From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 32614 invoked by alias); 5 May 2011 22:22:30 -0000 Received: (qmail 32593 invoked by uid 22791); 5 May 2011 22:22:28 -0000 X-SWARE-Spam-Status: No, hits=-2.7 required=5.0 tests=ALL_TRUSTED,AWL,BAYES_00 X-Spam-Check-By: sourceware.org Received: from localhost (HELO gcc.gnu.org) (127.0.0.1) by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Thu, 05 May 2011 22:22:14 +0000 From: "alexis.menard at openbossa dot org" To: gcc-bugs@gcc.gnu.org Subject: [Bug libstdc++/48891] std functions conflicts with C functions when building with c++0x support (and using namespace std) X-Bugzilla-Reason: CC X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: gcc X-Bugzilla-Component: libstdc++ X-Bugzilla-Keywords: X-Bugzilla-Severity: normal X-Bugzilla-Who: alexis.menard at openbossa dot org X-Bugzilla-Status: UNCONFIRMED X-Bugzilla-Priority: P3 X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org X-Bugzilla-Target-Milestone: --- X-Bugzilla-Changed-Fields: Message-ID: In-Reply-To: References: X-Bugzilla-URL: http://gcc.gnu.org/bugzilla/ Auto-Submitted: auto-generated Content-Type: text/plain; charset="UTF-8" MIME-Version: 1.0 Date: Thu, 05 May 2011 22:22:00 -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 X-SW-Source: 2011-05/txt/msg00488.txt.bz2 http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48891 --- Comment #3 from Alexis Menard 2011-05-05 22:17:36 UTC --- (In reply to comment #2) > (In reply to comment #0) > > > > and build it with : g++ main.cpp -std=c++0x -std=gnu++0x -o test > > There's no point specifying two -std options, only the last one takes effect. > > > If I deactivate the c++0x support it works. > > Because in C++98 there is no std::isnan, so you only get the version in the > global namespace from That explain. > > > The real issue is that the c++0x standard removes the prohibition on C++ > > headers declaring C names in the global namespace. The problem here is that > > math.h is included therefore the declarations are in the global namespace. > > I don't think that's the problem, because libstdc++ has always declared the > names in the global namespace even though it wasn't valid in C++03 - we haven't > changed that for C++0x (all that happened is the standard was relaxed to > reflect the reality of actual implementations) > Sorry for my ignorance. > > > I'm not really sure how the compiler can solve that but this new "feature" of > > c++0x seems to be very annoying. I could solve it by not using namespace std > > but let say the project is huge, it will requires lot of modifications. > > > > Basically any time you use using namespace std, you may have conflicts with the > > underlaying C libraries, it's even more annoying with your own namespace > > because your functions can conflict with all the stuff in the global namespace > > put by C libraries and it's very common in a cpp file to use "using namespace > > foo;" > > > > Any suggestions on how I could "workaround" that? > > Qualify isnan explicitly, by calling either ::isnan or std::isnan Well that requires me to modify my entire project, namely WebKit :(. But the more I'm stuck on that issue, the more it seems to be the only solution.