Implement LWG#2948: unique_ptr does not define operator<< for stream output

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@319038 91177308-0d34-0410-b5e6-96231b3b80d8

test/std/utilities/memory/unique.ptr/unique.ptr.special/io.fail.cpp

@@ -0,0 +1,31 @@
+//===----------------------------------------------------------------------===//
+//
+//                     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.
+//
+//===----------------------------------------------------------------------===//
+
+// <memory>
+
+// unique_ptr
+
+// template<class CharT, class Traits, class Y, class D>
+//   basic_ostream<CharT, Traits>&
+//   operator<<(basic_ostream<CharT, Traits>& os, const unique_ptr<Y, D>& p);
+
+//   -?- Remarks: This function shall not participate in overload resolution unless os << p.get() is a valid expression.
+
+#include <memory>
+#include <sstream>
+#include <cassert>
+
+class A {};
+
+int main()
+{
+    std::unique_ptr<A> p(new A);
+    std::ostringstream os;
+    os << p;
+}

test/std/utilities/memory/unique.ptr/unique.ptr.special/io.pass.cpp

@@ -0,0 +1,29 @@
+//===----------------------------------------------------------------------===//
+//
+//                     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.
+//
+//===----------------------------------------------------------------------===//
+
+// <memory>
+
+// unique_ptr
+
+// template<class CharT, class Traits, class Y, class D>
+//   basic_ostream<CharT, Traits>&
+//   operator<<(basic_ostream<CharT, Traits>& os, const unique_ptr<Y, D>& p);
+
+#include <memory>
+#include <sstream>
+#include <cassert>
+
+int main()
+{
+    std::unique_ptr<int> p(new int(3));
+    std::ostringstream os;
+    assert(os.str().empty());
+    os << p;
+    assert(!os.str().empty());
+}