[re.alg.search]/5 declares

template <class iterator, class charT, class traits>
bool regex_search(iterator first, iterator last,
                  const basic_regex<charT, traits>& e,
                  regex_constants::match_flag_type flags =
                      regex_constants::match_default);

where it's not explained, which iterator category the parameter iterator belongs to. This is inconsistent to the preceding declaration in the synopsis section [re.syn], which says:

template <class BidirectionalIterator, class charT, class traits>
bool regex_search(BidirectionalIterator first, BidirectionalIterator last,
                  const basic_regex<charT, traits>& e,
                  regex_constants::match_flag_type flags =
                      regex_constants::match_default);