What about regexp-nothing or re-nothing?
________________________________
发件人: Emacs-devel <emacs-devel-bounces+netjune=outlook.com@gnu.org> 代表 Eric Abrahamsen <eric@ericabrahamsen.net>
发送时间: 2019年5月16日 18:12
收件人: Mattias Engdegård
抄送: Stefan Monnier; emacs-devel@gnu.org
主题: Re: regular expressions that match nothing

Mattias Engdegård <mattiase@acm.org> writes:

> tis 2019-05-14 klockan 15:41 -0400 skrev Stefan Monnier:
>
>> Yes, please.  I'd recommend a `regexp-` prefix for it.
>
> Well, since you asked so nicely!
>
>> [ And I'll carefully avoid having an opinion on the rest of the name.
>> ]
>
> The correct name is obviously something like `regexp-empty', but I have
> to concede that it might be misinterpreted. The attached patch uses
> `regexp-unmatchable' which is reasonably descriptive. Better
> suggestions are welcome.

regexp-null? It's also a little cryptic, but it's short!