[Boost-bugs] [Boost C++ Libraries] #1722: [TR1/Fusion] Conflict between TR1 and Fusion headers

Subject: [Boost-bugs] [Boost C++ Libraries] #1722: [TR1/Fusion] Conflict between TR1 and Fusion headers
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2008-03-27 14:30:41

#1722: [TR1/Fusion] Conflict between TR1 and Fusion headers
---------------------------------------------------------+------------------
 Reporter:  Richard Webb <Richard.Webb_at_[hidden]>  |       Owner:  djowel 
     Type:  Bugs                                         |      Status:  new    
Milestone:  Boost 1.36.0                                 |   Component:  fusion 
  Version:  Boost Development Trunk                      |    Severity:  Problem
 Keywords:                                               |  
---------------------------------------------------------+------------------
 Originally posted @
 http://article.gmane.org/gmane.comp.lib.boost.devel/171545 - opening it
 here so that it doesn't get forgotten. (I'm not sure if this should be
 assigned to TR1 or Fusion - assigning it to Fusion for now).


 {{{
 Hi,
 I've got a project that uses Boost.TR1 (by adding boost/tr1/tr1 to my
 include
 path) and Fusion, and i've run into some errors when including the Fusion
 headers.
 For example:

 boost/fusion/tuple/make_tuple.hpp(21) : error C2027: use of undefined type
 'boost::fusion::tuple<>'

 boost/fusion/iterator/prior.hpp(50) : error C2039: 'tag_of' : is not a
 member
 of 'boost::fusion::detail'

 This seems to be caused by the inclusion of <utility> in
 <boost/fusion/support/tag_of.hpp>, which when using Boost.TR1 like this
 causes
 the Fusion headers to be included again. At the point when <utility> is
 included, the tag_of include guard has been defined but tag_of itself
 hasn't
 been declared, so nested inclusions of tag_of.hpp do nothing and the build
 fails.

 My code builds ok if i either:
 -Include <utility> myself before Fusion
 -Remove the include <utility> from tag_of.hpp (it doesnt actually seem to
 be
 required - at least, the regression tests all pass with it removed)

 This seems a bit fragile though. Is there a better way it can be fixed?

 }}}

-- 
Ticket URL: <http://svn.boost.org/trac/boost/ticket/1722>
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