是自初始化'A a = a;'允许？ [英] Is self-initialization 'A a = a;' allowed?

问题描述

此代码在运行时在复制构造函数中失败。

但是编译器（MSVS2008）不会发出警告。

This code fails at runtime in the copy constructor.
But the compiler (MSVS2008) issues no warnings.

引用标准）这段代码是非法还是什么？

Could you explain (preferably cite the standard) whether this code is illegal or what?

我明白A a = a;不应该写在第一个地方，
，但我正在寻找理论背景。

I understand that A a = a; should never be written at the first place, but I am looking for a theoretical background.

 class A
 {
 public: 

    A()
    :p(new int)
    {
    }

    A(const A& rv)
    {
        p = new int(*rv.p);
    }

    ~A()
    {
        delete p;
    }


 private:

    int *p;
 };

 int main()
 {
    A a = a;
 }

推荐答案

您的代码不会调用标准构造函数，但是复制构造函数，因此您正在访问未初始化的指针。

Your code is not calling the standard constructor but the copy constructor, so you are accessing an uninitialized pointer.

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