From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 48) id 961F43858D1E; Tue, 8 Feb 2022 21:00:16 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 961F43858D1E From: "redi at gcc dot gnu.org" To: gcc-bugs@gcc.gnu.org Subject: [Bug libstdc++/84568] libstdc++-v3 configure checks for atomic operations fail on riscv Date: Tue, 08 Feb 2022 21:00:16 +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: 8.0 X-Bugzilla-Keywords: build X-Bugzilla-Severity: normal X-Bugzilla-Who: redi at gcc dot gnu.org 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: 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, 08 Feb 2022 21:00:16 -0000 https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D84568 --- Comment #11 from Jonathan Wakely --- (In reply to palmer from comment #10) > After signing off last night I realized that none of that would work anyw= ay, > though, as even with the same library on both ends users would end up wit= h a > different mutex and thus races. So I think that one isn't worth worrying > about. Agreed. > I'm not > sure if folks are shipping clang-built libstdc++ anywhere (and if so, are They're not, and it's unsupported. Libstdc++ is part of GCC and must be bui= lt by GCC. > I guess I'm not really sure here: normally I'd say we're stuck with the > default being ABI compatible, but I don't know the rules in libstdc++. I= 'm > assuming that forcing the default to be mutex could still allow users who > want atomic to configure with --with-libstdcxx-lock-policy=3Datomic, so at Yup. > least there's a path forward. IIUC users will get link errors when moving > between the two flavors (the explicit template instantiations will have > different integer values), Not necessarily. The std::shared_ptr type isn't affected by that template parameter, only its base class is. So APIs defined in terms of the public std::shared_ptr type do not get linker errors if the private std::__shared_= ptr type differs.=