System.Runtime.CompilerServices.Unsafe linked away in release leading to crashes

[ddobrev]

This is most probably related to dotnet/efcore#8922 . None of the workarounds there help. The major problem is that it's simply impossible to force the linker to preserve an entire assembly.

Steps to Reproduce

1. Use a library, such as Microsoft.Extensions.Identity.Stores, which (indirectly) depends on System.Runtime.CompilerServices.Unsafe, in a Xamarin.Android project;
2. Build the project in Release - ensure linking is not set to "None";
3. Run it on a device.

Expected Behavior

The application runs.

Actual Behavior

The application does not load at all with:
Could not load assembly 'System.Runtime.CompilerServices.Unsafe' during startup registration.

Version Information

Microsoft Visual Studio Community 2017
Version 15.5.3
VisualStudio.15.Release/15.5.3+27130.2020
Microsoft .NET Framework
Version 4.7.02558

Installed Version: Community

Visual Basic 2017 00369-60000-00001-AA416
Microsoft Visual Basic 2017

Visual C# 2017 00369-60000-00001-AA416
Microsoft Visual C# 2017

Visual C++ 2017 00369-60000-00001-AA416
Microsoft Visual C++ 2017

Visual F# 4.1 00369-60000-00001-AA416
Microsoft Visual F# 4.1

Application Insights Tools for Visual Studio Package 8.10.01106.1
Application Insights Tools for Visual Studio

ASP.NET and Web Tools 2017 15.0.31127.0
ASP.NET and Web Tools 2017

ASP.NET Core Razor Language Services 1.0
Provides languages services for ASP.NET Core Razor.

ASP.NET Web Frameworks and Tools 2017 5.2.51007.0
For additional information, visit https://www.asp.net/

Azure App Service Tools v3.0.0 15.0.31106.0
Azure App Service Tools v3.0.0

Common Azure Tools 1.10
Provides common services for use by Azure Mobile Services and Microsoft Azure Tools.

EZ-GIT 1.7.2

GradleBindings.VisualStudio 1.0
Creates Xamarin Android Binding projects from a gradle file.

JavaScript Language Service 2.0
JavaScript Language Service

Merq 1.1.17-rc (cba4571)
Command Bus, Event Stream and Async Manager for Visual Studio extensions.

Microsoft Azure Tools 2.9
Microsoft Azure Tools for Microsoft Visual Studio 2017 - v2.9.51120.3

Microsoft Continuous Delivery Tools for Visual Studio 0.3
Simplifying the configuration of continuous build integration and continuous build delivery from within the Visual Studio IDE.

Microsoft JVM Debugger 1.0
Provides support for connecting the Visual Studio debugger to JDWP compatible Java Virtual Machines

Microsoft MI-Based Debugger 1.0
Provides support for connecting Visual Studio to MI compatible debuggers

Microsoft Visual C++ Wizards 1.0
Microsoft Visual C++ Wizards

Microsoft Visual Studio Tools for Containers 1.1
Develop, run, validate your ASP.NET Core applications in the target environment. F5 your application directly into a container with debugging, or CTRL + F5 to edit & refresh your app without having to rebuild the container.

Microsoft Visual Studio VC Package 1.0
Microsoft Visual Studio VC Package

Mono Debugging for Visual Studio 4.8.4-pre (3fe64e3)
Support for debugging Mono processes with Visual Studio.

NpgsqlVSPackage Extension 1.0
NpgsqlVSPackage Visual Studio Extension Detailed Info

NuGet Package Manager 4.5.0
NuGet Package Manager in Visual Studio. For more information about NuGet, visit http://docs.nuget.org/.

Qt Visual Studio Tools 2.1.2
The Qt Visual Studio Tools allow developers to use the standard development environment without having to worry about any Qt-related build steps or tools.

SQL Server Data Tools 15.1.61710.120
Microsoft SQL Server Data Tools

Visual Studio Code Debug Adapter Host Package 1.0
Interop layer for hosting Visual Studio Code debug adapters in Visual Studio

Visual Studio Tools for CMake 1.0
Visual Studio Tools for CMake

VisualStudio.Mac 1.0
Mac Extension for Visual Studio

Xamarin 4.8.0.757 (7f9ec2a)
Visual Studio extension to enable development for Xamarin.iOS and Xamarin.Android.

Xamarin Designer 4.8.188 (c5813fa34)
Visual Studio extension to enable Xamarin Designer tools in Visual Studio.

Xamarin.Android SDK 8.1.3.0 (HEAD/ef47226b7)
Xamarin.Android Reference Assemblies and MSBuild support.

Xamarin.iOS and Xamarin.Mac SDK 11.6.1.2 (6857dfc)
Xamarin.iOS and Xamarin.Mac Reference Assemblies and MSBuild support.

[jonpryor]

it's simply impossible to force the linker to preserve an entire assembly

It should be possible to preserve an entire assembly, either via the $(AndroidLinkSkip) MSBuild property or via the @(LinkDescription) Build action and a linker configuration file.

[ddobrev]

Either does not work. I think the problem might have to do with System.Runtime.CompilerServices.Unsafe being considered a "reference-only" assembly.

[radekdoulik]

Not sure what "reference-only" assembly mean here. Could you please attach a project which reproduces the issue?

Are you sure the AndroidLinkSkip is indeed set? Do you have diagnostic build output?

[jonpryor]

@radekdoulik: "Reference only assembly" means Issue #1154. It is an assembly with the System.Runtime.CompilerServices.ReferenceAssemblyAttribute assembly-level custom attribute.

Mono will not load reference assemblies.

[ddobrev]

UnsafeLinkerBug.zip

[ddobrev]

In case it doesn't work, try a Xamarin.Forms application in which the .NET Standard has the reference to Stores.

[radekdoulik]

Wasn't able to reproduce it with XA 8.1.1.1. I will try 8.1.5 next.

BTW, I don't see AndroidLinkSkip property set in the project file.

[ddobrev]

@radekdoulik try "AndroidLinkSkip" yourself, I have little intention of reapplying once more all the workarounds which failed to work. Also, see the issue I have linked at the beginning.

[radekdoulik]

Works OK for me in XA 8.1.5 as well.

[ddobrev]

Try Xamarin.Forms.

[radekdoulik]

OK, I have got a link to a simple app from @JonDouglas which reproduces the issue - https://github.com/aspnet/EntityFrameworkCore/files/1372571/Desktop.zip (App2). Looks like it is indeed related to #1154

[JonDouglas]

A simple reproduction is the following:

1. Create a File->New Xamarin.Android Project
2. Include Microsoft.EntityFrameworkCore.Sqlite as a <PackageReference> from NuGet.

Here are some relevant logs similar to those in #1154

2>BuildApk Task
2>  ApkInputPath: obj\Debug\android\bin\packaged_resources
    ...
2>    obj\Debug\android\assets\System.Runtime.CompilerServices.Unsafe.dll

2>BuildApk Task
    ...
2>Task Parameter:
2>    EmbeddedNativeLibraryAssemblies=
   ...
2>                Version=
2>        C:\Users\dougl\.nuget\packages\system.runtime.compilerservices.unsafe\4.4.0\ref
2>etstandard2.0\System.Runtime.CompilerServices.Unsafe.dll
2>                CopyLocal=false
2>                FusionName=System.Runtime.CompilerServices.Unsafe, Version=4.0.3.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a
2>                ImageRuntime=v4.0.30319
2>                NuGetIsFrameworkReference=false
2>                NuGetPackageId=System.Runtime.CompilerServices.Unsafe
2>                NuGetPackageVersion=4.4.0
2>                NuGetSourceType=Package
2>                OriginalItemSpec=C:\Users\dougl\.nuget\packages\system.runtime.compilerservices.unsafe\4.4.0\ref
2>etstandard2.0\System.Runtime.CompilerServices.Unsafe.dll
2>                Private=false
2>                ReferenceAssembly=C:\Users\dougl\.nuget\packages\system.runtime.compilerservices.unsafe\4.4.0\ref
2>etstandard2.0\System.Runtime.CompilerServices.Unsafe.dll
2>                ReferenceSourceTarget=ResolveAssemblyReference
2>                ResolvedFrom={RawFileName}

1>Task "LinkAssemblies" (TaskId:327)
1>  Task Parameter:UseSharedRuntime=True (TaskId:327)
1>  Task Parameter:MainAssembly=obj\Debug\android\assets\EntityFrameworkFailure.dll (TaskId:327)
1>  Task Parameter:OutputDirectory=obj\Debug\linkdst\ (TaskId:327)
1>  Task Parameter:OptionalDestinationDirectory=obj\Debug\android\assets\ (TaskId:327)
1>  Task Parameter:LinkMode=None (TaskId:327)
1>  Task Parameter:LinkOnlyNewerThan=obj\Debug\link.flag (TaskId:327)
1>  Task Parameter:
1>      ResolvedAssemblies=
    ...
1>          C:\Users\dougl\.nuget\packages\system.runtime.compilerservices.unsafe\4.4.0\ref\netstandard2.0\System.Runtime.CompilerServices.Unsafe.dll

[ddobrev]

@radekdoulik until the fix is released, is there a reliable workaround?

[dazinator]

I have just hit this after converting my csproj from using packages.config to using packagereference. Prior to that my app was working but I had to use linker mode "SdkOnly". Now after converting to package reference, system.runtime.compilerservices.unsafe gets linked away.