From: NightStrike <nightstrike@gmail.com>
To: gcc-help <gcc-help@gcc.gnu.org>
Subject: Strange warning on printf checks
Date: Sun, 31 May 2020 14:32:33 -0400 [thread overview]
Message-ID: <CAF1jjLtT6FezTsdZ5EU0+eH5pyR9m1zWT6-Ebv91PvxX-0tw-A@mail.gmail.com> (raw)
I'm curious if this is a gcc bug or not. The warning I get is trying to
highlight a real problem, but it's referring to a string literal as a
directive, which I thought was just for the %XX printf commands. Given the
following:
#include <stdio.h>
void f() {
char x[4];
char y[5];
sprintf(x, "%s_%s", y, y);
}
$ gcc a.c -c -Wall
a.c: In function 'f':
a.c:6:16: warning: '_' directive writing 1 byte into a region of size
between 0 and 4 [-Wformat-overflow=]
6 | sprintf(x, "%s_%s", y, y);
| ^
a.c:6:2: note: 'sprintf' output between 2 and 10 bytes into a destination
of size 4
6 | sprintf(x, "%s_%s", y, y);
| ^~~~~~~~~~~~~~~~~~~~~~~~~
I hope the fixed width display shows this correctly. The point is that the
^ points to the underscore, which is right, but the message calls the
underscore a printf directive.
Maybe I'm splitting hairs, but this confused me for a good half hour before
I realized what was wrong.
next reply other threads:[~2020-05-31 18:32 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-31 18:32 NightStrike [this message]
2020-05-31 18:35 ` NightStrike
2020-05-31 20:28 ` Jonathan Wakely
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