a ConcurrentBag to a ReadOnlyCollection and then to array, when interfaces are involved in generic types.

Reproduction Steps

1. dotnet new ios
2. Update .csproj to include <PublishAot>true</PublishAot>
3. Add the following code to FinishedLaunching(), e.g. just before the return true:

   var bag = new System.Collections.Concurrent.ConcurrentBag<MyClass>();
   IReadOnlyCollection<IMyInterface> collection = bag;
   var array = collection.ToArray();

   And define these types, e.g. at the end of the same file:

   public class MyClass : IMyInterface {}
   public interface IMyInterface {}

4. Run the published app on an iPhone:

   dotnet publish -c Release -f net8.0-ios
   ios-deploy -b bin/Release/net8.0-ios/ios-arm64/publish/*.ipa
   

Expected behavior

Don't crash

Actual behavior

App crashes after startup

Regression?

It works fine without NativeAOT.

Known Workarounds

none

Configuration

• .NET 8.0.100
• iPhone X v14.5

Other information

No response

Author:	vaind
Assignees:	-
Labels:	bug, untriaged, os-ios, area-NativeAOT-coreclr
Milestone:	-

[lambdageek]

/cc FYI @ivanpovazan

Update removing ios label since it repros on Windows, too

[MichalStrehovsky]

Nice bug! It has been in the product for a while, probably years (we shipped with this in .NET 7 but nobody hit/reported this).

The necessary condition to hit this is to not have MyClass allocated anywhere in the program. What happens is that MyClass had its interface list optimized away and ConcurrentBag<MyClass> no longer casts to IEnumerable<IMyInterface> at runtime.