Support forward_list<Incomplete Type>. Patch by Zhihao Yuan!

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@200814 91177308-0d34-0410-b5e6-96231b3b80d8

test/containers/sequences/forwardlist/forwardlist.cons/default_recursive.pass.cpp

@@ -0,0 +1,25 @@
+//===----------------------------------------------------------------------===//
+//
+//                     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.
+//
+//===----------------------------------------------------------------------===//
+
+// <forward_list>
+
+// class forward_list
+
+// forward_list();
+
+#include <forward_list>
+
+struct X
+{
+    std::forward_list<X> q;
+};
+
+int main()
+{
+}