Subject: Re: bug#38261: Recent changes to emacs build system

From: Maxim Cournoyer <[email-masked]>
Date: Wed, 20 Nov 2019 06:14:46 +0900

Hello Brett,

Thank you for the heads-up concerning the latest changes to the way
Emacs find its libraries and the adjustments done to the
emacs-build-system.

[email-masked] writes:

> On 19.11.2019 01:32, [email-masked] wrote:
>> On 19.11.2019 01:27, [email-masked] wrote:
>>> On 18.11.2019 22:34, [email-masked] wrote:
>>>> On 18.11.2019 21:33, [email-masked] wrote:
>>>>> On 18.11.2019 21:28, [email-masked] wrote:
>>>>>> On 18.11.2019 20:01, [email-masked] wrote:
>>>>>>> Hey all, the recent changes to the emacs build system result in
>>>>>>> a few
>>>>>>> broken packages like emacs-pdf-tools, or basically anything
>>>>>>> that uses
>>>>>>> a phase for emacs-set-emacs-load-path.
>>>>>>>
>>>>>>> For example, I borrowed the technique used by emacs-pdf-tools to
>>>>>>> package emacs-telega, resulting in both packages failing to build:
>>>>>>>
>>>>>>> Here is the code for emacs-telega:
>>>>>>>
>>>>>>> https://git.sr.ht/~brettgilio/cfg/tree/master/channel/non-gnu/packages/emacs-xyz.scm#L99
>>>>>>>
>>>>>>> The issue is in this phase for both emacs-pdf-tools and my
>>>>>>> channel package:
>>>>>>>
>>>>>>>  (add-after 'compress-documentation 'emacs-set-emacs-load-path
>>>>>>> 			  (assoc-ref emacs:%standard-phases 'set-emacs-load-path))
>>>>>>>
>>>>>>> Resulting in:
>>>>>>>
>>>>>>> starting phase `emacs-set-emacs-load-path'
>>>>>>> Backtrace:
>>>>>>>            5 (primitive-load
>>>>>>> "/gnu/store/5b1p1gsvfyi4fbx4s42rhab2dns…")
>>>>>>> In ice-9/eval.scm:
>>>>>>>    191:35  4 (_ _)
>>>>>>> In ice-9/boot-9.scm:
>>>>>>>     829:9  3 (catch _ _ #<procedure 7ffff3bbb518 at
>>>>>>> /gnu/store/zmkg…> …)
>>>>>>> In srfi/srfi-1.scm:
>>>>>>>    863:16  2 (every1 #<procedure 7ffff30ae160 at
>>>>>>> /gnu/store/zmkgrvv…> …)
>>>>>>> In
>>>>>>> /gnu/store/zmkgrvvhmrix2b1z7id6zrg9bb7qxzdl-module-import/guix/build/gnu-build-system.scm:
>>>>>>>    839:30  1 (_ _)
>>>>>>> In unknown file:
>>>>>>>            0 (_ #:source
>>>>>>> "/gnu/store/qw8xbmk6ryl9a2jrp0gip3yffmsdix…" …)
>>>>>>>
>>>>>>> ERROR: Wrong type to apply: #f

Sorry for failing to foresee this problem.  I've fixed the couple
packages that were impacted on master now.  You can have a look at the
fixes (they are fairly simple).

>>>>>>> If we suspect that changes are going to be non-backwards
>>>>>>> compatible
>>>>>>> could we use the news system to pass along that message? Much
>>>>>>> appreciated. Thanks.
>>>>>>>
>>>>>>> Brett Gilio
>>>>>>
>>>>>> I applied a hotfix to the package by replacing 'set-emacs-load-path
>>>>>> with 'add-source-to-load-path. I believe this fix would work for
>>>>>> all
>>>>>> other affected packages.
>>>>>
>>>>> https://git.sr.ht/~brettgilio/cfg/commit/c24a6db9d25151c487e9db675bd74e4bb3912173

Indeed!

>>>> Ricardo, just wanted to make you aware that this emacs-build-system
>>>> change does break your guile-studio. I discovered this because I
>>>> adopted some of your ideas of autoloading in the generated emacs lisp
>>>> from guile-studio when creating my own emacs configuration dependent
>>>> on guix, which resulted in
>>>>
>>>> progn: Wrong number of arguments: (lambda nil "Autoload Emacs
>>>> packages
>>>> found in EMACSLOADPATH.
>>>>
>>>> 'Autoload' means to load the 'autoloads' files matching
>>>> `guix-emacs-autoloads-regexp'." (interactive) (let* ((emacs-load-path
>>>> (getenv "EMACSLOADPATH")) (emacs-non-core-load-path-directories
>>>> (seq-filter (function (lambda (dir) (string-match-p
>>>> "/share/emacs/site-lisp" dir))) (split-string emacs-load-path ":")))
>>>> (autoloads (mapcan (function guix-emacs-find-autoloads)
>>>> emacs-non-core-load-path-directories))) (mapc (function (lambda (f)
>>>> (load f (quote noerror)))) autoloads))), 78
>>>>
>>>> I'll let you know if I can find any fix for this when I get some
>>>> time.
>>>> But just wanted to pass the message along.
>>>>
>>>> Brett
>>>
>>> I tried removing the arguments passed to
>>> `guix-emacs-autoload-packages' as the updated version
>>> (http://git.savannah.gnu.org/cgit/guix.git/tree/gnu/packages/aux-files/emacs/guix-emacs.el?id=47b3b4c2aa49e21f4cc32c97ff7bbbd069bb849c)
>>> does not carry arguments anymore, instead depending on a variable
>>> EMACSLOADPATH. However, whenever that is done it returns
>>>
>>> split-string: Wrong type argument: stringp, nil
>>>
>>> possibly because my system is not finding EMACSLOADPATH.

Yes, that's the reason.  Perhaps it could be worthwhile to give a better
message in this condition, but it's unclear to me why this condition
would arise at all.  Would you mind giving some more background to how
you got into that situation?  I'll try building guile-studio and see if
I could get a hint or two.

>>> I will keep investigating.
>>
>> I can confirm, when running something analogous to `guix environment
>> --ad-hoc emacs-dashboard` no changes are being made to the
>> $GUIX_ENVIRONMENT/etc/profile to resemble EMACSLOADPATH.
>
> So I have investigated the issue with EMACSLOADPATH: Similar to
> Ricardo's guile-studio,
> my package enlign was using the autoload function from guix-emacs.el
> to propagate a list
> of packages called from inputs to be loaded with the start of emacs.
>
> I have since revised this to just call the autoload function directly,
> no longer passing any arguments, and had to modify my enlign package
> to respect the EMACSLOADPATH variable. This is only possible if all of
> the packages are passed as propagated-inputs though, which is less
> than desirable in my opinion (though I am willing to be convinced.)

Is your package an Emacs library/package? If so, just defining the other
Elisp dependencies of this package as propagated inputs would be the
correct solution.

For other cases (I can't think of how that would work exactly), perhaps
wrapping the package's script with the computed EMACSLOADPATH
environment variable could do?

> This additionally leads to having to require emacs as a propagated
> input as well, as leading it native or regular input leads to an error
> with emacs not recognizing simple.el or mule-util.

Do you mean, that your package somehow uses Emacs without having Emacs
installed in the profile (not being propagated)?  If this is the case,
wrapping your program with EMACSLOADPATH (and patching its reference to
Emacs) should work, without having to propagate anything.

> Overall, I am not sure if I like the recent change to guix-emacs.el. I
> understand where the incentive is to do this, but ultimately it seems
> to lead to more headache when creating packages around emacs.
>
> https://git.sr.ht/~brettgilio/cfg/commit/47bc9ae544ba10c0cacef1435625dcb0114e8cf5
>
> Anyways,
>
> If there is no other comment, this issue really just needs to fix
> emacs-pdf-tools and other affected packages from the recent string of
> changes.

I'm sorry you've had some problems with this recent change!  Thanks for
bringing them out.  Please do continue, I'm interested to know about any
remaining issues you might find.

Maxim