bug#63757: 29.0.91 order of package paths changed: random old versions of packages in load-path

[Eli Zaretskii]

> From: Philip Kaludercic <philipk@posteo.net>
> Cc: artscan@list.ru,  monnier@iro.umontreal.ca,  63757@debbugs.gnu.org
> Date: Sun, 04 Jun 2023 12:32:17 +0000
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> >> -      (dolist (pkg-dir (directory-files dir t "\\`[^.]" t))
> >> +      (dolist (pkg-dir (directory-files dir t "\\`[^.]"))
> >>          (when (file-directory-p pkg-dir)
> >>            (package-load-descriptor pkg-dir))))))
> >>  
> >> (I attached the *vc-diff* buffer, but before sending the message I
> >> invoked vc-diff again which modified the buffer contents.  Should have
> >> just copied the diff manually...)
> >
> > Thanks, now it at least makes sense.
> >
> > But why does it matter whether the package directory names are sorted
> > or not?  Is sorting package versions the same as sorting the names of
> > their directories?
> 
> No, because directories are sorted by their names and by that metric,
> "foo-10" is less than "foo-9".  But since package archives like MELPA
> use ISO 8601-like release-dates as version numbers, the order "works".
> If we disable sorting, the files returned in any order the operating
> system might have arbitrary stored the directory entries in which might
> even change depending on the file system.  So at the very least we can
> argue that while sorting does not solve the issue, it provides a quick
> hack to prevent sudden breakage from Emacs 28 to Emacs 29, due to users
> relying on this kind of behaviour.  A proper solution, that takes
> version numbers into account should be prepared on the master branch.

OK, thanks.  Please install on emacs-29, and let's hope this doesn't
cause new problems.