unknownue/vulkan-tutorial-rust

Validation errors never happen because Drop impl never gets called after upgrading to winit 0.20

valignatev opened this issue · 4 comments

valignatev commented

Hi! Thanks for a great port of a vulkan-tutorial, it really helps!
I completed the fourth part of the tutorial (Logical Device) and forgot to call self.device.destroy_device(None). It didn't break anything, but now I wonder if validation layers should've complained about it?

They certainly do apply to the device creation process, because if I try to pass something silly to p_next field of the vk::DeviceCreateInfo, I get expected "unknown struct type" errors in the console.

UPD: Maybe this question is better be asked in the ash issue tracker 🤔

pezcode commented

Did you destroy the Vulkan instance? The call to destroy_instance would trigger the validation message. If you don't call that, the validation layers have no chance to check if the device was properly destroyed or not.

valignatev commented

I did. My Drop impl looked exactly like this:
https://github.com/unknownue/vulkan-tutorial-rust/blob/master/src/tutorials/04_logical_device.rs#L192-L204

But without destroy_device part

pezcode commented

I can't seem to reproduce this. My second thought was it might be because of not passing debug messenger info in vk::InstanceCreateInfo::p_next but even then the debug layers correctly print out a warning for me:

UNASSIGNED-ObjectTracker-ObjectLeak(ERROR / SPEC): msgNum: 0 - OBJ ERROR : VK_DEBUG_REPORT_OBJECT_TYPE_DEVICE_EXT object VkDevice 0x2837e5138d0[] has not been destroyed.

(SDK 1.1.114)

What SDK version are you using? And what validation layers did you enable?

valignatev commented

Ok, after you've clarified that validation errors indeed must appear, I started to look into how my application finishes more closely and I get now why there's no validation errors:

in winit 0.20 event_loop.run hijacks the thread and calls std::process.exit(0) internally when the loop ends, so Drop impl for VulkanApp never gets called. It even explicitly said in the winit docs:

Any values not passed to this function will *not* be dropped.

So unless self in the main_loop is used in the event loop callback, or run_return is used, VulkanApp's drop won't be called. The first tutorial chapter when it happens is 15_hello_triangle.rs, and all chapters before that don't execute the destructor, I checked that by running examples from the repo.

I think that I can fix that and submit a PR

Also, winit 0.20 reorganized platform modules so the examples do not compile on Linux because winit::os::unix::WindowExt became winit::platform::unix::WindowExtUnix although it is a separate issue, I think, and should be reported separately (I'll do that).

@pezcode Thanks a lot for you help with finding this ❤️

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