From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: Stefan Monnier Newsgroups: gmane.emacs.devel Subject: Re: [Emacs-diffs] emacs-24 d69e9f1: CC Mode: Stop Font Lock forcing fontification from BOL. Fixes debbugs#19669. Date: Mon, 02 Feb 2015 13:54:20 -0500 Message-ID: References: <20150201212213.17840.3710@vcs.savannah.gnu.org> NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain X-Trace: ger.gmane.org 1422903281 16352 80.91.229.3 (2 Feb 2015 18:54:41 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Mon, 2 Feb 2015 18:54:41 +0000 (UTC) Cc: Alan Mackenzie To: emacs-devel@gnu.org Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Mon Feb 02 19:54:40 2015 Return-path: Envelope-to: ged-emacs-devel@m.gmane.org Original-Received: from lists.gnu.org ([208.118.235.17]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1YIM8s-0006Pm-RM for ged-emacs-devel@m.gmane.org; Mon, 02 Feb 2015 19:54:38 +0100 Original-Received: from localhost ([::1]:56061 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YIM8r-00038w-Rv for ged-emacs-devel@m.gmane.org; Mon, 02 Feb 2015 13:54:37 -0500 Original-Received: from eggs.gnu.org ([2001:4830:134:3::10]:43504) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YIM8e-00038r-EE for emacs-devel@gnu.org; Mon, 02 Feb 2015 13:54:25 -0500 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1YIM8b-0007uy-8M for emacs-devel@gnu.org; Mon, 02 Feb 2015 13:54:24 -0500 Original-Received: from ironport2-out.teksavvy.com ([206.248.154.181]:30715) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YIM8b-0007uq-4O for emacs-devel@gnu.org; Mon, 02 Feb 2015 13:54:21 -0500 X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: AskIAOwQflRsoX+8/2dsb2JhbABbgweDYMp3BAICgSQXAQEBAQEBfIQDAQEEViMQCzQHCxQYDYh31lkBAQEBBgEBAQEekG8HFoQyBYsBnRCHHoF4gjeBYiGCdwEBAQ X-IPAS-Result: AskIAOwQflRsoX+8/2dsb2JhbABbgweDYMp3BAICgSQXAQEBAQEBfIQDAQEEViMQCzQHCxQYDYh31lkBAQEBBgEBAQEekG8HFoQyBYsBnRCHHoF4gjeBYiGCdwEBAQ X-IronPort-AV: E=Sophos;i="5.07,502,1413259200"; d="scan'208";a="109472336" Original-Received: from 108-161-127-188.dsl.teksavvy.com (HELO ceviche.home) ([108.161.127.188]) by ironport2-out.teksavvy.com with ESMTP/TLS/DHE-RSA-AES256-SHA; 02 Feb 2015 13:54:20 -0500 Original-Received: by ceviche.home (Postfix, from userid 20848) id 4D45F66100; Mon, 2 Feb 2015 13:54:20 -0500 (EST) In-Reply-To: (Alan Mackenzie's message of "Sun, 01 Feb 2015 21:22:13 +0000") User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/25.0.50 (gnu/linux) X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. X-Received-From: 206.248.154.181 X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: "Emacs development discussions." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Original-Sender: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Xref: news.gmane.org gmane.emacs.devel:182283 Archived-At: > + ;; Prevent `font-lock-default-fontify-region' extending the region it will > + ;; fontify to whole lines by removing `font-lock-extend-region-whole-lines' > + ;; (and, coincidentally, `font-lock-extend-region-multiline' (which we do > + ;; not need)) from `font-lock-extend-region-functions'. (Emacs only). This > + ;; fixes Emacs bug #19669. My general understanding of font-lock's highlighting is that using a smaller region is only ever useful for performance reason, rather than for correctness (and this line of thinking influences the design of the code). So I'm really curious to understand how this counter-example works, since it might hint at further (latent) bugs elsewhere. Can you walk me through what happens in the scenario of bug#19669? Stefan