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* [Bug c++/33738] New: -Wtype-limits misses a warning when comparing enums
@ 2007-10-11 17:50 dnovillo at gcc dot gnu dot org
2007-10-11 18:09 ` [Bug c++/33738] " pinskia at gcc dot gnu dot org
` (13 more replies)
0 siblings, 14 replies; 15+ messages in thread
From: dnovillo at gcc dot gnu dot org @ 2007-10-11 17:50 UTC (permalink / raw)
To: gcc-bugs
This was found on GCC 4.2.1. In this test case, VRP quietly folds a comparison
between an enum type and a constant value that the enum type can never take.
With -Wtype-limits, this should give the warning:
comparison always false due to limited range of data type
extern void link_error (void);
enum Alpha {
ZERO = 0, ONE, TWO, THREE
};
Alpha a2;
int m1 = -1;
int GetM1() {
return m1;
}
int main() {
a2 = static_cast<Alpha>(GetM1());
if (a2 == -1) { <-- VRP should warn when folding this.
link_error ();
}
return 0;
}
This is not warned by the front end because we promote -1 to the same type as
a2. But during VRP, we *do* fold the predicate, so warning when -Wtype-limits
is given in this case would be a good QOI feature.
I have a patch in the works to make VRP warn when it linearizes this predicate.
--
Summary: -Wtype-limits misses a warning when comparing enums
Product: gcc
Version: 4.3.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
AssignedTo: dnovillo at gcc dot gnu dot org
ReportedBy: dnovillo at gcc dot gnu dot org
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33738
^ permalink raw reply [flat|nested] 15+ messages in thread
* [Bug c++/33738] -Wtype-limits misses a warning when comparing enums
2007-10-11 17:50 [Bug c++/33738] New: -Wtype-limits misses a warning when comparing enums dnovillo at gcc dot gnu dot org
@ 2007-10-11 18:09 ` pinskia at gcc dot gnu dot org
2007-11-13 4:56 ` manu at gcc dot gnu dot org
` (12 subsequent siblings)
13 siblings, 0 replies; 15+ messages in thread
From: pinskia at gcc dot gnu dot org @ 2007-10-11 18:09 UTC (permalink / raw)
To: gcc-bugs
------- Comment #1 from pinskia at gcc dot gnu dot org 2007-10-11 18:09 -------
Warnings from optimizers are semi a no-no. Yes we have them for strict
aliasing and overflow but I think those cases are a bit weird. This is
unspecified behavior no matter what and there is no flag to change the behavior
here.
--
pinskia at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
Severity|normal |enhancement
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33738
^ permalink raw reply [flat|nested] 15+ messages in thread
* [Bug c++/33738] -Wtype-limits misses a warning when comparing enums
2007-10-11 17:50 [Bug c++/33738] New: -Wtype-limits misses a warning when comparing enums dnovillo at gcc dot gnu dot org
2007-10-11 18:09 ` [Bug c++/33738] " pinskia at gcc dot gnu dot org
@ 2007-11-13 4:56 ` manu at gcc dot gnu dot org
2008-02-05 4:19 ` dnovillo at gcc dot gnu dot org
` (11 subsequent siblings)
13 siblings, 0 replies; 15+ messages in thread
From: manu at gcc dot gnu dot org @ 2007-11-13 4:56 UTC (permalink / raw)
To: gcc-bugs
------- Comment #2 from manu at gcc dot gnu dot org 2007-11-13 04:55 -------
(In reply to comment #1)
> Warnings from optimizers are semi a no-no. Yes we have them for strict
> aliasing and overflow but I think those cases are a bit weird. This is
> unspecified behavior no matter what and there is no flag to change the behavior
> here.
Well, Wtype-limits is supposed to warn about this and it doesn't. Can we do it
from the front-end? If not, then warning from the middle-end seems the right
thing to do as long as it is not complex/intrusive.
--
manu at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |manu at gcc dot gnu dot org
Status|UNCONFIRMED |NEW
Ever Confirmed|0 |1
Last reconfirmed|0000-00-00 00:00:00 |2007-11-13 04:55:56
date| |
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33738
^ permalink raw reply [flat|nested] 15+ messages in thread
* [Bug c++/33738] -Wtype-limits misses a warning when comparing enums
2007-10-11 17:50 [Bug c++/33738] New: -Wtype-limits misses a warning when comparing enums dnovillo at gcc dot gnu dot org
2007-10-11 18:09 ` [Bug c++/33738] " pinskia at gcc dot gnu dot org
2007-11-13 4:56 ` manu at gcc dot gnu dot org
@ 2008-02-05 4:19 ` dnovillo at gcc dot gnu dot org
2008-02-05 4:30 ` dnovillo at gcc dot gnu dot org
` (10 subsequent siblings)
13 siblings, 0 replies; 15+ messages in thread
From: dnovillo at gcc dot gnu dot org @ 2008-02-05 4:19 UTC (permalink / raw)
To: gcc-bugs
------- Comment #3 from dnovillo at gcc dot gnu dot org 2008-02-05 04:18 -------
Subject: Bug 33738
Author: dnovillo
Date: Tue Feb 5 04:17:58 2008
New Revision: 132111
URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=132111
Log:
http://gcc.gnu.org/ml/gcc-patches/2008-02/msg00110.html
PR 33738
* tree-vrp.c (vrp_evaluate_conditional): With
-Wtype-limits, emit a warning when comparing against a
constant outside the natural range of OP0's type.
testsuite/ChangeLog
PR 33738
* testsuite/g++.dg/warn/pr33738.C: New.
Added:
trunk/gcc/testsuite/g++.dg/warn/pr33738.C
Modified:
trunk/gcc/ChangeLog
trunk/gcc/testsuite/ChangeLog
trunk/gcc/tree-vrp.c
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33738
^ permalink raw reply [flat|nested] 15+ messages in thread
* [Bug c++/33738] -Wtype-limits misses a warning when comparing enums
2007-10-11 17:50 [Bug c++/33738] New: -Wtype-limits misses a warning when comparing enums dnovillo at gcc dot gnu dot org
` (2 preceding siblings ...)
2008-02-05 4:19 ` dnovillo at gcc dot gnu dot org
@ 2008-02-05 4:30 ` dnovillo at gcc dot gnu dot org
2008-02-05 10:19 ` rguenth at gcc dot gnu dot org
` (9 subsequent siblings)
13 siblings, 0 replies; 15+ messages in thread
From: dnovillo at gcc dot gnu dot org @ 2008-02-05 4:30 UTC (permalink / raw)
To: gcc-bugs
------- Comment #4 from dnovillo at gcc dot gnu dot org 2008-02-05 04:29 -------
Fixed. http://gcc.gnu.org/ml/gcc-patches/2008-02/msg00110.html.
--
dnovillo at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |RESOLVED
Resolution| |FIXED
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33738
^ permalink raw reply [flat|nested] 15+ messages in thread
* [Bug c++/33738] -Wtype-limits misses a warning when comparing enums
2007-10-11 17:50 [Bug c++/33738] New: -Wtype-limits misses a warning when comparing enums dnovillo at gcc dot gnu dot org
` (3 preceding siblings ...)
2008-02-05 4:30 ` dnovillo at gcc dot gnu dot org
@ 2008-02-05 10:19 ` rguenth at gcc dot gnu dot org
2008-02-05 11:22 ` manu at gcc dot gnu dot org
` (8 subsequent siblings)
13 siblings, 0 replies; 15+ messages in thread
From: rguenth at gcc dot gnu dot org @ 2008-02-05 10:19 UTC (permalink / raw)
To: gcc-bugs
--
rguenth at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
Keywords| |diagnostic
Target Milestone|--- |4.3.0
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33738
^ permalink raw reply [flat|nested] 15+ messages in thread
* [Bug c++/33738] -Wtype-limits misses a warning when comparing enums
2007-10-11 17:50 [Bug c++/33738] New: -Wtype-limits misses a warning when comparing enums dnovillo at gcc dot gnu dot org
` (4 preceding siblings ...)
2008-02-05 10:19 ` rguenth at gcc dot gnu dot org
@ 2008-02-05 11:22 ` manu at gcc dot gnu dot org
2008-02-05 16:16 ` dnovillo at google dot com
` (7 subsequent siblings)
13 siblings, 0 replies; 15+ messages in thread
From: manu at gcc dot gnu dot org @ 2008-02-05 11:22 UTC (permalink / raw)
To: gcc-bugs
------- Comment #5 from manu at gcc dot gnu dot org 2008-02-05 11:21 -------
You should use OPT_Wtype_limits instead of OPT_Wextra.
Also, the code could simply do:
+ tree op0 = TREE_OPERAND (cond, 0);
+ tree op1 = TREE_OPERAND (cond, 1);
+ tree type = TREE_TYPE (op0);
+ value_range_t *vr0 = get_value_range (op0);
+
+ if (vr0->type != VR_VARYING
+ && INTEGRAL_TYPE_P (type)
+ && vrp_val_is_min (vr0->min)
+ && vrp_val_is_max (vr0->max)
+ && is_gimple_min_invariant (op1))
+ {
+ location_t locus;
+ const char *warnmsg = NULL;
+
+ if (!EXPR_HAS_LOCATION (stmt))
+ locus = input_location;
+ else
+ locus = EXPR_LOCATION (stmt);
+
+ if (integer_zerop (ret))
+ warnmsg = G_("comparison always false due to limited range of "
+ "data type");
+ else
+ warnmsg = G_("comparison always true due to limited range of "
+ "data type");
+
+ warning (OPT_Wextra, "%H%s", &locus, warnmsg);
+ }
And BTW, what is G_ for?
--
manu at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
Last reconfirmed|2007-11-13 04:55:56 |2008-02-05 11:21:26
date| |
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33738
^ permalink raw reply [flat|nested] 15+ messages in thread
* [Bug c++/33738] -Wtype-limits misses a warning when comparing enums
2007-10-11 17:50 [Bug c++/33738] New: -Wtype-limits misses a warning when comparing enums dnovillo at gcc dot gnu dot org
` (5 preceding siblings ...)
2008-02-05 11:22 ` manu at gcc dot gnu dot org
@ 2008-02-05 16:16 ` dnovillo at google dot com
2008-02-05 16:32 ` dnovillo at gcc dot gnu dot org
` (6 subsequent siblings)
13 siblings, 0 replies; 15+ messages in thread
From: dnovillo at google dot com @ 2008-02-05 16:16 UTC (permalink / raw)
To: gcc-bugs
------- Comment #6 from dnovillo at google dot com 2008-02-05 16:15 -------
Subject: Re: -Wtype-limits misses a warning when comparing enums
On 5 Feb 2008 11:21:26 -0000, manu at gcc dot gnu dot org
<gcc-bugzilla@gcc.gnu.org> wrote:
> You should use OPT_Wtype_limits instead of OPT_Wextra.
Ah, yes, thanks.
> Also, the code could simply do:
Well, I explicitly wanted to separate the decision making from the
warning machinery.
> And BTW, what is G_ for?
That's the i18n marker. I c-n-p it from other messages in the same file.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33738
^ permalink raw reply [flat|nested] 15+ messages in thread
* [Bug c++/33738] -Wtype-limits misses a warning when comparing enums
2007-10-11 17:50 [Bug c++/33738] New: -Wtype-limits misses a warning when comparing enums dnovillo at gcc dot gnu dot org
` (6 preceding siblings ...)
2008-02-05 16:16 ` dnovillo at google dot com
@ 2008-02-05 16:32 ` dnovillo at gcc dot gnu dot org
2008-02-05 19:54 ` reichelt at gcc dot gnu dot org
` (5 subsequent siblings)
13 siblings, 0 replies; 15+ messages in thread
From: dnovillo at gcc dot gnu dot org @ 2008-02-05 16:32 UTC (permalink / raw)
To: gcc-bugs
------- Comment #7 from dnovillo at gcc dot gnu dot org 2008-02-05 16:32 -------
Subject: Bug 33738
Author: dnovillo
Date: Tue Feb 5 16:31:20 2008
New Revision: 132124
URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=132124
Log:
http://gcc.gnu.org/ml/gcc-patches/2008-02/msg00140.html
PR 33738
* tree-vrp.c (vrp_evaluate_conditional): Revert fix for
PR 33738.
testsuite/ChangeLog
PR 33738
* g++.dg/warn/pr33738.C: Remove.
Removed:
trunk/gcc/testsuite/g++.dg/warn/pr33738.C
Modified:
trunk/gcc/ChangeLog
trunk/gcc/testsuite/ChangeLog
trunk/gcc/tree-vrp.c
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33738
^ permalink raw reply [flat|nested] 15+ messages in thread
* [Bug c++/33738] -Wtype-limits misses a warning when comparing enums
2007-10-11 17:50 [Bug c++/33738] New: -Wtype-limits misses a warning when comparing enums dnovillo at gcc dot gnu dot org
` (7 preceding siblings ...)
2008-02-05 16:32 ` dnovillo at gcc dot gnu dot org
@ 2008-02-05 19:54 ` reichelt at gcc dot gnu dot org
2008-02-05 19:57 ` manu at gcc dot gnu dot org
` (4 subsequent siblings)
13 siblings, 0 replies; 15+ messages in thread
From: reichelt at gcc dot gnu dot org @ 2008-02-05 19:54 UTC (permalink / raw)
To: gcc-bugs
------- Comment #8 from reichelt at gcc dot gnu dot org 2008-02-05 19:54 -------
Reopened, since the patch was reverted.
--
reichelt at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|RESOLVED |REOPENED
Resolution|FIXED |
Target Milestone|4.3.0 |---
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33738
^ permalink raw reply [flat|nested] 15+ messages in thread
* [Bug c++/33738] -Wtype-limits misses a warning when comparing enums
2007-10-11 17:50 [Bug c++/33738] New: -Wtype-limits misses a warning when comparing enums dnovillo at gcc dot gnu dot org
` (8 preceding siblings ...)
2008-02-05 19:54 ` reichelt at gcc dot gnu dot org
@ 2008-02-05 19:57 ` manu at gcc dot gnu dot org
2008-02-05 19:59 ` pinskia at gcc dot gnu dot org
` (3 subsequent siblings)
13 siblings, 0 replies; 15+ messages in thread
From: manu at gcc dot gnu dot org @ 2008-02-05 19:57 UTC (permalink / raw)
To: gcc-bugs
--
manu at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
OtherBugsDependingO| |33702
nThis| |
Target Milestone|--- |4.3.0
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33738
^ permalink raw reply [flat|nested] 15+ messages in thread
* [Bug c++/33738] -Wtype-limits misses a warning when comparing enums
2007-10-11 17:50 [Bug c++/33738] New: -Wtype-limits misses a warning when comparing enums dnovillo at gcc dot gnu dot org
` (9 preceding siblings ...)
2008-02-05 19:57 ` manu at gcc dot gnu dot org
@ 2008-02-05 19:59 ` pinskia at gcc dot gnu dot org
2008-02-24 16:42 ` dnovillo at gcc dot gnu dot org
` (2 subsequent siblings)
13 siblings, 0 replies; 15+ messages in thread
From: pinskia at gcc dot gnu dot org @ 2008-02-05 19:59 UTC (permalink / raw)
To: gcc-bugs
--
pinskia at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |pinskia at gcc dot gnu dot
| |org
Target Milestone|4.3.0 |---
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33738
^ permalink raw reply [flat|nested] 15+ messages in thread
* [Bug c++/33738] -Wtype-limits misses a warning when comparing enums
2007-10-11 17:50 [Bug c++/33738] New: -Wtype-limits misses a warning when comparing enums dnovillo at gcc dot gnu dot org
` (10 preceding siblings ...)
2008-02-05 19:59 ` pinskia at gcc dot gnu dot org
@ 2008-02-24 16:42 ` dnovillo at gcc dot gnu dot org
2008-03-11 5:56 ` dnovillo at gcc dot gnu dot org
2008-12-29 6:11 ` pinskia at gcc dot gnu dot org
13 siblings, 0 replies; 15+ messages in thread
From: dnovillo at gcc dot gnu dot org @ 2008-02-24 16:42 UTC (permalink / raw)
To: gcc-bugs
------- Comment #9 from dnovillo at gcc dot gnu dot org 2008-02-24 16:41 -------
Subject: Bug 33738
Author: dnovillo
Date: Sun Feb 24 16:40:32 2008
New Revision: 132591
URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=132591
Log:
http://gcc.gnu.org/ml/gcc-patches/2008-02/msg01094.html
PR 33738
* tree-vrp.c (vrp_evaluate_conditional): With
-Wtype-limits, emit a warning when comparing against a
constant outside the natural range of OP0's type.
* c.opt (Wtype-limits): Move ...
* common.opt (Wtype-limits): ... here.
testsuite/ChangeLog
PR 33738
* g++.dg/warn/pr33738.C: New.
Added:
trunk/gcc/testsuite/g++.dg/warn/pr33738.C
Modified:
trunk/gcc/ChangeLog
trunk/gcc/c.opt
trunk/gcc/common.opt
trunk/gcc/testsuite/ChangeLog
trunk/gcc/tree-vrp.c
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33738
^ permalink raw reply [flat|nested] 15+ messages in thread
* [Bug c++/33738] -Wtype-limits misses a warning when comparing enums
2007-10-11 17:50 [Bug c++/33738] New: -Wtype-limits misses a warning when comparing enums dnovillo at gcc dot gnu dot org
` (11 preceding siblings ...)
2008-02-24 16:42 ` dnovillo at gcc dot gnu dot org
@ 2008-03-11 5:56 ` dnovillo at gcc dot gnu dot org
2008-12-29 6:11 ` pinskia at gcc dot gnu dot org
13 siblings, 0 replies; 15+ messages in thread
From: dnovillo at gcc dot gnu dot org @ 2008-03-11 5:56 UTC (permalink / raw)
To: gcc-bugs
------- Comment #10 from dnovillo at gcc dot gnu dot org 2008-03-11 05:56 -------
Fixed on mainline (4.4).
--
dnovillo at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|REOPENED |RESOLVED
Resolution| |FIXED
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33738
^ permalink raw reply [flat|nested] 15+ messages in thread
* [Bug c++/33738] -Wtype-limits misses a warning when comparing enums
2007-10-11 17:50 [Bug c++/33738] New: -Wtype-limits misses a warning when comparing enums dnovillo at gcc dot gnu dot org
` (12 preceding siblings ...)
2008-03-11 5:56 ` dnovillo at gcc dot gnu dot org
@ 2008-12-29 6:11 ` pinskia at gcc dot gnu dot org
13 siblings, 0 replies; 15+ messages in thread
From: pinskia at gcc dot gnu dot org @ 2008-12-29 6:11 UTC (permalink / raw)
To: gcc-bugs
--
pinskia at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
Target Milestone|--- |4.4.0
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33738
^ permalink raw reply [flat|nested] 15+ messages in thread
end of thread, other threads:[~2008-12-29 6:11 UTC | newest]
Thread overview: 15+ messages (download: mbox.gz / follow: Atom feed)
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2007-10-11 17:50 [Bug c++/33738] New: -Wtype-limits misses a warning when comparing enums dnovillo at gcc dot gnu dot org
2007-10-11 18:09 ` [Bug c++/33738] " pinskia at gcc dot gnu dot org
2007-11-13 4:56 ` manu at gcc dot gnu dot org
2008-02-05 4:19 ` dnovillo at gcc dot gnu dot org
2008-02-05 4:30 ` dnovillo at gcc dot gnu dot org
2008-02-05 10:19 ` rguenth at gcc dot gnu dot org
2008-02-05 11:22 ` manu at gcc dot gnu dot org
2008-02-05 16:16 ` dnovillo at google dot com
2008-02-05 16:32 ` dnovillo at gcc dot gnu dot org
2008-02-05 19:54 ` reichelt at gcc dot gnu dot org
2008-02-05 19:57 ` manu at gcc dot gnu dot org
2008-02-05 19:59 ` pinskia at gcc dot gnu dot org
2008-02-24 16:42 ` dnovillo at gcc dot gnu dot org
2008-03-11 5:56 ` dnovillo at gcc dot gnu dot org
2008-12-29 6:11 ` pinskia at gcc dot gnu dot org
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