From: "René Scharfe" <l.s.r@web.de>
To: Junio C Hamano <gitster@pobox.com>
Cc: Mario Grgic <mario_grgic@hotmail.com>,
demerphq <demerphq@gmail.com>,
git@vger.kernel.org
Subject: Re: git bug: Perl compatible regular expressions do not work as expected
Date: Tue, 28 Mar 2023 19:56:01 +0200 [thread overview]
Message-ID: <4e03ea47-b0aa-d69e-6c54-fcbadb3b0641@web.de> (raw)
In-Reply-To: <xmqqsfdpj8ci.fsf@gitster.g>
Am 28.03.23 um 15:47 schrieb Junio C Hamano:
> Junio C Hamano <gitster@pobox.com> writes:
>
>> I suspect that 54463d32ef was done in a conservative way to avoid
>> unintended side effects to make ERE "enhanced". I am not 100%
>> certain, but after reading the documentation you pointed at, I do
>> not see a valid expression without ENHANCED flag starting to mean
>> totally different thing with it (well, an extra '?' turning a
>> pattern from greedy to minimal may count as such a change in
>> semantics, but I do not see anybody sensible adding an extra '?'
>> in a pattern in the first place).
>
> Sorry, but that is nonsense. We cannot avoid being backward
> incompatible if we suddenly flip the "enhanced" bit for BRE. A
> sane pattern written expecting non-enhanced BRE can change its
> meaning when the "enhanced" mode is enabled.
Right, and there are even more enhancements for ERE, i.e. more
incompatibilities. Not sure how big of a problem that actually would
be, though.
> But if "enhanced" is what users want, and if that is what the other
> tools on the platform use, then perhaps flipping the "enhanced" bit
> may not be a bad idea.
Apple's grep(1) uses it, with and without -E:
https://github.com/apple-oss-distributions/text_cmds/search?q=REG_ENHANCED
E.g. awk(1) and sed(1) don't, AFAICS.
René
next prev parent reply other threads:[~2023-03-28 17:56 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-25 12:31 git bug: Perl compatible regular expressions do not work as expected Mario Grgic
2023-03-25 12:42 ` Kristoffer Haugsbakk
2023-03-25 12:59 ` Mario Grgic
2023-03-25 13:04 ` demerphq
2023-03-25 13:09 ` Mario Grgic
2023-03-25 13:24 ` demerphq
2023-03-25 18:09 ` René Scharfe
2023-03-27 16:29 ` Junio C Hamano
2023-03-27 17:23 ` René Scharfe
2023-03-27 21:33 ` Junio C Hamano
2023-03-28 13:47 ` Junio C Hamano
2023-03-28 17:56 ` René Scharfe [this message]
2023-03-25 14:16 ` Mario Grgic
2023-03-25 15:39 ` Mario Grgic
2023-03-27 16:30 ` Junio C Hamano
2023-03-27 17:22 ` Mario Grgic
2023-03-27 21:11 ` Junio C Hamano
2023-03-28 0:03 ` Mario Grgic
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