public inbox for gcc-bugs@sourceware.org
help / color / mirror / Atom feed
* [Bug c/50171] New: False positive -Wuninitialized warning
@ 2011-08-24 0:06 kirill at shutemov dot name
2011-08-24 3:12 ` [Bug c/50171] " pinskia at gcc dot gnu.org
` (3 more replies)
0 siblings, 4 replies; 5+ messages in thread
From: kirill at shutemov dot name @ 2011-08-24 0:06 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50171
Bug #: 50171
Summary: False positive -Wuninitialized warning
Classification: Unclassified
Product: gcc
Version: 4.6.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
AssignedTo: unassigned@gcc.gnu.org
ReportedBy: kirill@shutemov.name
Created attachment 25085
--> http://gcc.gnu.org/bugzilla/attachment.cgi?id=25085
test case
$ cat test.i
int baz(char **, const char *);
int quux(char *);
static int bar(char **out, const char *in)
{
char *t;
if (!baz(&t, in))
return -1;
*out = t;
return 0;
}
int foo(const char *a)
{
char *b;
if (!bar(&b, a))
return -1;
return quux(b);
}
$ gcc -c -O -Wuninitialized test.i
test.i: In function ‘foo’:
test.i:23:9: warning: ‘b’ may be used uninitialized in this function
[-Wuninitialized]
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug c/50171] False positive -Wuninitialized warning
2011-08-24 0:06 [Bug c/50171] New: False positive -Wuninitialized warning kirill at shutemov dot name
@ 2011-08-24 3:12 ` pinskia at gcc dot gnu.org
2011-08-24 8:17 ` jakub at gcc dot gnu.org
` (2 subsequent siblings)
3 siblings, 0 replies; 5+ messages in thread
From: pinskia at gcc dot gnu.org @ 2011-08-24 3:12 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50171
--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> 2011-08-24 00:05:25 UTC ---
int baz(char **, const char *);
int quux(char *);
int foo(const char *a)
{
char *b;
int t1;
{
char *t;
if (!baz(&t, a))
t1 = -1
b = t;
t1 = 0;
}
if (!t1)
return -1;
return quux(b);
}
--- CUT ---
After some more optimization:
int foo(const char *a)
{
char *b;
char *t;
if (!baz(&t, a))
;
else
return -1;
return quux(b);
}
looks like a correct uninitialized warning to me after inlinining has happened.
b is initialized when the return value (t1) is 0 and uninitialized otherwise.
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug c/50171] False positive -Wuninitialized warning
2011-08-24 0:06 [Bug c/50171] New: False positive -Wuninitialized warning kirill at shutemov dot name
2011-08-24 3:12 ` [Bug c/50171] " pinskia at gcc dot gnu.org
@ 2011-08-24 8:17 ` jakub at gcc dot gnu.org
2011-08-24 11:17 ` kirill at shutemov dot name
2011-08-24 11:35 ` rguenth at gcc dot gnu.org
3 siblings, 0 replies; 5+ messages in thread
From: jakub at gcc dot gnu.org @ 2011-08-24 8:17 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50171
Jakub Jelinek <jakub at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |RESOLVED
CC| |jakub at gcc dot gnu.org
Resolution| |INVALID
--- Comment #2 from Jakub Jelinek <jakub at gcc dot gnu.org> 2011-08-24 06:46:44 UTC ---
Yeah, this is definitely not a false positive, but completely correct warning,
the code is buggy. Your pseudo-inlined version isn't correct, after that t1 =
-1 you need ; goto out; and out:; after t1 = 0;.
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug c/50171] False positive -Wuninitialized warning
2011-08-24 0:06 [Bug c/50171] New: False positive -Wuninitialized warning kirill at shutemov dot name
2011-08-24 3:12 ` [Bug c/50171] " pinskia at gcc dot gnu.org
2011-08-24 8:17 ` jakub at gcc dot gnu.org
@ 2011-08-24 11:17 ` kirill at shutemov dot name
2011-08-24 11:35 ` rguenth at gcc dot gnu.org
3 siblings, 0 replies; 5+ messages in thread
From: kirill at shutemov dot name @ 2011-08-24 11:17 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50171
--- Comment #3 from Kirill A. Shutemov <kirill at shutemov dot name> 2011-08-24 10:57:30 UTC ---
Sorry, I've made mistake trying to simplify the test case.
Is it still correct to generate warning for the code below?
int error(void);
int baz(char **, const char *);
int quux(char *);
static int bar(char **out, const char *in)
{
char *t;
int err;
err = baz(&t, in);
if (err < 0)
return error();
*out = t;
return 0;
}
int foo(const char *a)
{
int err;
char *b;
err = bar(&b, a);
if (err < 0)
return error();
return quux(b);
}
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug c/50171] False positive -Wuninitialized warning
2011-08-24 0:06 [Bug c/50171] New: False positive -Wuninitialized warning kirill at shutemov dot name
` (2 preceding siblings ...)
2011-08-24 11:17 ` kirill at shutemov dot name
@ 2011-08-24 11:35 ` rguenth at gcc dot gnu.org
3 siblings, 0 replies; 5+ messages in thread
From: rguenth at gcc dot gnu.org @ 2011-08-24 11:35 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50171
--- Comment #4 from Richard Guenther <rguenth at gcc dot gnu.org> 2011-08-24 11:29:35 UTC ---
Yes, if error does not return a value < 0 then it will be used uninitialized.
^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2011-08-24 11:29 UTC | newest]
Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2011-08-24 0:06 [Bug c/50171] New: False positive -Wuninitialized warning kirill at shutemov dot name
2011-08-24 3:12 ` [Bug c/50171] " pinskia at gcc dot gnu.org
2011-08-24 8:17 ` jakub at gcc dot gnu.org
2011-08-24 11:17 ` kirill at shutemov dot name
2011-08-24 11:35 ` rguenth at gcc dot gnu.org
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).