From: Vladimir Marek Date: Sat, 27 Apr 2013 10:11:35 +0000 (+0200) Subject: Re: [PATCH] don't store temporary value returned from c_str() X-Git-Url: http://git.tremily.us/?a=commitdiff_plain;h=2949282a7cc5da8bd8798790a775866433bbeffc;p=notmuch-archives.git Re: [PATCH] don't store temporary value returned from c_str() --- diff --git a/52/38c5ebee1001b669054557485d55639fbeb2f6 b/52/38c5ebee1001b669054557485d55639fbeb2f6 new file mode 100644 index 000000000..bcba600c6 --- /dev/null +++ b/52/38c5ebee1001b669054557485d55639fbeb2f6 @@ -0,0 +1,108 @@ +Return-Path: +X-Original-To: notmuch@notmuchmail.org +Delivered-To: notmuch@notmuchmail.org +Received: from localhost (localhost [127.0.0.1]) + by olra.theworths.org (Postfix) with ESMTP id EC7BB431FAF + for ; Sat, 27 Apr 2013 03:13:45 -0700 (PDT) +X-Virus-Scanned: Debian amavisd-new at olra.theworths.org +X-Spam-Flag: NO +X-Spam-Score: -2.299 +X-Spam-Level: +X-Spam-Status: No, score=-2.299 tagged_above=-999 required=5 + tests=[RCVD_IN_DNSWL_MED=-2.3, UNPARSEABLE_RELAY=0.001] + autolearn=disabled +Received: from olra.theworths.org ([127.0.0.1]) + by localhost (olra.theworths.org [127.0.0.1]) (amavisd-new, port 10024) + with ESMTP id vTg4-tH3BV7L for ; + Sat, 27 Apr 2013 03:13:45 -0700 (PDT) +Received: from aserp1040.oracle.com (aserp1040.oracle.com [141.146.126.69]) + (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) + (No client certificate requested) + by olra.theworths.org (Postfix) with ESMTPS id 5803D431FAE + for ; Sat, 27 Apr 2013 03:13:45 -0700 (PDT) +Received: from acsinet21.oracle.com (acsinet21.oracle.com [141.146.126.237]) + by aserp1040.oracle.com (Sentrion-MTA-4.3.1/Sentrion-MTA-4.3.1) with + ESMTP id r3RADZBZ008948 + (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK); + Sat, 27 Apr 2013 10:13:35 GMT +Received: from userz7022.oracle.com (userz7022.oracle.com [156.151.31.86]) + by acsinet21.oracle.com (8.14.4+Sun/8.14.4) with ESMTP id + r3RADWdT009868 + (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=FAIL); + Sat, 27 Apr 2013 10:13:33 GMT +Received: from ubhmt101.oracle.com (ubhmt101.oracle.com [156.151.24.6]) + by userz7022.oracle.com (8.14.4+Sun/8.14.4) with ESMTP id + r3RADWFA020416; Sat, 27 Apr 2013 10:13:32 GMT +Received: from pub.cz.oracle.com (/10.163.101.122) + by default (Oracle Beehive Gateway v4.0) + with ESMTP ; Sat, 27 Apr 2013 03:13:32 -0700 +Date: Sat, 27 Apr 2013 12:11:35 +0200 +From: Vladimir Marek +To: Tomi Ollila +Subject: Re: [PATCH] don't store temporary value returned from c_str() +Message-ID: <20130427101134.GI10394@pub.cz.oracle.com> +Mail-Followup-To: Tomi Ollila , notmuch@notmuchmail.org, + Vladimir Marek +References: <1366405933-17223-1-git-send-email-Vladimir.Marek@oracle.com> + +MIME-Version: 1.0 +Content-Type: text/plain; charset=utf-8 +Content-Disposition: inline +In-Reply-To: +User-Agent: Mutt/1.5.21 (2010-09-15) +X-Source-IP: acsinet21.oracle.com [141.146.126.237] +Cc: notmuch@notmuchmail.org, Vladimir Marek +X-BeenThere: notmuch@notmuchmail.org +X-Mailman-Version: 2.1.13 +Precedence: list +List-Id: "Use and development of the notmuch mail system." + +List-Unsubscribe: , + +List-Archive: +List-Post: +List-Help: +List-Subscribe: , + +X-List-Received-Date: Sat, 27 Apr 2013 10:13:46 -0000 + +> > From: Vladimir Marek +> > +> > This is causing problems when compiled by Oracle Studio. Memory pointed +> > by (const char*)term was already changed once talloc_strdup was called. +> +> If that changes, I'd like to understand why (and stated in the commit +> message). If that is clear to everyone else I will withdraw the question -- +> I am not too familiar with these iterators magic... :D + +Well, a) standards says that + +A temporary bound to a reference parameter in a function call (5.2.2) +persists until the completion of the full expression containing the call + +(you can find the message all over the net, but I can't find actual link +to the standard :-/) + + +b) Imagine the function c_str() looks like that: + +const char* +string::c_str(void) { + char buf[100]; + + strcpy (buf, this->internal_representation); + return buf; +} + +you can't do: +char *my_tmp = string.c_str(); +printf(my_tmp); + +you can do: +printf(string.c_str()); + +Hopefully I made the example right ... + +Cheers +-- + Vlad