Re: [Boost-bugs] [Boost C++ Libraries] #6126: Signed integer members of Boost.Fusion adapted ADTs are not output correctly with Boost.Spirit.Karma rules

Subject: Re: [Boost-bugs] [Boost C++ Libraries] #6126: Signed integer members of Boost.Fusion adapted ADTs are not output correctly with Boost.Spirit.Karma rules
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2012-02-02 01:31:39

#6126: Signed integer members of Boost.Fusion adapted ADTs are not output
correctly with Boost.Spirit.Karma rules
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  Reporter:  t0rt1e@…          |       Owner:  hkaiser                                                                                                             
      Type:  Bugs              |      Status:  new                                                                                                                 
 Milestone:  To Be Determined  |   Component:  spirit                                                                                                              
   Version:  Boost 1.48.0      |    Severity:  Regression                                                                                                          
Resolution:                    |    Keywords:  patch proposed, Boost.Spirit.Karma, Boost.Fusion, BOOST_FUSION_ADAPT_CLASS, BOOST_FUSION_ADAPT_ADT, short, int, long
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Comment (by hkaiser):

 Replying to [comment:16 Seth Heeren <bugs@…>]:
 > Replying to [comment:15 hkaiser]:
 > >
 > > That's excellent news! Thanks. That allows to revert the patch above.
 >
 > Do you have ideas on how to fix it?  My suggestion for the OP is really
 a workaround:
 >
 >  * bug: ADT accessors returning by value leads to UB
 >  * workaround: don't do that, then?
 >
 > The docs clearly suggest that returning by value from the accessors is
 `ok` practice (and that adds value, IMO). However, the code appears to
 have the assumption that attributes can always be fully 'resolved' to a
 reference.

 The docs are Fusion related. There it is possible and valid to do such
 things. The problem is that Karma (falsely) assumes this as well.

 > Apart from specializing extract_from_attribute for adt_attribute_proxy I
 don't see an easy way to resolve this. And I wouldn't think that this
 approach is entirely trivial, either (it might be enough due to the
 implicit conversion of the proxy to its exposed type?)

 Yep, that's what I think needs to be done, at least as a first step.

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/6126#comment:17>
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