Function free_command_buffers 

pub unsafe fn free_command_buffers(
    device: VkHandleRef<'_, VkDevice>,
    command_pool: VkHandleRefMut<'_, VkCommandPool>,
    buffers: &[VkHandleRefMut<'_, VkCommandBuffer>],
)

Safety

• buffers must be allocated from command_pool.
• command_pool must be created from device.