HLSL shader seems to compile do combined image sampler but spirv cross does not detect it.

[Makogan]

I am not sure if the issue is with spirv cross or shaderc but I am leaning towards spirv-cross.

I have this HLSL shader:

[[vk::combinedImageSampler]][[vk::binding(1)]]
Texture2D<float4> textures[3];
[[vk::combinedImageSampler]][[vk::binding(1)]]
SamplerState samp;

float4 main(
    [[vk::location(0)]] float3 normal : NORMAL0,
    [[vk::location(1)]] float3 uv : UV0
) : SV_TARGET
{
  return textures[int(uv.z)].Sample(samp, uv.xy);
}

Which shader C compiles. Note the directive [[vk::combinedImageSampler]]. In my current code base I am getting this validation error:

"Validation Error: [ VUID-VkGraphicsPipelineCreateInfo-layout-00756 ] Object 0: handle = 0x55fe20a67de0, name = Logical device from NVIDIA GeForce GTX 1070, type = VK_OBJECT_TYPE_DEVICE; | MessageID = 0x45717876 | Shader uses descriptor slot 0.1 (expected `VK_DESCRIPTOR_TYPE_COMBINED_IMAGE_SAMPLER, VK_DESCRIPTOR_TYPE_SAMPLED_IMAGE`) but not declared in pipeline layout The Vulkan spec states: layout must be consistent with all shaders specified in pStages (https://vulkan.lunarg.com/doc/view/1.3.211.0/linux/1.3-extensions/vkspec.html#VUID-VkGraphicsPipelineCreateInfo-layout-00756)"', crates/vulkan_bindings/src/hardware_interface.rs:914:5

After some debugging I realised that spirv-cross considers there are only separate shaders and samplers in the spirv code I am feeding it, i.e. sampeld_images is empty but separate_images has one entry.

So either shaderc has a bug and it is not recognising the directive (which is valid as per the microsoft documentation) or spirv-cross is making a mistake when parsing.

It seems the compiled shader does expect a combined image sampler, that makes me think it might be a mistake on spirv-cross's end. WHen I remove the directive I get a different error so it very much seems shaderc is correctly using the directive when making the shader?

[HansKristian-Work]

Do you have the SPIR-V? DXC (which I think shaderc has to build on?) complains with

/tmp/test.hlsl:1:3: error: 'combinedImageSampler' attribute only applies to Textures (e.g., Texture2D) and SamplerState
[[vk::combinedImageSampler]][[vk::binding(1)]]
  ^

[HansKristian-Work]

Ping.