id,summary,reporter,owner,description,type,status,milestone,component,version,severity,resolution,keywords,cc
8749,"Accessing type of insert<map<>, pair<A,B> >::type discards inserted elements",guylaingreer@…,Aleksey Gurtovoy,"The following code sample illustrates the problem

    typedef insert<map<>, pair<int, int> >::type little_map;

    BOOST_STATIC_ASSERT(size<little_map>::value == 1); /* Success */
    BOOST_STATIC_ASSERT(size<little_map::type>::value == 1); /* Failure */

I have traced the problem to the file boost/mpl/map/aux_/item.hpp in the class definition of m_item.  m_item derives from Base (which is a map<...> type) but does not define a ""typedef m_item type;"" to act as a unary metafunction returning itself.  The result is that Base::type is found instead which means that m_item acts as a unary metafunction returning a map with all the inserted elements removed.  The class m_item_ at the bottom of the file properly defines a ""typedef m_item_ type;"" which strengthens my belief that it missing from m_item is a bug.

The solution, quite staightforwardly is to simply add the line ""typedef m_item type;"" to the class' definition.

It should be noted that I am running version 1.48 of Boost, but have checked http://www.boost.org/doc/libs/1_52_0/boost/mpl/map/aux_/item.hpp and it still lacks the define so I'm convinced that this problem will still be there when I download the latest version of boost.",Bugs,new,To Be Determined,mpl,Boost 1.52.0,Problem,,,