Add test to ensure that the converting constructor in N4089 is present and working

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@261874 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/test/std/utilities/memory/unique.ptr/unique.ptr.dltr/unique.ptr.dltr.dflt1/convert_ctor.pass.cpp b/test/std/utilities/memory/unique.ptr/unique.ptr.dltr/unique.ptr.dltr.dflt1/convert_ctor.pass.cpp
new file mode 100644
index 0000000..c00e98f
--- /dev/null
+++ b/test/std/utilities/memory/unique.ptr/unique.ptr.dltr/unique.ptr.dltr.dflt1/convert_ctor.pass.cpp
@@ -0,0 +1,27 @@
+//===----------------------------------------------------------------------===//
+//
+//                     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>
+
+// default_delete[]
+
+// template <class U>
+//   default_delete(const default_delete<U[]>&);
+//
+// This constructor shall not participate in overload resolution unless
+//   U(*)[] is convertible to T(*)[].
+
+#include <memory>
+#include <cassert>
+
+int main()
+{
+    std::default_delete<int[]> d1;
+    std::default_delete<const int[]> d2;
+}