Re: attachment: link type export to HTML invalid attach dir

[Bastien]

Okay, I've done my home work :)

TL;DR: (1) The change is fresh, let's take the time to work together
at making it right before 9.4*; (2) the current state with the line
3216 in org-element.el is not okay; (3) let's try implementing what
Nicolas suggests wrt to attachment=>file link resolution.

* Sorry that I rushed you into having this discussion by announcing
  the release with such a short notice, I should have seen this was
  not resolve.

Now into more details.

- The new feature for attachments is nice and useful.  And I'm quite
  happy Gustav is now more acquainted with org-element.el -- we need
  more people with a good knowledge of that core file (thanks!)

- My definition of Org core link types = the minimal set of types to
  which other types can be translated to.  Given this definition, an
  attachment is not a core link type as it can resolve to file type.

- org-element.el should only know about core link types.

- Link type resolution should happen at exporting time: I think the
  design consistency is worth the potential parsing time cost.

- One advantage of this approach (on top of design consistency) is
  that exporters won't each depend on org-attach.el to deal with file
  attachments, as they do right now.

Now, I'm not sure who wants to try implementing Nicolas suggestion to
let ox.el expand attachments into file links: since you both know the
issue better than I do, I suggest one of you can try?

We are not pressed by time, so whoever has the energy to finish this.

Thanks!

-- 
 Bastien