Re: [PATCH] meson: disable PCRE2 dependency by default

> Carlo Arenas <carenas@gmail.com> writes:
> 
> >> For most
> >> builds on Linux, the system libpcre2 is the right one and users will
> >> expect to find PCRE support by default.
> >
> > Agree with you on that, and indeed I think every packager
> > of git (except for NonStop) does enable it at packaging time.
> >
> > Maybe this is an argument to enable it by default?, one thing
> > that I wonder though, is if we should first isolate the code on
> > its own and link it only with `git grep`.
> 
> If we decide that PCRE is good enough to do BRE and ERE emulation in
> compatible enough way more performantly everywhere, it certainly is
> an option that wrap our calls to platform native regcomp/regexec
> that we use for our use of BRE/ERE and internally use PCRE for them.
> 
> Before that happens, "struct grep_pat" that encapsulates the
> distinction between using BRE/ERE and PCRE and compile_regexp() that
> compiles an end-user supplied regular expression string into members
> of "struct grep_pat" so that it can be used to match against in-core
> buffer we have, would need to be exposed outside the "grep.[ch]"
> machinery, and direct uses of regcomp() and regexec() in the rest of
> the codebase has to be rewritten to work with "struct grep_pat".
> 
> And after that happens, teaching "git log --grep=<foo>" and "git
> blame -L'/<foo>/,/<bar>/'" an equivalent to "git grep -P" option
> that tells the command that the pattern given is PCRE would come
> almost for free.
> 
> Is that the kind of isolation you are referring to?