Error: forming pointer to reference type 'cons

I'm getting some errors when trying to use -> in an iterator type. When I dig in the library defining the iterator, it seems to me that everyhing is allright and that there is no reason for the error. Here is the code, part of boost::multi_array:

template <class T>
struct operator_arrow_proxy
{
  operator_arrow_proxy(T const& px) : value_(px) {}
  T* operator->() const { return &value_; }
  // This function is needed for MWCW and BCC, which won't call operator->
  // again automatically per 13.3.1.2 para 8
  operator T*() const { return &value_; }
  mutable T value_;
};

which is instantiated with const std::pair<double, unsigned int>&; then the compiler complains about "forming pointer to reference type 'const std::pair<double, unsigned int>&'".Those are internal, library substantiations. For the record, here is what I have in my code:

typedef uint32_t object_indentifier_t;
typedef std::pair< double, object_identifier_t > object_tab_t;
typedef boost::multi_array< object_tab_t, 2 > index_t;

and here is the usage that provokes the trouble:

object_identifier const& center; // Actually a parameter
index_t::const_subarray<1>::type::const_iterator pos_iterator_left = std::lower_bound( ix[i].begin(), ix[i].end(), sk[i], comparer ); 
assert( pos_iterator_left -> second == center ); // <-- Error steams from here

Here's more error context:

/opt/boost_1_48_0/include/boost/multi_array/iterator.hpp: In instantiation of 'struct boost::detail::multi_array::operator_arrow_proxy<const std::pair<double, unsigned int>&>':
csrc/lsh_cpp/lsh.cpp|125 col 13| required from here
/opt/boost_1_48_0/include/boost/multi_array/iterator.hpp|40 col 10| error: forming pointer to reference type 'const std::pair<double, unsigned int>&'
/opt/boost_1_48_0/include/boost/multi_array/iterator.hpp|43 col 7| error: forming pointer to reference type 'const std::pair<double, unsigned int>&'
 csrc/lsh_cpp/lsh.cpp: In member function 'lsh_cpp::neighbour_iterator_t lsh_cpp::lsh_t::pimpl_t::query(const object_identifier_t&) const':
csrc/lsh_cpp/lsh.cpp|125 col 13| error: result of 'operator->()' yields non-pointer result

NOTE: This class is part of boost::multi_array, (I already wrote that), and I'm not instantiating it directly. I wrote above my instantiation. The class is instantiated by boost::multi_array this way:

 operator_arrow_proxy<reference>
 operator->() const
 {
     return operator_arrow_proxy<reference>(this->dereference());
 }

The use of "reference" makes me think that the reference is intended. Is there a reason for taking address to a reference to not work? I think to remember having done it myself a couple of times, and getting the address of the original, aliased variable that way....

Taking address of a reference is not a problem, but it returns pointer to the underlying type, not pointer to reference. Pointers to reference can't be created nor would they make sense since references cannot be rebound. Declaring a pointer to reference type is an error.

The return type T * therefore won't work if T is a reference type. Similarly declaring a mutable T makes no sense if T is a reference type, because references cannot be rebound. So the operator_arrow_proxy is apparently written to expect a non-reference.

If boost instantiates it with reference member of anything, which is always a reference type, it looks like a bug. Indeed, appears to be reported as bug #6554.