bug#19032: 24.4; icomplete cannot select matches with C-x b with no input

[Ole Laursen <olau@iola.dk>]

Thanks!

I'm a former iswitchb user, and this problem keeps me from switching
to icomplete (I'm currently on ido-switch-buffer), even though I would
like to have access to more advanced completion.


Ole

Den tor. 13. aug. 2020 kl. 11.34 skrev Lars Ingebrigtsen <larsi@gnus.org>:
>
> Matthew Leach <matthew@mattleach.net> writes:
>
> >> Run emacs -Q, evaluate
> >>
> >>   (icomplete-mode 1)
> >>   (setq icomplete-show-matches-on-no-input t)
> >>
> >> Make sure you have three buffers, e.g. by finding three files. Then
> >> hit C-x b which should immediately show all buffers and use C-. or C-,
> >> to select any other buffer than  what the modeline declares to be the
> >> default, and hit C-j or RET.
> >>
> >> Emacs then switches to the default buffer instead of the selected buffer.
> >
> > I'm not sure if this is expected behaviour, since the "default" prompt
> > in the minibuffer doesn't disappear when cycling through results.
> > Nevertheless attached is a patch that fixes this.
>
> I've respun the patch for Emacs 28, and I think the new behaviour makes
> a lot more sense than the old behaviour, which I couldn't understand the
> point of at all.
>
> But I'm not an icomplete user, so perhaps the old behaviour is what
> people want?
>
> This also has possible ramifications for other completion styles
> (although only icomplete enables it with this patch), so I wonder
> whether Stefan has any comments here?
>
> diff --git a/lisp/icomplete.el b/lisp/icomplete.el
> index 3747ae3d28..e3f7043e2c 100644
> --- a/lisp/icomplete.el
> +++ b/lisp/icomplete.el
> @@ -432,6 +432,8 @@ icomplete-minibuffer-setup
>                                          (current-local-map)))
>      (add-hook 'pre-command-hook  #'icomplete-pre-command-hook  nil t)
>      (add-hook 'post-command-hook #'icomplete-post-command-hook nil t)
> +    (when icomplete-show-matches-on-no-input
> +      (setq-local completion-use-stored-completions-when-no-input t))
>      (run-hooks 'icomplete-minibuffer-setup-hook)))
>
>  (defvar icomplete--in-region-buffer nil)
> diff --git a/lisp/minibuffer.el b/lisp/minibuffer.el
> index d2c3f9045e..c3e5440956 100644
> --- a/lisp/minibuffer.el
> +++ b/lisp/minibuffer.el
> @@ -1126,6 +1126,7 @@ completion--cycle-threshold
>  (defvar-local completion-all-sorted-completions nil)
>  (defvar-local completion--all-sorted-completions-location nil)
>  (defvar completion-cycling nil)      ;Function that takes down the cycling map.
> +(defvar completion-use-stored-completions-when-no-input nil)
>
>  (defvar completion-fail-discreetly nil
>    "If non-nil, stay quiet when there  is no match.")
> @@ -1510,8 +1511,15 @@ completion--complete-and-exit
>  COMPLETION-FUNCTION is called if the current buffer's content does not
>  appear to be a match."
>      (cond
> -     ;; Allow user to specify null string
> -   ((= beg end) (funcall exit-function))
> +     ;; Allow user to specify null string.  In the case that
> +     ;; `completion-use-stored-completions-when-no-input' is t, use
> +     ;; the car of `completion-all-sorted-completions' as the
> +     ;; candidate.
> +     ((= beg end)
> +      (when completion-use-stored-completions-when-no-input
> +        (completion--replace beg end (car completion-all-sorted-completions)))
> +      (funcall exit-function))
> +
>       ((test-completion (buffer-substring beg end)
>                         minibuffer-completion-table
>                         minibuffer-completion-predicate)
>
>
> --
> (domestic pets only, the antidote for overdose, milk.)
>    bloggy blog: http://lars.ingebrigtsen.no