GNU bug report logs - #64394
[PATCH] Fix `async-shell-command-display-buffer' display

Previous Next

Full log

Message #23 received at 64394 <at> debbugs.gnu.org (full text, mbox):

From: Juri Linkov <juri <at> linkov.net>
To: martin rudalics <rudalics <at> gmx.at>
Cc: Eliza Velasquez <eliza <at> eliza.sh>, Eli Zaretskii <eliz <at> gnu.org>,
 64394 <at> debbugs.gnu.org
Subject: Re: bug#64394: [PATCH] Fix `async-shell-command-display-buffer'
 display
Date: Sun, 02 Jul 2023 21:03:58 +0300

>>> I'm probably missing something, but how can display-buffer fail to
>>> support any action function, such as display-buffer-no-window?
>>>
>>> Martin, what am I missing here?
>
> We may have to ask Juri, he conceived the "allow-no-window" concept.

I don't remember the details why we decided to design it that way.
But now I don't see why not enable allow-no-window by default,
i.e. why not to make it opt-out instead of opt-in.

>> Technically it seems that you can add `(allow-no-window . t)' to
>> `display-buffer-alist' to always force the buffer never to appear, but
>> that doesn't seem at all like its intended use.
>
> Maybe "force" is too strong here.  You can "force" it by adding an
> 'allow-no-window' entry to the alist _and_ a 'display-buffer-no-window'
> action in a position that precedes any other display buffer action.

Indeed, it's possible to add 'allow-no-window' in customization:

  (setq display-buffer-alist
        '(("\\*Async Shell Command\\*"
           display-buffer-no-window
           (allow-no-window . t))))
  (setq async-shell-command-display-buffer nil)

> I suppose (Juri will correct me) that this snippet in 'shell-command'
>
>                 (if async-shell-command-display-buffer
>                     ;; Display buffer immediately.
>                     (display-buffer buffer '(nil (allow-no-window . t))) <<<<<
>                   ;; Defer displaying buffer until first process output.
>                   ;; Use disposable named advice so that the buffer is
>                   ;; displayed at most once per process lifetime.
>                   (let ((nonce (make-symbol "nonce")))
>                     (add-function :before (process-filter proc)
>                                   (lambda (proc _string)
>                                     (let ((buf (process-buffer proc)))
>                                       (when (buffer-live-p buf)
>                                         (remove-function (process-filter proc)
>                                                          nonce)
>                                         (display-buffer buf)))) <<<<<
>                                   `((name . ,nonce)))))))
>
> adding an 'allow-no-window' entry if and only if
> 'async-shell-command-display-buffer' is non-nil is responsible for the
> behavior Eliza sees.  I have no idea whether adding such an entry in the
> second case could cause problems.  We could give
> 'async-shell-command-display-buffer' a third value, say 'allow-no-window
> and, if a user has set it to that value, have 'shell-command' add an
> 'allow-no-window' entry in the second case too.

I think it's a plain bug that the first call of 'display-buffer'
sets 'allow-no-window' to t, but the second call doesn't.

These two 'display-buffer' calls were intended to do the same thing.
Only the second call is delayed until input arrives.

Previous Next

GNU bug tracking system
Copyright (C) 1999 Darren O. Benham, 1997,2003 nCipher Corporation Ltd, 1994-97 Ian Jackson.