[Boost-bugs] [Boost C++ Libraries] #11070: async_connect never calls back on mac with -fvisibility=hidden

Subject: [Boost-bugs] [Boost C++ Libraries] #11070: async_connect never calls back on mac with -fvisibility=hidden
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2015-03-04 14:50:25

#11070: async_connect never calls back on mac with -fvisibility=hidden
------------------------------+----------------------------
 Reporter:  blastrock         |      Owner:  chris_kohlhoff
     Type:  Bugs              |     Status:  new
Milestone:  To Be Determined  |  Component:  asio
  Version:  Boost 1.55.0      |   Severity:  Problem
 Keywords:                    |
------------------------------+----------------------------
 See the attached file for a minimal code to reproduce. I have tested this
 on mac os yosemite with "Apple LLVM version 6.0 (clang-600.0.56) (based on
 LLVM 3.5svn)".

 To test:

 {{{
 mkdir build
 cd build
 cmake ..
 make
 ./main
 }}}


 Result:
 The program never returns

 Expected:
 The program finishes (possibly with a "connection refused" error)

 What I do is to create a socket in the main binary (without using it) and
 do an async_connect in a library with hidden symbols.

 This code works if I comment the -fvisibility=hidden line in the
 CMakeLists.txt or if I comment the socket creation in main().

 This seems to be related to
 boost::asio::detail::service_registry::keys_match which compares service
 types. It relies on typeinfo to do that (unless BOOST_ASIO_NO_TYPEID is
 set).

 For that to work, typeid_wrapper is forced to default visibility (see
 #pragma at boost/asio/detail/service_registry.hpp:32), but in recent mac
 os versions it seems that it is not enough anymore. It seems that a symbol
 Foo<T> is exported if and only if Foo AND T are set to default visibility.
 So, in this case, we have two typeinfos for the same type
 typeid_wrapper<stream_socket_service<ip::tcp>> and they are not merged at
 dynamic linking because the symbols are hidden.

 One possible fix is to set default visibility to stream_socket_service and
 ip::tcp. This makes my example work, but it should be needed also for
 other services and protocols as well. I have made a patch for for this,
 but I don't know if this is the right way to fix it.

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/11070>
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