C++20 structured bindings with std::map causing unexpected reference lifetimes
I'm working on a project and hit a roadblock. I've been working on this all day and I've spent hours debugging this and I'm working on a project and hit a roadblock. I'm working with a puzzling scenario when using structured bindings with a `std::map` in C++20. I have a map of integers to strings, and I'm trying to iterate through it using structured bindings to work with both the key and value directly. However, I'm running into a question where the reference to the value seems to become invalid after the loop, which leads to undefined behavior when I try to use it afterward. Here is a minimal example that reproduces the scenario: ```cpp #include <iostream> #include <map> #include <string> int main() { std::map<int, std::string> myMap = {{1, "One"}, {2, "Two"}, {3, "Three"}}; for (const auto &[key, value] : myMap) { std::cout << "Key: " << key << ", Value: " << value << '\n'; } // Attempting to access value after the loop // This should be valid, but I suspect it causes issues std::cout << "Last value: " << value << '\n'; return 0; } ``` When I run this code, I expect to see the last value printed after the loop, but instead, I get a compiler warning about using `value` outside of its initialized scope, implying that the reference might be dangling. I tried changing the loop to use a plain copy instead of structured bindings, like so: ```cpp for (const auto &pair : myMap) { const int key = pair.first; const std::string value = pair.second; std::cout << "Key: " << key << ", Value: " << value << '\n'; } ``` This works without any issues, but I really want to use structured bindings for clarity and conciseness. Is there a way to safely use structured bindings while ensuring the references remain valid? I'm using g++ version 10.2.0. Any insights into why this is happening or how I might resolve it would be greatly appreciated! For context: I'm using C++ on Ubuntu. Any ideas what could be causing this? Is there a better approach? This is my first time working with C++ 3.10.