From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 1449 invoked by alias); 12 Dec 2014 23:00:44 -0000 Mailing-List: contact gcc-bugs-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Id: List-Archive: List-Post: List-Help: Sender: gcc-bugs-owner@gcc.gnu.org Received: (qmail 1398 invoked by uid 48); 12 Dec 2014 23:00:40 -0000 From: "kcc at gcc dot gnu.org" To: gcc-bugs@gcc.gnu.org Subject: [Bug bootstrap/63888] [5 Regression] bootstrap failed when configured with -with-build-config=bootstrap-asan --disable-werror Date: Fri, 12 Dec 2014 23:00:00 -0000 X-Bugzilla-Reason: CC X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: gcc X-Bugzilla-Component: bootstrap X-Bugzilla-Version: 5.0 X-Bugzilla-Keywords: X-Bugzilla-Severity: normal X-Bugzilla-Who: kcc at gcc dot gnu.org X-Bugzilla-Status: NEW X-Bugzilla-Priority: P3 X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org X-Bugzilla-Target-Milestone: 5.0 X-Bugzilla-Flags: X-Bugzilla-Changed-Fields: Message-ID: In-Reply-To: References: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit X-Bugzilla-URL: http://gcc.gnu.org/bugzilla/ Auto-Submitted: auto-generated MIME-Version: 1.0 X-SW-Source: 2014-12/txt/msg01518.txt.bz2 https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63888 --- Comment #18 from Kostya Serebryany --- (In reply to Jakub Jelinek from comment #17) > (In reply to Kostya Serebryany from comment #16) > > Frankly, I realize that I don't understand the subtleties of this problem. > > :( > > > > First, if this is C++ we clearly have a bug (ODR violation) and we are done. > > So it is an ODR violation in C++, but you won't report it (remember, the > binary is not instrumented), just it will misbehave (can mark valid memory > of other vars in the binary as poisoned, e.g.). > > > Then, if this is C w/o any extra flags we will not instrument these globals. > > Not true, the vars are initialized, thus are not common. Or the var in the > binary could be common, and the var in the shared library not, etc. > And I've actually verified both clang and gcc instrument it. > > Registering something assuming padding has been added (and aligned) when you > don't have a control on it is just wrong, and the local alias is an very > easy way to avoid it. I am disoriented. Can you please give a full repro (with command lines, etc) where we'll now produce a false positive (in clang or in gcc)?