👀 Views: 72 💬 Answers: 1 📅 Created: 2025-08-29

C++11 std::shared_ptr std::function C++

I'm maintaining legacy code that I'm working with a double free behavior when using `std::shared_ptr` with a custom deleter in a situation where I'm also utilizing `std::function` to encapsulate some behavior. The scenario arises when I try to store a lambda function that captures a shared pointer, which is supposed to manage the lifetime of an object. Here’s a simplified version of my code: ```cpp #include <iostream> #include <memory> #include <functional> class MyClass { public: MyClass() { std::cout << "MyClass constructed" << std::endl; } ~MyClass() { std::cout << "MyClass destructed" << std::endl; } }; int main() { auto myPtr = std::shared_ptr<MyClass>(new MyClass(), [](MyClass* p) { std::cout << "Custom deleter called" << std::endl; delete p; }); std::function<void()> func = [myPtr]() { std::cout << "Inside lambda" << std::endl; }; func(); return 0; } ``` When I run this code, I observe the following output, but eventually, I get a double free behavior when the lambda goes out of scope: ``` MyClass constructed Inside lambda Custom deleter called MyClass destructed *** behavior in `./a.out`: double free or corruption (!prev): 0x0000000001b8f0c0 *** ``` I've tried switching to a `std::unique_ptr` instead, but the scenario continues since I'm still using the shared pointer to store the lambda. I'm unsure if I'm managing the lifetime of `myPtr` correctly. Is there something I'm missing in this setup, particularly with regards to how `std::function` interacts with `std::shared_ptr`? Are there best practices for using `std::function` with shared pointers that I should follow to avoid these kinds of issues? Any insights would be greatly appreciated. This is part of a larger web app I'm building. Thanks, I really appreciate it!