implementing std::variant and std::visit in C++17 when dealing with nested variants
I'm dealing with I tried several approaches but none seem to work... I'm working with problems using `std::variant` along with `std::visit` in C++17, particularly when dealing with nested variants. I have a situation where I want to hold either an `int`, a `std::string`, or another `std::variant` that can hold a `float` or a `bool`. However, when I try to access the values using `std::visit`, I'm running into a compile-time behavior that says 'no matching function for call to `std::visit`'. Here’s a simplified version of my code: ```cpp #include <variant> #include <iostream> #include <string> using NestedVariant = std::variant<float, bool>; using MyVariant = std::variant<int, std::string, NestedVariant>; void handleVariant(const MyVariant& var) { std::visit([](auto&& arg) { std::cout << "Value: " << arg << '\n'; }, var); } int main() { MyVariant var = NestedVariant(3.14f); handleVariant(var); return 0; } ``` The compiler behavior I get is: ``` behavior: no matching function for call to ‘std::visit(...)’ ``` I've tried changing the lambda to take `const auto&` instead of `auto&&`, but that doesn't help. I also tried breaking the cases down into separate functions for each variant type, but that just complicates the code further. What am I missing here? Is there a specific way to work with nested `std::variant`s that I should follow? Also, are there any best practices for handling errors when the variant doesn't hold the expected type? This is part of a larger CLI tool I'm building. I'd really appreciate any guidance on this. I'm coming from a different tech stack and learning C++.