Describe the bug

Consider the following:

public interface IBase
{    
    void M1();
    
    void M2();
}

public interface IDerived : IBase
{
    new void M2();
}

It is not compatible to remove IDerived.M2() because the runtime will fail to load a type if it claims to implement an interface member on the derived interface.

To Reproduce

See apiCompatInterface.zip for a repro.

Install apicompat tool and run the repro script.

You can run the application to demonstrate the binary breaking change:

Unhandled exception. System.MissingMethodException: Method not found: 'Void lib.IDerived.M2()'.
   at Program.<Main>$(String[] args)

Expect: Compat error for removing the method.
Actual: No error

This is likely because for classes it's compatible to remove a method if that method was hiding a method on the base. That's not the case for interfaces.