bug#48782: 28.0.50; fido-mode: shell variables distort find-file behaviour

[Dmitry Gutov <dgutov@yandex.ru>]

Joao, could you take a look?

On 01.06.2021 20:29, simon254--- via Bug reports for GNU Emacs, the 
Swiss army knife of text editors wrote:
> with emacs -Q
> 
> 1)
> M-x -> fido-mode
> C-x C-f -> type "$HOME" -> enter opens dired buffer in $HOME directory
> instead of continuing find-file $HOME to select a file to open
> 
> 2)
> similar thing happens if:
> M-x -> fido-mode
> C-x C-f -> type "$HOME/.emacs.d" -> enter opens dired buffer in $HOME/emacs.d directory
> instead of continuing find-file $HOME/emacs.d to select a file to open
> 
> in pure icomplete-mode find-file seems to work as expected after typing "$HOME/"
> -> descent into directories via C-M-i?
> 
> ido-mode will not match environment variables but when typing
> 
> M-x -> ido-mode
> C-x C-f -> type "$HOME/" -> ido expands $HOME to the actuall path and
> find-file continues as expected
> 
> ido.el has
> 
> (defun ido-complete ()
>    "Try and complete the current pattern amongst the file names."
>    (interactive)
>    (let (res)
>      (cond
>       (ido-incomplete-regexp
>        ;; Do nothing
>        )
>       ((and (memq ido-cur-item '(file dir))
> 	   (string-match "[$]" ido-text))
>        (let ((evar (substitute-in-file-name (concat ido-current-directory ido-text))))
> 	(if (not (file-exists-p (file-name-directory evar)))
> 	    (message "Expansion generates non-existing directory name")
> 	  (if (file-directory-p evar)
> 	      (ido-set-current-directory evar)
> 	    (let ((d (or (file-name-directory evar) "/"))
> 		  (f (file-name-nondirectory evar)))
> 	      (when (file-directory-p d)
> 		  (ido-set-current-directory d)
> 		  (setq ido-text-init f))))
> 	  (setq ido-exit 'refresh)
> 	  (exit-minibuffer))))