Re: Embedded modifiers in the regex engine

[Dima Kogan <lists@dima.secretsauce.net>]

Eli Zaretskii <eliz@gnu.org> writes:

>> From: Dima Kogan <dima@secretsauce.net>
>> Date: Thu, 25 Feb 2016 23:19:32 -0800
>> CC: emacs-devel@gnu.org
>> 
>> I'm looking at importing the regex test suite in glibc to emacs.
>> Would this be possible even if the copyright holders of those tests
>> haven't assigned their work to the fsf? These are tests and not part
>> of emacs on some level, so would that make it ok?
>
> If the test suite is GPL v3+, I don't think there should be a
> problem

If only. Some of the test cases in glibc are their own (LGPL) and some
others came from other projects (boost, BSD, MIT). To be clear, I'm
talking about the test cases themselves, not the code that evaluates the
tests. Does this mean we need to write our own test if we want them?

I did write an evaluator for one of the set of tests. It told me that
the emacs regexen don't support the [.xxx.] and [=xxx=] constructs,
which we already know. It also told me that the glibc regex engine
throws an error when you give it an invalid range, such as [b-a], but
emacs silently matches nothing. I think this is a bug, but probably not
one that's worth fixing on its own.

From the earlier emails it wasn't obvious if there was already a
long-term plan to replace the regex engine. Is there such a plan? What
do we hope to move to?

Thanks!