std::iter::Skip::count currently calls count on the inner iterator but that can overflow even if the Skip itself doesn't return more that usize::max_value() items.

For example:

(0..usize::max_value()).chain(0..10).skip(usize::max_value()).count()

This should return 10 but currently triggers an attempt to add with overflow (or returns 0 if overflow checks are disabled).

This is caused by