struct MyConstantBuffer {
    float4 myParam1[8];
};

cbuffer myCBuffer : register(b0) {
  MyConstantBuffer myConstantBuffer;
}

struct MyConstantBufferWrapper {
    MyConstantBuffer constants;

    float4 GetParam1(uint index) { return constants.myParam1[index]; }
};

MyConstantBufferWrapper CreateWrapper() {
    MyConstantBufferWrapper wrapper;
    wrapper.constants = myConstantBuffer;
    return wrapper;
};

struct VS_OUTPUT {
    float4  m_ScreenPos  : VS_OUT_POSITION;
};

struct MyStruct {
    uint myIndex;
};

static MyConstantBufferWrapper myWrapper = CreateWrapper();

float4 main(VS_OUTPUT In) : SV_Target {
    MyStruct myStruct = (MyStruct)0;

    // Causes the issue:
    float4 myParam = myWrapper.GetParam1(myStruct.myIndex);

    // Works fine:
    //float4 myParam = myConstantBuffer.myParam1[myStruct.myIndex];

    return myParam;
}

error: line 101: OpFunctionCall Argument <id> '21[%myWrapper]'s type does not match Function <id> '52[%_ptr_Function_MyConstantBufferWrapper]'s parameter type.
  %47 = OpFunctionCall %v4float %MyConstantBufferWrapper_GetParam1 %myWrapper %param_var_index