c++ - 当 Injected-Class-Name 发生时会发生什么？ (C++)

Question

根据https://en.cppreference.com/w/cpp/language/injected-class-name

In a class scope, the name of the current class is treated as if it were a public member name; this is called injected-class-name. The point of declaration of the name is immediately following the opening brace of the class definition.

int X;
struct X {
    void f() {
        X* p; // OK. X refers to the injected-class-name
        ::X* q; // Error: name lookup finds a variable name, which hides the struct name
    }
};

那么代码中到底发生了什么？是 X* p变成了X::X* p ?

Answer 1

So what is really happening in the code? Is X* p turned into X::X* p?

基本上。名称查找规则从最窄的范围开始。当你这样做 X* p;在 f正在查看 f的范围，并没有找到任何东西。然后它检查 X的范围自 f范围为 X .它找到 X因为它被注入(inject)到类范围中，所以它停在那里，你得到了类类型。

当你这样做 ::X* q;然后 ::X说寻找 X在全局命名空间中，并且找到了一个变量，而不是一个类型，所以你会得到一个错误。