C ++模板，静态方法和构造函数

Question

Following code crashes on(/after) the Food-destructor; as shown in the stack below;

6 operator delete()  0xb7e5f4bf 
5 std::string::_Rep::_M_destroy()  0xb7ec648b   
4 <symbol is not available> 0xb7ec64d0  
3 std::basic_string<char, std::char_traits<char>, std::allocator<char> >::~basic_string()  0xb7ec653e   
2 Food::~Food() Main.cpp:126 0x0804c33c 
1 main() Main.cpp:199 0x0804c288    

The Food-ctor is never called but the destructor is? AFAICT things go haywire when resources of "string _text" are being freed, but I can't seem to understand why this is going wrong. Obviously I could change "string _text" to "string* _text", but I'd rather understand why this goes wrong.

class Food {
private:
    string _text;
public:
    Food(){
        cout << "ctor Food" << endl;
    }
    Food(string name) {
        cout << "ctor Food: name=" << name << endl;
    }

    virtual ~Food() {
        cout << "dtor Food" << endl;
    }
};

template<typename T>
class Action {
public:
    static T eat(int i) {
        cout << "Eat: " << i << endl;
    }
};

int main() {
    auto x = Action<Food>::eat(1);
}

Answer 1

What you are doing is undefined behavior . You define a function ( eat ) as returning a type T , but you are not actually returning anything. This leads to the assignment being undefined.