From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 29694 invoked by alias); 16 Apr 2012 14:58:03 -0000 Received: (qmail 29686 invoked by uid 22791); 16 Apr 2012 14:58:02 -0000 X-SWARE-Spam-Status: No, hits=-7.2 required=5.0 tests=AWL,BAYES_00,KHOP_RCVD_UNTRUST,KHOP_THREADED,RCVD_IN_DNSWL_HI,RCVD_IN_HOSTKARMA_W,SPF_HELO_PASS,TW_EG,T_RP_MATCHES_RCVD X-Spam-Check-By: sourceware.org Received: from mx1.redhat.com (HELO mx1.redhat.com) (209.132.183.28) by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Mon, 16 Apr 2012 14:57:44 +0000 Received: from int-mx11.intmail.prod.int.phx2.redhat.com (int-mx11.intmail.prod.int.phx2.redhat.com [10.5.11.24]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id q3GEvM0g014973 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK); Mon, 16 Apr 2012 10:57:22 -0400 Received: from [127.0.0.1] (ovpn01.gateway.prod.ext.phx2.redhat.com [10.5.9.1]) by int-mx11.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id q3GEvKDY032163; Mon, 16 Apr 2012 10:57:21 -0400 Message-ID: <4F8C3350.1030601@redhat.com> Date: Mon, 16 Apr 2012 15:03:00 -0000 From: Pedro Alves User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:11.0) Gecko/20120329 Thunderbird/11.0.1 MIME-Version: 1.0 To: Joel Brobecker CC: Doug Evans , gdb-patches@sourceware.org Subject: Re: [RFA] Ensure result of make_cleanup is never NULL. References: <20120416144011.GH2852@adacore.com> In-Reply-To: <20120416144011.GH2852@adacore.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Mailing-List: contact gdb-patches-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-patches-owner@sourceware.org X-SW-Source: 2012-04/txt/msg00418.txt.bz2 On 04/16/2012 03:40 PM, Joel Brobecker wrote: >> +/* A fencepost used to mark the end of a cleanup chain. >> + The value is chosen to be non-NULL so that make_cleanup never returns NULL, >> + and cause a segv if dereferenced. */ >> +#define CLEANUP_FENCEPOST ((struct cleanup *) 1) > > Just a tiny idea, not really important, but JIC: Could we use an enum > intead of a define so that GDB prints "CLEANUP_FENCEPOST" rather than > a numeric value when we print a cleanup pointer that's the fencepost? No, because what you'll be printing will have type struct cleanup pointer, not whatever enum it was cast from. I see at least two ways to get something like that: - a gdb specific pretty printer for cleanups. - Make the sentinel a real object: static struct cleanup sentinel_cleanup; #define CLEANUP_FENCEPOST &sentinel_cleanup And get Tromey's "set print symbol" patch in, which IIRC/IIUC, the latest version makes GDB print the symbol name corresponding to addresses by default. Then gdb would print something like: (gdb) p old_chain $1 = 0xfoobar -- Pedro Alves