What are SCARY iterators?

If you're using them, there's no need to get SCAREd... just ignore their SCARY-ness.

If you're making them, that means you have to make your iterators independent of the container's allocator type, and of other generic parameters to the container that don't affect the iterators.

From the linked PDF, at http://www.open-std.org/jtc1/sc22/WG21/docs/papers/2009/n2911.pdf

The acronym SCARY describes assignments and initializations that are Seemingly erroneous (appearing Constrained by conflicting generic parameters), but Actually work with the Right implementation (unconstrained bY the conflict due to minimized dependencies).