Incorrect Object Construction with std::variant in C++17 - Unexpected Type Behavior
I'm not sure how to approach I'm sure I'm missing something obvious here, but I'm working with an scenario when using `std::variant` in C++17 for type-safe union-like behavior. I have a variant that can hold either an `int` or a `std::string`, and I'm trying to construct it with an `int`, but it seems to be default constructing to `std::string` instead. Here's a simplified version of my code: ```cpp #include <iostream> #include <variant> #include <string> std::variant<int, std::string> myVariant; int main() { myVariant = 42; // Assigning an int std::cout << std::get<int>(myVariant) << '\n'; myVariant = std::string("Hello World"); // Assigning a string std::cout << std::get<std::string>(myVariant) << '\n'; return 0; } ``` When I run this code, everything seems fine, and I get the expected output. However, I added a function that takes the variant as a parameter and tries to manipulate it: ```cpp void processVariant(std::variant<int, std::string> v) { // Attempting to process the variant if (std::holds_alternative<int>(v)) { std::cout << "Processing int: " << std::get<int>(v) << '\n'; } else { std::cout << "Processing string: " << std::get<std::string>(v) << '\n'; } } ``` After further testing, I found that if I attempt to call `processVariant(myVariant)` right after assigning it an `int`, sometimes it behaves as if it's still holding the `std::string`, and I get a runtime exception: `bad_variant_access`. The scenario seems to occur when I have a vector of variants and pass it around. Here's the relevant code snippet: ```cpp std::vector<std::variant<int, std::string>> variants; variants.push_back(42); processVariant(variants[0]); // Sometimes fails here with bad_variant_access ``` I've checked and confirmed that Iām not accidentally modifying the variant after pushing it to the vector. Am I missing something about the lifecycle of `std::variant`, or could this be a result of improper type handling in my vector? Any insights would be greatly appreciated. How would you solve this? For context: I'm using C++ on Ubuntu 20.04. I'm developing on CentOS with C++. Thanks for your help in advance!