re PR libstdc++/64475 (FAIL: 28_regex/algorithms/regex_match/ecma/char/backref.cc)

	PR libstdc++/64475
	* include/bits/regex_executor.tcc (_Executor<>::_M_dfs): Copy the
	iterator, since the original one shouldn't be mutated.

From-SVN: r219151

libstdc++-v3/ChangeLog

+2015-01-02  Tim Shen  <timshen@google.com>
+
+	PR libstdc++/64475
+	* include/bits/regex_executor.tcc (_Executor<>::_M_dfs): Copy the
+	iterator, since the original one shouldn't be mutated.
+
 2015-01-02  Bernd Edlinger  <bernd.edlinger@hotmail.de>
 
 	PR libstdc++/64422

libstdc++-v3/include/bits/regex_executor.tcc

@@ -310,7 +310,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 	    if (!__submatch.matched)
 	      break;
 	    auto __last = _M_current;
-	    for (auto& __tmp = __submatch.first;
+	    for (auto __tmp = __submatch.first;
 		 __last != _M_end && __tmp != __submatch.second;
 		 ++__tmp)
 	      ++__last;