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* [Bug c/38470] New: Feature request: smarter signed/unsigned warning
@ 2008-12-10 10:35 m dot j dot thayer at googlemail dot com
2008-12-10 10:38 ` [Bug c/38470] " m dot j dot thayer at googlemail dot com
` (8 more replies)
0 siblings, 9 replies; 10+ messages in thread
From: m dot j dot thayer at googlemail dot com @ 2008-12-10 10:35 UTC (permalink / raw)
To: gcc-bugs
This is a request to drop the signed/unsigned comparison warning if the
compiler can clearly see that the unsigned value is positive. E.g. in the
following case:
if (foo >= 0 && foo < sizeof(bar)) ...
This would avoid the need for a typecase. Please correct me if this is still
not safe for other reasons.
--
Summary: Feature request: smarter signed/unsigned warning
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: m dot j dot thayer at googlemail dot com
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38470
^ permalink raw reply [flat|nested] 10+ messages in thread
* [Bug c/38470] Feature request: smarter signed/unsigned warning
2008-12-10 10:35 [Bug c/38470] New: Feature request: smarter signed/unsigned warning m dot j dot thayer at googlemail dot com
@ 2008-12-10 10:38 ` m dot j dot thayer at googlemail dot com
2010-02-24 13:16 ` manu at gcc dot gnu dot org
` (7 subsequent siblings)
8 siblings, 0 replies; 10+ messages in thread
From: m dot j dot thayer at googlemail dot com @ 2008-12-10 10:38 UTC (permalink / raw)
To: gcc-bugs
--
m dot j dot thayer at googlemail dot com changed:
What |Removed |Added
----------------------------------------------------------------------------
Severity|normal |enhancement
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38470
^ permalink raw reply [flat|nested] 10+ messages in thread
* [Bug c/38470] Feature request: smarter signed/unsigned warning
2008-12-10 10:35 [Bug c/38470] New: Feature request: smarter signed/unsigned warning m dot j dot thayer at googlemail dot com
2008-12-10 10:38 ` [Bug c/38470] " m dot j dot thayer at googlemail dot com
@ 2010-02-24 13:16 ` manu at gcc dot gnu dot org
2010-02-24 13:17 ` manu at gcc dot gnu dot org
` (6 subsequent siblings)
8 siblings, 0 replies; 10+ messages in thread
From: manu at gcc dot gnu dot org @ 2010-02-24 13:16 UTC (permalink / raw)
To: gcc-bugs
------- Comment #1 from manu at gcc dot gnu dot org 2010-02-24 13:16 -------
We need a complete testcase.
--
manu at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |manu at gcc dot gnu dot org
Status|UNCONFIRMED |WAITING
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38470
^ permalink raw reply [flat|nested] 10+ messages in thread
* [Bug c/38470] Feature request: smarter signed/unsigned warning
2008-12-10 10:35 [Bug c/38470] New: Feature request: smarter signed/unsigned warning m dot j dot thayer at googlemail dot com
2008-12-10 10:38 ` [Bug c/38470] " m dot j dot thayer at googlemail dot com
2010-02-24 13:16 ` manu at gcc dot gnu dot org
@ 2010-02-24 13:17 ` manu at gcc dot gnu dot org
2010-02-24 14:00 ` paolo dot carlini at oracle dot com
` (5 subsequent siblings)
8 siblings, 0 replies; 10+ messages in thread
From: manu at gcc dot gnu dot org @ 2010-02-24 13:17 UTC (permalink / raw)
To: gcc-bugs
------- Comment #2 from manu at gcc dot gnu dot org 2010-02-24 13:16 -------
We need a complete testcase. See http://gcc.gnu.org/bugs
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38470
^ permalink raw reply [flat|nested] 10+ messages in thread
* [Bug c/38470] Feature request: smarter signed/unsigned warning
2008-12-10 10:35 [Bug c/38470] New: Feature request: smarter signed/unsigned warning m dot j dot thayer at googlemail dot com
` (2 preceding siblings ...)
2010-02-24 13:17 ` manu at gcc dot gnu dot org
@ 2010-02-24 14:00 ` paolo dot carlini at oracle dot com
2010-02-24 14:04 ` [Bug c/38470] dataflow would improve -Wsign-compare manu at gcc dot gnu dot org
` (4 subsequent siblings)
8 siblings, 0 replies; 10+ messages in thread
From: paolo dot carlini at oracle dot com @ 2010-02-24 14:00 UTC (permalink / raw)
To: gcc-bugs
------- Comment #3 from paolo dot carlini at oracle dot com 2010-02-24 13:59 -------
I think submitter ask for something like this:
int f(int foo, double bar)
{
if (foo >= 0 && foo < sizeof(bar))
return 1;
return foo;
}
to not warn with -Wsign-compare.
--
paolo dot carlini at oracle dot com changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|WAITING |NEW
Ever Confirmed|0 |1
Last reconfirmed|0000-00-00 00:00:00 |2010-02-24 13:59:45
date| |
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38470
^ permalink raw reply [flat|nested] 10+ messages in thread
* [Bug c/38470] dataflow would improve -Wsign-compare
2008-12-10 10:35 [Bug c/38470] New: Feature request: smarter signed/unsigned warning m dot j dot thayer at googlemail dot com
` (3 preceding siblings ...)
2010-02-24 14:00 ` paolo dot carlini at oracle dot com
@ 2010-02-24 14:04 ` manu at gcc dot gnu dot org
2010-02-24 14:07 ` m dot j dot thayer at googlemail dot com
` (3 subsequent siblings)
8 siblings, 0 replies; 10+ messages in thread
From: manu at gcc dot gnu dot org @ 2010-02-24 14:04 UTC (permalink / raw)
To: gcc-bugs
------- Comment #4 from manu at gcc dot gnu dot org 2010-02-24 14:03 -------
(In reply to comment #3)
> I think submitter ask for something like this:
[snip]
> to not warn with -Wsign-compare.
That would be nice, but it would require moving the warning to the middle-end
or some form of dataflow in the front-end. And no one is working on either, so
don't hold your breath.
--
manu at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
Summary|Feature request: smarter |dataflow would improve -
|signed/unsigned warning |Wsign-compare
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38470
^ permalink raw reply [flat|nested] 10+ messages in thread
* [Bug c/38470] dataflow would improve -Wsign-compare
2008-12-10 10:35 [Bug c/38470] New: Feature request: smarter signed/unsigned warning m dot j dot thayer at googlemail dot com
` (4 preceding siblings ...)
2010-02-24 14:04 ` [Bug c/38470] dataflow would improve -Wsign-compare manu at gcc dot gnu dot org
@ 2010-02-24 14:07 ` m dot j dot thayer at googlemail dot com
2010-02-24 14:11 ` [Bug c/38470] value range propagation (VRP) " manu at gcc dot gnu dot org
` (2 subsequent siblings)
8 siblings, 0 replies; 10+ messages in thread
From: m dot j dot thayer at googlemail dot com @ 2010-02-24 14:07 UTC (permalink / raw)
To: gcc-bugs
------- Comment #5 from m dot j dot thayer at googlemail dot com 2010-02-24 14:07 -------
Comment 3 describes what I meant. And re comment 4, it is a "would be nice to
have", obviously if it is too much pain to do then such is life. Thanks in any
case.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38470
^ permalink raw reply [flat|nested] 10+ messages in thread
* [Bug c/38470] value range propagation (VRP) would improve -Wsign-compare
2008-12-10 10:35 [Bug c/38470] New: Feature request: smarter signed/unsigned warning m dot j dot thayer at googlemail dot com
` (5 preceding siblings ...)
2010-02-24 14:07 ` m dot j dot thayer at googlemail dot com
@ 2010-02-24 14:11 ` manu at gcc dot gnu dot org
2010-02-24 14:13 ` manu at gcc dot gnu dot org
2010-02-24 14:17 ` m dot j dot thayer at googlemail dot com
8 siblings, 0 replies; 10+ messages in thread
From: manu at gcc dot gnu dot org @ 2010-02-24 14:11 UTC (permalink / raw)
To: gcc-bugs
------- Comment #6 from manu at gcc dot gnu dot org 2010-02-24 14:11 -------
Fixing this is even more unlikely than fixing PR 23608, since the latter only
asks for constant propagation, but this one requires value range propagation.
--
manu at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
BugsThisDependsOn| |23608
Summary|dataflow would improve - |value range propagation
|Wsign-compare |(VRP) would improve -Wsign-
| |compare
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38470
^ permalink raw reply [flat|nested] 10+ messages in thread
* [Bug c/38470] value range propagation (VRP) would improve -Wsign-compare
2008-12-10 10:35 [Bug c/38470] New: Feature request: smarter signed/unsigned warning m dot j dot thayer at googlemail dot com
` (6 preceding siblings ...)
2010-02-24 14:11 ` [Bug c/38470] value range propagation (VRP) " manu at gcc dot gnu dot org
@ 2010-02-24 14:13 ` manu at gcc dot gnu dot org
2010-02-24 14:17 ` m dot j dot thayer at googlemail dot com
8 siblings, 0 replies; 10+ messages in thread
From: manu at gcc dot gnu dot org @ 2010-02-24 14:13 UTC (permalink / raw)
To: gcc-bugs
------- Comment #7 from manu at gcc dot gnu dot org 2010-02-24 14:12 -------
(In reply to comment #5)
> Comment 3 describes what I meant. And re comment 4, it is a "would be nice to
> have", obviously if it is too much pain to do then such is life. Thanks in any
> case.
Please, do not understand me wrong. I totally agree it would be nice to have
and we should leave this open in case someone steps up to the task (patches
welcome, as they say). I was just commenting that you should not expect a quick
fix because it is more complex than it seems. And thanks for the report.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38470
^ permalink raw reply [flat|nested] 10+ messages in thread
* [Bug c/38470] value range propagation (VRP) would improve -Wsign-compare
2008-12-10 10:35 [Bug c/38470] New: Feature request: smarter signed/unsigned warning m dot j dot thayer at googlemail dot com
` (7 preceding siblings ...)
2010-02-24 14:13 ` manu at gcc dot gnu dot org
@ 2010-02-24 14:17 ` m dot j dot thayer at googlemail dot com
8 siblings, 0 replies; 10+ messages in thread
From: m dot j dot thayer at googlemail dot com @ 2010-02-24 14:17 UTC (permalink / raw)
To: gcc-bugs
------- Comment #8 from m dot j dot thayer at googlemail dot com 2010-02-24 14:16 -------
Of course. I asked this without knowing much about compiler internals, but I
do have experience of users asking for "little" features which would involve
somewhat more work than they would like to think :)
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38470
^ permalink raw reply [flat|nested] 10+ messages in thread
end of thread, other threads:[~2010-02-24 14:17 UTC | newest]
Thread overview: 10+ messages (download: mbox.gz / follow: Atom feed)
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2008-12-10 10:35 [Bug c/38470] New: Feature request: smarter signed/unsigned warning m dot j dot thayer at googlemail dot com
2008-12-10 10:38 ` [Bug c/38470] " m dot j dot thayer at googlemail dot com
2010-02-24 13:16 ` manu at gcc dot gnu dot org
2010-02-24 13:17 ` manu at gcc dot gnu dot org
2010-02-24 14:00 ` paolo dot carlini at oracle dot com
2010-02-24 14:04 ` [Bug c/38470] dataflow would improve -Wsign-compare manu at gcc dot gnu dot org
2010-02-24 14:07 ` m dot j dot thayer at googlemail dot com
2010-02-24 14:11 ` [Bug c/38470] value range propagation (VRP) " manu at gcc dot gnu dot org
2010-02-24 14:13 ` manu at gcc dot gnu dot org
2010-02-24 14:17 ` m dot j dot thayer at googlemail dot com
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