struct {int count;} *v1;
int c;
int k;
extern void baz(int);
static int bar(int *j)
{
if (k == 4)
{
*j = 1;
return 1;
}
return 0;
}
void foo(void)
{
int i;
if (!bar(&i))
{
if (!c)
return;
v1->count++;
}
if (!c)
{
baz(i);
}
}
produces this warning when compiled with "-Wall -O2":
$ gcc-4.0.0-RC1 -Wall -O2 -c final.c
final.c: In function ‘foo’:
final.c:18: warning: ‘i’ may be used uninitialized in this function
GCC 3.4.3 and previous versions I tested did not generate this warning.
I believe this warning is improper because one of these two scenarios must be
true:
1) k == 4, in which case i is initialized before it can be used
2) k != 4, in which case i is not used
Adding -fno-inline avoids the warning by preventing bar from being inlined into
foo.
I was unable to reduce the test case further without making the warning
disappear. In particular, removing the increment of v1->count makes the warning
disappear.
This is GCC 4.0.0 RC1:
$ gcc-4.0.0-RC1 -v
Using built-in specs.
Target: i686-pc-linux-gnu
Configured with: ../gcc-4.0.0-20050410/configure --program-suffix=-4.0.0-RC1
Thread model: posix
gcc version 4.0.0 20050410 (prerelease)
This warning still appears on mainline.
--
Summary: [4.0/4.1 Regression] Spurious "may be used
uninitialized" warning
Product: gcc
Version: 4.0.0
Status: UNCONFIRMED
Severity: normal
Priority: P2
Component: c
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: James dot Juran at baesystems dot com
CC: gcc-bugs at gcc dot gnu dot org
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20968
