Emacs C source

Emacs C source

[Kristoffer Ström]

Hello! I'm running emacs in a guix shell, and wonder how/where to get
the C source code directory for xref-find-definitions.

I've grepped the /gnu/store/*emacs but cannot find the C source, is
there some special package/output or procedure needed to get it included
in the shell environment?

Re: Emacs C source

[Tomas Volf]

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On 2023-12-15 15:56:34 +0100, Kristoffer Ström wrote:
>
> Hello! I'm running emacs in a guix shell, and wonder how/where to get
> the C source code directory for xref-find-definitions.
>
> I've grepped the /gnu/store/*emacs but cannot find the C source, is
> there some special package/output or procedure needed to get it included
> in the shell environment?

You can download source archives for any package using build --sources, like
this:

    $ guix build --sources emacs
    substitute: updating substitutes from 'https://ci.guix.gnu.org'... 100.0%
    43.3 MB will be downloaded:
      /gnu/store/c4xfnis0g5g2v1ssl3wqgk8h6s3xjfk6-emacs-29.1.tar.xz
    substituting /gnu/store/c4xfnis0g5g2v1ssl3wqgk8h6s3xjfk6-emacs-29.1.tar.xz...
    downloading from https://bordeaux.guix.gnu.org/nar/lzip/c4xfnis0g5g2v1ssl3wqgk8h6s3xjfk6-emacs-29.1.tar.xz ...
     emacs-29.1.tar.xz  41.3MiB                                                                                                                         16.6MiB/s 00:02 ▕██████████████████▏ 100.0%

    /gnu/store/c4xfnis0g5g2v1ssl3wqgk8h6s3xjfk6-emacs-29.1.tar.xz

You can then extract the archive somewhere.

Hope this helps,
Tomas

--
There are only two hard things in Computer Science:
cache invalidation, naming things and off-by-one errors.

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Re: Emacs C source

[Kristoffer Ström]

> You can download source archives for any package using build --sources, like
> this:

That's nice to know! However i would greatly prefer if there was some
way to make it be available as part of a manifest, i'm building multiple
environments using guix shell containers, and doing this as an extra
step in each one is not very pleasant.

something along the lines of `guix shell -D emacs` but for sources

Re: Emacs C source

[Simon Tournier]

Hi,

On Sun, 17 Dec 2023 at 14:18, Kristoffer Ström <kristoffer@rymdkoloni.se> wrote:

> That's nice to know! However i would greatly prefer if there was some
> way to make it be available as part of a manifest,

Well, I am not aware of such out-of-box feature.

>                                                    i'm building multiple
> environments using guix shell containers, and doing this as an extra
> step in each one is not very pleasant.

Hum, I am missing context but I do not see what would be the workflow.

> something along the lines of `guix shell -D emacs` but for sources

Somehow Guix will manipulate read-only items in the store; thus the
source is not directly useful.  Something like that ugly,

--8<---------------cut here---------------start------------->8---
(use-modules (guix scripts build))

(specifications->manifest
 (map
  (lambda (spec)
    (begin
      (guix-build "--source" spec)
      spec))
  (list
   "emacs"
   "coreutils"
   )))
--8<---------------cut here---------------end--------------->8---

allows to fetch the corresponding source of each package.  However, the
source (tarball) are not part of the ’manifest’ and thus not visible
inside the container.

It is possible to do it using some plumbing Guix procedures, I
guess. :-)

Aside, I initially wrote a Guix script (see below) for mainly demoing
and now, I am using more or more. :-) I think something in this area is
missing.  I would like such workflow

   guix <something> emacs custom/path/to/emacs
   cd custom/path/to/emacs
   guix shell -C -D emacs
   … hack …

And the script just shows how to download the source of a package.

    (Please note that “guix build --source” returns the source after the
applying snippets, and the tiny script manipulated the URL of source,
i.e., before the applications of snippets.)

Cheers,
simon


--8<---------------cut here---------------start------------->8---
$ cat examples/scripts/show-me-fetch.scm 
#!/usr/bin/env -S guix repl -q --
;; -*- mode: scheme -*-
!#
;;; Copyright © 2023 Simon Tournier <zimon.toutoune@gmail.com>
;;;
;;;
;;; This script show URL of packages.
;;;

(use-modules
 (ice-9 match)

 ((gnu packages) #:select (specification->package))
 (guix packages)

 ((web uri) #:select (string->uri
                      uri->string))
 ((guix build download) #:select (maybe-expand-mirrors))
 ((guix download) #:select (%mirrors))
 (guix git-download))

(let ((pkgs (match (command-line)
              ((prog-name pkgs ...)
               (map specification->package pkgs))
              (_
               (begin
                 (format #t "Error. Try: ./show-me-url.scm hello")
                 (exit 1))))))
  (for-each
   (lambda (pkg)
     (match (package-source pkg)
       ;; See 'origin->json' from file build-package-metadata.scm in repository
       ;; maintenance.git for an exhaustive case handling.
       ((? origin? o)
        (match (origin-uri o)
          ((? string? s)
           ;; Pick only the first (car) of the potenial long list
           (let ((url (car (map uri->string
                                (maybe-expand-mirrors (string->uri s) %mirrors)))))
             (format #t "wget      ~a~%" url)))
          ((? git-reference? g)
           (let* ((url (git-reference-url g))
                 (revision (git-reference-commit g))
                 (tmpdir (string-append "/tmp/" (package-name pkg)))
                 (git (string-append "git -C " tmpdir)))
             (format #t "mkdir -p ~a ~%" tmpdir)
             (format #t "&& ~a init --initial-branch=main ~%" git)
             (format #t "&& ~a remote add origin ~a ~%" git url)
             (format #t "&& ~a fetch --depth 1 origin ~a ~%" git revision)
             (format #t "&& ~a checkout FETCH_HEAD ~%" git)))
          ;; All the other cases
          (_ #f)))))
   pkgs)
  (exit 0))
--8<---------------cut here---------------end--------------->8---

Re: Emacs C source

[Kristoffer Ström]

> --8<---------------cut here---------------start------------->8---
> (use-modules (guix scripts build))
>
> (specifications->manifest
>  (map
>   (lambda (spec)
>     (begin
>       (guix-build "--source" spec)
>       spec))
>   (list
>    "emacs"
>    "coreutils"
>    )))
> --8<---------------cut here---------------end--------------->8---
>
> allows to fetch the corresponding source of each package.  However, the
> source (tarball) are not part of the ’manifest’ and thus not visible
> inside the container.

This looks like a good start to get somehting automatic. Thank you!

Re: Emacs C source

[Ian Eure]

Kristoffer Ström <kristoffer@rymdkoloni.se> writes:

> Hello! I'm running emacs in a guix shell, and wonder how/where 
> to get
> the C source code directory for xref-find-definitions.
>
> I've grepped the /gnu/store/*emacs but cannot find the C source, 
> is
> there some special package/output or procedure needed to get it 
> included
> in the shell environment?
>

There is no C source for xref-find-definitions, it’s written in 
Emacs Lisp:

    xref-find-definitions is an interactive native-compiled Lisp 
    function
    in ‘xref.el’.

The source is available in any environment the Emacs package is 
installed.

  — Ian