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* [Bug c/52078] New: Bogus may be used uninitialized warning
@ 2012-02-01 2:38 rmansfield at qnx dot com
2012-02-01 8:18 ` [Bug middle-end/52078] " manu at gcc dot gnu.org
2012-02-01 9:29 ` rguenth at gcc dot gnu.org
0 siblings, 2 replies; 3+ messages in thread
From: rmansfield at qnx dot com @ 2012-02-01 2:38 UTC (permalink / raw)
To: gcc-bugs
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: unassigned@gcc.gnu.org
ReportedBy: rmansfield@qnx.com
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.
^ permalink raw reply [flat|nested] 3+ messages in thread
* [Bug middle-end/52078] Bogus may be used uninitialized warning
2012-02-01 2:38 [Bug c/52078] New: Bogus may be used uninitialized warning rmansfield at qnx dot com
@ 2012-02-01 8:18 ` manu at gcc dot gnu.org
2012-02-01 9:29 ` rguenth at gcc dot gnu.org
1 sibling, 0 replies; 3+ messages in thread
From: manu at gcc dot gnu.org @ 2012-02-01 8:18 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52078
Manuel López-Ibáñez <manu at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |manu at gcc dot gnu.org
--- Comment #1 from Manuel López-Ibáñez <manu at gcc dot gnu.org> 2012-02-01 08:17:27 UTC ---
I haven't followed development for a while, but I don't think GCC uninit
analysis is powerful enough to detect this or even simpler cases like PR36550
and PR20968.
^ permalink raw reply [flat|nested] 3+ messages in thread
* [Bug middle-end/52078] Bogus may be used uninitialized warning
2012-02-01 2:38 [Bug c/52078] New: Bogus may be used uninitialized warning rmansfield at qnx dot com
2012-02-01 8:18 ` [Bug middle-end/52078] " manu at gcc dot gnu.org
@ 2012-02-01 9:29 ` rguenth at gcc dot gnu.org
1 sibling, 0 replies; 3+ messages in thread
From: rguenth at gcc dot gnu.org @ 2012-02-01 9:29 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52078
Richard Guenther <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |NEW
Last reconfirmed| |2012-02-01
Blocks| |24639
Ever Confirmed|0 |1
--- Comment #2 from Richard Guenther <rguenth at gcc dot gnu.org> 2012-02-01 09:28:49 UTC ---
Yeah, it's simply too confusing code for GCCs static analysis. Thus the "may
be used uninitialized".
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2012-02-01 9:29 UTC | newest]
Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
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2012-02-01 2:38 [Bug c/52078] New: Bogus may be used uninitialized warning rmansfield at qnx dot com
2012-02-01 8:18 ` [Bug middle-end/52078] " manu at gcc dot gnu.org
2012-02-01 9:29 ` rguenth at gcc dot gnu.org
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