Re: std::pair, segmentation fault, why?

Hello, every one!
I wrote some codes, there seems somgthing wrong with the std::pair.

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#include <iostream>
#include <set>
#include <boost/tuple/tuple.hpp>

typedef boost::tuple<std::set<int>, int> first_type;
typedef boost::tuple<std::set<int>, std::pair<int, int>>
second_type;

first_type&& foo1()
{
std::set<int> s{1, 2, 3};

return std::move(boost::make_tuple(s, 22));
}

second_type&& foo2()
{
std::set<int> s{1, 2, 3};

/* Is there something wrong with the pair? */
return std::move(boost::make_tuple(s, std::make_pair(2, 3)));
}