bug#34272: 26.1.91 M-x flyspell-mode

[Eli Zaretskii]

> Date: Sat, 09 Feb 2019 18:48:31 +0900 (JST)
> Cc: homeros.misasa@gmail.com, 34272@debbugs.gnu.org,
>  tkk@misasa.okayama-u.ac.jp
> From: Tak Kunihiro <tkk@misasa.okayama-u.ac.jp>
> 
> I think that I found issue.  In my environment, `ispell-call-process'
> returns empty string with `null-device'.

That's strange.  What is the value of null-device on your system?

> * With `null-device'
> 
> (with-temp-buffer
>   (ispell-call-process ispell-program-name
>                                      null-device
>                                      t
>                                      nil
>                        ;; Hunspell 1.7.0 (and later?) won't
>                        ;; show LOADED DICTIONARY unless
>                        ;; there's at least one file argument
>                        ;; on the command line.  So we feed
>                        ;; it with the null device.
>                                      "-D" null-device)
>   (buffer-string))                      ; => ""

Did you make sure ispell-program-name is set to "hunspell" when you
evaluated the above form?  Its default value is something else.