test: Mark 316 tests as XFAIL to rename to xfail.pass.cpp.

test/input.output/string.streams/istringstream/istringstream.assign/member_swap.xfail.pass.cpp

@@ -0,0 +1,56 @@
+//===----------------------------------------------------------------------===//
+//
+//                     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_istringstream
+
+// void swap(basic_istringstream& rhs);
+
+#include <sstream>
+#include <cassert>
+
+int main()
+{
+    {
+        std::istringstream ss0(" 123 456");
+        std::istringstream ss(" 789 321");
+        ss.swap(ss0);
+        assert(ss.rdbuf() != 0);
+        assert(ss.good());
+        assert(ss.str() == " 123 456");
+        int i = 0;
+        ss >> i;
+        assert(i == 123);
+        ss >> i;
+        assert(i == 456);
+        ss0 >> i;
+        assert(i == 789);
+        ss0 >> i;
+        assert(i == 321);
+    }
+    {
+        std::wistringstream ss0(L" 123 456");
+        std::wistringstream ss(L" 789 321");
+        ss.swap(ss0);
+        assert(ss.rdbuf() != 0);
+        assert(ss.good());
+        assert(ss.str() == L" 123 456");
+        int i = 0;
+        ss >> i;
+        assert(i == 123);
+        ss >> i;
+        assert(i == 456);
+        ss0 >> i;
+        assert(i == 789);
+        ss0 >> i;
+        assert(i == 321);
+    }
+}