[futures.promise]. Depends on rvalue-ref support to work 100%.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@112388 91177308-0d34-0410-b5e6-96231b3b80d8

test/thread/futures/futures.promise/set_lvalue_at_thread_exit.pass.cpp

@@ -0,0 +1,36 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// <future>
+
+// class promise<R>
+
+// void promise<R&>::set_value_at_thread_exit(R& r);
+
+#include <future>
+#include <memory>
+#include <cassert>
+
+int i = 0;
+
+void func(std::promise<int&>& p)
+{
+    p.set_value_at_thread_exit(i);
+    i = 4;
+}
+
+int main()
+{
+    {
+        std::promise<int&> p;
+        std::future<int&> f = p.get_future();
+        std::thread(func, std::move(p)).detach();
+        assert(f.get() == 4);
+    }
+}