Move libc++ pair/tuple assign test to libcxx/ test directory.

Libc++ implements the pair& operator=(pair<U, V>) assignment operator
using a single template that handles assignment from all tuple-like types.

This patch moves the test for that to the libcxx test directory since
it's non-standard. It also adds additional tests to the std/.../pair
directory to test the standard behavior this template implements.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@328758 91177308-0d34-0410-b5e6-96231b3b80d8

test/libcxx/utilities/utility/pairs/pairs.pair/assign_tuple_like.pass.cpp

@@ -0,0 +1,104 @@
+//===----------------------------------------------------------------------===//
+//
+//                     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
+
+// <utility>
+
+// template <class T1, class T2> struct pair
+
+// template<class U, class V> pair& operator=(tuple<U, V>&& p);
+
+#include <utility>
+#include <tuple>
+#include <array>
+#include <memory>
+#include <cassert>
+
+#include "archetypes.hpp"
+
+// Clang warns about missing braces when initializing std::array.
+#if defined(__clang__)
+#pragma clang diagnostic ignored "-Wmissing-braces"
+#endif
+
+int main()
+{
+    using C = TestTypes::TestType;
+    {
+       using P = std::pair<int, C>;
+       using T = std::tuple<int, C>;
+       T t(42, C{42});
+       P p(101, C{101});
+       C::reset_constructors();
+       p = t;
+       assert(C::constructed == 0);
+       assert(C::assigned == 1);
+       assert(C::copy_assigned == 1);
+       assert(C::move_assigned == 0);
+       assert(p.first == 42);
+       assert(p.second.value == 42);
+    }
+    {
+       using P = std::pair<int, C>;
+       using T = std::tuple<int, C>;
+       T t(42, -42);
+       P p(101, 101);
+       C::reset_constructors();
+       p = std::move(t);
+       assert(C::constructed == 0);
+       assert(C::assigned == 1);
+       assert(C::copy_assigned == 0);
+       assert(C::move_assigned == 1);
+       assert(p.first == 42);
+       assert(p.second.value == -42);
+    }
+    {
+       using P = std::pair<C, C>;
+       using T = std::array<C, 2>;
+       T t = {42, -42};
+       P p{101, 101};
+       C::reset_constructors();
+       p = t;
+       assert(C::constructed == 0);
+       assert(C::assigned == 2);
+       assert(C::copy_assigned == 2);
+       assert(C::move_assigned == 0);
+       assert(p.first.value == 42);
+       assert(p.second.value == -42);
+    }
+    {
+       using P = std::pair<C, C>;
+       using T = std::array<C, 2>;
+       T t = {42, -42};
+       P p{101, 101};
+       C::reset_constructors();
+       p = t;
+       assert(C::constructed == 0);
+       assert(C::assigned == 2);
+       assert(C::copy_assigned == 2);
+       assert(C::move_assigned == 0);
+       assert(p.first.value == 42);
+       assert(p.second.value == -42);
+    }
+    {
+       using P = std::pair<C, C>;
+       using T = std::array<C, 2>;
+       T t = {42, -42};
+       P p{101, 101};
+       C::reset_constructors();
+       p = std::move(t);
+       assert(C::constructed == 0);
+       assert(C::assigned == 2);
+       assert(C::copy_assigned == 0);
+       assert(C::move_assigned == 2);
+       assert(p.first.value == 42);
+       assert(p.second.value == -42);
+    }
+}