C++20 std::variant optimization guide as expected with lambda expressions and std::visit
I'm optimizing some code but After trying multiple solutions online, I still can't figure this out... I keep running into I've been banging my head against this for hours. Quick question that's been bugging me - I've looked through the documentation and I'm still confused about I'm working with an scenario with `std::variant` in C++20 when trying to use `std::visit` with a lambda expression. I have a variant that can hold either `int` or `std::string`, and I'm attempting to handle both types using a lambda. However, I'm getting a compilation behavior that seems to indicate a question with type deduction. Here's a simplified version of my code: ```cpp #include <variant> #include <string> #include <iostream> std::variant<int, std::string> myVariant; void processVariant(const std::variant<int, std::string>& var) { std::visit([](auto&& arg) { std::cout << "Value: " << arg << std::endl; }, var); } int main() { myVariant = 42; processVariant(myVariant); myVariant = std::string("Hello, World!"); processVariant(myVariant); return 0; } ``` When I compile this code, I get the following behavior: ``` behavior: no matching function for call to ‘std::visit(...)’ ``` I’ve confirmed that both `int` and `std::string` are included in the variant, and I've tried separating the lambda into its own named function to see if that changes anything, but the behavior continues. I'm using GCC 11.2, and I wonder if this could be related to how I'm capturing the argument in the lambda. Any insights or suggestions on what might be going wrong? I’m also concerned about possible compatibility issues with different compilers or settings. For context: I'm using C++ on macOS. Thanks in advance! I'm working on a CLI tool that needs to handle this. Any advice would be much appreciated. This is part of a larger service I'm building. I'd be grateful for any help. This issue appeared after updating to C++ 3.10. Is there a better approach?