From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 34769 invoked by alias); 30 Nov 2018 02:02:05 -0000 Mailing-List: contact gcc-patches-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Id: List-Archive: List-Post: List-Help: Sender: gcc-patches-owner@gcc.gnu.org Received: (qmail 34752 invoked by uid 89); 30 Nov 2018 02:02:04 -0000 Authentication-Results: sourceware.org; auth=none X-Spam-SWARE-Status: No, score=-1.9 required=5.0 tests=BAYES_00,SPF_HELO_PASS autolearn=ham version=3.3.2 spammy=funny, right X-HELO: mx1.redhat.com Received: from mx1.redhat.com (HELO mx1.redhat.com) (209.132.183.28) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Fri, 30 Nov 2018 02:02:02 +0000 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id A038B6EB89; Fri, 30 Nov 2018 02:02:01 +0000 (UTC) Received: from localhost.localdomain (ovpn-112-27.rdu2.redhat.com [10.10.112.27]) by smtp.corp.redhat.com (Postfix) with ESMTP id 4AD8E601B9; Fri, 30 Nov 2018 02:02:00 +0000 (UTC) Subject: Re: [PING #4][PATCH] avoid warning on constant strncpy until next statement is reachable (PR 87028) To: Martin Sebor , Richard Biener Cc: GCC Patches References: <88de1ee3-6ee4-d8d9-3e57-3a42474a4169@redhat.com> <27235a6d-6f2c-1f2d-d456-d4cd9b941894@redhat.com> <23ea3d13-d9c5-1b02-f01c-d2a0e11f3a10@redhat.com> <9e3f6d62-47b9-b80f-b8ac-5711628579c5@redhat.com> <09ce3b57-33a3-86ae-1308-39fd02f25228@gmail.com> <1437ae83-c0c2-e18f-0dc8-92717c2fdcfe@gmail.com> <8a346afb-382f-cac9-a2b7-7107ef678dee@redhat.com> From: Jeff Law Openpgp: preference=signencrypt Message-ID: Date: Fri, 30 Nov 2018 02:02:00 -0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.3.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit X-IsSubscribed: yes X-SW-Source: 2018-11/txt/msg02523.txt.bz2 On 11/29/18 4:43 PM, Martin Sebor wrote: >> The fallout on existing tests is minimal.  What's more concerning is >> that it doesn't actually pass the new test from Martin's original >> submission.  We get bogus warnings. >> >> At least part of the problem is weakness in maybe_diag_stxncpy_trunc. >> It can't handle something like this: >> >> test_literal (char * d, struct S * s) >> { >>    strncpy (d, "1234567890", 3); >>    _1 = d + 3; >>    *_1 = 0; >> } >> >> >> Note the pointer arithmetic between the strncpy and storing the NUL >> terminator. > > Right.  I'm less concerned about this case because it involves > a literal that's obviously longer than the destination but it > would be nice if the suppression worked here as well in case > the literal comes from macro expansion.  It will require > another tweak. OK. If this isn't at the core of the regression BZ, then xfailing those particular cases and coming back to them is fine. > > But the test from my patch passes with the changes to calls.c > from my patch, so that's an improvement. > > I have done the test suite cleanup in the attached patch.  It > was indeed minimal -- not sure why I saw so many failures with > my initial approach. Richi's does the folding as part of gimple lowering. So it's still pretty early -- basically it ends up hitting just a few tests that are looking for folded stuff in the .gimple dump. I had actually targeted this patch as one to work through and try to get resolved today. Kind of funny that we were poking at it at the same time. > > I can submit a patch to handle the literal case above as > a followup unless you would prefer it done at the same time. Follow-up is fine by me. jeff