bug#68801: 30.0.50; minibuffer-visible-completions=t makes RET in completion-in-region a no-op with nothing selected

[Spencer Baugh <sbaugh@janestreet.com>]

sbaugh@catern.com writes:
>>> Alternatively... as a completely separate point, I'd like
>>> completion-in-region to select the first completion candidate by
>>> default.  I think that's useful in some cases and, for
>>> completion-in-region, doesn't have any negatives: we couldn't do it in
>>> the minibuffer because it would interfere with accepting the default,
>>> but there are no defaults in completion-in-region.
>>>
>>> If we make c-i-r select the first completion candidate by default, that
>>> would both:
>>>
>>> - Make the completion-show-help help render correctly with the "only
>>>   override RET when there's a selected completion" patch.
>>>
>>> - Partially mitigate the RET issue all on its own
>>
>> Calling 'first-completion' makes sense even for the minibuffer,
>> at least optionally.
>
> What about this simple patch?
>
> If minibuffer-visible-completions=nil, it just calls first-completion.
> This doesn't meaningfully change anything, since previously M-RET would
> just no-op in that situation.  And it's actually quite useful, because
> it makes M-RET useful without having to ever actually do M-<down>; one
> can just type text to narrow the completions and then hit M-RET.  Which
> is sometimes nice.
>
> If minibuffer-visible-completions=t, it calls first-completion only when
> there's no minibuffer-default; that way a simple RET will still select
> the minibuffer default.
>
> diff --git a/lisp/simple.el b/lisp/simple.el
> index 8246b9cab81..715ab672655 100644
> --- a/lisp/simple.el
> +++ b/lisp/simple.el
> @@ -10355,7 +10355,10 @@ completion-setup-function
>                       "Type \\[minibuffer-choose-completion] on a completion to select it.\n")))
>            (insert (substitute-command-keys
>  		   "Type \\[minibuffer-next-completion] or \\[minibuffer-previous-completion] \
> -to move point between completions.\n\n")))))))
> +to move point between completions.\n\n"))))
> +      (unless (and minibuffer-visible-completions minibuffer-default)
> +        (with-minibuffer-completions-window
> +          (first-completion))))))
>  
>  (add-hook 'completion-setup-hook #'completion-setup-function)
>  

I found selecting first-completion in the minibuffer to be annoying, so
now I'm trying with the following instead (which also fixes the
highlight to actually be shown):

(defun minibuffer-cir-first-completion ()
  "Move point to the first completion in the *Completions* window."
  (when completion-in-region-mode
    (with-selected-window (get-buffer-window standard-output 0)
      (when completions-highlight-face
        (setq-local cursor-face-highlight-nonselected-window t))
      (first-completion))))
(add-hook 'completion-setup-hook #'minibuffer-cir-first-completion 90)