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class A
{
public:
    ~A() { std::cout << "A" << std::endl; }
};

class B : public A
{
public:
    ~B() { std::cout << "B" << std::endl; }
};

template <typename T>
class MySharedV2
{
public:
    template <typename T2>
    MySharedV2(T2 *p)
    {
        data_ = p;
        deleter_ = [p](){ delete p;};
    }
    ~MySharedV2()
    {
        deleter_();
    }
    T* operator->()
    {
        return data_;
    }
private:
    std::function<void()> deleter_;
    T* data_ = nullptr;
};

int main(){
    MySharedV2<A> ptr(new B());
}

对于上述代码，B的析构函数被调用我能理解，因为MySharedV2的析构函数会调用B的析构函数，但A的析构函数为什么也会被调用，是什么地方调用的它？

我明白了，如此写等价于直接delete B类型指针，当然会调用A的析构函数