27 Iterators library [iterators]

27.5 Iterator adaptors [predef.iterators]

27.5.1 Reverse iterators [reverse.iterators]

27.5.1.3 reverse_­iterator operations [reverse.iter.ops]

27.5.1.3.11 operator-= [reverse.iter.op-=]

constexpr reverse_iterator& operator-=(difference_type n);