.NET 4.6.1/.NET Standard 2.0 build with SGen fails

[emmanuelguerin]

The context is a .NET Standard 2.0 targeted library Lib. It is referenced by a .NET Framework 4.6.1 targeted library LibNetFramework.
(see GitHub repository: https://github.com/emmanuelguerin/issue-sgen)

In LibNetFramework, serialization assemblies generation is forced by the use of the GenerateSerializationAssemblies property set to On. Typically, this would happen when adding a WebReference to the project.

The compilation fails with the message

SGEN : error : An attempt was made to load an assembly with an incorrect format: C:\Program Files (x86)\Microsoft Visual Studio\2017\Community\MSBuild\Microsoft\Microsoft.NET.Build.Extensions\net461\ref\netfx.force.conflicts.dll.

The issue might have been corrected by the use of the patch in #1582, that is put ine the LibNetFrameworkPatched project in the GitHub repo.

But this breaks the build, as the netstandard.dll reference is no longer added to the compilation:

LibNetFrameworkPatched\Class1.cs(9,30,9,34): error CS0012: The type 'Object' is defined in an assembly that is not referenced. You must add a reference to assembly 'netstandard, Version=2.0.0.0, Culture=neutral, PublicKeyToken=cc7b13ffcd2ddd51'.

You can find an appveyor build failing on the VS2017, and VS2017 preview:
https://ci.appveyor.com/project/emmanuelguerin/issue-sgen/build/1.0.6

[emmanuelguerin]

One thing that allowed me to go on, was to patch quite violently the GenerateSerializationAssemblies target with the following.

This removed the ref DLLs from the list of DLLs passed to the SGen task.

  <Target
    Name="GenerateSerializationAssemblies"
    Condition="'$(_SGenGenerateSerializationAssembliesConfig)' == 'On' or ('@(WebReferenceUrl)'!='' and '$(_SGenGenerateSerializationAssembliesConfig)' == 'Auto')"
    DependsOnTargets="AssignTargetPaths;Compile;ResolveKeySource"
    Inputs="$(MSBuildAllProjects);@(IntermediateAssembly)"
    Outputs="$(IntermediateOutputPath)$(_SGenDllName)">

    <PropertyGroup>
      <SGenMSBuildArchitecture Condition="'$(SGenMSBuildArchitecture)' == ''">$(PlatformTargetAsMSBuildArchitecture)</SGenMSBuildArchitecture>
    </PropertyGroup>

    <PropertyGroup>
      <SGenRefDirectory>$([System.IO.Path]::GetDirectoryName('$(MicrosoftNETBuildExtensionsTargets.Substring(3))'))\net461\ref\</SGenRefDirectory>
    </PropertyGroup>
    <ItemGroup>
      <SGenReference Include="@(ReferencePath)" Condition="'%(Directory)' != '$(SGenRefDirectory)'" />
    </ItemGroup>

    <SGen
      BuildAssemblyName="$(TargetFileName)"
      BuildAssemblyPath="$(IntermediateOutputPath)"
      References="@(SGenReference)"
      ShouldGenerateSerializer="$(SGenShouldGenerateSerializer)"
      UseProxyTypes="$(SGenUseProxyTypes)"
      UseKeep="$(SGenUseKeep)"
      KeyContainer="$(KeyContainerName)"
      KeyFile="$(KeyOriginatorFile)"
      DelaySign="$(DelaySign)"
      ToolPath="$(SGenToolPath)"
      SdkToolsPath="$(TargetFrameworkSDKToolsDirectory)"
      EnvironmentVariables="$(SGenEnvironment)"
      MSBuildArchitecture="$(SGenMSBuildArchitecture)"
      SerializationAssembly="$(IntermediateOutputPath)$(_SGenDllName)"
      Platform="$(SGenPlatformTarget)"
      Types="$(SGenSerializationTypes)">

      <Output TaskParameter="SerializationAssembly" ItemName="SerializationAssembly"/>

    </SGen>

  </Target>

[jnm2]

My company just ran into this. I'm not quite brave enough to use the workaround yet.

We don't run into this so long as we don't add a package reference to SourceLink.Embed.AllSourceFiles.

[emmanuelguerin]

I'll have to have a look again at this. The workaround is simple enough to implement: copy paste the target in the .csproj after the Import of the targets ().
https://github.com/emmanuelguerin/issue-sgen/blob/master/LibNetFrameworkPatched/LibNetFrameworkPatched.csproj

[jnm2]

I'm just afraid to entirely replace the target. I just found a workaround for my particular case which I'll post here.

[mouadhtrabelsi]

do your patch work for .NET Framework 4.7.1 ?
i added
<Target Name="ImplicitlyExpandNETStandardFacades" ..>
..
to my csproj , but did not fix the problem,

I get this error
error : An attempt was made to load an assembly with an incorrect format: C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework.NETFramework\v4.7.1\Facades\System.IO.Compression.ZipFile.dll.

But i m not referincing this DLL in my project !

any help please ?

[livarcocc]

@joperezr can you take a look and comment?

[joperezr]

@mouadhtrabelsi that reference is automatically added in order to ensure compatibility between your .Net Framework component and your .Net standard one. Do you mind sharing a repro and also the version of VS that you are using so that I can provide a workaround?

[DanTup]

@joperezr There are some simple repro steps at dotnet/msbuild#2707

[tomek14]

I have the same problem as @mouadhtrabelsi, in my WebForms App targeting 4.7.1 when building Relase.

[mouadhtrabelsi]

I I got this error only in project having web service refrences
@tomek14 to fix it i disabled GenerateSerializationAssemblies
on teh csproj i added this line for all the build config
<GenerateSerializationAssemblies>Off</GenerateSerializationAssemblies>

<PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|AnyCPU' ">
  <DebugSymbols>true</DebugSymbols>
  <DebugType>full</DebugType>
  <Optimize>false</Optimize>
  <OutputPath>bin\Debug\</OutputPath>
  <DefineConstants>DEBUG;TRACE</DefineConstants>
  <ErrorReport>prompt</ErrorReport>
  <WarningLevel>4</WarningLevel>
  <GenerateSerializationAssemblies>Off</GenerateSerializationAssemblies>
</PropertyGroup>

[tomek14]

@mouadhtrabelsi It worked! Thanks a lot!

[scottsauber]

I am getting this on a regular ASP.NET project when I upgraded to .NET 4.7.1 and it has references to .NET Standard 2.0 libs. Is there any official guidance on how this is going to get addressed?

I'm on the latest VS - 15.5.6

[joperezr]

I believe we do know now what is happening here. In order for SGen to work correctly on 4.7.1, it will require one of two possible solutions:

• Add binding redirects to it's config file. (This is the least invasive to your project, but it does mean modifying things inside VisualStudio installation, which might break things once you upgrade to the next version of .NET, so I would advise option 2)
• Add a couple of targets to your .csproj file to make sure we don't include the design time facades when generating the serialization assemblies. In order to go with this option, simply add the following code right before the </Project> tag.

  <Target Name="RemoveDesignTimeFacadesBeforeSGen" BeforeTargets="GenerateSerializationAssemblies">
    <ItemGroup>
      <ReferencePath Remove="@(_DesignTimeFacadeAssemblies_Names->'%(OriginalIdentity)')" />
    </ItemGroup>
    <Message Importance="normal" Text="Removing DesignTimeFacades from ReferencePath before running SGen." />
  </Target>
 
  <Target Name="ReAddDesignTimeFacadesBeforeSGen" AfterTargets="GenerateSerializationAssemblies">
    <ItemGroup>
      <ReferencePath Include="@(_DesignTimeFacadeAssemblies_Names->'%(OriginalIdentity)')" />
    </ItemGroup>
    <Message Importance="normal" Text="Adding back DesignTimeFacades from ReferencePath now that SGen has run." />
  </Target>