bug#38309: Recent $EMACSLOADPATH changes crash gnome-session

[clement@lassieur.org (Clément Lassieur)]

Hello Maxim,

Thanks for taking the time to look into this.  I've seen your other
email, you can install libpcre3-dbg to have PCRE's debug symbols.  It
might help.

Maxim Cournoyer <maxim.cournoyer@gmail.com> writes:

> Hello Ludovic,
>
> Ludovic Courtès <ludo@gnu.org> writes:
>
>> Hi Maxim,
>>
>> Maxim Cournoyer <maxim.cournoyer@gmail.com> skribis:
>>
>>> There would be a couple more commits to include in the revert to undo
>>> the changes (one to the build system, others to adapt the renaming of
>>> the emacs-set-load-path phase for some packages:
>>
>> Oh indeed.

Well, maybe it would make sense to squash them into one revert commit,
that would be re-reverted when the bug is fixed?

>> I must say I haven’t looked closely at the changes nor at the reasons
>> for the regression, but IIUC, the regression is serious enough that we
>> should have a way to address it quickly.
>
> The regression only seems to affect the "restarting the session",
> e.g. logout then login, not the first boot, which means there's an
> (inconvenient) workaround available for single user systems.

Before the patches, restarting Emacs was enough to have new packages
installed.  Now I have to reboot my computer every time I 'guix package
-i emacs-something'.  Emacs is central to my workflow and I often change
things around (as do a lot of Guix users).  It is inconvenient, really.

> I've been trying to reproduce in a VM to get a backtrace (if those
> affected by the problem could produce one, that'd help pinpoint the
> problematic call to PCRE and its origin), but that'll need some more
> time.

Even if you find a solution, the fix will take a lot of time to land
onto an Ubuntu release.

> If those affected judge the situation dire enough, I don't mind
> reverting the changes to the Emacs library loading mechanism for the
> time being.

Please, do so :)

Lots of users don't have that bug, but there's still a change in their
workflow: they have to restart their session after installing new Emacs
packages.  Maybe when that bug is fixed and this set of patch is
re-applied, there will be an opportunity to communicate about this?  On
info-guix maybe, or on 'guix pull'.  It would explain the pros and cons
of this new way of dealing with Emacs.  I don't know if there was such
an announcement already, I didn't see it.  WDYT?

Thanks again,
Clément