[boost] Code question on fusion tag_of.hpp

Subject: [boost] Code question on fusion tag_of.hpp
From: Dave Steffen (dave.steffen_at_[hidden])
Date: 2012-08-08 17:39:33

Hi Folks

During a recent bug hunt, we came across the following (Boost 1.49, 
fusion/adapted/std_tuple/tag_of.hpp):

#include <tuple>

namespace std
{
     template <typename... Elements>
     class tuple;
}

We find this rather puzzling -- why is this here?  As far as we can 
tell, this doesn't do anything.

(Well, it did participate in a long, ugly compiler error about variadic 
templates, which is why we found it.)

What are we missing?

Thanks for any insight.

-- 
Dave Steffen
Software Engineer
NUMERICA CORPORATION
www.numerica.us
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