Boost C++ Libraries

...one of the most highly regarded and expertly designed C++ library projects in the world. — Herb Sutter and Andrei Alexandrescu, C++ Coding Standards

Struct template get_hash<void, T>

boost::intrusive::get_hash<void, T>

// In header: <boost/intrusive/hashtable.hpp>

template<typename T> 
struct get_hash<void, T> {
  // types
  typedef ::boost::hash< T > type;
};