// In header: <boost/mpi/allocator.hpp>

class allocator<void> {
public:
  // types
  typedef void *       pointer;      
  typedef const void * const_pointer;
  typedef void         value_type;   
  // member classes/structs/unions
  template<typename U> 
  struct rebind {
    // types
    typedef allocator< U > other;
  };
};