Fix invalid reference to dropped PipelineCache object in ComputePipeline (#1469)

* Fix invalid reference to dropped cache object in compute pipeline

This is achieved by preventing the cache object from being partially
moved.

This fixes issue #1466.

* Add entry to changelog

CHANGELOG_VULKANO.md

@@ -2,6 +2,7 @@
 
 - Added support for `ImageAspect` and YV12/NV12 formats,  for use with the UnsafeImage API.
 - Added basic VK_KHR_external_memory, VK_KHR_external_memory_fd, and VK_EXT_external_memory_dma_buf support.
+- Fixed potential segmentation fault in `ComputePipeline` when referencing `PipelineCache` objects.
 
 # Version 0.20.0 (2020-12-26)
 

vulkano/src/pipeline/compute_pipeline.rs

@@ -163,7 +163,7 @@ impl<Pl> ComputePipeline<Pl> {
             };
 
             let cache_handle = match cache {
-                Some(cache) => cache.internal_object(),
+                Some(ref cache) => cache.internal_object(),
                 None => vk::NULL_HANDLE,
             };