From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Ihor Radchenko Newsgroups: gmane.emacs.bugs Subject: bug#64596: 30.0.50; On FIXME: in src/buffer.c:1481 (force-mode-line-update) Date: Fri, 14 Jul 2023 11:53:02 +0000 Message-ID: <87bkgeiuap.fsf@localhost> References: <877cr4nez9.fsf@localhost> <83v8eo3pfv.fsf@gnu.org> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="10827"; mail-complaints-to="usenet@ciao.gmane.io" Cc: Stefan Monnier , 64596@debbugs.gnu.org To: Eli Zaretskii Original-X-From: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane-mx.org@gnu.org Fri Jul 14 13:54:21 2023 Return-path: Envelope-to: geb-bug-gnu-emacs@m.gmane-mx.org Original-Received: from lists.gnu.org ([209.51.188.17]) by ciao.gmane.io with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1qKHNM-0002cR-RQ for geb-bug-gnu-emacs@m.gmane-mx.org; Fri, 14 Jul 2023 13:54:20 +0200 Original-Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1qKHN6-0001JF-EF; Fri, 14 Jul 2023 07:54:04 -0400 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1qKHN5-0001Io-0o for bug-gnu-emacs@gnu.org; Fri, 14 Jul 2023 07:54:03 -0400 Original-Received: from debbugs.gnu.org ([2001:470:142:5::43]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1qKHN4-0002jQ-PS for bug-gnu-emacs@gnu.org; Fri, 14 Jul 2023 07:54:02 -0400 Original-Received: from Debian-debbugs by debbugs.gnu.org with local (Exim 4.84_2) (envelope-from ) id 1qKHN4-0005fr-CC for bug-gnu-emacs@gnu.org; Fri, 14 Jul 2023 07:54:02 -0400 X-Loop: help-debbugs@gnu.org Resent-From: Ihor Radchenko Original-Sender: "Debbugs-submit" Resent-CC: bug-gnu-emacs@gnu.org Resent-Date: Fri, 14 Jul 2023 11:54:02 +0000 Resent-Message-ID: Resent-Sender: help-debbugs@gnu.org X-GNU-PR-Message: followup 64596 X-GNU-PR-Package: emacs Original-Received: via spool by 64596-submit@debbugs.gnu.org id=B64596.168933558621744 (code B ref 64596); Fri, 14 Jul 2023 11:54:02 +0000 Original-Received: (at 64596) by debbugs.gnu.org; 14 Jul 2023 11:53:06 +0000 Original-Received: from localhost ([127.0.0.1]:41557 helo=debbugs.gnu.org) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from ) id 1qKHM9-0005ee-PK for submit@debbugs.gnu.org; Fri, 14 Jul 2023 07:53:06 -0400 Original-Received: from mout01.posteo.de ([185.67.36.65]:60659) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from ) id 1qKHM6-0005e8-CL for 64596@debbugs.gnu.org; Fri, 14 Jul 2023 07:53:04 -0400 Original-Received: from submission (posteo.de [185.67.36.169]) by mout01.posteo.de (Postfix) with ESMTPS id 5F715240027 for <64596@debbugs.gnu.org>; Fri, 14 Jul 2023 13:52:56 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=posteo.net; s=2017; t=1689335576; bh=fuDynePCm5w31s51KG9yzpJqO01WXcZnoJG2SAt3Bno=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version: Content-Transfer-Encoding:From; b=ImuoX09h/XGccc2YqVzqg9XP31Iv8CrZ0SuqjnxyGLQR92ZDyefBrZmyIprULhw9l j2zcpmA3lFfC/nzNCPvt+Wb2D7MmI/lvXykfgRd+zOXbKYjCfCXBs6fdjhhyzmRDN+ lCxlBDAuYm6HngA4kZNW1MrW9kmZ8ZeGbFzxPpMsAjTB4tmazev6Ng99c7jcAYt5mk ltzOEKu6YvmPGXMb0BAgWYBh5tCN4ml6VqZxG8oczOVqcBG/7ryT+u8RvTqBey3zJo 7Jej4T6JQUqiB2l3jVjZae2DT0noSPTJFW/HyLyFXHCJvY89kakaR8IiS1V5pFxsj5 H5K9mV9kxLnYA== Original-Received: from customer (localhost [127.0.0.1]) by submission (posteo.de) with ESMTPSA id 4R2VGb1G1pz9rxT; Fri, 14 Jul 2023 13:52:54 +0200 (CEST) In-Reply-To: <83v8eo3pfv.fsf@gnu.org> X-BeenThere: debbugs-submit@debbugs.gnu.org X-Mailman-Version: 2.1.18 Precedence: list X-BeenThere: bug-gnu-emacs@gnu.org List-Id: "Bug reports for GNU Emacs, the Swiss army knife of text editors" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane-mx.org@gnu.org Original-Sender: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane-mx.org@gnu.org Xref: news.gmane.io gmane.emacs.bugs:265083 Archived-At: Eli Zaretskii writes: >> AFAIU, the purpose of disabling redisplay optimizations is avoiding the >> situation when the modification flag is unset in the buffer, but the >> buffer was actually modified, and has to be redrawn. > > No, it's more subtle. In a nutshell, it is meant to prevent redisplay > from applying certain optimizations (search xdisp.c for the uses of > this flag). These optimizations are based on various assumptions, > such as that the current glyph matrix of the window is up-to-date. > Setting the prevent_redisplay_optimizations_p flag tells the display > engine that those assumptions are (or might be) false. I'm afraid that the very existence of prevent_redisplay_optimizations_p flag is a mistake hiding bugs with redisplay optimizations logic. Currently, redisplay_internal has a number of conditions used to determine if one or another optimization is safe to use + assertion that !prevent_redisplay_optimizations_p. When some code outside xdisp.c sets this flag, it is nothing but a statement: "I was lazy enough to update xdisp.c properly, so I just force bypassing optimizations". > Updating the mode line usually requires more thorough redisplay, > especially when the only reason for that is that some Lisp called > force-mode-line-update -- without setting that flag, the display > engine could easily decide that the window doesn't need to be redrawn. I have explored xdisp a bit and AFAIU, once we are in redisplay_window, mode line will be updated as long as update_mode_line is set (at least to UPDATE_SOME), except when current window is MINI_WINDOW_P (this code branch is not prevented by prevent_redisplay_optimizations_p though) or when we give up redisplaying. Calling redisplay_window may be prevented via needs_no_redisplay, unless we have buffer->text->redisplay, which is set in bset_update_mode_line. [ setting buffer->text->redisplay is rather awkward way to single mode line update though ] redisplay_window may also be postponed for frames that are not visible or that are obscured, but it appears to be by design and not influenced by prevent_redisplay_optimizations_p anyway =F0=9F=98=95 So, I see not why calling bset_update_mode_line is not sufficient to force mode line update in all windows associated with a single buffer. >> If my understanding is correct, >> current_buffer->prevent_redisplay_optimizations_p =3D true does not belo= ng >> to `force-mode-line-update', but rather to `restore-buffer-modified-p'. > > The purpose of force-mode-line-update is to do what its name says, > regardless of whether the buffer was modified or not, and how it was > modified. The idea is that Lisp programs which change something that > they know must affect the mode line call this function to make sure > the mode line is redrawn with up-to-date information. By contrast, > buffer modifications could be such that don't affect redisplay at all, > or allow redisplay to use some shortcuts and redraw only a very small > portion of the window. Then, why do we need to call Fforce_mode_line_update in set-buffer-modified-p? Wouldn't calling bset_redisplay be better? --=20 Ihor Radchenko // yantar92, Org mode contributor, Learn more about Org mode at . Support Org development at , or support my work at