C++：删除由new创建的指针时的内存问题

我对以下代码有点困惑

int main()
{
    int* a = new int{12};
    int* b = new int;

    b = a;
    delete a;

    delete b;

    return 0;
}

该代码返回一个错误

a.out(27538,0x10ade7e00) malloc: *** error for object 0x7f8c18504160: pointer being freed was not allocated
a.out(27538,0x10ade7e00) malloc: *** set a breakpoint in malloc_error_break to debug
zsh: abort      ./a.out

我的问题是，当我删除 a 时，它会自动删除 b 吗？这里的机制是什么，我有点迷路了。

回答

b = a;    // here the int that b pointed at "leaks" (you have no way of deleting it)

delete a; // here "a" is deleted first

delete b; // here "a" is deleted a second time (undefined behavior)