Subject: Re: bug#66187: read-file-name unexpected behavior when MUSTMATCH is a function

From: Stefan Monnier <[email-masked]>
Date: Sun, 28 Jan 2024 14:20:47 -0500

> Ping!  I hope a fix like this can be merged into Emacs 29 still :)

Duh, I can't believe I left you waiting for so long, this is awful.
I just pushed this to `emacs-29`, thank you.
I hope there might still be a next time, so I get a chance to do better.

        Stefan

> From 609bf4964f88b01f4843e29b2cf71ee1cd2f6125 Mon Sep 17 00:00:00 2001
> From: Joseph Turner <[email-masked]>
> Date: Sun, 12 Nov 2023 13:21:50 -0800
> Subject: [PATCH] Fix completing-read functional REQUIRE-MATCH behavior
>
> * lisp/minibuffer.el (completion--complete-and-exit): If
> minibuffer-completion-confirm is a function which returns nil,
> immediately fail to complete.
>
> See bug#66187.
> ---
>  lisp/minibuffer.el | 11 +++++++----
>  1 file changed, 7 insertions(+), 4 deletions(-)
>
> diff --git a/lisp/minibuffer.el b/lisp/minibuffer.el
> index 3e30b68d5e9..9fad3e71fad 100644
> --- a/lisp/minibuffer.el
> +++ b/lisp/minibuffer.el
> @@ -1847,10 +1847,13 @@ appear to be a match."
>     ;; Allow user to specify null string
>     ((= beg end) (funcall exit-function))
>     ;; The CONFIRM argument is a predicate.
> -   ((and (functionp minibuffer-completion-confirm)
> -         (funcall minibuffer-completion-confirm
> -                  (buffer-substring beg end)))
> -    (funcall exit-function))
> +   ((functionp minibuffer-completion-confirm)
> +    (if (funcall minibuffer-completion-confirm
> +                 (buffer-substring beg end))
> +        (funcall exit-function)
> +      (unless completion-fail-discreetly
> +	(ding)
> +	(completion--message "No match"))))
>     ;; See if we have a completion from the table.
>     ((test-completion (buffer-substring beg end)
>                       minibuffer-completion-table