https://gcc.gnu.org/bugzilla/show_bug.cgi?id=119004
Bug ID: 119004
Summary: Inconsistent set of flags to trigger -Wstrict-overflow
diagnostics
Product: gcc
Version: 14.2.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: alx at kernel dot org
Target Milestone: ---
-Wstrict-overflow somehow is not enough to trigger its own diagnostics. I seem
to need -Wall too. :|
alx@debian:~/tmp$ cat foo.c
#include <limits.h>
int
dont_call_me_thrice(void)
{
static int i = 0;
if (++i >= 3)
return -1;
return 0;
}
alx@debian:~/tmp$ gcc -Wstrict-overflow -S foo.c
alx@debian:~/tmp$ gcc -Wstrict-overflow=0 -S foo.c
alx@debian:~/tmp$ gcc -Wstrict-overflow=1 -S foo.c
alx@debian:~/tmp$ gcc -Wstrict-overflow=2 -S foo.c
alx@debian:~/tmp$ gcc -Wstrict-overflow=3 -S foo.c
alx@debian:~/tmp$ gcc -Wstrict-overflow=4 -S foo.c
alx@debian:~/tmp$ gcc -Wstrict-overflow=5 -S foo.c
alx@debian:~/tmp$ gcc -Wstrict-overflow -Wstrict-overflow=5 -S foo.c
alx@debian:~/tmp$ gcc -Wall -Wstrict-overflow=5 -S foo.c
foo.c: In function ‘dont_call_me_thrice’:
foo.c:11:1: warning: assuming signed overflow does not occur when changing X +-
C1 cmp C2 to X cmp C2 -+ C1 [-Wstrict-overflow]
11 | }
| ^
alx@debian:~/tmp$ gcc -Wall -S foo.c
alx@debian:~/tmp$
(Don't mind that this is a false positive of -Wstrict-overflow; I'll report
that separately.)
