C++在基类问题上返回带有模板的嵌套类

class Base {
public:
    template<typename T>
    class Nested {
        // 嵌套类的实现
    };
};

template<typename Derived>
class DerivedBase : public Base {
public:
    template<typename T>
    typename Derived::template Nested<T> createNested() {
        return typename Derived::template Nested<T>();
    }
};

class Derived : public DerivedBase<Derived> {
public:
    using DerivedBase<Derived>::DerivedBase;
};

int main() {
    Derived derived;
    auto nested = derived.createNested<int>();
    // 使用nested对象
}