advanced patterns with custom allocator in std::map causing memory leaks in C++17
Can someone help me understand I'm prototyping a solution and I'm sure I'm missing something obvious here, but I've been struggling with this for a few days now and could really use some help... I'm working with an scenario with a custom allocator for `std::map` that seems to lead to memory leaks. I implemented a custom allocator derived from `std::allocator` to manage memory for a project using C++17. While my allocator works fine with `std::vector`, when I switch to `std::map`, I'm noticing that elements appear to be constructed and destructed properly, but the memory still isn't being freed as expected. Here's a simplified version of my allocator: ```cpp #include <memory> template <typename T> struct CustomAllocator : std::allocator<T> { using value_type = T; CustomAllocator() = default; template <typename U> CustomAllocator(const CustomAllocator<U>&) {} T* allocate(std::size_t n) { return static_cast<T*>(::operator new(n * sizeof(T))); } void deallocate(T* p, std::size_t n) { ::operator delete(p); } }; ``` I'm using this allocator with the `std::map` like this: ```cpp #include <map> std::map<int, std::string, std::less<int>, CustomAllocator<std::pair<const int, std::string>>> myMap; ``` I've tested inserting and removing elements, and each time I check the memory usage, it seems to be increasing continuously without being released. I confirmed that my `deallocate` method is being called, but I'm still seeing memory usage grow. The program runs until it exhausts memory, which is not what I expected. I also tried comparing my implementation against the default allocator, and there doesn’t seem to be any scenario with the default. I'm not sure where I went wrong with my custom allocator. Are there any specific rules I need to follow when implementing allocators for complex containers like `std::map`? Any insights or suggestions would be greatly appreciated! I'm working on a API that needs to handle this. My development environment is macOS. Is there a better approach? I'm working in a macOS environment.