API Compat: the reference assembly is allowed to have more overrides than the implementation

[terrajobst]

Suppos a reference assembly includes an overide that the implementation doesn't have. Then, API Compat creates an error like this:

MembersMustExist : Member 'System.IO.FileStream.Read(System.Span<System.Byte>)' does not exist in the implementation but it does exist in the contract.

However, IL was designed to handle cases like this. In fact, we may want to always have all the overrides to bad base calls in C# should we add an overide later.

See this thread for more context.

[markwilkie]

cc/ @ericstj

[ericstj]

Yeah, this is an ask to relax a rule in APICompat. Any chance we can have labels to triage this sort of thing @markwilkie?

[terrajobst]

Also, should we archive dotnet/build tools now?

[markwilkie]

If a label is needed, I think that's fine. We use epic assigned via ZenHub which I'd prefer, but I understand if that's not really tenable.

[ericstj]

We should look more closely at the override behavior in general. The contact can have more overrides than implementation. If the implementation has an override not in the contract we may want to flag that as well for the same reason @terrajobst mentioned.