[boost] [Iterator][Type_Erasure] Conflicting declaration. (Fix is provided.)

Subject: [boost] [Iterator][Type_Erasure] Conflicting declaration. (Fix is provided.)
From: Deniz Bahadir (deniz.bahadir_at_[hidden])
Date: 2015-07-16 13:19:57

Hi there,

I noticed a "conflicting declaration" error when developing a program 
which uses Boost.Program_Options and Boost.Type_Erasure.
Further investigation showed me, that the conflict is actually between 
Boost.Iterator and Boost.Type_Erasure.

A test-case which demonstrates this compiler-error is the following 
simple two-liner:

     #include <boost/type_erasure/iterator.hpp>
     #include <boost/iterator/iterator_adaptor.hpp>

Clang is quite verbose and outputs the following:

     /tmp/boost-1_58/boost/iterator/iterator_adaptor.hpp:44:18: error: 
target of using declaration conflicts with declaration already in scope
     using iterators::use_default;
                      ^
     /tmp/boost-1_58/boost/iterator/iterator_adaptor.hpp:40:10: note: 
target of using declaration
       struct use_default;
              ^
     /tmp/boost-1_58/boost/type_erasure/iterator.hpp:27:8: note: 
conflicting declaration
     struct use_default;
            ^
     1 error generated.

The fix is actually quite simple and should be applied to 
Boost.Iterator. I already provided a pull-request [1] for this.

I hope this fix can still make it into the upcoming 1.59 release of Boost.

Best regards,
Deniz Bahadir

[1] https://github.com/boostorg/iterator/pull/15

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