From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 48) id 3D542393BC01; Tue, 7 Jun 2022 14:58:40 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 3D542393BC01 From: "jens.maurer at gmx dot net" To: gcc-bugs@gcc.gnu.org Subject: [Bug tree-optimization/105651] bogus "may overlap" memcpy warning with std::string Date: Tue, 07 Jun 2022 14:58:40 +0000 X-Bugzilla-Reason: CC X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: gcc X-Bugzilla-Component: tree-optimization X-Bugzilla-Version: 13.0 X-Bugzilla-Keywords: diagnostic X-Bugzilla-Severity: normal X-Bugzilla-Who: jens.maurer at gmx dot net X-Bugzilla-Status: UNCONFIRMED X-Bugzilla-Resolution: X-Bugzilla-Priority: P3 X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org X-Bugzilla-Target-Milestone: --- X-Bugzilla-Flags: X-Bugzilla-Changed-Fields: cc 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: Tue, 07 Jun 2022 14:58:40 -0000 https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D105651 Jens Maurer changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |jens.maurer at gmx dot net --- Comment #5 from Jens Maurer --- Here's a more compact reproducer (gcc 12.1): #include void f(const long long v) { std::string line; line +=3D " " + std::to_string(v); } $ g++ -Wall -O3 -std=3Dc++20 -o test_warning.o -c test_warning.cxx [...] inlined from 'void f(long long int)' at test_warning.cxx:9:15: /opt/crosstool/x86_64-gcc-12.1.0-glibc-2.12.2/x86_64-unknown-linux-gnu/incl= ude/c++/12.1.0/bits/char_traits.h:431:56:=20 warning: 'void* __builtin_memcpy(void*, const void*, long unsigned int)'=20 accessing 9223372036854775810 or more bytes at offsets [2,=20 9223372036854775807] and 1 may overlap up to 9223372036854775813 bytes=20 at offset -3 [-Wrestrict] 431 | return static_cast(__builtin_memcpy(__s1,=20 __s2, __n));=