initial value of reference to non-const must be an lvalue

[soumik12345]

Hi, I was trying to follow the excellent article by @straaljager. While trying to run this codebase using Cuda 11, I am getting the following error:
main.cu(191): error: initial value of reference to non-const must be an lvalue
Can someone please suggest how to resolve this issue?

[JurriaanD]

I had to make two changes to the code to work with CUDA 12.8:

• smallptCUDA.cu:113 change the ray argument in radiance from Ray &r to Ray r
• cutil_math.h:339 implement an extra multiplication operator version

inline __host__ __device__ void operator*=(float3 &a, const float3 b)
{
    a.x *= b.x; a.y *= b.y; a.z *= b.z;
}

The code compiled at this point but I was getting a black output image. I added a check for any CUDA errors in the main method

std::cout << "Render kernel status: " << cudaPeekAtLastError() << ": " << cudaGetErrorString(cudaPeekAtLastError()) << std::endl;

Which pointed me towards a version mismatch between my installed driver and cuda/nvcc versions.