Keith Hill 在评论中提到这是 V3 中一个叫做 Member Enumeration 的新功能.

Keith Hill mentioned in the comment that this is a new feature called Member Enumeration in V3.

请参阅新的 V3 语言功能"在 devblogs.microsoft.com 上.

Refer to "New V3 Language Features" on devblogs.microsoft.com.