id	summary	reporter	owner	description	type	status	milestone	component	version	severity	resolution	keywords	cc
1469	[mpl] nested typedef of set has two different meanings	sven.vanechelpoel@…	Aleksey Gurtovoy	"This problem was diagnosed by Steve Watanabe after my posting on the developer list (see http://thread.gmane.org/gmane.comp.lib.boost.devel/168339/focus=168366)

Basically the following doesn't compile:

{{{
#include <boost/mpl/set.hpp>
#include <boost/mpl/vector.hpp>
#include <boost/mpl/copy.hpp>
#include <boost/mpl/insert.hpp>
#include <boost/mpl/inserter.hpp>

using namespace boost::mpl;

template<
  typename T
> >
struct as_set :
  copy<
    T
  , inserter<
      set<>
    , insert< _1, _2 >
    >
  >
{};

typedef set<int,char>             a_set;
typedef vector<int,int,char>      a_vector;
typedef as_set< a_set >::type     set_as_set;
typedef as_set< a_vector >::type  vector_as_set;

typedef next< begin< a_set >::type >::type
THIS_IS_OK;
typedef next< next< begin< a_set >::type >::type >::type
THIS_IS_OK_AS_WELL;
typedef next< begin< a_vector >::type >::type
THIS_IS_OK_TOO;
typedef next< begin< set_as_set >::type >::type
THIS_WORKS_TOO;
typedef next< next< begin< set_as_set >::type >::type >::type
THIS_FAILS;
typedef next< next< begin< vector_as_set >::type >::type >::type
THIS_FAILS_TOO;
}}}

Steve Watanabe diagnosed this to be a problem of mpl::set using the nested typedef 'type' for two different purposes: one as an alias of the set<>, the other refering to the item type. The result is that upon iteration the termination condition isn't recognized and the iterator blows up"	Bugs	new	To Be Determined	mpl	Boost 1.34.1	Problem