bug#65575: [PATCH 3/3] gnu: emacs: Reload subdirs.el files in 'guix-emacs-autoload-packages'.

[Liliana Marie Prikler]

Hi Maxim,

Am Montag, dem 28.08.2023 um 01:11 -0400 schrieb Maxim Cournoyer:
> This fixes a regression introduced with 79cfe30f3 ("build-system:
> emacs: Use subdirectories again.") which caused the
> 'guix-emacs-autoload-packages' to no
> longer be able to autoload all packages.
> 
> * gnu/packages/aux-files/emacs/guix-emacs.el
> (guix-emacs-autoload-packages-called): New variable.
> (guix-emacs-autoload-packages): Reload subdirs.el files an all but
> the first call of this procedure.
> * doc/guix.texi (Application Setup): Document that
> 'guix-emacs-autoload-packages' can be invoked interactively to auto-
> reload newly installed Emacs packages.
> 
> ---
Thank you for looking at this.  I agree that even if we don't want to
generally load new packages into existing Emacs processes for the
breakages they might induce, not being able to do so at all is also not
a great option.  However, I don't think that tracking is the right
solution here, see below.

>  doc/guix.texi                              | 11 +++++++----
>  gnu/packages/aux-files/emacs/guix-emacs.el | 12 ++++++++++++
>  2 files changed, 19 insertions(+), 4 deletions(-)
> 
> diff --git a/doc/guix.texi b/doc/guix.texi
> index f82bb99069..66da4f9cd4 100644
> --- a/doc/guix.texi
> +++ b/doc/guix.texi
> @@ -2167,12 +2167,15 @@ Application Setup
>  Emacs through the @env{EMACSLOADPATH} environment variable, which is
>  set when installing Emacs itself.
>  
> +@cindex guix-emacs-autoload-packages, refreshing Emacs packages
>  Additionally, autoload definitions are automatically evaluated at
> the
>  initialization of Emacs, by the Guix-specific
> -@code{guix-emacs-autoload-packages} procedure.  If, for some reason,
> you
> -want to avoid auto-loading the Emacs packages installed with Guix,
> you
> -can do so by running Emacs with the @option{--no-site-file} option
> -(@pxref{Init File,,, emacs, The GNU Emacs Manual}).
> +@code{guix-emacs-autoload-packages} procedure.  This procedure can
> be
> +interactively invoked to have newly installed Emacs packages
> discovered,
> +without having to restart Emacs.  If, for some reason, you want to
> avoid
> +auto-loading the Emacs packages installed with Guix, you can do so
> by
> +running Emacs with the @option{--no-site-file} option (@pxref{Init
> +File,,, emacs, The GNU Emacs Manual}).
>  
>  @quotation Note
>  Emacs can now compile packages natively.  Under the default
> diff --git a/gnu/packages/aux-files/emacs/guix-emacs.el
> b/gnu/packages/aux-files/emacs/guix-emacs.el
> index ed0c913163..b4a4fd1d91 100644
> --- a/gnu/packages/aux-files/emacs/guix-emacs.el
> +++ b/gnu/packages/aux-files/emacs/guix-emacs.el
> @@ -54,6 +54,9 @@ The files in the list do not have extensions (.el,
> .elc)."
>                          (expand-file-name "subdirs.el" dir))
>                        (guix-emacs--non-core-load-path))))
>  
> +(defvar guix-emacs-autoload-packages-called nil
> +  "True if `guix-emacs-autoload-packages' was already run.")
> +
>  ;;;###autoload
>  (defun guix-emacs-autoload-packages ()
>    "Autoload Emacs packages found in EMACSLOADPATH.
> @@ -61,6 +64,15 @@ The files in the list do not have extensions (.el,
> .elc)."
>  'Autoload' means to load the 'autoloads' files matching
>  `guix-emacs-autoloads-regexp'."
>    (interactive)
> +  ;; Reload the subdirs.el files such as the one generated by the
> Guix profile
> +  ;; hook, so that newly installed Emacs packages located under
> +  ;; sub-directories are put on the load-path without having to
> restart Emacs.
> +  (if guix-emacs-autoload-packages-called
> +      (progn
> +        (mapc #'load-file (guix-emacs--subdirs-files))
> +        (setq load-path (delete-dups load-path)))
> +    (setq guix-emacs-autoload-packages-called t))
> +
Rather than keeping track of whether the function was already called
(which would make debugging more tedious if you also have e.g. broken
packages from another source on your EMACSLOADPATH), I think the user
ought to signal their intent to reload the subdirs files via the
universal argument.

e.g. 
(defun guix-emacs-autoload-packages (&optional reload)
  "..."
  (interactive "P")
  (when reload (mapc #'load-file (guix-emacs--subdirs-files)))
  ...)

WDYT?