Hi John, I'd like to suppress GCC's backward-compatibility warnings by using <unordered_set> instead of <backward/hash_set> or whatever it is, but I can't find a config macro that tells me <unordered_set> is available. Can we set one up, or something else I can use for that purpose? Thanks, -- Dave Abrahams BoostPro Computing http://www.boostpro.com