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From: Lars Ingebrigtsen <larsi@HIDDEN>
To: Allen Li <darkfeline@HIDDEN>
Subject: Re: 26.1; Re-running shell wipes font-lock from xterm-color
References: <CADbSrJwFuELWfZHNiSyPKWDMsBZRt3UaZT4m7rmKL+zdeNbnoQ@HIDDEN>
Date: Wed, 30 Oct 2019 20:18:13 +0100
In-Reply-To: <CADbSrJwFuELWfZHNiSyPKWDMsBZRt3UaZT4m7rmKL+zdeNbnoQ@HIDDEN>
(Allen Li's message of "Fri, 19 Oct 2018 00:16:48 -0700")
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Content preview: Allen Li <darkfeline@HIDDEN> writes: > The `shell'
command will call `make-comint-in-buffer' and `shell-mode'. > > `shell-mode'
will then call `comint-mode' as a derived mode. > > `comint-mode' will call
`kill-all-local-variables'. > > ` [...]
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Allen Li <darkfeline@HIDDEN> writes:
> The `shell' command will call `make-comint-in-buffer' and `shell-mode'.
>
> `shell-mode' will then call `comint-mode' as a derived mode.
>
> `comint-mode' will call `kill-all-local-variables'.
>
> `comint-mode' also adds `font-lock-defontify' to
> `change-major-mode-hook'. Since we're already in `shell-mode' derived
> from `comint-mode', switching "back" to `shell-mode' wipes font-lock.
>
> I can work around this pretty easily in my personal config, by removing
> `font-lock-defontify' from `change-major-mode-hook' with a well-placed
> advice, but the current behavior doesn't seem comfortable to me.
Yes, that seems odd. Unfortunately the commit log for this just says:
commit 3dd4c1c5af3cdf77ba98b7255ec4034051107c6f
Author: Richard M. Stallman <rms@HIDDEN>
Date: Tue Sep 10 16:44:58 2002 +0000
(comint-mode): Add font-lock-defontify to change-major-mode-hook.
So I have no idea what this was supposed to fix. Richard, do you
remember, by any chance?
--
(domestic pets only, the antidote for overdose, milk.)
bloggy blog: http://lars.ingebrigtsen.no
bug-gnu-emacs@HIDDEN:bug#33092; Package emacs.
Full text available.Received: (at submit) by debbugs.gnu.org; 19 Oct 2018 07:17:18 +0000 From debbugs-submit-bounces <at> debbugs.gnu.org Fri Oct 19 03:17:18 2018 Received: from localhost ([127.0.0.1]:58056 helo=debbugs.gnu.org) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from <debbugs-submit-bounces <at> debbugs.gnu.org>) id 1gDP26-0006xI-F6 for submit <at> debbugs.gnu.org; Fri, 19 Oct 2018 03:17:18 -0400 Received: from eggs.gnu.org ([208.118.235.92]:43874) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from <darkfeline@HIDDEN>) id 1gDP25-0006x4-7d for submit <at> debbugs.gnu.org; Fri, 19 Oct 2018 03:17:17 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from <darkfeline@HIDDEN>) id 1gDP1y-0001Up-32 for submit <at> debbugs.gnu.org; Fri, 19 Oct 2018 03:17:11 -0400 X-Spam-Checker-Version: SpamAssassin 3.3.2 (2011-06-06) on eggs.gnu.org X-Spam-Level: X-Spam-Status: No, score=-0.0 required=5.0 tests=BAYES_20 autolearn=disabled version=3.3.2 Received: from lists.gnu.org ([2001:4830:134:3::11]:47001) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from <darkfeline@HIDDEN>) id 1gDP1v-0001SP-8g for submit <at> debbugs.gnu.org; Fri, 19 Oct 2018 03:17:08 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:53463) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from <darkfeline@HIDDEN>) id 1gDP1u-0007jo-A7 for bug-gnu-emacs@HIDDEN; Fri, 19 Oct 2018 03:17:07 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from <darkfeline@HIDDEN>) id 1gDP1r-0001OQ-Li for bug-gnu-emacs@HIDDEN; Fri, 19 Oct 2018 03:17:04 -0400 Received: from mail-wm1-x32b.google.com ([2a00:1450:4864:20::32b]:55379) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from <darkfeline@HIDDEN>) id 1gDP1r-0001Lb-7L for bug-gnu-emacs@HIDDEN; Fri, 19 Oct 2018 03:17:03 -0400 Received: by mail-wm1-x32b.google.com with SMTP id 206-v6so2547371wmb.5 for <bug-gnu-emacs@HIDDEN>; Fri, 19 Oct 2018 00:17:02 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=felesatra-moe.20150623.gappssmtp.com; s=20150623; h=mime-version:from:date:message-id:subject:to; bh=KeymhNhCyoGzxpEezH4+Yx9OGvSy587lube8SaGkqk8=; b=Zg90YazCWOYRBD6YIwfLd3BLxYimLTDRw6CdwTKgih2+WtWS2sV/d+PoIum1QGap+7 boew7ThnuHu0tXD+I7n7MgHKsK/CpoIKgGaPb0h1U5SHtMN6Zk07seJgOXeVjC4D90Yy sbCvWbynMbrwR71W6IndfoAx4ZVz7eufXV+NZ2UiWQChqihfB0UNydZE6Pae/dKL2g/G Ex2kDFPOr8oBR8El0wO31NvApI9CQMJG+4wpX1IMGdApwfuTiffeTaMtpgMZu9mnViTV qUYZEpwZswcSlzCTYjXqn5UHwGITPoD+CWBBzgxaY4CpT+ZzQu48M5RBVgCY1lOY1cY7 /9RQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:from:date:message-id:subject:to; bh=KeymhNhCyoGzxpEezH4+Yx9OGvSy587lube8SaGkqk8=; b=Lstiivq6OASwnWFUPwvTGaVNZAu8zH5xIsNNcpaWCHObpyHD8KsAV5n2Bjn09Uov+X 17tVX/1ycSEVd0SleaC9G+6Ukdw0wb3zoz+Ox76ZtwOHxJF4USxanv267dqRz+45Yo1U BTmbvSEu+XqFQ2DrFT0CWBO38Q09U/MxfE2hvWEVhSnzlZkzvk5CQvBOFkEUXdMIK7qf J+Z4bzCkpT9KkvdXx8ka5H3OWXzvbpV6F2U/xAKy2aLncWQKqtd3GVHIpswTD302PVoi r6JA9bRWr26fxiH/cU7jaqtdPZ/SoK4i0kAzIdaEdhLE7k24jh2QRPJTKC9W5aDf2KL9 QMMg== X-Gm-Message-State: ABuFfog4m170wduSY3UhoEGVbnNBQ6PZhbUkj5vl0TJfh5v+VbNNx/1W Ewb0skMiI0+lVIDsLJ0FVS6uAAUTEyUwPDS3GjJVe+VfyNE= X-Google-Smtp-Source: ACcGV63HzK2IM4xMy9PVVqmAhxYlVxQ6uLdYF20MgiQ9DWn2tBEu5hk65q0EIQE2u89fBRWLtE/w3MKirerPLTXYyCE= X-Received: by 2002:a1c:2bc3:: with SMTP id r186-v6mr3729707wmr.51.1539933420997; Fri, 19 Oct 2018 00:17:00 -0700 (PDT) MIME-Version: 1.0 From: Allen Li <darkfeline@HIDDEN> Date: Fri, 19 Oct 2018 00:16:48 -0700 Message-ID: <CADbSrJwFuELWfZHNiSyPKWDMsBZRt3UaZT4m7rmKL+zdeNbnoQ@HIDDEN> Subject: 26.1; Re-running shell wipes font-lock from xterm-color To: bug-gnu-emacs@HIDDEN Content-Type: text/plain; charset="UTF-8" X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.6.x X-Received-From: 2001:4830:134:3::11 X-Spam-Score: -4.0 (----) X-Debbugs-Envelope-To: submit X-BeenThere: debbugs-submit <at> debbugs.gnu.org X-Mailman-Version: 2.1.18 Precedence: list List-Id: <debbugs-submit.debbugs.gnu.org> List-Unsubscribe: <https://debbugs.gnu.org/cgi-bin/mailman/options/debbugs-submit>, <mailto:debbugs-submit-request <at> debbugs.gnu.org?subject=unsubscribe> List-Archive: <https://debbugs.gnu.org/cgi-bin/mailman/private/debbugs-submit/> List-Post: <mailto:debbugs-submit <at> debbugs.gnu.org> List-Help: <mailto:debbugs-submit-request <at> debbugs.gnu.org?subject=help> List-Subscribe: <https://debbugs.gnu.org/cgi-bin/mailman/listinfo/debbugs-submit>, <mailto:debbugs-submit-request <at> debbugs.gnu.org?subject=subscribe> Errors-To: debbugs-submit-bounces <at> debbugs.gnu.org Sender: "Debbugs-submit" <debbugs-submit-bounces <at> debbugs.gnu.org> X-Spam-Score: -5.0 (-----) Where to begin? The problem I am having is that when there is already a *shell* buffer without a running process, re-running the `shell' command will reuse the buffer and wipe the font-lock color added by xterm-color.el, a third-party package. I'm reporting this here because it seems like Emacs could be improved in some way to avoid this class of problem. What causes this is as follows: The `shell' command will call `make-comint-in-buffer' and `shell-mode'. `shell-mode' will then call `comint-mode' as a derived mode. `comint-mode' will call `kill-all-local-variables'. `comint-mode' also adds `font-lock-defontify' to `change-major-mode-hook'. Since we're already in `shell-mode' derived from `comint-mode', switching "back" to `shell-mode' wipes font-lock. I can work around this pretty easily in my personal config, by removing `font-lock-defontify' from `change-major-mode-hook' with a well-placed advice, but the current behavior doesn't seem comfortable to me. First, if we're reusing the buffer, do we have to switch to `shell-mode' again? The advantage is that it clears out some buffer state, so it's kind of like running a "fresh" `shell'. But the existing output in the buffer isn't cleared (although it is defontified as I found out to my dismay). The `default-directory' isn't reset either; normally running `shell' starts the shell with the `default-directory' of the buffer of your current window, but not if it reuses a *shell* buffer. So the current behavior of `shell', if it reuses the *shell* buffer, is to do a half-hearted reset of the buffer state. As a user this is very hard to understand and I certainly would not have understood it had I not taken Edebug to the problem. `shell' should either fully reset the buffer or touch as little as possible. The reset option is indistinguishable from killing the existing *shell* buffer and creating a new one. Therefore, if we are going to reuse the buffer, I think the desired intent would be to touch as little as possible, in which case we want to avoid the `shell-mode' reset if we are reusing the *shell* buffer. In GNU Emacs 26.1 (build 1, x86_64-pc-linux-gnu, GTK+ Version 3.22.30) of 2018-07-05 built on juergen Windowing system distributor 'The X.Org Foundation', version 11.0.12001000 Configured using: 'configure --prefix=/usr --sysconfdir=/etc --libexecdir=/usr/lib --localstatedir=/var --with-x-toolkit=gtk3 --with-xft --with-modules 'CFLAGS=-march=x86-64 -mtune=generic -O2 -pipe -fstack-protector-strong -fno-plt' CPPFLAGS=-D_FORTIFY_SOURCE=2 LDFLAGS=-Wl,-O1,--sort-common,--as-needed,-z,relro,-z,now' Configured features: XPM JPEG TIFF GIF PNG RSVG IMAGEMAGICK SOUND GPM DBUS GSETTINGS NOTIFY ACL GNUTLS LIBXML2 FREETYPE M17N_FLT LIBOTF XFT ZLIB TOOLKIT_SCROLL_BARS GTK3 X11 MODULES THREADS LIBSYSTEMD LCMS2 Important settings: value of $LANG: en_US.UTF-8 locale-coding-system: utf-8-unix
Allen Li <darkfeline@HIDDEN>:bug-gnu-emacs@HIDDEN.
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