Get ambiguous type identity error when using package 'Microsoft.CodeAnalysis.CSharp/2.0.0' in a project that targets 'netcoreapp2.0'

[daxian-dbw]

I ran into this when using the package Microsoft.CodeAnalysis.CSharp/2.0.0 (2.0.0 is the latest version I can find) in my project targeting netcoreapp2.0. Microsoft.CodeAnalysis.CSharp/2.0.0 depends on Microsoft.CodeAnalysis.Common/2.0.0 which pulls in System.ValueTuple/4.3.0. However, the types in System.ValueTuple.dll are already exposed from System.Runtime.dll when targeting netcoreapp2.0, and thus using any of those types results in ambiguous type identity error:

Program.cs(9,45): error CS0433: The type 'TupleExtensions' exists in both 'System.ValueTuple, Version=4.0.1.0, Culture=neutral, PublicKeyToken=cc7b13ffcd2ddd51' and 'System.Runtime, Version=4.2.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a' [D:\apps\netcore2\test\test.csproj]

Here is a simple repro:

using System;

namespace test
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine(typeof(System.TupleExtensions).FullName);
        }
    }
}

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <TargetFramework>netcoreapp2.0</TargetFramework>
    <RuntimeIdentifier>win10-x64</RuntimeIdentifier>
  </PropertyGroup>

  <ItemGroup>
    <PackageReference Include="Microsoft.CodeAnalysis.CSharp" Version="2.0.0" />
  </ItemGroup>

</Project>

It looks netcoreapp2.0 doesn't come with Microsoft.CodeAnalysis.CSharp.dll and Microsoft.CodeAnalysis.dll. How should I consume the Microsoft.CodeAnalysis.CSharp package then?

[karelz]

@weshaggard @ericeil @jcouv what is the story around ValueTuple? I know it was somewhat special, but don't remember details ...

cc @terrajobst

[jcouv]

CoreFx was updated to type-forward to System.Runtime (PR dotnet/corefx#14786).
But this was done after the initial release of the ValueTuple package (4.3.0).
@ericstj is about to publish an updated package (for mono), which I suspect will also contain those type-forwards. I'll let him confirm if that's the case.

[weshaggard]

This is because ValueTuple hasn't been added to the shared framework yet. I'm going to take care of this today.

@daxian-dbw you can workaround this issue by referencing the latest System.ValueTuple package from myget (https://dotnet.myget.org/feed/dotnet-core/package/nuget/System.ValueTuple/4.4.0-preview1-25203-01).

[daxian-dbw]

@weshaggard it works fine after referencing to a recent version of System.ValueTuple package. Thanks!

This is because ValueTuple hasn't been added to the shared framework yet.

I guess once ValueTuple is added to the shared framework, I won't need to reference to System.ValueTuple/4.4.0-preview1-25203-01 in order to use Microsoft.CodeAnalysis.CSharp/2.0.0, is that correct?

[weshaggard]

I guess once ValueTuple is added to the shared framework, I won't need to reference to System.ValueTuple/4.4.0-preview1-25203-01 in order to use Microsoft.CodeAnalysis.CSharp/2.0.0, is that correct?

That's correct.

[danmoseley]

@daxian-dbw sounds like this is resolved, I"ll close , feel free to reopen

[jcouv]

@weshaggard I'm not very familiar with the concept of shared framework. I looked at your PRs from early April. I saw you did some netstandard changes (both in corefx and standard repos) for ValueTuple. Were those related to the shared framework?

[weshaggard]

I did a lot of changes you will need to be more specific. I can tell you that ValueTuple has been added to the shared framework for .NET Core.

[jcouv]

Cool. That addresses my question. Thanks! :-)