[Boost-users] [system] symbol visibility and GCC vs. Clang

Subject: [Boost-users] [system] symbol visibility and GCC vs. Clang
From: James Walker (jamesw_at_[hidden])
Date: 2012-10-22 17:29:34

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.
-- 
   James W. Walker, Innoventive Software LLC
   <http://www.frameforge3d.com/>