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From: "msebor at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c/103343] Invalid codegen when comparing pointer to one past the end and then dereferencing that pointer
Date: Mon, 22 Nov 2021 16:28:23 +0000 [thread overview]
Message-ID: <bug-103343-4-ew9JPqGHzb@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-103343-4@http.gcc.gnu.org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103343
Martin Sebor <msebor at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |msebor at gcc dot gnu.org
--- Comment #2 from Martin Sebor <msebor at gcc dot gnu.org> ---
(In reply to Gabriel Ravier from comment #0)
> PS: This also results in plenty of invalid warnings when compiling with
> -Wall:
>
> <source>: In function 'f':
> <source>:6:9: warning: array subscript 1 is outside array bounds of 'int[1]'
> [-Warray-bounds]
> 6 | *p = 2;
> | ^~
> <source>:1:12: note: at offset 4 into object 'x' of size 4
> 1 | extern int x[1], y;
> | ^
The warning in this case is valid and helpful: it's undefined to attempt to
access an object using a pointer derived from a pointer to an unrelated object
(the equality between pointers to adjacent objects notwithstanding).
next prev parent reply other threads:[~2021-11-22 16:28 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-21 3:01 [Bug c/103343] New: " gabravier at gmail dot com
2021-11-21 4:46 ` [Bug c/103343] " pinskia at gcc dot gnu.org
2021-11-22 16:28 ` msebor at gcc dot gnu.org [this message]
2021-11-22 20:54 ` gabravier at gmail dot com
2021-11-22 23:07 ` leni536 at gmail dot com
2021-11-22 23:13 ` pinskia at gcc dot gnu.org
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