Add tests for LWG 2796

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@289780 91177308-0d34-0410-b5e6-96231b3b80d8

test/std/utilities/tuple/tuple.tuple/tuple.cnstr/dtor.pass.cpp

@@ -0,0 +1,38 @@
+//===----------------------------------------------------------------------===//
+//
+//                     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.
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++98, c++03
+
+// Doesn't pass due to use of is_trivially_* trait.
+// XFAIL: gcc-4.9
+
+// <tuple>
+
+// template <class... Types> class tuple;
+
+// ~tuple();
+
+#include <tuple>
+#include <string>
+#include <cassert>
+#include <type_traits>
+
+int main()
+{
+  static_assert(std::is_trivially_destructible<
+      std::tuple<> >::value, "");
+  static_assert(std::is_trivially_destructible<
+      std::tuple<void*> >::value, "");
+  static_assert(std::is_trivially_destructible<
+      std::tuple<int, float> >::value, "");
+  static_assert(!std::is_trivially_destructible<
+      std::tuple<std::string> >::value, "");
+  static_assert(!std::is_trivially_destructible<
+      std::tuple<int, std::string> >::value, "");
+}

test/std/utilities/utility/pairs/pairs.pair/dtor.pass.cpp

@@ -0,0 +1,35 @@
+//===----------------------------------------------------------------------===//
+//
+//                     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.
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++98, c++03
+
+// Doesn't pass due to use of is_trivially_* trait.
+// XFAIL: gcc-4.9
+
+// <utility>
+
+// template <class T1, class T2> struct pair
+
+// ~pair()
+
+
+#include <utility>
+#include <type_traits>
+#include <string>
+#include <cassert>
+
+#include "test_macros.h"
+
+int main()
+{
+  static_assert((std::is_trivially_destructible<
+      std::pair<int, float> >::value), "");
+  static_assert((!std::is_trivially_destructible<
+      std::pair<int, std::string>::value), "");
+}