Re: [PATCH 1/3] emacs: Handle compiled and compressed autoloads.

[ludo@gnu.org (Ludovic Courtès)]

Alex Kost <alezost@gmail.com> skribis:

> Ludovic Courtès (2015-12-08 02:00 +0300) wrote:
>
>> Alex Kost <alezost@gmail.com> skribis:
>>
>>> * emacs/guix-emacs.el (guix-emacs-autoloads-regexp): New variable.
>>>   (guix-emacs-find-autoloads-in-directory): Return a list of autoloads
>>>   without extensions.
>>
>> LGTM.
>>
>> However, note that autoloads may only be compressed when we know they do
>> not embed store file names (which I think is usually the case.)
>
> Thanks for the info, currently none of the emacs packages provides a
> compressed 'autoloads' file.

Perfect.

>> Otherwise there’s a risk of fooling the GC, as in
>> <http://bugs.gnu.org/20765>.
>
> Hm, OK.  I don't fully understand the issue though.  So *.el files of
> 'emacs-w3m-1.4.538+0.20141022' will be compressed, and some of these
> *.el.gz files contain store file names.  Do these files fool GC?

Yes.  When a derivation build completes, the daemon scans all the files
in the derivation outputs for /gnu/store/… patterns, and then records
those patterns in the ‘References’ table of /var/guix/db/db.sqlite.

This is what makes sure that if /gnu/store/A refers to /gnu/store/B, and
if /gnu/store/A is live, then /gnu/store/B will not be GC’.d

> If so, I think 'emacs-w3m' should be configured with
> '--without-compress-install', right?

Sounds like it!

Thanks,
Ludo’.