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!