bug#74191: 31.0.50; file-directory-p broken when minibuffer-completing-file-name is non nil

[Michael Albinus via "Bug reports for GNU Emacs, the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>]

Thierry Volpiatto <thievol@posteo.net> writes:

> Hi Michael,

Hi Thierry,

>>> In Emacs-30+:
>>>
>>> (let ((minibuffer-completing-file-name t)) (file-directory-p "/ssh"))
>>> => t
>>>
>>> which is wrong obviously.
>>
>> No, it isn't. It is intended.
>
> Hmm, It is perhaps intended and I believe it fixes some problem, but it is
> wrong anyway, "/ssh" is NOT a directory.

Nobody says so. Remember, we're in file name completion, and Tramp must
trigger some action from the completion machinery. A non-nil return of
file-directory-p is such a trigger.

> Can I use file-attributes instead or it is affected as well?

Should work. Check tramp-completion-file-name-handler-alist. It cares
only about

--8<---------------cut here---------------start------------->8---
((expand-file-name . tramp-completion-handle-expand-file-name)
 (file-directory-p . tramp-completion-handle-file-directory-p)
 (file-exists-p . tramp-completion-handle-file-exists-p)
 (file-name-all-completions . tramp-completion-handle-file-name-all-completions)
 (file-name-completion . tramp-completion-handle-file-name-completion)
 (file-name-directory . tramp-completion-handle-file-name-directory)
 (file-name-nondirectory . tramp-completion-handle-file-name-nondirectory))
--8<---------------cut here---------------end--------------->8---

Alternatively, you could bind temporarily tramp-mode to nil. See
tramp-completion-file-name-handler:

--8<---------------cut here---------------start------------->8---
  (if-let*
      ((fn (and tramp-mode minibuffer-completing-file-name
		(assoc operation tramp-completion-file-name-handler-alist))))
      (save-match-data (apply (cdr fn) args))
    (tramp-run-real-handler operation args)))
--8<---------------cut here---------------end--------------->8---

> Thanks.

Best regards, Michael.