-------- Original Message -------- Subject: Re: [system] symbol visibility and GCC vs. Clang Date: Tue, 23 Oct 2012 10:40:42 -0700 From: James Walker <jamesw@frameforge3d.com> Reply-To: boost-users@lists.boost.org To: boost-users@lists.boost.org CC: Mathias Gaunard <mathias.gaunard@ens-lyon.org> Newsgroups: gmane.comp.lib.boost.user References: <5085BABE.9030609@frameforge3d.com> <50868205.6070508@ens-lyon.org> On 10/23/2012 4:39 AM, Mathias Gaunard wrote:

On 22/10/12 23:29, James Walker wrote:

...

When trying to link a bunch of libraries on OS X, I got this linker warning:

ld: warning: direct access in boost::system::system_error::~system_error() to global weak symbol vtable for boost::system::system_error means the weak symbol cannot be overridden at runtime. This was likely caused by different translation units being compiled with different visibility settings.

As far as I can tell, everything is compiled using the flags -fvisibility=hidden -fvisibility-inlines-hidden.

I'm wondering whether the problem is that some of the libraries were built using gcc and some were built using Clang. In boost/system/system_error.hpp, the declaration of boost::system::system_error is decorated with BOOST_SYMBOL_VISIBLE. In boost/config/compiler/gcc.hpp, BOOST_SYMBOL_VISIBLE is defined to be __attribute__((visibility("default"))), whereas boost/config/compiler/clang.hpp does not define BOOST_SYMBOL_VISIBLE.

This looks like a significant bug, POSIX-style symbol visibility doesn't work with Clang. Please file a ticket.

OK, thanks. <https://svn.boost.org/trac/boost/ticket/7559> -- James W. Walker, Innoventive Software LLC <http://www.frameforge3d.com/>