https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105080
Bug ID: 105080
Summary: Bugus -Wformat-truncation
Product: gcc
Version: 12.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: marcandre.lureau at gmail dot com
Target Milestone: ---
With Fedora gcc-12.0.1-0.12.fc36.x86_64
gcc (GCC) 12.0.1 20220308 (Red Hat 12.0.1-0)
test.c:
#include <stdio.h>
void main(void)
{
char foo[3];
int i;
for (i = 0; i < 16; i++) {
snprintf(foo, sizeof(foo), "%d", i);
}
}
$ gcc -Wformat-truncation test.c
test.c: In function ‘main’:
test.c:9:45: warning: ‘%d’ directive output may be truncated writing between 1
and 11 bytes into a region of size 3 [-Wformat-truncation=]
9 | snprintf(foo, sizeof(foo), "%d", i);
| ^~
test.c:9:44: note: directive argument in the range [-2147483647, 15]
9 | snprintf(foo, sizeof(foo), "%d", i);
| ^~~~
test.c:9:17: note: ‘snprintf’ output between 2 and 12 bytes into a destination
of size 3
9 | snprintf(foo, sizeof(foo), "%d", i);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The computed range seems incorrect. There are similar variants of this bug that
have been found while compiling QEMU
(https://patchew.org/QEMU/20220328084717.367993-1-marcandre.lur...@redhat.com/)
