bug#64088: [PATCH] Make project-root for vc projects return an absolute path

[Dmitry Gutov]

On 19/08/2023 15:57, sbaugh@catern.com wrote:
> > > Meaning it will be called N times (for the number of projects) every
> > > time the list is displayed, instead of just once, when the project is
> > > saved/visited. But maybe it's fine too? How slow could that be?
> > I was sad about this but I think I've got the solution now: We just
> > maintain project--list in abbreviated form and project-list-file in
> > expanded form.

Here's something else I thought of: project--write-project-list is 
called every time a different project is returned by (project-current t) 
-- i.e. when MAYBE-PROMPT=t, and when the found dir is not at the top of 
the project history already.

So under certain conditions (slow CPU/spinning media/long project 
history) it might slow down (project-current t) calls. In my testing 
it's totally fine, though, and there are possible mitigations (limit the 
history and/or move saving to kill-hook). Just something to keep in mind.

> > I think that solves all the problems: the persistent file is independent
> > of user configuration, so if the user changes their abbreviations
> > they'll get new ones the next time the file is read (presumably the next
> > time they run Emacs).  But project--list is abbreviated, so
> > project-prompt-project-dir gets abbreviated dirs.
> >
> > It does mean that if they change their directory-abbrev-alist while
> > Emacs is running they could get duplicate entries, but that already
> > could happen before this patch, and it's not a big problem IMO.
> >
> > See patch below.
> Oops, this patch needed a few tweaks.  Especially, skipping the
> expansion and abbreviation for remote files, to avoid making unnecesary
> remote connections.

Thanks! Pushed to master, and finally closing ;-)