Re: PATCH: migrate pcre module to pcre2

[Oliver Kiddle <opk@zsh.org>]

On 12 May, Phil Pennock wrote:
> I handed in my commit bit a while back because I used it so rarely and
> it felt better for commit to be only the people more actively involved.
> Shells and their provenance matter.  So I can't commit.

If I remember correctly, you indicated at the time that it shouldn't be
committed, at least not at that time. We probably have more of a problem
with patches getting missed than having to be backed out later. Trust
and competence don't expire if not used.

> My main motivation with RE2 was to get to something which all vendors
> will actually include when distributing.  The reason can't be licensing,
> since the PCRE lib is BSD licensed.

Do Apple include any of pcre, pcre2 and re2 already with macOS? It's
difficult to guess at their motivations. Zsh's build system linking pcre
into every ELF file by default if you enable pcre may not help. They
must have put some thought into at least their initial packaging of zsh
as they stripped out some of the shell functions.

> I'd seen RE2 pick up quite a bit of steam and wanted to explore to see
> how feasible it was.
>
> Ideally, we'd have a contact within Apple who can tell us what they
> might or might not consider, so that we can have working regexps with
> semantics younger than POSIX.2 (1992) and some more actual utility.  I'm

The one time I had a chance to speak to an actual Apple employee, and
that was someone far removed from the Unix layer, they only reinforced
my general impression that Apple really don't care about the shell and
Unix part of macOS in general. The change of default shell was likely
due to licencing alone. Did Apple at least provide 5.8.1 as a security
patch? RHEL 8 still comes with a vulnerable 5.8 so it would seem that
us doing security only releases is a waste of time.

I generally stick with zsh pattern matching out of habit. =~ seems to be
a popular feature, though, I guess people know and understand regexes.
Does bash ignore the system regex library and use the GNU one on all
systems? That's equivalent to us pulling something like TRE or PCRE into
the zsh source tree and forcing its use.

Oliver