c++ - 命名空间成员定义

Question

namespace M{
   void f();
   void M::f(){}
}

int main(){}

上面的代码报错如下:

"ComeauTest.c", line 3: error: qualified name is not allowed in namespace member declaration void M::f(){}

和

G++ also gives error.

但是

VS2010 compiles fine.

我的问题是:

a) 预期的行为是什么？

b)$7.3.1.2好像没有讲这个限制。标准的哪一部分指导此类代码的行为？

Answer 1

Which portion of the Standard guides the behavior of such code?

C++03 第 $​​8.3 节说

A declarator-id shall not be qualified except for the definition of a member function (9.3) or static data member (9.4) out-side of its class, the definition or explicit instantiation of a function or variable member of a namespace out-side of its namespace, or the definition of a previously declared explicit specialization outside of its name-space, or the declaration of a friend function that is a member of another class or namespace (11.4).

所以你的代码格式不正确。

然而在讨论issue 548 CWG 同意取消在其 namespace 内使用合格声明符的禁令¹。

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