http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52078
Bug #: 52078
Summary: Bogus may be used uninitialized warning
Classification: Unclassified
Product: gcc
Version: 4.7.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
AssignedTo: [email protected]
ReportedBy: [email protected]
Host: x86_64-linux-gnu
Target: x86_64-linux-gnu
Build: x86_64-linux-gnu
gcc version 4.7.0 20120201 (experimental) [trunk revision 183790] (GCC)
Testcase:
#include <string.h>
int
foo (char *nname, char *oname)
{
int cmp;
while (nname != oname && (cmp = strcmp (nname, oname)) < 0)
{
break;
}
if (nname == oname || cmp == 0)
{
return 1;
}
else
{
return 0;
}
}
$ ./xgcc -B. -O2 -Wall ~/init.c -c
/home/ryan/init.c: In function 'foo':
/home/ryan/init.c:12:29: warning: 'cmp' may be used uninitialized in this
function [-Wmaybe-uninitialized]
Since both && and || operators guarantee left-to-right evaluation, in the case
where nname == oname, strcmp is never called but in the (name == oname || cmp
== 0) expression, nname == oname and the second operand is not evaluated so cmp
is never used uninitialized.
