Misleading error message in case of ref-returning this in a reference type

[alrz]

Version Used: 0694d5c

Steps to Reproduce:

public class C 
{
    public ref C M()
    {
        return ref this;
    }
}

Expected Behavior:

error CS1605: Cannot use 'this' as a ref or out value because it is read-only

Actual Behavior:

error CS8170: Struct members cannot return 'this' or other instance members by reference

[jcouv]

FYI @VSadov

[gafter]

Actually, I think the existing error is not bad. If we add support for readonly refs, this would still be an error for the reason mentioned in the diagnostic.

[alrz]

I don't get it. the error is clearly misleading as I'm not using a struct. What you say applies to the "expected" message, not actual.

[gafter]

Yes, I see you're right.