basic_regex();
explicit basic_regex(const charT* p, flag_type f = regex_constants::ECMAScript);
basic_regex(const charT* p, size_t len, flag_type f = regex_constants::ECMAScript);
basic_regex(const basic_regex& e);
basic_regex(basic_regex&& e) noexcept;
template<class ST, class SA>
explicit basic_regex(const basic_string<charT, ST, SA>& s,
flag_type f = regex_constants::ECMAScript);
template<class ForwardIterator>
basic_regex(ForwardIterator first, ForwardIterator last,
flag_type f = regex_constants::ECMAScript);
basic_regex(initializer_list<charT> il, flag_type f = regex_constants::ECMAScript);