42     std::basic_regex re(s1.begin(), s1.end());  in main()  local
44     static_assert(std::is_same_v<decltype(re), std::basic_regex<char>>, "");  in main()
45     assert(re.flags() == std::regex_constants::ECMAScript);  in main()
46     assert(re.mark_count() == 0);  in main()
51     std::basic_regex re(s1.begin(), s1.end(), std::regex_constants::basic);  in main()  local
53     static_assert(std::is_same_v<decltype(re), std::basic_regex<wchar_t>>, "");  in main()
54     assert(re.flags() == std::regex_constants::basic);  in main()
55     assert(re.mark_count() == 1);  in main()
61     std::basic_regex re("(a([bc]))"s);  in main()  local
62     static_assert(std::is_same_v<decltype(re), std::basic_regex<char>>, "");  in main()
63     assert(re.flags() == std::regex_constants::ECMAScript);  in main()
64     assert(re.mark_count() == 2);  in main()
69     std::basic_regex re(L"(a([bc]))"s, std::regex_constants::awk);  in main()  local
70     static_assert(std::is_same_v<decltype(re), std::basic_regex<wchar_t>>, "");  in main()
71     assert(re.flags() == std::regex_constants::awk);  in main()
72     assert(re.mark_count() == 2);  in main()
77     std::basic_regex re("ABCDE");  in main()  local
78     static_assert(std::is_same_v<decltype(re), std::basic_regex<char>>, "");  in main()
79     assert(re.flags() == std::regex_constants::ECMAScript);  in main()
80     assert(re.mark_count() == 0);  in main()
85     std::basic_regex re(L"ABCDE", std::regex_constants::grep);  in main()  local
86     static_assert(std::is_same_v<decltype(re), std::basic_regex<wchar_t>>, "");  in main()
87     assert(re.flags() == std::regex_constants::grep);  in main()
88     assert(re.mark_count() == 0);  in main()
93     std::basic_regex re("ABCDEDEF", 7);  in main()  local
94     static_assert(std::is_same_v<decltype(re), std::basic_regex<char>>, "");  in main()
95     assert(re.flags() == std::regex_constants::ECMAScript);  in main()
96     assert(re.mark_count() == 0);  in main()
101     std::basic_regex re(L"ABCDEDEF", 8, std::regex_constants::awk);  in main()  local
102     static_assert(std::is_same_v<decltype(re), std::basic_regex<wchar_t>>, "");  in main()
103     assert(re.flags() == std::regex_constants::awk);  in main()
104     assert(re.mark_count() == 0);  in main()
110     std::basic_regex re(source);  in main()  local
111     static_assert(std::is_same_v<decltype(re), std::basic_regex<char>>, "");  in main()
112     assert(re.flags() == source.flags());  in main()
113     assert(re.mark_count() == source.mark_count());  in main()
124     std::basic_regex re({'A', 'B', 'F', 'E', 'D'});  in main()  local
125     static_assert(std::is_same_v<decltype(re), std::basic_regex<char>>, "");  in main()
126     assert(re.flags() == std::regex_constants::ECMAScript);  in main()
127     assert(re.mark_count() == 0);  in main()
132     std::basic_regex re({L'A', L'B', L'F', L'E', L'D'}, std::regex_constants::grep);  in main()  local
133     static_assert(std::is_same_v<decltype(re), std::basic_regex<wchar_t>>, "");  in main()
134     assert(re.flags() == std::regex_constants::grep);  in main()
135     assert(re.mark_count() == 0);  in main()