How to use .NET 6 Preview Generic Math in Visual Studio 2022?

Question

There are several articles explaining the new .NET 6 Preview features of Generic Math, often based on this Microsoft article:

https://devblogs.microsoft.com/dotnet/preview-features-in-net-6-generic-math/

In the preview versions, and the first release of Visual Studio 2022 this works fine. But in Visual Studio 2022 version 17.0.3 and 17.0.4 (the current release) I simply cannot get this to compile.

I actually went back to VS2022 version 17.0.0 to make sure I had correctly followed the article steps. The code compiles just fine. Upgrade to VS2022 version 17.0.3 and the same project fails to build with the error:

Error   CS0246  The type or namespace name 'INumber<>' could not be found (are you missing a using directive or an assembly reference?)

Anyone got any ideas? I assume I have to make a further change to the csproj file, but what change?

In the NuGet Package Manager I found the option to upgrade System.Runtime.Experimental to version 6.0.0, which changed the entry in my csproj file from:

  <ItemGroup>
    <PackageReference Include="System.Runtime.Experimental" Version="6.0.0-preview.7.21377.19" />
  </ItemGroup>

to:

  <ItemGroup>
    <PackageReference Include="System.Runtime.Experimental" Version="6.0.0" />
  </ItemGroup>

rebooting doesn't help. Cleaning the solution doesn't help. I am not seeing anything to help me in the release notes for Visual Studio 2022 either.

The complete csproj file, for reference, already containing the extra bits you need, is:

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

    <PropertyGroup>
        <OutputType>Exe</OutputType>
        <TargetFramework>net6.0</TargetFramework>
        <ImplicitUsings>enable</ImplicitUsings>
        <Nullable>enable</Nullable>
        <EnablePreviewFeatures>True</EnablePreviewFeatures>
        <LangVersion>preview</LangVersion>
    </PropertyGroup>

    <ItemGroup>
        <PackageReference Include="System.Runtime.Experimental" Version="6.0.0" />
    </ItemGroup>
</Project>

Answer 1

Step 1

As explained in the blog article you've linked at the top of the question: add

    <EnablePreviewFeatures>true</EnablePreviewFeatures>

into a <PropertyGroup> element in your project file.

Step 2

Now the above is confirmed: have you tried the preview version of VS2022 (currently V17.1 Preview 1.1)?

Just tried it: No.

Step 3

See Hans Passant's comment on to the question: need to wait on this (or do you own builds of what is being built to be .NET 7...)

Update for VS 2002 17.2.0 Preview 3.0

With V6.0.2 of System.Runtime.Experimental this now works.

Answer 2

I got the same error with VS2022 17.0.4. Now, VS2022 17.1.0 Preview 1.1 seems to work fine.