Dynamic resources validation errors: All metadata must be used by dxil.!55 = !{i32 1}

Compiling this code with -T ps_6_6 -E PSMain outputs: error: All metadata must be used by dxil.!55 = !{i32 1}

Is this code invalid or is it a compiler bug in DXC?

https://godbolt.org/z/4fMjoW4Gv

struct PSInput
{
    float4 position : SV_Position;
    float4 color    : COLOR0;
};

cbuffer Ids {
    int id1;
    int id2;
};

static const Texture2D<float4> textures[2] = {
    Texture2D<float4>(ResourceDescriptorHeap[id1]),
    Texture2D<float4>(ResourceDescriptorHeap[id2])
};

SamplerState ss: register(s0);

float4 PSMain(PSInput input) : SV_Target0
{
    float4 sample = textures[NonUniformResourceIndex(int(input.color.x))].Sample(ss, float2(0, 1));
    return sample;
}

Reproduce the report using the linked Godbolt example and the -T ps_6_6 -E PSMain command. Inspect the handling of dynamic resources and the emitted dxil.!55 metadata around the “All metadata must be used” diagnostic. Done means determining whether the HLSL is valid and, if so, correcting the validation failure with coverage for this case.