https://svn.boost.org/trac10/ticket/8749 <p> The following code sample illustrates the problem </p> <blockquote> <p> typedef insert&lt;map&lt;&gt;, pair&lt;int, int&gt; &gt;::type little_map; </p> </blockquote> <blockquote> <p> BOOST_STATIC_ASSERT(size&lt;little_map&gt;::value == 1); /* Success */ BOOST_STATIC_ASSERT(size&lt;little_map::type&gt;::value == 1); /* Failure */ </p> </blockquote> <p> 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&lt;...&gt; 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. </p> <p> The solution, quite staightforwardly is to simply add the line "typedef m_item type;" to the class' definition. </p> <p> It should be noted that I am running version 1.48 of Boost, but have checked <a href="http://www.boost.org/doc/libs/1_52_0/boost/mpl/map/aux_/item.hpp">http://www.boost.org/doc/libs/1_52_0/boost/mpl/map/aux_/item.hpp</a> 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. </p> en-us /htdocs/site/boost.png https://svn.boost.org/trac10/ticket/8749 Trac 1.4.3 anonymous Tue, 14 Oct 2014 15:51:57 GMT