From: "Dr. Arne Babenhauserheide" <arne_bab@web.de>
To: Juanma Barranquero <lekktu@gmail.com>
Cc: "Mattias Engdegård" <mattias.engdegard@gmail.com>, emacs-devel@gnu.org
Subject: Re: Warn about comparing quoted lists (etc) using `eq`
Date: Thu, 15 Dec 2022 07:34:10 +0100 [thread overview]
Message-ID: <87359h8968.fsf@web.de> (raw)
In-Reply-To: <CAAeL0SRGszwv5gmS7+M8onPmuZip5SdUH6bsOPS-2hz9FRRErw@mail.gmail.com>
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Juanma Barranquero <lekktu@gmail.com> writes:
> Note that your patch has a false positive with the empty string, which is optimized to be always the same object (well, ISTR there are two, a unibyte
> one and a multibyte one).
>
> (byte-compile '(let ((x "")) (eq x ""))) => Warning: `eq' called with literal string that may never match (arg 2)
>
> (let ((x "")) (eq x "")) => t
Is this guaranteed or just an implementation detail?
If it is not guaranteed, then "may never match" sounds correct.
I miss a suggestion, though: the warning as it is is not actionable. It
would be great if it could say something along the lines of
"... (arg 2). Consider using `equal'."
Best wishes,
Arne
--
Unpolitisch sein
heißt politisch sein,
ohne es zu merken.
draketo.de
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next prev parent reply other threads:[~2022-12-15 6:34 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-12-14 18:17 Warn about comparing quoted lists (etc) using `eq` Mattias Engdegård
2022-12-14 18:29 ` Eli Zaretskii
2022-12-14 20:57 ` Mattias Engdegård
2022-12-14 18:57 ` [External] : " Drew Adams
2022-12-15 4:17 ` Juanma Barranquero
2022-12-15 6:34 ` Dr. Arne Babenhauserheide [this message]
2022-12-15 7:00 ` Juanma Barranquero
2022-12-15 9:36 ` Mattias Engdegård
2022-12-15 10:06 ` Juanma Barranquero
2022-12-15 10:50 ` Ihor Radchenko
2022-12-15 13:58 ` Mattias Engdegård
2022-12-15 16:13 ` [External] : " Drew Adams
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