Unexpected Behavior with std::unique_ptr and Custom Deleter in C++17
I'm maintaining legacy code that This might be a silly question, but Hey everyone, I'm running into an issue that's driving me crazy. I've searched everywhere and can't find a clear answer. I've been struggling with this for a few days now and could really use some help. I'm encountering an issue when using `std::unique_ptr` with a custom deleter in C++17. My intention is to manage the lifetime of dynamically allocated objects, but I'm seeing unexpected behavior where the object is not being deleted as intended, leading to a resource leak. Here's a simplified version of my code: ```cpp #include <iostream> #include <memory> struct MyObject { MyObject() { std::cout << "MyObject created" << std::endl; } ~MyObject() { std::cout << "MyObject destroyed" << std::endl; } }; void customDeleter(MyObject* obj) { std::cout << "Custom deleter called" << std::endl; delete obj; } int main() { std::unique_ptr<MyObject, decltype(&customDeleter)> ptr(new MyObject(), customDeleter); // Intentional mistake: resetting the unique_ptr without a new object ptr.reset(); // ptr should now be nullptr, but I'm unsure if the custom deleter has been called return 0; } ``` When I run this code, I expect the output to show the creation and destruction of `MyObject`, as well as the call to the custom deleter. However, I get the output: ``` MyObject created ``` It seems that the destructor for `MyObject` is not being called, and the custom deleter isn't executed. I've tried checking if `ptr` is actually `nullptr` after the reset, but it seems I might be misinterpreting how `std::unique_ptr` handles the deletion when reset. Could someone explain why the custom deleter is not being invoked in this scenario? Is there something I might be overlooking regarding the ownership transfer or the behavior of `std::unique_ptr` in this context? Any insights would be greatly appreciated! What's the best practice here? I'm working on a application that needs to handle this. Any help would be greatly appreciated! For context: I'm using C++ on Linux. Is there a better approach? For reference, this is a production CLI tool.