MSVC std::_Container_base12 在 _Myproxy 中有错误的数据

Question

I use ENTT and add the following component to every entity.

    template<typename T, typename... Args>
    T& AddComponent(Args&&... args)
    {
        HZ_CORE_ASSERT(!HasComponent<T>(), "Entity already has component!");
        T& component = m_Scene->m_Registry.emplace<T>(m_EntityHandle, std::forward<Args>(args)...);
        m_Scene->OnComponentAdded<T>(*this, component);
        return component;
    }

    struct TagComponent
    {
        std::string Tag;

        TagComponent() = default;
        TagComponent(const TagComponent& other) : Tag(other.Tag) {};
        TagComponent(const std::string tag) : Tag(tag) {}
    };

Sometimes it will throw "access violation exception" when _Container_base12::_Orphan_all() is called during reallocation. I find that the address for the two pointers in std::Container_proxy is weird. _Mycont should have one byte more for the address to make sense. _Myfirstiter should not have the byte 0xfd at the front, it should be a nullptr.

What's the possible reason?

Answer 1

0xfd ? I bet there are 4 bytes with that value, not one: What are the debug memory fill patterns in Visual Studio C++ and Windows?

You're probabably looking at the remnants of a destroyed object.