From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!.POSTED.blaine.gmane.org!not-for-mail From: Keith David Bershatsky Newsgroups: gmane.emacs.devel Subject: Re: Debugging printing to stderr prior glyph row values .... Date: Fri, 24 May 2019 07:56:25 -0700 Message-ID: Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Injection-Info: blaine.gmane.org; posting-host="blaine.gmane.org:195.159.176.226"; logging-data="106294"; mail-complaints-to="usenet@blaine.gmane.org" Cc: emacs-devel@gnu.org To: Eli Zaretskii Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Fri May 24 17:10:41 2019 Return-path: Envelope-to: ged-emacs-devel@m.gmane.org Original-Received: from lists.gnu.org ([209.51.188.17]) by blaine.gmane.org with esmtps (TLS1.0:RSA_AES_256_CBC_SHA1:256) (Exim 4.89) (envelope-from ) id 1hUBqC-000RW6-B7 for ged-emacs-devel@m.gmane.org; Fri, 24 May 2019 17:10:40 +0200 Original-Received: from localhost ([127.0.0.1]:55991 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1hUBqB-0006GS-82 for ged-emacs-devel@m.gmane.org; Fri, 24 May 2019 11:10:39 -0400 Original-Received: from eggs.gnu.org ([209.51.188.92]:53749) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1hUBo9-0004mO-5g for emacs-devel@gnu.org; Fri, 24 May 2019 11:08:34 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hUBcd-00011x-9R for emacs-devel@gnu.org; Fri, 24 May 2019 10:56:40 -0400 Original-Received: from gateway24.websitewelcome.com ([192.185.51.209]:44736) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1hUBcc-0000sH-Rs for emacs-devel@gnu.org; Fri, 24 May 2019 10:56:39 -0400 Original-Received: from cm14.websitewelcome.com (cm14.websitewelcome.com [100.42.49.7]) by gateway24.websitewelcome.com (Postfix) with ESMTP id 1D8C73578 for ; Fri, 24 May 2019 09:56:27 -0500 (CDT) Original-Received: from gator3053.hostgator.com ([50.87.144.69]) by cmsmtp with SMTP id UBcQhY7LM2qH7UBcQhmqKs; Fri, 24 May 2019 09:56:27 -0500 X-Authority-Reason: nr=8 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lawlist.com ; s=default; h=Content-Type:MIME-Version:Subject:Cc:To:From:Message-ID:Date: Sender:Reply-To:Content-Transfer-Encoding:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: In-Reply-To:References:List-Id:List-Help:List-Unsubscribe:List-Subscribe: List-Post:List-Owner:List-Archive; bh=uyIl9YUxyrk+4LHSbzz1sDufhZmIVb/GTThgFEDiYSE=; b=eJH0lJE6a/Ys9GaSqgjwmGR2RT pZH+o4n7Roh5HJff/hHKEPMDlUeAJRYiQuF8fdysEfVE4maPdjv8oMeiH/KwlJpdda9W/wzTA8dKn 4tojkyVA6HXOp+Z8iZfnXa/HGvg+k3ONqBSgjeobkLDxnPKortpQov5OdvvP+s/9q7yNcJ84rS8oi Ln7TaSvbnkxIuBRFl9nmRyvtEBdWnOcfoofpgPoMsk3x1YGTdTdgBN7S4tGAh0HgLzYMk4P9JgUfn XsLi65oKumxPS+vcwtJyWqmpnS8tEj2sKt+TFpTZmfnbo8aehN1ru/xOWJhyA29U0SlKf96KtOaiq RIKr/p2g==; Original-Received: from cpe-45-48-239-195.socal.res.rr.com ([45.48.239.195]:49377 helo=server.local) by gator3053.hostgator.com with esmtpsa (TLSv1:DHE-RSA-AES256-SHA:256) (Exim 4.91) (envelope-from ) id 1hUBcQ-00055d-Bx; Fri, 24 May 2019 09:56:26 -0500 X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - gator3053.hostgator.com X-AntiAbuse: Original Domain - gnu.org X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - lawlist.com X-BWhitelist: no X-Source-IP: 45.48.239.195 X-Source-L: No X-Exim-ID: 1hUBcQ-00055d-Bx X-Source-Sender: cpe-45-48-239-195.socal.res.rr.com (server.local) [45.48.239.195]:49377 X-Source-Auth: lawlist X-Email-Count: 3 X-Source-Cap: bGF3bGlzdDtsYXdsaXN0O2dhdG9yMzA1My5ob3N0Z2F0b3IuY29t X-Local-Domain: yes X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 192.185.51.209 X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.21 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" Xref: news.gmane.org gmane.emacs.devel:236962 Archived-At: Thank you, Eli, for teaching me how to debug this particular issue and also how to avoid crashes of this nature in the future. I was unaware that an enabled_p (true) row could have zero glyphs. Now that I know this is possible, I can programmatically deal with it. Inasmuch as rows following a row with _only_ ZV contain an ends_at_zv_p flag that is also true, and because there may be no guarantee that the preceding row in the matrix can be relied upon to ascertain whether it ends at ZV, I believe a new flag would be helpful (at least in this particular context) -- i.e., beyond_zv_p versus ends_at_zv_p. That way, only one row in the entire matrix will have a flag that indicates an at-ZV versus a post-ZV situation. I'll spend some time on Saturday digging around xdisp.c ... ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; > Date: [05-23-2019 23:45:44] <24 May 2019 09:45:44 +0300> > From: Eli Zaretskii > To: Keith David Bershatsky > CC: emacs-devel@gnu.org > Subject: Re: Debugging printing to stderr prior glyph row values .... > > > Date: Thu, 23 May 2019 17:03:36 -0700 > > From: Keith David Bershatsky > > Cc: emacs-devel@gnu.org > > > > I got it to crash ... again. "pgrowx previous_row" from gdb prints nothing and returns to a new gdb command prompt. > > This means the previous glyph row had its 'used' member equal to zero. > > > [CAVEAT: I wanted a crash, so I did not insert a test for the 'used' member being greater than zero.] > > And it shows: > > > (gdb) print *previous_row > > $3 = { > > glyphs = {0x11a800000, 0x11a800000, 0x11a803520, 0x11a803520}, > > used = {0, 0, 0, 0}, > > See? all of the 'used' members are zero. IOW, there are no glyphs in > that row.