* If pname:pAllocator is not `NULL`, pname:pAllocator must: be a pointer to a valid sname:VkAllocationCallbacks structure
* If pname:pipelineCache is a valid handle, it must: have been created, allocated or retrieved from pname:device
* Each of pname:device and pname:pipelineCache that are valid handles must: have been created, allocated or retrieved from the same sname:VkPhysicalDevice
* If sname:VkAllocationCallbacks were provided when pname:pipelineCache was created, a compatible set of callbacks must: be provided here
* If no sname:VkAllocationCallbacks were provided when pname:pipelineCache was created, pname:pAllocator must: be `NULL`