Re: [Boost-bugs] [Boost C++ Libraries] #3996: Enable use of BOOST_FOREACH over const-ref of noncopyable ptr_containers

Subject: Re: [Boost-bugs] [Boost C++ Libraries] #3996: Enable use of BOOST_FOREACH over const-ref of noncopyable ptr_containers
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2010-06-24 22:17:58

#3996: Enable use of BOOST_FOREACH over const-ref of noncopyable ptr_containers
--------------------------------------------------------+-------------------
  Reporter:  Kazutoshi Satoda <k_satoda@…>              |       Owner:  nesotto                     
      Type:  Patches                                    |      Status:  new                         
 Milestone:  Boost 1.43.0                               |   Component:  ptr_container               
   Version:  Boost 1.42.0                               |    Severity:  Problem                     
Resolution:                                             |    Keywords:  BOOST_FOREACH is_noncopyable
--------------------------------------------------------+-------------------

Comment (by eric_niebler):

 Do NOT accept this patch. For every instantiation of
 reversible_ptr_container, you are instantiating foreach::is_noncopyable to
 (optionally) inherit from noncopyable. This is the wrong way to do it and
 will lead to ODR violations when different translation units see different
 specializations of foreach::is_noncopyable. Instead, define a partial
 specialization of foreach::is_noncopyable< reversible_ptr_container<...>
 >:

 {{{
 namespace boost { namespace foreach {
   template<typename T, typename A, typenale CA>
   struct is_noncopyable<ptr_vector<T,A,CA> > : is_noncopyable<T> {};
 }}
 }}}

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/3996#comment:2>
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