Rust-GPU / Rust-GPU/rust-gpu

entry point fn with too many params fails

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bug
Dominant language
Rust
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Description

I am trying to convert a project of mine from wgsl to rust-gpu. I got the basics done, but I have a shader I can't get to compile

This is the entry point

#[spirv(compute(threads(8, 8, 1)))]
pub fn cs_main(
    #[spirv(global_invocation_id)] gid: UVec3,
    #[spirv(uniform, descriptor_set = 1, binding = 0)] globals: &SBGlobalData,
    #[spirv(uniform, descriptor_set = 2, binding = 0)] camera: &SBCameraData,
    #[spirv(storage_buffer, descriptor_set = 3, binding = 0)] tlas_nodes: &[BvhNode],
    #[spirv(storage_buffer, descriptor_set = 3, binding = 1)] tlas_instances: &[TlasInstance],
    #[spirv(storage_buffer, descriptor_set = 3, binding = 2)] blas_nodes: &[BvhNode],
    #[spirv(storage_buffer, descriptor_set = 3, binding = 3)] blas_tris: &[Triangle],
    #[spirv(descriptor_set = 3, binding = 4)] rt_out: &Image!(2D, format = rgba16f, sampled = false, arrayed = false, multisampled = false),
    #[spirv(uniform, descriptor_set = 3, binding = 5)] rt_consts: &RaytracerConsts,
    #[spirv(uniform, descriptor_set = 3, binding = 6)] mat_consts: &RtLightConsts,
    #[spirv(storage_buffer, descriptor_set = 3, binding = 7)] rt_materials: &[RtMaterialEntry],
    #[spirv(descriptor_set = 3, binding = 8)] albedo_sampler: &Sampler,
    #[spirv(descriptor_set = 4, binding = 0)] albedo_tex_table: &RuntimeArray<Image!(2D, type = f32, sampled = true, arrayed = false, multisampled = false)>,
) {
Expected Behaviour

Shader compiles fine

Example & Steps To Reproduce

This is the errors I am getting

info: latest update on 2026-04-11 for version 1.96.0-nightly (02c7f9bec 2026-04-10)
info: component rust-src is up to date
warn: skipping unavailable component rust-std for target spirv-unknown-vulkan1.2
   Compiling shader-bench-rsgpu-user v0.1.0 (F:\rust\ideas\shader-bench\projects\raytracer-rs\.shader-bench\shader-cache\rust-gpu-build\ce910f26f4188d71)
warning: an unknown error occurred
  |
  = note: spirv-opt failed, leaving as unoptimized
error: [VUID-StandaloneSpirv-OpTypeRuntimeArray-04680] OpVariable, <id> '14[%albedo_tex_table]', is attempting to create memory for an illegal type, OpTypeRuntimeArray.

For Vulkan OpTypeRuntimeArray can only appear as the final member of an OpTypeStruct, thus cannot be instantiated via OpVariable
         %albedo_tex_table = OpVariable %_ptr_UniformConstant__runtimearr_94 UniformConstant

Bonus: u32.saturated_sub is not implemented btw

System Info

Windows + custom compiler wrap to compile rust-gpu shader at runtime without having my whole workspace on the specific nightly toolchain

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start by reproducing the reported rust-gpu build with the provided cs_main entry point and its RuntimeArray parameter. Inspect the generated SPIR-V around albedo_tex_table and the Vulkan OpTypeRuntimeArray error; done means the shader compiles without creating an illegal OpVariable for the runtime array.

Written by the indexing model from the issue text.

Assessment

Tech stack
rust
Domain
compilers
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Quiet
Clarity
Mostly clear
Newbie friendliness
48/100

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