fix overflow bug when attempting to access match results

test/regex_replace_overflow.cpp

@@ -0,0 +1,29 @@
+#include <boost/regex.hpp>
+
+#include <iostream>
+#include <iterator>
+#include <sstream>
+#include <string>
+
+#include <boost/core/lightweight_test.hpp>
+
+int main() {
+   std::string format_string = "$2$2147483647";
+   boost::regex e2("(<)|(>)|(&)|\\r");
+
+   std::string in = 
+      "#include <iostream>"
+      ""
+      "int main() { std::cout << \"Hello, world!\\n\"; }";
+
+   std::ostringstream t( std::ios::out | std::ios::binary );
+   std::ostream_iterator<char, char> oi( t );
+
+   boost::regex_replace(oi, in.begin(), in.end(), e2, format_string,
+                        boost::match_default | boost::format_all);
+
+   std::string s(t.str());
+
+   BOOST_TEST(!s.empty());
+   return boost::report_errors();
+}