Bug Failed to properly override default interface method

Code (CSharp):

1. public interface ITest { int Prop => 10; }
2. public abstract class CTest : ITest {}
3. public class CTestChild : CTest { public virtual int Prop => 20; }
4.  
5. ITest a = new CTestChild();
6. Debug.Log(a.Prop);

I'm using Unity 2021.3.15, the result shown in the above code is 10, while my expected result is 20.

In a normal dotnet runtime, the result is 20.

Can you help me confirm that this issue still exists in the new version? I would like to know if it is necessary to upgrade Unity.

 

I tried some patterns in 2022.2.11, here's the result:

Code (CSharp):

1. // Yours, output: 10
2. public abstract class CTest : ITest { }
3. public class CTestChild : CTest { public virtual int Prop => 20; }
4.  
5. // Move the prop to parent class, output: 20
6. public abstract class CTest : ITest { public virtual int Prop => 20; }
7. public class CTestChild : CTest { }
8.  
9. // Child also inherit ITest interface, output: 20
10. public abstract class CTest : ITest { }
11. public class CTestChild : CTest, ITest { public virtual int Prop => 20; }

(By the way, recently Unity is trying to update to CoreCLR, maybe it will fix the problem; but it might take 1~2 years)

 

Thank you very much for your help