Merge to upstream r225300.

Change-Id: I2b23715db9ac129ff80aa78ad5824db0a4d6fbb3

test/std/input.output/string.streams/stringstream.cons/default.pass.cpp

@@ -0,0 +1,46 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// <sstream>
+
+// template <class charT, class traits = char_traits<charT>, class Allocator = allocator<charT> >
+// class basic_stringstream
+
+// explicit basic_stringstream(ios_base::openmode which = ios_base::out|ios_base::in);
+
+#include <sstream>
+#include <cassert>
+
+int main()
+{
+    {
+        std::stringstream ss;
+        assert(ss.rdbuf() != 0);
+        assert(ss.good());
+        assert(ss.str() == "");
+    }
+    {
+        std::stringstream ss(std::ios_base::in);
+        assert(ss.rdbuf() != 0);
+        assert(ss.good());
+        assert(ss.str() == "");
+    }
+    {
+        std::wstringstream ss;
+        assert(ss.rdbuf() != 0);
+        assert(ss.good());
+        assert(ss.str() == L"");
+    }
+    {
+        std::wstringstream ss(std::ios_base::in);
+        assert(ss.rdbuf() != 0);
+        assert(ss.good());
+        assert(ss.str() == L"");
+    }
+}