[futures.task] and [futures.async]. Requires variadics and rvalue-ref support.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@112500 91177308-0d34-0410-b5e6-96231b3b80d8

test/thread/futures/futures.tas/futures.task.members/assign_copy.fail.cpp

@@ -0,0 +1,48 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// <future>
+
+// class packaged_task<R(ArgTypes...)>
+
+// packaged_task& operator=(packaged_task&) = delete;
+
+#include <future>
+#include <cassert>
+
+class A
+{
+    long data_;
+
+public:
+    explicit A(long i) : data_(i) {}
+
+    long operator()(long i, long j) const {return data_ + i + j;}
+};
+
+int main()
+{
+    {
+        std::packaged_task<double(int, char)> p0(A(5));
+        std::packaged_task<double(int, char)> p;
+        p = p0;
+        assert(!p0);
+        assert(p);
+        std::future<double> f = p.get_future();
+        p(3, 'a');
+        assert(f.get() == 105.0);
+    }
+    {
+        std::packaged_task<double(int, char)> p0;
+        std::packaged_task<double(int, char)> p;
+        p = p0;
+        assert(!p0);
+        assert(!p);
+    }
+}