初始化具有合法性的参考会员吗? [英] Initialising a reference member with itself legal?

问题描述

这是我在使用Valgrind的服务器应用程序中发现的错误.

This was a bug I found in a server application using Valgrind.

struct Foo
{
    Foo(const std::string& a)
        : a_(a_)
    {
    }
    const std::string& a_;
};

使用gcc -Wall，您不会收到警告.为什么这样的法律法规?

with gcc -Wall you don't get a warning. Why is this legal code?

推荐答案

所违反的内容 8.3.2/4 A ...引用应初始化为引用有效的对象或函数.因此，这绝对是非法的.

What you've got violates 8.3.2/4 A ... reference shall be initialized to refer to a valid object or function. So it is most certainly illegal.

请注意，并非所有错误程序都必须由编译器检测，尽管老实说我认为这是其中之一.

Note that not all erroneous programs are required to be detected by the compiler, although I honestly would have thought this was one of them.

值得一提的是，启用最大编译器警告的g ++版本4.4.1可以愉快地接受该程序，而不会发出警告:

For what it's worth, g++ version 4.4.1 with maximal compiler warnings turned on happily accepts this program without a warning either:

int main(void)
{   
    int *p = 0;
    *p = 5;
}

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