https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81981
Bug ID: 81981
Summary: [8 Regression] -fsanitize=undefined makes a
-Wmaybe-uninitialized warning disappear
Product: gcc
Version: 8.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: sanitizer
Assignee: unassigned at gcc dot gnu.org
Reporter: vincent-gcc at vinc17 dot net
CC: dodji at gcc dot gnu.org, dvyukov at gcc dot gnu.org,
jakub at gcc dot gnu.org, kcc at gcc dot gnu.org, marxin at
gcc dot gnu.org
Target Milestone: ---
Consider:
int foo (int i)
{
int t[1], u[1];
int n = 0;
if (i)
{
t[n] = i;
u[0] = i;
}
return t[0] + u[0];
}
With gcc (Debian 20170823-1) 8.0.0 20170823 (experimental) [trunk revision
251306], I get:
zira% gcc-snapshot -Wmaybe-uninitialized -O2 -c tst.c -fsanitize=undefined
tst.c: In function 'foo':
tst.c:12:15: warning: 'u[0]' may be used uninitialized in this function
[-Wmaybe-uninitialized]
return t[0] + u[0];
~~~~~^~~~~~
zira% gcc-snapshot -Wmaybe-uninitialized -O2 -c tst.c
tst.c: In function 'foo':
tst.c:12:15: warning: 'u[0]' may be used uninitialized in this function
[-Wmaybe-uninitialized]
return t[0] + u[0];
~~~~~^~~~~~
tst.c:12:15: warning: 't[0]' may be used uninitialized in this function
[-Wmaybe-uninitialized]
i.e. with -fsanitize=undefined, I do not get the warning on t[0].
This is a regression. No such problem with GCC 7.2.0, 6.4.0 and 5.4.1.
