Re: [Boost-bugs] [Boost C++ Libraries] #2114: Patch for export symbols from shared library

Subject: Re: [Boost-bugs] [Boost C++ Libraries] #2114: Patch for export symbols from shared library
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2009-10-12 16:59:06

#2114: Patch for export symbols from shared library
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 Reporter:  arhip                                                                 |       Owner:  johnmaddock
     Type:  Patches                                                               |      Status:  new        
Milestone:  To Be Determined                                                      |   Component:  config     
  Version:  Boost Development Trunk                                               |    Severity:  Cosmetic   
 Keywords:  symbol export shared library gcc exception dynamic shared object dso  |  
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Comment(by anonymous):

 Boost.Exception should be fixed as well.

 Let me explain: If I make a DSO, say a.so, which throws an exception, say
 my_exception, which is derived from std::exception and boost::exception,
 and use the GCC -fvisibility=hidden flag in building the a.so,
 boost::exception typeinfo is not visible to the application using the
 a.so, since it will be looked for inside the DSO where it's hidden. As a
 consequence, for example, if I try to catch a my_exception thrown from the
 a.so in the application side as a reference to boost::exception, it will
 pass right through and bad things will happen. Hence IMO boost::exception
 should always use default visibility with GCC similar to std::exception.
 In 1.40 it does not.

 Another issue with Boost.Exception is the BOOST_THROW_EXCEPTION macro
 since it seems to throw an instance of
 boost::exception_detail::clone_impl<my_exception>. Since it is a template,
 there is an easy, non-intrusive workaround: I can just declare the
 specialization in my own header file with default visibility attribute.
 Unfortunately this can not be done for boost::exception.

 All in all, IMO boost::exception should always use default visibility.
 Setting it in boost/exception/exception.hpp at least fixed my problems
 with visibility and boost exceptions.

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Ticket URL: <https://svn.boost.org/trac/boost/ticket/2114#comment:17>
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