I'm not sure if I've discovered a bug or if I'm doing something wrong, but this issue is not listed in the known issues of .NET 6:

I've got a unit test project with a single file that looks like this:

using System;
using Microsoft.VisualStudio.TestTools.UnitTesting;

namespace UnitTest
{
    [TestClass]
    public class TestFoo
    {
        [TestMethod]
        public void Test()
        {
            var foo = new Foo();
        }
    }

    public class Foo : IAdditionOperators<Foo, Foo, Foo>
    {
        public static Foo operator +(Foo left, Foo right) => new();
    }
}

The test fails because of the following runtime error:

System.TypeLoadException: Virtual static method 'op_Addition' is not implemented on type 'UnitTest.Foo' from assembly 'UnitTest, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null'.

But I very clearly have implemented the addition operator. In fact, when I build using dotnet build it compiles just fine until I remove the addition operator. Am I missing something?

Here is my project file:

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

  <PropertyGroup>
    <EnablePreviewFeatures>true</EnablePreviewFeatures>
    <LangVersion>preview</LangVersion>
    <TargetFramework>net6.0</TargetFramework>
  </PropertyGroup>

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


  <ItemGroup>
    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="16.9.4" />
    <PackageReference Include="MSTest.TestAdapter" Version="2.2.3" />
    <PackageReference Include="MSTest.TestFramework" Version="2.2.3" />
    <PackageReference Include="coverlet.collector" Version="3.0.2" />
  </ItemGroup>

</Project>