CUDA randState intializer kernel identifier "curandState_t" is undefined

The problem

I am compiling a CUDA shared library that I've written, for this library, I need the capability to randomly sample stuff, therefore, as specified by the docs, I am initializing an array of curandState_t:

/**
 * @brief Sets up random number generators for each thread
 *
 * @param state pointer to the array of curandState
 * @param seed seed for the random number generator
 */
__global__ void rand_setup(curandState_t* state, unsigned long seed)
{
    /* 3D grid of 3D blocks id */
    size_t gid = getGlobalIdx_3D_3D();

    curand_init(seed, gid, 0, &state[gid]);

    printf("Initializing random number generator for thread %d");
}

The getGlobalIdx_3D_3D() call just retrieves the global ID through a bunch of tedious calculations, such as:

/**
 * @brief Get the global identifier of the thread
 *
 * thanks to: https://cs.calvin.edu/courses/cs/374/CUDA/CUDA-Thread-Indexing-Cheatsheet.pdf
 * for the snippet
 *
 * @return size_t The global index of the thread
 */
__device__ size_t getGlobalIdx_3D_3D()
{
    size_t blockId = blockIdx.x + blockIdx.y * gridDim.x
        + gridDim.x * gridDim.y * blockIdx.z;
    size_t threadId = blockId * (blockDim.x * blockDim.y * blockDim.z)
        + (threadIdx.z * (blockDim.x * blockDim.y))
        + (threadIdx.y * blockDim.x) + threadIdx.x;
    return threadId;
}

The errors

I am getting a cascade of compilation errors (I have just completed a substantial amount of work), however, many of them seem to stem from the fact that curandState_t is not recognized as a proper type, hence I get this annoying dump:

D:\Repos\MulticoreTree\shared\libkernel.cu(325): error: attribute "__global__" does not apply here

D:\Repos\MulticoreTree\shared\libkernel.cu(325): error: incomplete type is not allowed

D:\Repos\MulticoreTree\shared\libkernel.cu(325): error: identifier "curandState_t" is undefined

D:\Repos\MulticoreTree\shared\libkernel.cu(325): error: identifier "state" is undefined

D:\Repos\MulticoreTree\shared\libkernel.cu(325): error: type name is not allowed

D:\Repos\MulticoreTree\shared\libkernel.cu(325): error: expected a ")"

D:\Repos\MulticoreTree\shared\libkernel.cu(326): error: expected a ";"

D:\Repos\MulticoreTree\shared\libkernel.cu(407): warning #12-D: parsing restarts here after previous syntax error

Looking online for documentation, there doesn't seem to be anything that tells me to import a specific header, also, I have #include <cuda_runtime.h> at the top of my file, so what could be wrong?

I personally think that the type is not being recognized, but there might also be a problem with something else in the function's signature causing it to fail compilation.