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From: "eggert at gnu dot org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c/43772] Errant -Wlogical-op warning when testing limits
Date: Sat, 28 Apr 2012 22:41:00 -0000 [thread overview]
Message-ID: <bug-43772-4-YpFgLuFgDl@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-43772-4@http.gcc.gnu.org/bugzilla/>
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43772
--- Comment #20 from eggert at gnu dot org 2012-04-28 22:40:27 UTC ---
(In reply to comment #19)
> > intmax_t i = (whatever);
> > if (INT_MAX < i && i <= LONG_MAX)
> Have you actually seen that?
No, I just now invented that example. It was based on experience I've
had in using macros like those in gnulib's intprops.h
<http://git.savannah.gnu.org/cgit/gnulib.git/tree/lib/intprops.h>
though none of those macros actually have that particular code.
>I would imagine the following to be more common:
>if(i<=INT_MAX)
> print("i is in 'int'");
>else if(i<=LONG_MAX)
Yes, intprops.h already has written code that way (instead of using &&)
in order to avoid a somewhat-similar bug in the Sun C compiler.
There's a comment to that effect in intprops.h.
> we are not talking of having this warning by default,
> this is an isolated warning not even included in -Wall -Wextra.
We can always disable -Wlogical-op when compiling
any code that has the problem. It's not a big deal,
though it is an annoyance that will prevent people from benefiting
from -Wlogical-op. I'm afraid I don't have any magic answers here.
next prev parent reply other threads:[~2012-04-28 22:41 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <bug-43772-4@http.gcc.gnu.org/bugzilla/>
2011-06-15 19:20 ` eggert at gnu dot org
2011-07-15 3:02 ` eggert at gnu dot org
2012-04-28 12:20 ` marc.glisse at normalesup dot org
2012-04-28 12:33 ` manu at gcc dot gnu.org
2012-04-28 12:34 ` marc.glisse at normalesup dot org
2012-04-28 12:38 ` manu at gcc dot gnu.org
2012-04-28 12:40 ` marc.glisse at normalesup dot org
2012-04-28 12:50 ` manu at gcc dot gnu.org
2012-04-28 12:56 ` marc.glisse at normalesup dot org
2012-04-28 13:08 ` manu at gcc dot gnu.org
2012-04-28 18:50 ` marc.glisse at normalesup dot org
2012-04-28 21:53 ` eggert at gnu dot org
2012-04-28 22:17 ` marc.glisse at normalesup dot org
2012-04-28 22:41 ` eggert at gnu dot org [this message]
2012-05-05 11:32 ` manu at gcc dot gnu.org
2012-05-05 12:15 ` manu at gcc dot gnu.org
2014-06-10 23:19 ` P at draigBrady dot com
2010-04-16 21:44 [Bug c/43772] New: " P at draigBrady dot com
2010-04-17 11:03 ` [Bug c/43772] " rguenth at gcc dot gnu dot org
2010-04-17 17:41 ` P at draigBrady dot com
2010-04-22 0:38 ` P at draigBrady dot com
2010-09-23 6:52 ` muntyan at fastmail dot fm
2010-09-23 8:13 ` manu at gcc dot gnu dot org
2010-09-23 8:24 ` manu at gcc dot gnu dot org
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