From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 48) id 5134738930FB; Thu, 17 Dec 2020 09:08:39 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 5134738930FB From: "tschwinge at gcc dot gnu.org" To: gcc-bugs@gcc.gnu.org Subject: [Bug libstdc++/66146] call_once not C++11-compliant on ppc64le Date: Thu, 17 Dec 2020 09:08:38 +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: 5.1.0 X-Bugzilla-Keywords: X-Bugzilla-Severity: normal X-Bugzilla-Who: tschwinge at gcc dot gnu.org X-Bugzilla-Status: ASSIGNED X-Bugzilla-Resolution: X-Bugzilla-Priority: P3 X-Bugzilla-Assigned-To: redi at gcc dot gnu.org X-Bugzilla-Target-Milestone: 11.0 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: Thu, 17 Dec 2020 09:08:39 -0000 https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D66146 Thomas Schwinge changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |tschwinge at gcc dot gnu.o= rg --- Comment #35 from Thomas Schwinge --- In an '--enable-werror' configuration (assuming that's relevant), I'm seeing new code from commit r11-4691-g93e79ed391b9c636f087e6eb7e70f14963cd10ad "libstdc++: Rewrite std::call_once to use futexes [PR 66146]" fail to build: [...]/source-gcc/libstdc++-v3/src/c++11/mutex.cc: In member function = =E2=80=98void std::once_flag::_M_finish(bool)=E2=80=99: [...]/source-gcc/libstdc++-v3/src/c++11/mutex.cc:77:11: error: unused variable =E2=80=98prev=E2=80=99 [-Werror=3Dunused-variable] 77 | int prev =3D __atomic_exchange_n(&_M_once, newval, __ATOMIC_RELEASE); | ^~~~ cc1plus: all warnings being treated as errors Makefile:648: recipe for target 'mutex.lo' failed make[5]: *** [mutex.lo] Error 1 make[5]: Leaving directory '[...]/build-gcc/x86_64-pc-linux-gnu/libstdc++-v3/src/c++11' Should a '(void) prev;' be added (my current workaround), or 'prev' get some attribute 'used' added, or something else?=