From: Eli Zaretskii <eliz@gnu.org>
To: "Óscar Fuentes" <ofv@wanadoo.es>
Cc: emacs-devel@gnu.org
Subject: Re: [Emacs-diffs] master 6cd5678: Clarify compiler-pacifier in frame.c
Date: Mon, 26 Aug 2019 21:39:17 +0300 [thread overview]
Message-ID: <83a7bvg4a2.fsf@gnu.org> (raw)
In-Reply-To: <87ftln4wm0.fsf@telefonica.net> (message from Óscar Fuentes on Mon, 26 Aug 2019 20:20:23 +0200)
> From: Óscar Fuentes <ofv@wanadoo.es>
> Date: Mon, 26 Aug 2019 20:20:23 +0200
>
> Valgrind knows nothing about UNINIT as it works with machine code, not
> with source code. But AFAIK that macro is conditionally defined to "=0"
> (for silencing bogus gcc warnings) or to nothing (for leaving the
> variable uninitalized at the declaration point). The later allows
> Valgrind to do a proper check.
>
> Simply changing
>
> int x;
>
> to
>
> int x = 0;
>
> just for silencing the gcc warning can hide a bug that Valgrind would
> detect otherwise.
This is backwards: it would mean we should use UNINIT all over the
place just to be sure we will be able to spot some imaginary bugs by
flipping a compiler switch.
The initialization in this case was added because GCC flagged a
potential use-before-define. After that, there's no more bug for
Valgrind to find, so I see no reason to leave UNINIT around.
I could understand using UNINIT (or something similar) when the
developer has no idea what not initializing could cause. But this is
not that case.
next prev parent reply other threads:[~2019-08-26 18:39 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-24 6:14 [Emacs-diffs] master 6cd5678: Clarify compiler-pacifier in frame.c Eli Zaretskii
2019-08-25 0:52 ` Paul Eggert
2019-08-25 7:13 ` Eli Zaretskii
2019-08-26 6:34 ` Paul Eggert
2019-08-26 7:54 ` Eli Zaretskii
2019-08-26 8:15 ` Paul Eggert
2019-08-26 9:47 ` Eli Zaretskii
2019-08-26 15:21 ` Óscar Fuentes
2019-08-26 16:13 ` Eli Zaretskii
2019-08-26 18:20 ` Óscar Fuentes
2019-08-26 18:39 ` Eli Zaretskii [this message]
2019-08-26 19:09 ` Paul Eggert
2019-08-26 19:15 ` Óscar Fuentes
2019-08-26 19:33 ` Eli Zaretskii
2019-08-26 19:49 ` Óscar Fuentes
2019-08-26 22:33 ` Paul Eggert
2019-08-27 6:12 ` Eli Zaretskii
2019-08-27 7:28 ` Paul Eggert
2019-08-27 8:02 ` Eli Zaretskii
2019-08-27 9:28 ` Paul Eggert
2019-08-27 10:15 ` Eli Zaretskii
2019-08-27 12:05 ` Paul Eggert
2019-08-27 12:43 ` Eli Zaretskii
2019-08-26 18:50 ` Paul Eggert
2019-08-26 18:56 ` Eli Zaretskii
2019-08-26 23:17 ` Richard Stallman
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