Add spirv target test coverage for vk::binding diagnostic on entry point parameters

[Copilot]

The diagnostic warning 38010 for unsupported vk::binding attributes on entry point parameters was already implemented but lacked test coverage for the spirv target—the primary use case for Vulkan bindings.

Changes

• Extended tests/diagnostics/entry-point-mod-errors.slang to include spirv target testing
• Added tests/diagnostics/vk-binding-entry-point-param-spirv.slang with a focused test case matching the reported scenario

Example

Users compiling this code with -target spirv now see the diagnostic:

[shader("compute")]
[numthreads(32, 1, 1)]
void main(
    [[vk::binding(0, 1)]] StructuredBuffer<float> a,  // warning 38010
    [[vk::binding(3, 2)]] RWStructuredBuffer<float> b  // warning 38010
) { }

The diagnostic correctly informs users that these attributes are unsupported on entry point parameters and will be ignored.

Original prompt

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This section details on the original issue you should resolve

<issue_title>vk::binding attribute ignored on entry point parameter</issue_title>
<issue_description># Issue Description

The vk::binding attribute is ignored if it is specified on an entry point parameter.

Reproducer Code

[numthreads(32, 1, 1)]
[shader("compute")]
void main(
    [[vk::binding(/* binding */ 0, /* set */ 1)]]
    StructuredBuffer<float> a,
    [[vk::binding(/* binding */ 3, /* set */ 2)]]
    RWStructuredBuffer<float> b,
)
{
    b[0] = a[0];
}

slang -entry main -o main.spv main.slang
spirv-dis main.spv

Expected Behavior

The SPIR-V object defines two descriptors, one with binding 0 set 1, and one with binding 3 set 2.

Actual Behavior

The SPIR-V object defines two descriptors, one with binding 0 set 0, and one with binding 1 set 0.

Environment

• Slang Version: v2025.23.2
• OS: NixOS 25.05
  </issue_description>

Comments on the Issue (you are @copilot in this section)

@bmillsNV This isn't supported, but there should be a diagnostic. @jhelferty-nv There should be a diagnostic, @zopsicle can you confirm that you're seeing it? ``` test.slang(5): warning 38010: attribute '[[vk::binding(...)]]' on parameter 'a' is unsupported on entry point parameters and will be ignored StructuredBuffer a, ^ test.slang(7): warning 38010: attribute '[[vk::binding(...)]]' on parameter 'b' is unsupported on entry point parameters and will be ignored RWStructuredBuffer b, ^ ```

• Fixes vk::binding attribute ignored on entry point parameter #9216

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