Re: [Boost-bugs] [Boost C++ Libraries] #8596: With C++0x enabled, boost::packaged_task stores a reference to function objects, instead of a copy

Subject: Re: [Boost-bugs] [Boost C++ Libraries] #8596: With C++0x enabled, boost::packaged_task stores a reference to function objects, instead of a copy
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2013-05-20 15:39:23

#8596: With C++0x enabled, boost::packaged_task stores a reference to function
objects, instead of a copy
-----------------------------------------------------------+----------------
  Reporter:  Kees-Jan Dijkzeul <kees-jan.dijkzeul@…>       |       Owner:  viboes  
      Type:  Bugs                                          |      Status:  assigned
 Milestone:  To Be Determined                              |   Component:  thread  
   Version:  Boost 1.53.0                                  |    Severity:  Problem 
Resolution:                                                |    Keywords:          
-----------------------------------------------------------+----------------

Comment (by Kees-Jan Dijkzeul <kees-jan.dijkzeul@…>):

 I see. It was unclear to me that you already accepted my ticket as a bug.
 In that case, I probably overreacted. I apologize. It is true, though,
 that I have high expectations of you guys. You yourselves contribute to
 that in large part by mostly living up to them :-)

 On the other hand, I was kind of proud having analysed this issue as far
 as I did. Being assigned more work without it being made explicitly clear
 that I was on to something and that it was for my own immediate benefit is
 kind of daunting :-)

 As for unblocking me: Your patch (and several variations I tried) triggers
 a build error, either because boost::forward() cannot handle what I throw
 at it, or because the task_object constructor expects only an rvalue, but
 not an lvalue.

 Taking a different approach, I observed that the packaged_task seems to
 store a reference only because I pass it one. Adding a static cast like
 so:
 {{{
   return
 boost::packaged_task<int>(static_cast<boost::function<int()>(fn));
 }}}
 also seems to work around the problem. You can consider me unblocked :-)

 Thanks very much for your support!

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/8596#comment:5>
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