From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 48) id 7940C3865488; Fri, 5 Mar 2021 12:40:29 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 7940C3865488 From: "redi at gcc dot gnu.org" To: gcc-bugs@gcc.gnu.org Subject: [Bug libstdc++/99402] [10/11 Regression] std::copy creates _GLIBCXX_DEBUG false positive for attempt to subscript a dereferenceable (start-of-sequence) iterator Date: Fri, 05 Mar 2021 12:40:29 +0000 X-Bugzilla-Reason: CC X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: gcc X-Bugzilla-Component: libstdc++ X-Bugzilla-Version: 10.2.0 X-Bugzilla-Keywords: X-Bugzilla-Severity: normal X-Bugzilla-Who: redi at gcc dot gnu.org X-Bugzilla-Status: NEW X-Bugzilla-Resolution: X-Bugzilla-Priority: P3 X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org X-Bugzilla-Target-Milestone: 10.3 X-Bugzilla-Flags: X-Bugzilla-Changed-Fields: Message-ID: In-Reply-To: References: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Bugzilla-URL: http://gcc.gnu.org/bugzilla/ Auto-Submitted: auto-generated MIME-Version: 1.0 X-BeenThere: gcc-bugs@gcc.gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Gcc-bugs mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 05 Mar 2021 12:40:29 -0000 https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D99402 --- Comment #4 from Jonathan Wakely --- This causes __valid_range to return {11, __dp_sign_max_size} and then we ch= eck __result._M_can_advance(11) which fails. We don't want to advance the result by the size of the other sequence, only= by distance(__first, __last). We don't care if there are elements in the seque= nce past __last because we're not trying to copy them.=