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. Forwarding to developers mailing list.