[Boost-users] How to implement a custom hash function for __uint128_t?

Hi all, How can I implement a hash function for a __uint128_t type that is compatible with Boost? I tried this: #include #include #ifdef USE_64 typedef uint64_t MyId; // works fine #else typedef __uint128_t MyId; #endif inline std::size_t hash_value (const MyId &x) { // not a very good hash function, but I just want to get it working first! return static_caststd::size_t(x); } int main (int argc, char *argv[]) { std::unordered_set s; s.insert(42); } but I get 144 lines of errors (!) using g++-4.7.2 with Boost v1.51.0 on 64-bit Scientific Linux 6.2: error: no matching function for call to 'hash_value(const __int128 unsigned&)' Any pointers/help would be muchly appreciated. Scott. :)