we just reject now but it is
valid code as far as I can tell:
template< class other>
  struct bin_search_tree_data_ 
{
  typedef typename other::node node;
  typedef node *node_pointer;
  ~bin_search_tree_data_()
  {
    m_p_head->~node();
  }
  node_pointer m_p_head;
};
struct blowup
{
  typedef int node;
};
bin_search_tree_data_< blowup >  r;

------------------------------ Here is one that ICEs also and closer to
the original code:
template< class other>
  struct bin_search_tree_data_
{
  typedef typename other::node node;
  typedef node *node_pointer;
  ~bin_search_tree_data_()
  {
    m_p_head->~node();
  }
  node_pointer m_p_head;
};
struct blowup2{};
struct blowup
{
  typedef blowup2 node;
};
bin_search_tree_data_< blowup >  r;
------
I am creating this after 15 hours of no activity on fixing the problem.