bug#66114: [PATCH] Fix interactive prompt for selecting checkout directory

[Philip Kaludercic <philipk@posteo.net>]

Joseph Turner <joseph@breatheoutbreathe.in> writes:

> Tags: patch
>
> This patch fixes the interactive prompt in package-vc-checkout. See
> commit message for details.
>
> From 70061d76542968575555f247d4715d18ed3c4e75 Mon Sep 17 00:00:00 2001
> From: Joseph Turner <joseph@breatheoutbreathe.in>
> Date: Tue, 19 Sep 2023 23:58:43 -0700
> Subject: [PATCH] Fix interactive prompt for selecting checkout directory
>
> * lisp/emacs-lisp/package-vc.el (package-vc-checkout): Use
> read-directory-name instead of read-file-name with
> predicate.  Previously, it was impossible to interactively navigate to
> a nested subdirectory.

I can "navigate" into whatever directory I want, but I don't get completion.

> ---
>  lisp/emacs-lisp/package-vc.el | 17 +++++++++++------
>  1 file changed, 11 insertions(+), 6 deletions(-)
>
> diff --git a/lisp/emacs-lisp/package-vc.el b/lisp/emacs-lisp/package-vc.el
> index c7a30736e32..29b540d86b8 100644
> --- a/lisp/emacs-lisp/package-vc.el
> +++ b/lisp/emacs-lisp/package-vc.el
> @@ -823,12 +823,17 @@ repository.  If REV has the special value
>  `:last-release' (interactively, the prefix argument), that stands
>  for the last released version of the package."
>    (interactive
> -   (let* ((name (package-vc--read-package-name "Fetch package source: ")))
> -     (list (cadr (assoc name package-archive-contents #'string=))
> -           (read-file-name "Clone into new or empty directory: " nil nil t nil
> -                           (lambda (dir) (or (not (file-exists-p dir))
> -                                             (directory-empty-p dir))))
> -           (and current-prefix-arg :last-release))))
> +   (let* ((name (package-vc--read-package-name "Fetch package source: "))
> +          (desc (cadr (assoc name package-archive-contents #'string=)))
> +          (dir (read-directory-name "Clone into new or empty directory: ")))
> +     (unless (or (not (file-exists-p dir))
> +                 (directory-empty-p dir))
> +       (let ((subdir (expand-file-name (package-desc-full-name desc) dir)))
> +         (if (and (not (file-exists-p subdir))
> +                  (y-or-n-p (format "Create new directory %s ?" subdir)))
> +             (setf dir subdir)

I'd prefer to use a setq here.

> +           (user-error "Directory not empty: %S" (expand-file-name dir)))))

This seems like an anti-feature to me, because you need to know what
directory is empty before confirming your choice, and if it is not
empty, you have to restart the entire command again.

> +     (list desc dir (and current-prefix-arg :last-release))))
>    (package-vc--archives-initialize)
>    (let ((pkg-spec (or (package-vc--desc->spec pkg-desc)
>                        (and-let* ((extras (package-desc-extras pkg-desc))