Default the copy and move constructors for __tuple_leaf. This fixes bugs 18853 and 19118. Add a test case for that.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@206829 91177308-0d34-0410-b5e6-96231b3b80d8

test/utilities/tuple/tuple.tuple/TupleFunction.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.
+//
+//===----------------------------------------------------------------------===//
+
+// This is for bugs 18853 and 19118
+
+#if __cplusplus >= 201103L
+
+#include <tuple>
+#include <functional>
+
+struct X
+{
+    X() {}
+
+    template <class T>
+    X(T);
+
+    void operator()() {}
+};
+
+int
+main()
+{
+    X x;
+    std::function<void()> f(x);
+}
+#else
+int main () {}
+#endif