From: Daniel Frey [mailto:daniel.frey@aixigo.de]
Should we propose std::regress (the counter-part for std::advance) for standardization (via a DR)? The current definition of std::advance seems to limit the number of elements that can be skipped backwards to signed types, but the container can be larger (OK, in theory, never tried it myself :). This would also nicely solve the implementation issue for us.
I don't think it's really a defect; there's a slight inconsistency with regards to the max/min values on most platforms, but nothing inherently wrong AFAICS. Note that the reverse_iterator trick can be used by client code too, so the "signed type limit" is easily defeated. [snip]
right? Although I wonder what happens if T is already a reverse iterator. Is it legal to reverse a reverse_iterator? Or do we need a trait and implement both cases separately?
Yes, reversing a reverse_iterator this way is fine (because a reverse_iterator satisfies the iterator requirements). Bjorn