为什么代码"foo :: foo :: foo :: foob"编译? [英] Why is the code "foo::foo::foo::foob" compiling?

问题描述

一个同事不小心写了这样的代码:

A co-worker accidentally wrote code like this:

struct foo {
  foo() : baz(foobar) {}
  enum bar {foobar, fbar, foob};
  bar baz;
};

void f() {
  for( auto x : { foo::foobar,
                  foo::fbar,
                  foo::
                  foo::
                  foo::foob } );
    // ...
}

GCC 5.1.0对此进行了编译.

GCC 5.1.0 compiles this.

进行此编译的规则是什么?

What's the rule that makes this compile?

推荐答案

注入了-此处使用类名，

出于查找(除非用于命名构造函数):这称为注入类名称

the name of the class within its own definition acts as a public member type alias of itself for the purpose of lookup (except when used to name a constructor): this is known as injected-class-name

然后

foo::
foo::
foo::foob

即foo::foo::foo::foob与foo::foob相同.

然后for (auto x : {foo::foobar, foo::fbar, foo::foob })是基于范围的for循环(因为C ++ 11)，它会在 braised-init-list 由3个枚举数组成.

And then for (auto x : {foo::foobar, foo::fbar, foo::foob }) is a range-based for loop (since C++11), which iterates on the braced-init-list formed by the 3 enumerators.

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