Re: [PATCH] Automatically set `geiser-guile-load-path' from .dir-locals

[Miguel Ángel Arruga Vivas]

Hi Maxim and Christopher,

Maxim Cournoyer <maxim.cournoyer@gmail.com> writes:
>[...]
> Christopher Lemmer Webber <cwebber@dustycloud.org> writes:
> [...]
>> I figured out what was happening!  The bug is *technically* in vc-mode.
>> However, nontheless it manifested here...
>>
>> Here's what happened.  vc-mode has some various hacks, as you can see
>> above with "hack-local-variables-apply"... which traverses the dirlocals
>> stuff.  (Not sure what the purpose is, didn't look too long.)

The file where these functions are located is lisp/files.el, right on
the Emacs core.  Some modes add hooks there, like flyspell or cc, but
not vc, so I don't really think the problem is exclusive from that mode
after some debugging.

This code ends up in file-local-variables-alist, even though
dir-local-variables-alist contains the correct values for some reason I
still don't really understand.

>> However for whatever reason, vc-mode also seems to be reusing buffers
>> such as `*vc-diff*'... and somehow still is left in the directory
>> context it *first* was used in.

This may be the culprit but I think it isn't the issue, as
file-local-variables-alist accumulates every eval marked as nil, not
only the first/last one... when it fails, as we've seen.

>> Thus if I C-x v = in a guix-oriented buffer first, and then switch to
>> another completely different project and do the same, it's loading the
>> dirlocals from Guix(...!!!!)
>>
>> This is clearly a bug in vc-mode, I'll try to report it as such.

> Thank you for the investigation.  I'd be really happy if you could
> report the problem upstream (M-x report-emacs-bug) aznd link to it here!

I haven't reported it yet, but as you can see I have a reproducer script
attached.  I haven't seen anything in vc-code that points in that
direction, surely though Emacs people will have a better understanding.

Christopher, would you mind to CC me if you open the bug?  I can do it
too if you tell me to, but I don't want to create a duplicate entry if
we do it roughly at the same time.

> [..] Miguel had written in IRC at the time of the initial report, but
> to no avail.

Maxim, could you test the script to check if we can narrow the cases?
It shows the README in the emacs it opens, so it should be
straight-forward.

>> In the meanwhile, I used this hacky "fix".  Maybe worth applying for the
>> moment... what do you think of it?
>
> I'd like to have the upstream bug linked in that fix rather than the
> Guix one; that way it'll be possible to track upstream resolution and
> know when the workaround can be removed.

Apart from the tracking reference, I agree that it's worth applying it.
And also, thank you both for making easier to work on guix. :-)

Happy hacking!
Miguel

reproducer.sh
Description: reproducer