Re: [Boost-bugs] [Boost C++ Libraries] #6174: [thread] packaged_task does correctly handle moving results

Subject: Re: [Boost-bugs] [Boost C++ Libraries] #6174: [thread] packaged_task does correctly handle moving results
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2011-12-03 15:23:43

#6174: [thread] packaged_task does correctly handle moving results
--------------------------------------+-------------------------------------
  Reporter:  onlyone@…                |       Owner:  viboes            
      Type:  Bugs                     |      Status:  assigned          
 Milestone:  To Be Determined         |   Component:  thread            
   Version:  Boost Development Trunk  |    Severity:  Showstopper       
Resolution:                           |    Keywords:  move packaged_task
--------------------------------------+-------------------------------------

Comment (by onlyone@…):

 Replying to [comment:2 viboes]:
 > Please, could you stay with which compiler this doesn't compile and log
 the compile error?
 >
 > I have no access to lambdas now. The following compiles for me with
 clang
 >
 >
 > {{{
 >
 boost::packaged_task<MovableButNonCopyable>(MovableButNonCopyable());
 > }}}
 >

 Bizarre. I tried the following:
 {{{
 #include <boost/thread.hpp>
 struct MovableButNonCopyable {
     MovableButNonCopyable(){}
     MovableButNonCopyable(MovableButNonCopyable&&){}
     MovableButNonCopyable& operator=(MovableButNonCopyable&&){return
 *this;}
 private:
     MovableButNonCopyable(MovableButNonCopyable const&);
     MovableButNonCopyable& operator=(MovableButNonCopyable const&);
 };

 MovableButNonCopyable construct() {return MovableButNonCopyable();}

 int main()
 {
     boost::packaged_task<MovableButNonCopyable>(construct);
 }
 }}}
 And it compiles without issue with both Clang and GCC. However, the code
 that I presented in the original ticket fails under GCC 4.6.2 (Macports
 version, x86_64), with the following message:
 {{{
 In file included from
 /Users/evan/Programming/boost/library/include/boost/thread.hpp:24:0,
                  from main.cpp:1:
 /Users/evan/Programming/boost/library/include/boost/thread/future.hpp: In
 static member function 'static void
 boost::detail::future_traits<T>::init(boost::detail::future_traits<T>::storage_type&,
 boost::detail::future_traits<T>::source_reference_type) [with T =
 MovableButNonCopyable, boost::detail::future_traits<T>::storage_type =
 boost::scoped_ptr<MovableButNonCopyable>,
 boost::detail::future_traits<T>::source_reference_type = const
 MovableButNonCopyable&]':
 /Users/evan/Programming/boost/library/include/boost/thread/future.hpp:308:17:
 instantiated from 'void
 boost::detail::future_object<T>::mark_finished_with_result_internal(boost::detail::future_object<T>::source_reference_type)
 [with T = MovableButNonCopyable,
 boost::detail::future_object<T>::source_reference_type = const
 MovableButNonCopyable&]'
 /Users/evan/Programming/boost/library/include/boost/thread/future.hpp:325:17:
 instantiated from 'void
 boost::detail::future_object<T>::mark_finished_with_result(boost::detail::future_object<T>::rvalue_source_type)
 [with T = MovableButNonCopyable,
 boost::detail::future_object<T>::rvalue_source_type =
 MovableButNonCopyable&&]'
 /Users/evan/Programming/boost/library/include/boost/thread/future.hpp:1224:21:
 instantiated from 'void boost::detail::task_object<R, F>::do_run() [with R
 = MovableButNonCopyable, F = main()::<lambda()>]'
 main.cpp:12:1:   instantiated from here
 /Users/evan/Programming/boost/library/include/boost/thread/future.hpp:239:17:
 error: use of deleted function
 'MovableButNonCopyable::MovableButNonCopyable(const
 MovableButNonCopyable&)'
 main.cpp:4:5: error: declared here
 }}}

 Unfortunately I do not have any other compilers that I can test it on
 right at the moment. When I get the chance, I will try a few more versions
 of GCC, Clang and MSVC. I will also see if I can find a way to reproduce
 the bug without using lambdas or defaulted/deleted functions. (I will
 report my findings some time this week).

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/6174#comment:4>
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