Basic (bad) experiments for a constexpr rand() function

constexpr_rand.cc

//
// Requires C++20
//
#include <cstdint>
#include <iostream>
#include <string>


constexpr static auto to_int(const char* str, int offset) {
    return static_cast<std::uint32_t>(str[offset] - '0') * 10 +
        static_cast<std::uint32_t>(str[offset + 1] - '0');
}

constexpr static uint64_t seed() {
    auto t = __TIME__;
    uint64_t l = to_int(t, 0) * 60 * 60 ;
    l+= to_int(t, 3) * 60; 
    l+= to_int(t, 6);
    return l;
}

consteval static uint64_t xorshift64(uint64_t seed)
{
    uint64_t x = seed;
    x ^= x << 13;
    x ^= x >> 17;
    x ^= x << 5;
    return x;
}

constinit const static uint64_t g_seed = seed();

consteval static uint64_t rand(uint64_t level)
{
    if(level == 0)
        return xorshift64(g_seed);
    return xorshift64(rand(level-1));
}

int main() 
{
    std::cout << rand(1024) << std::endl;
    return 0;
}