Driver.compileOfAst fails on Xamarin.Mac due to reference to .NET Core

[praeclarum]

I am trying to port my .NET IDE Continuous to macOS. Unfortunately, the latest F# compiler service is failing due to a type load exception with Microsoft.DotNet.DependencyManager.

It is importing the .NET Standard 2.0 version of "lib/netstandard2.0/FSharp.Compiler.Service.dll"

Ironically, this same package works fine on Xamarin.iOS with AOT.

My guess is this is a bug in the DependencyManager, but I would love to know if I can use the F# compiler without it. I swear I had this working on older versions. Is the DependencyManager new?

System.TypeLoadException: Could not load type of field 'Microsoft.DotNet.DependencyManager.AssemblyResolveHandlerCoreclr:handler' (1) due to: Could not resolve type with token 01000013 from typeref (expected class 'System.Runtime.Loader.AssemblyLoadContext' in assembly 'System.Runtime.Loader, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a') assembly:System.Runtime.Loader, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a type:System.Runtime.Loader.AssemblyLoadContext member:(null)
  at Microsoft.DotNet.DependencyManager.DependencyProvider..ctor (Microsoft.DotNet.DependencyManager.AssemblyResolutionProbe assemblyProbingPaths, Microsoft.DotNet.DependencyManager.NativeResolutionProbe nativeProbingRoots) [0x00014] in /Users/chethusk/oss/FCS/src/fsharp/Microsoft.DotNet.DependencyManager/DependencyProvider.fs:266 
  at Microsoft.DotNet.DependencyManager.DependencyProvider..ctor (Microsoft.DotNet.DependencyManager.NativeResolutionProbe nativeProbingRoots) [0x00000] in /Users/chethusk/oss/FCS/src/fsharp/Microsoft.DotNet.DependencyManager/DependencyProvider.fs:325 
  at FSharp.Compiler.CompileOps+TcConfigBuilder.CreateNew (FSharp.Compiler.ReferenceResolver+Resolver legacyReferenceResolver, System.String defaultFSharpBinariesDir, FSharp.Compiler.AbstractIL.ILBinaryReader+ReduceMemoryFlag reduceMemoryUsage, System.String implicitIncludeDir, System.Boolean isInteractive, System.Boolean isInvalidationSupported, FSharp.Compiler.CompileOps+CopyFSharpCoreFlag defaultCopyFSharpCore, Microsoft.FSharp.Core.FSharpFunc`2[T,TResult] tryGetMetadataSnapshot) [0x002ce] in /Users/chethusk/oss/FCS/src/fsharp/CompileOps.fs:2489 
  at FSharp.Compiler.Driver.main1OfAst[a,b,c,d] (a ctok, FSharp.Compiler.ReferenceResolver+Resolver legacyReferenceResolver, FSharp.Compiler.AbstractIL.ILBinaryReader+ReduceMemoryFlag reduceMemoryUsage, System.String assemblyName, FSharp.Compiler.CompileOps+CompilerTarget target, b outfile, Microsoft.FSharp.Core.FSharpOption`1[T] pdbFile, Microsoft.FSharp.Collections.FSharpList`1[T] dllReferences, System.Boolean noframework, d exiter, FSharp.Compiler.Driver+ErrorLoggerProvider errorLoggerProvider, Microsoft.FSharp.Collections.FSharpList`1[T] inputs) [0x00000] in /Users/chethusk/oss/FCS/src/fsharp/fsc.fs:1954 
...

Repro steps

Provide the steps required to reproduce the problem:

1. Crate a Xamarin.Mac application
2. Reference FCS 37
3. Use the Compile API

Expected behavior

Compile proceeds

Actual behavior

FSharp.Compiler.Driver.main1OfAst fails because Microsoft.DotNet.DependencyManager has a hard reference to a .NET Core assembly (I'm using .NET Standard).

System.TypeLoadException: Could not load type of field 'Microsoft.DotNet.DependencyManager.AssemblyResolveHandlerCoreclr:handler' (1) due to: Could not resolve type with token 01000013 from typeref (expected class 'System.Runtime.Loader.AssemblyLoadContext' in assembly 'System.Runtime.Loader, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a') assembly:System.Runtime.Loader, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a type:System.Runtime.Loader.AssemblyLoadContext member:(null)
  at Microsoft.DotNet.DependencyManager.DependencyProvider..ctor (Microsoft.DotNet.DependencyManager.AssemblyResolutionProbe assemblyProbingPaths, Microsoft.DotNet.DependencyManager.NativeResolutionProbe nativeProbingRoots) [0x00014] in /Users/chethusk/oss/FCS/src/fsharp/Microsoft.DotNet.DependencyManager/DependencyProvider.fs:266 
  at Microsoft.DotNet.DependencyManager.DependencyProvider..ctor (Microsoft.DotNet.DependencyManager.NativeResolutionProbe nativeProbingRoots) [0x00000] in /Users/chethusk/oss/FCS/src/fsharp/Microsoft.DotNet.DependencyManager/DependencyProvider.fs:325 
  at FSharp.Compiler.CompileOps+TcConfigBuilder.CreateNew (FSharp.Compiler.ReferenceResolver+Resolver legacyReferenceResolver, System.String defaultFSharpBinariesDir, FSharp.Compiler.AbstractIL.ILBinaryReader+ReduceMemoryFlag reduceMemoryUsage, System.String implicitIncludeDir, System.Boolean isInteractive, System.Boolean isInvalidationSupported, FSharp.Compiler.CompileOps+CopyFSharpCoreFlag defaultCopyFSharpCore, Microsoft.FSharp.Core.FSharpFunc`2[T,TResult] tryGetMetadataSnapshot) [0x002ce] in /Users/chethusk/oss/FCS/src/fsharp/CompileOps.fs:2489 
  at FSharp.Compiler.Driver.main1OfAst[a,b,c,d] (a ctok, FSharp.Compiler.ReferenceResolver+Resolver legacyReferenceResolver, FSharp.Compiler.AbstractIL.ILBinaryReader+ReduceMemoryFlag reduceMemoryUsage, System.String assemblyName, FSharp.Compiler.CompileOps+CompilerTarget target, b outfile, Microsoft.FSharp.Core.FSharpOption`1[T] pdbFile, Microsoft.FSharp.Collections.FSharpList`1[T] dllReferences, System.Boolean noframework, d exiter, FSharp.Compiler.Driver+ErrorLoggerProvider errorLoggerProvider, Microsoft.FSharp.Collections.FSharpList`1[T] inputs) [0x00000] in /Users/chethusk/oss/FCS/src/fsharp/fsc.fs:1954 
  at FSharp.Compiler.Driver.compileOfAst (FSharp.Compiler.AbstractIL.Internal.Library+CompilationThreadToken ctok, FSharp.Compiler.ReferenceResolver+Resolver legacyReferenceResolver, FSharp.Compiler.AbstractIL.ILBinaryReader+ReduceMemoryFlag reduceMemoryUsage, System.String assemblyName, FSharp.Compiler.CompileOps+CompilerTarget target, System.String targetDll, Microsoft.FSharp.Core.FSharpOption`1[T] targetPdb, Microsoft.FSharp.Collections.FSharpList`1[T] dependencies, System.Boolean noframework, FSharp.Compiler.ErrorLogger+Exiter exiter, FSharp.Compiler.Driver+ErrorLoggerProvider loggerProvider, Microsoft.FSharp.Collections.FSharpList`1[T] inputs, Microsoft.FSharp.Core.FSharpOption`1[T] tcImportsCapture, Microsoft.FSharp.Core.FSharpOption`1[T] dynamicAssemblyCreator) [0x00000] in /Users/chethusk/oss/FCS/src/fsharp/fsc.fs:2222 
  at FSharp.Compiler.SourceCodeServices.CompileHelpers+result@181-11.Invoke (FSharp.Compiler.ErrorLogger+Exiter exiter) [0x00000] in /Users/chethusk/oss/FCS/src/fsharp/service/service.fs:182 
  at FSharp.Compiler.SourceCodeServices.CompileHelpers.tryCompile (FSharp.Compiler.ErrorLogger+ErrorLogger errorLogger, Microsoft.FSharp.Core.FSharpFunc`2[T,TResult] f) [0x0001f] in /Users/chethusk/oss/FCS/src/fsharp/service/service.fs:157 
  at FSharp.Compiler.ErrorLogger+ErrorLoggerExtensions.ReraiseIfWatsonable (System.Exception exn) [0x0003f] in /Users/chethusk/oss/FCS/src/fsharp/ErrorLogger.fs:369 
  at FSharp.Compiler.ErrorLogger+ErrorLoggerExtensions.ErrorLogger.ErrorRecovery (FSharp.Compiler.ErrorLogger+ErrorLogger x, System.Exception exn, FSharp.Compiler.Range+range m) [0x000d8] in /Users/chethusk/oss/FCS/src/fsharp/ErrorLogger.fs:417 
  at FSharp.Compiler.ErrorLogger+ErrorLoggerExtensions.ErrorLogger.StopProcessingRecovery (FSharp.Compiler.ErrorLogger+ErrorLogger x, System.Exception exn, FSharp.Compiler.Range+range m) [0x000b4] in /Users/chethusk/oss/FCS/src/fsharp/ErrorLogger.fs:430 
  at FSharp.Compiler.SourceCodeServices.CompileHelpers.tryCompile (FSharp.Compiler.ErrorLogger+ErrorLogger errorLogger, Microsoft.FSharp.Core.FSharpFunc`2[T,TResult] f) [0x00034] in /Users/chethusk/oss/FCS/src/fsharp/service/service.fs:160 
  at FSharp.Compiler.SourceCodeServices.CompileHelpers.compileFromAsts (FSharp.Compiler.AbstractIL.Internal.Library+CompilationThreadToken ctok, FSharp.Compiler.ReferenceResolver+Resolver legacyReferenceResolver, Microsoft.FSharp.Collections.FSharpList`1[T] asts, System.String assemblyName, System.String outFile, Microsoft.FSharp.Collections.FSharpList`1[T] dependencies, System.Boolean noframework, Microsoft.FSharp.Core.FSharpOption`1[T] pdbFile, Microsoft.FSharp.Core.FSharpOption`1[T] executable, Microsoft.FSharp.Core.FSharpOption`1[T] tcImportsCapture, Microsoft.FSharp.Core.FSharpOption`1[T] dynamicAssemblyCreator) [0x00039] in /Users/chethusk/oss/FCS/src/fsharp/service/service.fs:180 
  at <StartupCode$FSharp-Compiler-Service>.$Service+Compile@1059-3.Invoke (Microsoft.FSharp.Core.Unit unitVar) [0x0000d] in /Users/chethusk/oss/FCS/src/fsharp/service/service.fs:1060 
  at FSharp.Compiler.AbstractIL.Internal.Library+CancellableModule+delay@741[T].Invoke (System.Threading.CancellationToken ct) [0x00000] in /Users/chethusk/oss/FCS/src/absil/illib.fs:741 
  at <StartupCode$FSharp-Compiler-Service>.$Reactor+EnqueueAndAwaitOpAsync@185-2[T].Invoke (FSharp.Compiler.AbstractIL.Internal.Library+CompilationThreadToken ctok) [0x00007] in /Users/chethusk/oss/FCS/src/fsharp/service/Reactor.fs:188 

Known workarounds

No know workarounds. :-( I would love to hear some options.

Related information

• Operating system: macOS 10.15.6
• .NET Runtime kind: Mono with Xamarin.Mac
• Editing Tools: VS for Mac

[baronfel]

Oof, that's a rough one. The provider itself I believe is a required component now, but individual implementations of dependency providers (ie #r "nuget:") are optional. If the core component is crashing then we have a pretty serious problem.

If possible, can you test your app with the latest FCS dependency from the MS nightly feeds? FCS is published there on a nightly cadence now and it should quickly let us know if that's still a problem. The nuget feed source url is https://pkgs.dev.azure.com/dnceng/public/_packaging/dotnet-tools/nuget/v3/index.json and it should have FCS 38 prereleases in it.

If the problem is still there that tells us we need to report upstream to dotnet/fsharp and fix it at the source.

[praeclarum]

OK I'll give 38 a whirl.

Did you say I can swap that component out? Would love to hear more if that's true.

I'm a bit afraid of what the default implementation of #r is going to do on iOS. :-)

[baronfel]

You can swap out #r handler implementations (or have none at all if you don't include any dlls that implement them), but from what I see in your stacktrace the problem is that the component that discovers/manages those implementations is blowing up.

The overall mechanism is just a hook for providing #load and #I statements, really :D