--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/3rdparty/vmime/cmake/cmake-cxx11/Modules/CheckCXX11Features/cxx11-test-regex.cpp	Tue Aug 17 11:19:54 2021 +0200
@@ -0,0 +1,26 @@
+#include <algorithm>
+#include <regex>
+
+int parse_line(std::string const& line)
+{
+	std::string tmp;
+	if(std::regex_search(line, std::regex("(\\s)+(-)?(\\d)+//(-)?(\\d)+(\\s)+"))) {
+		tmp = std::regex_replace(line, std::regex("(-)?(\\d)+//(-)?(\\d)+"), std::string("V"));
+	} else if(std::regex_search(line, std::regex("(\\s)+(-)?(\\d)+/(-)?(\\d)+(\\s)+"))) {
+		tmp = std::regex_replace(line, std::regex("(-)?(\\d)+/(-)?(\\d)+"), std::string("V"));
+	} else if(std::regex_search(line, std::regex("(\\s)+(-)?(\\d)+/(-)?(\\d)+/(-)?(\\d)+(\\s)+"))) {
+		tmp = std::regex_replace(line, std::regex("(-)?(\\d)+/(-)?(\\d)+/(-)?(\\d)+"), std::string("V"));
+	} else {
+		tmp = std::regex_replace(line, std::regex("(-)?(\\d)+"), std::string("V"));
+	}
+	return static_cast<int>(std::count(tmp.begin(), tmp.end(), 'V'));
+}
+
+int main()
+{
+	bool test = (parse_line("f 7/7/7 -3/3/-3 2/-2/2") == 3) &&
+				(parse_line("f 7//7 3//-3 -2//2") == 3) &&
+				(parse_line("f 7/7 3/-3 -2/2") == 3) &&
+				(parse_line("f 7 3 -2") == 3);
+	return test ? 0 : 1;
+}