Re: [PATCH v2] grep: skip UTF8 checks explicitly

[Carlo Arenas <carenas@gmail.com>]

FWIW, the changes in grep.h are IMHO optional and hadn't been really
tested as I couldn't find a version of PCRE1 old enough to trigger it
but I am hoping are simple enough to work.

As in my original proposal, there is no test because this is going to
(as documented) trigger undefined behaviour and so I don't see how we
can reliably test that.  Goes without saying tthough, that the same is
triggered when JIT is enabled and the JIT fast path is being used, so
this is not a regression and will be more visible once
ab/pcre-jit-fixes gets merged because we are moving out of the JIT
fast path with a patch[0] in that series

While Ævar made a point[1] that this wasn't a solution to the problem,
it was because PCRE2 could have a better one (still missing but based
on ab/pcre-jit-fixes), and it was expected that PCRE2 will be used a
lot more and so it wasn't a good idea for it (something that doesn't
apply to PCRE1)

the patch was based on maint (like all bugfixes) but applies cleanly
to master and next, it will conflict with pu but for easy of merge I'd
applied it on top of cb/pcre1-cleanup and make it available in
GitHub[2]; that branch could be used as well as a reroll for that
topic (if that is preferred)

the error message hasn't been changed on this patch, as it might make
sense to improve it as well for PCRE2, but at least shouldn't be
triggered anymore (ex, from running a freshly built git without the
patch and linked against a non JIT enabled PCRE1):

$ ./git-grep -P 'Nguyễn Thái.Ngọc'
.mailmap:Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
fatal: pcre_exec failed with error code -10

Carlo

[0] 685668faaa (grep: stop using a custom JIT stack with PCRE v1, 2019-07-26)
[1] https://public-inbox.org/git/87lfwn70nb.fsf@evledraar.gmail.com/
[2] https://github.com/carenas/git/tree/pcre1-cleanup