In-Reply-To: <d0vsa6$bkm$1@sea.gmane.org> abarbati@iaanus.com (Alberto Barbati) wrote (abridged):

2) provide the hash function (with reintepret_cast<>) only for those platforms that we are able to check in advance that will satisfy those requirements and make any use of such function produce a static assert for all other platforms

In the case of (2), the platform may provide another implementation which can be used. For example, perhaps the pointers are segment+offset and the offset part is suitable. In my view, boost should be allowed to vary the implementation of the hash functions to suit the local platform. One interesting case is compacting garbage collectors. These already have problems with std::less() and I'd rather not make things worse by over-specifying hashing. -- Dave Harris, Nottingham, UK