Re: [Boost-bugs] [Boost C++ Libraries] #2548: Let's fix the logical constness of value_initialized!

Subject: Re: [Boost-bugs] [Boost C++ Libraries] #2548: Let's fix the logical constness of value_initialized!
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2009-06-28 21:39:16

#2548: Let's fix the logical constness of value_initialized!
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 Reporter:  niels_dekker  |       Owner:  niels_dekker
     Type:  Bugs          |      Status:  assigned    
Milestone:  Boost 1.38.0  |   Component:  utility     
  Version:  Boost 1.37.0  |    Severity:  Problem     
 Keywords:                |  
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Comment(by niels_dekker):

 Daniel, thanks for your feedback. Yes, I would still like the issue to be
 fixed.  It's now more than four months after committing the fix to the
 trunk, [51355], and I haven't heard any compaint. (I did announce the fix
 at the Boost dev mailing list.) Intel 9 is the only compiler on the
 regression site that doesn't compile implicit conversions from
 value_initialized<T> to reference-to-T anymore, because of the fix. It's
 no problem to Intel 10 and 11, and any other compiler included with the
 regression tests.

 There are various possible workarounds for Intel 9:
  a. Do nothing. Intel 9 users can still retrieve a reference to the
 value_initialized data by using {{{boost::get}}}, or
 {{{value_initialized::data()}}}
  b. Revert the fix, but only for Intel 9 (using BOOST_WORKAROUND).  Leave
 the fix in there for other compilers.
  c. Offer to Intel 9 users only the const-version of the conversion
 operator (using BOOST_WORKAROUND)
  d. Offer to Intel 9 users only the non-const-version of the conversion
 operator (using BOOST_WORKAROUND)

 I do prefer workaround "d.", which allows Intel 9 users to convert from
 value_initialized<T> to T&, but protects {{{const value_initialized<T>}}}
 objects against such a conversion. As attached:
 intel_9_value_init_conversion-operator.patch  Please let me know if you
 think this patch is fine to you.

 PS Thanks also for reminding me to update the version number in the
 documentation!

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/2548#comment:5>
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