Re: [Boost-bugs] [Boost C++ Libraries] #10399: Breaking change in Boost.Optional

Subject: Re: [Boost-bugs] [Boost C++ Libraries] #10399: Breaking change in Boost.Optional
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2015-01-20 09:52:10

#10399: Breaking change in Boost.Optional
-------------------------------+---------------------------------
  Reporter:  mikhailberis      |      Owner:  fcacciola
      Type:  Bugs              |     Status:  new
 Milestone:  To Be Determined  |  Component:  optional
   Version:  Boost 1.54.0      |   Severity:  Regression
Resolution:                    |   Keywords:  optional regression
-------------------------------+---------------------------------

Comment (by akrzemi1):

 This is caused by a compiler bug in MSVC, see
 [https://connect.microsoft.com/VisualStudio/feedback/details/967397

 /incorrect-conversion-handling-in-c]. This was added when implementing
 move semantics and cannot be taken out without taking move semantics out.
 I could forcibly counteract Microsoft double conversions, but do not feel
 that this is a good idea. The problem is also observable in Boost.Variant,
 and no-one seams to be questioning it implementing move semantics:


 {{{
 #include <boost/variant.hpp>

 struct Wrapper
 {
   operator int () { return 9; }
   operator boost::variant<int, long> () { return 7; }
 };

 int main()
 {
   boost::variant<int, long> v = Wrapper();
   assert(boost::get<int>(v) == 7);
 }
 }}}

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/10399#comment:2>
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