Re: [Boost-bugs] [Boost C++ Libraries] #4530: errors with is_convertible on msvc10

Subject: Re: [Boost-bugs] [Boost C++ Libraries] #4530: errors with is_convertible on msvc10
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2010-08-12 11:11:13

#4530: errors with is_convertible on msvc10
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  Reporter:  cschmidt                 |       Owner:  johnmaddock
      Type:  Bugs                     |      Status:  assigned   
 Milestone:  Boost 1.44.0             |   Component:  type_traits
   Version:  Boost Development Trunk  |    Severity:  Problem    
Resolution:                           |    Keywords:             
--------------------------------------+-------------------------------------
Changes (by johnmaddock):

  * status:  new => assigned

Comment:

 Hmmm... I think this is a compiler bug, in trying to work out if test<A>
 is convertible to A the compiler is for some reason trying to instantiate
 test<A>::test<A>(test<A>) which causes a cyclic dependency in
 is_convertible.  GCC handles the same code just fine, and switching to
 std::tr1::is_convertible at the top level breaks the cyclic dependency.

 I think I can fix this long term by switching over to using the _
 _is_convertible compiler intrinsic - but this also means switching
 is_convertible over to C++0x behaviour from TR1 behaviour which will be a
 breaking change.... and I'm not sure C++0x behaviour can even be
 implemented in the language yet for compilers that don't have the
 intrinsic!

 Will investigate some more.

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/4530#comment:1>
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