Reference metadata is not preserved by ImplicitlyExpandNETStandardFacades

For a project targeting .Net Framework 4.7.1 with a reference to netstandard libraries, the target ImplicitlyExpandNETStandardFacades replaces certain references with their Facades so netstandard based assemblies work as expected. This currently works great if the project does not associate metadata(like aliases) with any of these references, but when it does - those aren’t honored breaking build.

Filing this issue to ensure that the missing metadata is preserved when the replacement is done.

Adding few more details, here is the reference in question:

<ReferenceInclude="System.Net.Http">
     <HintPath>E:\SomeRandomProjectPath\bin\debug\System.Net.Http.dll</HintPath>
     <Aliases>snh</Aliases>
     <EmbedInteropTypes>False</EmbedInteropTypes>
   </Reference>

and here is what is passed on to csc:

E:\Program Files (x86)\Microsoft Visual Studio\15.7Prev\Enterprise\MSBuild\15.0\bin\Roslyn\csc.exe /noconfig /unsafe+ /nowarn:1587,1591,1701,1702 /nostdlib+ /errorreport:prompt /warn:4 /define:DEBUG;TRACE /highentropyva+  /reference:"E:\Program Files (x86)\Microsoft Visual Studio\15.7Prev\Enterprise\MSBuild\Microsoft\Microsoft.NET.Build.Extensions\net471\lib\System.Net.Http.dll ...."

Notice the missing alias to System.Net.http.

[dsplaisted]

For reference, the workaround posted for the Fakes issue is to put the following in Directory.Build.targets:

<Project xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
  
  <Target Name="PrivateFakesAfterFacadesSwitch"
            Condition="'$(ImplicitlyExpandNETStandardFacades)' == 'true' and $(AssemblyName.EndsWith('.Fakes'))"
            AfterTargets="ImplicitlyExpandNETStandardFacades" DependsOnTargets="ImplicitlyExpandNETStandardFacades">

    <ItemGroup Condition="'@(_NETStandardLibraryNETFrameworkLib)' != ''">
      <SnhReference Include = "@(_NETStandardLibraryNETFrameworkLib)" Condition="'%(_NETStandardLibraryNETFrameworkLib.FileName)' == 'System.Net.Http'" />
      
      <Reference Remove="%(SnhReference.FileName)" Condition="'@(SnhReference)' != ''"/>
      <Reference Include="%(SnhReference.FileName)" Condition="'@(SnhReference)' != ''">
        <HintPath>%(SnhReference.Identity)</HintPath>
        <Private>false</Private>
        <Aliases>snh</Aliases>
      </Reference>
    </ItemGroup>

  </Target>

</Project>

[dsplaisted]

@entei-11 Yes, this fix is only available in the .NET Core SDK 3.0.100 and higher, which only works with VS 2019.