Provide rvalue cast operator for ResultValue

Allows objects returned as ResultValue (instead of
ResultValueType::type) to be moved without requiring
additional casting or explicit use of ResultValue::value.

Resolves #589

tests/ResultValueRValue/ResultValueRValue.cpp

@@ -0,0 +1,38 @@
+// Copyright(c) 2020, Collabora Ltd. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+// VulkanHpp Test: Compile only test for issue 589.
+
+#define VULKAN_HPP_DISPATCH_LOADER_DYNAMIC 1
+
+#include "vulkan/vulkan.hpp"
+
+VULKAN_HPP_DEFAULT_DISPATCH_LOADER_DYNAMIC_STORAGE
+
+template <typename T>
+struct Wrapper
+{
+  Wrapper( T && raw ) : raw{ raw } {}
+
+  T raw;
+};
+
+void test()
+{
+  auto device = vk::Device{};
+  // We should be able to move created vk objects, regardless of the
+  // result type they were returned in.
+  Wrapper<vk::Image>{ device.createImage( {} ) };
+  Wrapper<vk::Pipeline>{ device.createGraphicsPipeline( {}, {} ) };
+}