Re: [Boost-bugs] [Boost C++ Libraries] #2137: BOOST_CONCEPT_REQUIRES fails on g++

Subject: Re: [Boost-bugs] [Boost C++ Libraries] #2137: BOOST_CONCEPT_REQUIRES fails on g++
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2008-07-22 17:26:05

#2137: BOOST_CONCEPT_REQUIRES fails on g++
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  Reporter:  john.femiani_at_[hidden]  |       Owner:         
      Type:  Bugs                  |      Status:  new    
 Milestone:  Boost 1.36.0          |   Component:  None   
   Version:  Boost 1.35.0          |    Severity:  Problem
Resolution:                        |    Keywords:         
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Comment(by dave):

 The library is doing what it's supposed to do on GCC.  In general, it
 isn't possible to check for concept conformance without causing an error,
 so BOOST_CONCEPT_REQUIRES is supposed to cause an error if conformance
 fails.  It doesn't try to do SFINAE, because, in general, SFINAE is not
 possible.

 I probably should have put this in the docs, but I didn't quite realize it
 until now: an overloaded function that uses BOOST_CONCEPT_REQUIRES should
 only require the least-refined concept in the overload set.  Otherwise the
 concept check will cause compilation to fail if a more-refined model is
 passed.  If you want to check for a more refined model, you need to use
 BOOST_CONCEPT_ASSERT((...)) in the function body.

-- 
Ticket URL: <http://svn.boost.org/trac/boost/ticket/2137#comment:1>
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