https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114374
Bug ID: 114374
Summary: [12/13 Regression] snprintf Wformat-truncation
Product: gcc
Version: 13.2.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: torsten.mandel at sap dot com
Target Milestone: ---
Source:
// ===========================================
#include "stdio.h"
int main() {
char buf[11];
int loop(1);
do {
snprintf(buf,sizeof(buf),"%d",loop++);
} while(true);
}
// ===========================================
Compiled with: gcc -Wall
triggers:
./buffertest.cpp: In function ‘int main()’:
./buffertest.cpp:8:37: warning: ‘snprintf’ output may be truncated before the
last format character [-Wformat-truncation=]
8 | snprintf(buf,sizeof(buf),"%d",loop++);
| ^
./buffertest.cpp:8:17: note: ‘snprintf’ output between 2 and 12 bytes into a
destination of size 11
8 | snprintf(buf,sizeof(buf),"%d",loop++);
| ~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
when using gcc-12 and gcc-13; gcc-11 compiled without error.
Replacing loop++ with ++loop does not trigger the error; neither case should be
an error as the overflow is UB in both cases and only positive numbers should
be considered regarding the target buffer size.
