Having written the RFC PR 9 proposal, I'll chime in just to say that your interpretation is exactly how I intended it. The idea was to use the same vtable as are currently used with fat pointers, and leave to single inheritance for some other RFC. The idea with linking to Niko's single inheritance post was not to advocate for that particular proposal. It was an example so that I could demonstrate how fat objects, plus some impelmentation of single inheritance, suffice to meet the requirements mentioned under Background above. I put this in the RFC to express that:
Single inheritance is necessary to meet all the listed requirements, but isn't really the focus of this RFC--another RFC should focus on choosing the exact form of it. It's included here by reference, just so I can use it to show that combining it with fat objects meets the requirements that inspired the
virtual structproposal.
I'm looking at the line notes on the PR and will update the branch to correct the noted errors in the sample code.