[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/swap.pass.cpp

@@ -0,0 +1,82 @@
+//===----------------------------------------------------------------------===//
+//
+//                     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 swap(promise& other);
+
+// template <class R> void swap(promise<R>& x, promise<R>& y);
+
+#include <future>
+#include <cassert>
+
+#include "../test_allocator.h"
+
+int main()
+{
+    assert(test_alloc_base::count == 0);
+    {
+        std::promise<int> p0(std::allocator_arg, test_allocator<int>());
+        std::promise<int> p(std::allocator_arg, test_allocator<int>());
+        assert(test_alloc_base::count == 2);
+        p.swap(p0);
+        assert(test_alloc_base::count == 2);
+        std::future<int> f = p.get_future();
+        assert(test_alloc_base::count == 2);
+        assert(f.valid());
+        f = p0.get_future();
+        assert(f.valid());
+        assert(test_alloc_base::count == 2);
+    }
+    assert(test_alloc_base::count == 0);
+    {
+        std::promise<int> p0(std::allocator_arg, test_allocator<int>());
+        std::promise<int> p(std::allocator_arg, test_allocator<int>());
+        assert(test_alloc_base::count == 2);
+        swap(p, p0);
+        assert(test_alloc_base::count == 2);
+        std::future<int> f = p.get_future();
+        assert(test_alloc_base::count == 2);
+        assert(f.valid());
+        f = p0.get_future();
+        assert(f.valid());
+        assert(test_alloc_base::count == 2);
+    }
+    assert(test_alloc_base::count == 0);
+    {
+        std::promise<int> p0(std::allocator_arg, test_allocator<int>());
+        std::promise<int> p;
+        assert(test_alloc_base::count == 1);
+        p.swap(p0);
+        assert(test_alloc_base::count == 1);
+        std::future<int> f = p.get_future();
+        assert(test_alloc_base::count == 1);
+        assert(f.valid());
+        f = p0.get_future();
+        assert(f.valid());
+        assert(test_alloc_base::count == 1);
+    }
+    assert(test_alloc_base::count == 0);
+    {
+        std::promise<int> p0(std::allocator_arg, test_allocator<int>());
+        std::promise<int> p;
+        assert(test_alloc_base::count == 1);
+        swap(p, p0);
+        assert(test_alloc_base::count == 1);
+        std::future<int> f = p.get_future();
+        assert(test_alloc_base::count == 1);
+        assert(f.valid());
+        f = p0.get_future();
+        assert(f.valid());
+        assert(test_alloc_base::count == 1);
+    }
+    assert(test_alloc_base::count == 0);
+}