[Boost-bugs] [Boost C++ Libraries] #8418: Boost Fusion foreach works for std::tuple OR boost::tuple depending on inclusion order

Subject: [Boost-bugs] [Boost C++ Libraries] #8418: Boost Fusion foreach works for std::tuple OR boost::tuple depending on inclusion order
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2013-04-08 12:16:00

#8418: Boost Fusion foreach works for std::tuple OR boost::tuple depending on
inclusion order
--------------------------+-------------------------------------------------
 Reporter:  bugs@…        |        Type:  Bugs                
   Status:  new           |   Milestone:  To Be Determined    
Component:  None          |     Version:  Boost 1.53.0        
 Severity:  Problem       |    Keywords:  fusion tuple adapted
--------------------------+-------------------------------------------------
 As my attached repro sample shows can't adapt std::tuple and boost::tuple
 at the same time.

 The headers

 {{{
 #   include <boost/fusion/adapted/boost_tuple.hpp>
 #   include <boost/fusion/adapted/std_tuple.hpp>
 }}}

 seem to mutually exclude each other (at least in this code sample). Which
 ever header of the two gets included _first_, determines which type of
 tuple will be usable as a fusion sequence in that TU.

 In the case of the 'blanket' include `boost/fusion/adapted.hpp` this means
 that std::tuple is not usable as a Fusion Sequence - unless one
 explicitely include `boost/fusion/adapted/std_tuple.hpp` _ahead_ of that.

 This is rather surprising, and obviously causes problems for people mixing
 std::tuple and boost::tuple within a sinlge TU.

 Also, although I haven't looked too deeply into the mechanics of it, I
 worry a bit that this may be a signal that '''ODR violations''' could be
 lurking when different TUs include the headers in different order.

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/8418>
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