implementing std::optional not holding a value after copy assignment in C++20
I'm working with a puzzling situation with `std::optional` in C++20. I have an `std::optional<int>` that I'm trying to assign a value to after copying it from another optional, but it ends up in an empty state instead of holding the expected value. Here’s a simplified version of my code: ```cpp #include <iostream> #include <optional> int main() { std::optional<int> opt1 = 42; std::optional<int> opt2; // Copy assignment from opt1 to opt2 opt2 = opt1; // Check if opt2 has a value if (opt2.has_value()) { std::cout << "opt2 has value: " << *opt2 << std::endl; } else { std::cout << "opt2 is empty!" << std::endl; } // Trying to reassign opt1 to a new value opt1 = std::nullopt; opt2 = opt1; // This is where I expect it to keep the previous value if (opt2.has_value()) { std::cout << "opt2 has value after reassignment: " << *opt2 << std::endl; } else { std::cout << "opt2 is empty after reassignment!" << std::endl; } return 0; } ``` When I run this code, after reassigning `opt1` to `std::nullopt`, I see that `opt2` is also empty, which is unexpected. I was under the impression that `std::optional` should maintain its value unless explicitly modified. I've also tried using `opt2 = std::move(opt1);` as well, and it behaves the same way. Is there something I'm missing about how `std::optional` handles copy assignments in this context? Any insights would be greatly appreciated. I'm open to any suggestions.