非const引用绑定到临时,Visual Studio错误? [英] Non-const reference bound to temporary, Visual Studio bug?
问题描述
我遇到这个,而编译一些便携式代码在 gcc
。基本上,这个奇怪的代码编译在Visual studio,这真的只是让我的脑海:
I ran into this while compiling some portable code in gcc
. Basically this strange code compiles in Visual studio which really just blows my mind:
class Zebra {int x;};
Zebra goo() {Zebra z; return z;}
void foo(Zebra &x)
{
Zebra y;
x = y;
foo(goo());
}
Visual studio
这一个飞。 gcc
会将此捕获为编译错误。有趣的是,如果你输入typedef Zebra to int, VC ++
会抱怨。相当矛盾的行为。
Visual studio
lets this one fly. gcc
will catch this as a compile error. Interestingly, If you typedef Zebra to int, VC++
will complain. Quite contradictory behavior. Thoughts?
推荐答案
这是Visual Studio的旧扩展,我在Microsoft网站上找到的唯一参考是这个错误报告: 临时对象可以绑定到非Const References ,其中有以下示例代码:
This is old extension to Visual Studio, the only reference I could find on the Microsoft site was this bug report: Temporary Objects Can be Bound to Non-Const References, which has the following example code:
struct A {};
A f1();
void f2(A&);
int main()
{
f2(f1()); // This line SHALL trigger an error, but it can be compiled without any errors or warnings.
}
其中一个回应说明:
有一个4级警告(如果你传递/ W4到编译器,则启用4级警告)
There is a level 4 warning (level 4 warning are enabled if you pass /W4 to the compiler) for it
这篇博客文章: Visual C ++是这样的Liberal ,它涵盖了这个扩展,注意到: p>
This blog post: Visual C++ is so Liberal which covers this extension notes that:
使用禁用语言扩展(/ Za)会出现错误:
Using Disable Language Extensions (/Za) makes it an error:
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