Pip Cet wrote:
> +      case PVEC_FINALIZER:
> +        VECTOR_MARK (ptr);
> +        mark_object (XFINALIZER (obj)->function);
> +        break;
> +
> 
> Isn't that precisely what the default code does?
> 
> Similarly for bool vectors, misc ptrs, and user ptrs.

Thanks for mentioning that opportunity for further simplification. Followup 
patch attached.

> I'm curious what ideas you have for the newly freed Lisp_Type tag.

I had been thinking of using it for immediate floats, if we want to insist on 
full IEEE double semantics for Emacs Lisp. But if there's something more 
important, we can use it for that instead.