Boost Visibility Linker Warnings

Issue : many linker warnings

Most opticks pkgs have many warnings like:

ld: warning: direct access in void boost::throw_exception<boost::bad_function_call>(boost::bad_function_call const&) to global weak symbol typeinfo for boost::exception_detail::clone_impl<boost::exception_detail::error_info_injector<boost::bad_function_call> > means the weak symbol cannot be overridden at runtime. This was likely caused by different translation units being compiled with different visibility settings.
ld: warning: direct access in boost::exception_detail::clone_impl<boost::exception_detail::error_info_injector<boost::bad_function_call> >::rethrow() const to global weak symbol typeinfo for boost::exception_detail::clone_impl<boost::exception_detail::error_info_injector<boost::bad_function_call> > means the weak symbol cannot be overridden at runtime. This was likely caused by different translation units being compiled with different visibility settings.
ld: warning: direct access in void boost::throw_exception<boost::bad_lexical_cast>(boost::bad_lexical_cast const&) to global weak symbol typeinfo for boost::exception_detail::clone_impl<boost::exception_detail::error_info_injector<boost::bad_lexical_cast> > means the weak symbol cannot be overridden at runtime. This was likely caused by different translation units being compiled with different visibility settings.

Solution ?

Rebuild boost libs with:

-fvisibility=hidden

• http://stackoverflow.com/questions/15059360/compiling-boost-1-53-libraries-with-gcc-with-symbol-visibility-hidden

Cause

• On Linux/OSX are using visibility=hidden in order to match WIN32 behaviour.
• This forces all symbols to be API exported eg with OKG4_API

okg4/OKG4_API_EXPORT.hh:

23 #if defined (_WIN32)
24
25    #if defined(okg4_EXPORTS)
26        #define  OKG4_API __declspec(dllexport)
27    #else
28        #define  OKG4_API __declspec(dllimport)
29    #endif
30
31 #else
32
33    #define OKG4_API  __attribute__ ((visibility ("default")))
34
35 #endif

cmake/Modules/EnvCompilationFlags:

set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fvisibility=hidden")