re PR libstdc++/66464 (codecvt_utf16 max_length returning incorrect value)

	PR libstdc++/66464
	* src/c++11/codecvt.cc (codecvt_utf16_base<char32_t>::do_max_length):
	Return 4 not 3.

From-SVN: r224415

libstdc++-v3/ChangeLog

+2015-06-12  Jonathan Wakely  <jwakely@redhat.com>
+
+	PR libstdc++/66464
+	* src/c++11/codecvt.cc (codecvt_utf16_base<char32_t>::do_max_length):
+	Return 4 not 3.
+
 2015-06-12  Ramana Radhakrishnan  <ramana.radhakrishnan@arm.com>
 
 	PR c++/66192

libstdc++-v3/src/c++11/codecvt.cc

@@ -1124,7 +1124,7 @@ do_length(state_type&, const extern_type* __from,
 
 int
 __codecvt_utf16_base<char32_t>::do_max_length() const throw()
-{ return 3; }
+{ return 4; }
 
 #ifdef _GLIBCXX_USE_WCHAR_T
 // Define members of codecvt_utf16<wchar_t> base class implementation.