[boost] [type_traits] Interesting problem with is_base_of.

23 Sep 2007

      Dears

There are two codes. The first is workig as it is specified in the 
documentation, but the second not. Why there are problems with the second 
code?

Regards.

// This code works perfectly

#include <boost/type_traits.hpp>
#include <boost/static_assert.hpp>
#include <boost/utility.hpp>

template <typename B, typename R> 
class test
{
public:
    test ()
    {
        BOOST_STATIC_ASSERT((boost::is_base_of<B, R>::value));
    }
};

int main()
{
    test <int, int> t ();
}

// The code belo is not working

#include <boost/type_traits.hpp>
#include <boost/static_assert.hpp>
#include <boost/utility.hpp>

template <typename B>
class test
{
public:
    template <typename R>
    test (R const &)
    {
        BOOST_STATIC_ASSERT((boost::is_base_of<B, R>::value));
    }
};

int main()
{
    test <int> t (static_cast<int>(0));
}

-- 

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