[HLSL] Misleading error message when using a UAV register for a raytracing acceleration structure

[DethRaid]

Functional impact

This bug provides a misleading error message when compiling a shader with a semantic error. This causes lots of confusion and doesn't lead the developer toward fixing the error

Minimal repro steps

• Write a shader with the HLSL code:

RaytracingAccelerationStructure opaque_as : register(u0);

Texture2D<float> depth_buffer : register(t0);

• Try to compile the shader
• Observe an error message saying that depth_buffer and opaque_as overlap their descriptors

Expected result

I'd expect the error message to say something like "raytracing acceleration structures must use SRV registers instead of UAV registers"

Actual result

The compiler gives an error message Shaders\Shadows\shadow.pixel.dxil.hlsl(17,1): error GDA5BD758: resource depth_buffer at register 0 overlaps with resource opaque_as at register 0, space 0

Further technical details

Brian Favela speculated that the HLSL compiler is assuming that a RT AS is always using a SRV register and ignoring the HLSL code that incorrectly says to use a UAV register

[damyanp]

@tex3d - can you do some initial investigation to help us repro and scope the issue.