Exception when trying to bake descriptor set with NULL bindings

[Silverlan]

Example:

auto dsgInfos = std::vector<std::unique_ptr<Anvil::DescriptorSetInfo>>{};
auto descSetInfo = Anvil::DescriptorSetInfo::create();
const auto numBindings = 5u;
for(auto i=0u;i<numBindings;++i)
{
	descSetInfo->add_binding(
		i, /* binding    */
		static_cast<VkDescriptorType>(vk::DescriptorType::eCombinedImageSampler),
		1u, /* n_elements */
		static_cast<VkShaderStageFlags>(vk::ShaderStageFlagBits::eFragment)
	);
}
dsgInfos.push_back(std::move(descSetInfo));
auto dsg = Anvil::DescriptorSetGroup::create(dev,dsgInfos,false);
auto ds = dsg->get_descriptor_set(0u);
for(auto i=0u;i<5u;++i)
{
	ds->set_binding_item(i,Anvil::DescriptorSet::CombinedImageSamplerBindingElement{
		static_cast<VkImageLayout>(vk::ImageLayout::eShaderReadOnlyOptimal),
		imgView,sampler
	});
}
drawCmd->record_bind_descriptor_sets(
	static_cast<VkPipelineBindPoint>(vk::PipelineBindPoint::eGraphics),
	GetPipelineLayout(),
	0u, /* first set */
	1u, /* set count */
	&ds,
	0u, /* dynamic offset count */
	nullptr
);

The code above works fine, both baking and binding run without issues.
However, if you change the second loop so it only binds 4 elements (i.e. one of the bindings is NULL):

for(auto i=0u;i<4u;++i)
{
	ds->set_binding_item(i,Anvil::DescriptorSet::CombinedImageSamplerBindingElement{
		static_cast<VkImageLayout>(vk::ImageLayout::eShaderReadOnlyOptimal),
		imgView,sampler
	});
}

then you get an exception during the baking process when trying to bind the descriptor set. The exception is caused in src/wrappers/descriptor_set.cpp (Anvil::DescriptorSet::bake()), in the vkUpdateDescriptorSets-call of this code block:

/* Issue the Vulkan call */
if (m_cached_ds_write_items_vk.size() > 0)
{
    std::shared_ptr<Anvil::BaseDevice> device_locked_ptr(m_device_ptr);

    lock();
    {
        vkUpdateDescriptorSets(device_locked_ptr->get_device_vk(),
                                static_cast<uint32_t>(m_cached_ds_write_items_vk.size() ),
                                &m_cached_ds_write_items_vk[0],
                                0,        /* copyCount         */
                                nullptr); /* pDescriptorCopies */
    }
    unlock();
}

I'm not actually sure if it is valid to have NULL bindings in a descriptor set when binding it, but I can't find anything in the vulkan specification that says otherwise.

[DominikWitczakAMD]

They should be fine, as long as you do not try to access corresponding bindings from the shader level.. Let me have a look at this now.

[DominikWitczakAMD]

Fixed internally. An update containing the patch will be pushed to this repo early next week.

[DominikWitczakAMD]

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