c - 为什么编译器不给出冲突错误？

Question

在下面的代码中，我声明了一个与结构名称同名的结构成员变量。

struct st 
{     
    int st;
};

int main()
{
   struct st t;
   t.st = 7;
   return 0;
}

我想知道，它在 GCC 编译器上运行良好，不会出现冲突错误。

所以，

• 编译器如何知道结构名和变量名？
• 编译器内部使用什么机制？

Answer 1

是的，这是有效的。结构标记和结构成员位于不同的命名空间中。

C11, 6.2.3 Name spaces of identifiers :

If more than one declaration of a particular identifier is visible at any point in a translation unit, the syntactic context disambiguates uses that refer to different entities. Thus, there are separate name spaces for various categories of identifiers, as follows:

• label names (disambiguated by the syntax of the label declaration and use);
• the tags of structures, unions, and enumerations (disambiguated by following any32) of the keywords struct, union, or enum);
• the members of structures or unions; each structure or union has a separate name space for its members (disambiguated by the type of the expression used to access the member via the . or -> operator);
• all other identifiers, called ordinary identifiers (declared in ordinary declarators or as enumeration constants).