* Can't turn off overflow_warning?
@ 2005-07-16 2:27 Bradley Lucier
2005-07-16 2:33 ` Andrew Pinski
2005-07-16 2:35 ` DJ Delorie
0 siblings, 2 replies; 4+ messages in thread
From: Bradley Lucier @ 2005-07-16 2:27 UTC (permalink / raw)
To: gcc; +Cc: Bradley Lucier
After examining the source and documentation, it appears to me that in
4.0.* and on mainline one cannot turn off the warning generated by
overflow_warning, in, for example,
[descartes:~] lucier% cat test.c
#include <stdio.h>
int main() {
if (1048256 * 1048256 < 0)
printf("1");
else
printf("2");
return 0;
}
[descartes:~] lucier% /pkgs/gcc-4.0.0/bin/gcc -v
Using built-in specs.
Target: powerpc-apple-darwin8.1.0
Configured with: ../configure --prefix=/pkgs/gcc-4.0.0
--with-gmp=/pkgs/gmp-4.1.3 --with-mpfr=/pkgs/gmp-4.1.3
Thread model: posix
gcc version 4.0.0
[descartes:~] lucier% /pkgs/gcc-4.0.0/bin/gcc -O1 -Wall -W -Wextra
-fwrapv test.c
test.c: In function 'main':
test.c:4: warning: integer overflow in expression
[descartes:~] lucier% ./a.out
1[descartes:~] lucier%
I'd like to be able to do this, since I'm auto-generating code that
explicitly uses overflow tests that assume that signed ints overflow
using twos-complement arithmetic and I don't want to be distracted by
extraneous warnings when constant propagation in the Scheme system puts
constants into this C code.
Personally, I'd like overflow_warning to be turned off for signed ints
if -fwrapv is passed as a flag. I suppose an explicit
-Wno-overflow-warning would be OK, too.
If I were to propose a patch, which way should I go?
Brad
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: Can't turn off overflow_warning?
2005-07-16 2:27 Can't turn off overflow_warning? Bradley Lucier
@ 2005-07-16 2:33 ` Andrew Pinski
2005-07-16 2:59 ` Gabriel Dos Reis
2005-07-16 2:35 ` DJ Delorie
1 sibling, 1 reply; 4+ messages in thread
From: Andrew Pinski @ 2005-07-16 2:33 UTC (permalink / raw)
To: Bradley Lucier; +Cc: gcc
On Jul 15, 2005, at 10:27 PM, Bradley Lucier wrote:
> After examining the source and documentation, it appears to me that in
> 4.0.* and on mainline one cannot turn off the warning generated by
> overflow_warning, in, for example,
IIRC the C standard requires that a warning here but I could be wrong.
-- Pinski
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: Can't turn off overflow_warning?
2005-07-16 2:27 Can't turn off overflow_warning? Bradley Lucier
2005-07-16 2:33 ` Andrew Pinski
@ 2005-07-16 2:35 ` DJ Delorie
1 sibling, 0 replies; 4+ messages in thread
From: DJ Delorie @ 2005-07-16 2:35 UTC (permalink / raw)
To: lucier; +Cc: gcc
> If I were to propose a patch, which way should I go?
Why not check out my recently posted -Wpragmas patch on gcc-patches?
It takes a set of existing non-optional warnings, and gives them an
option that can be used to disable them, which defaults to on
(i.e. -Wno-pragmas is the useful option).
That way, you get control but the default action stays the same.
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: Can't turn off overflow_warning?
2005-07-16 2:33 ` Andrew Pinski
@ 2005-07-16 2:59 ` Gabriel Dos Reis
0 siblings, 0 replies; 4+ messages in thread
From: Gabriel Dos Reis @ 2005-07-16 2:59 UTC (permalink / raw)
To: Andrew Pinski; +Cc: Bradley Lucier, gcc
Andrew Pinski <pinskia@physics.uc.edu> writes:
| On Jul 15, 2005, at 10:27 PM, Bradley Lucier wrote:
|
| > After examining the source and documentation, it appears to me that
| > in 4.0.* and on mainline one cannot turn off the warning generated
| > by overflow_warning, in, for example,
|
| IIRC the C standard requires that a warning here but I could be wrong.
Please not again.
The C standard knows nothing about warning. There is a notion of
diagnostic but I don't think it makes any sense in the particular case
Brad describes.
|
| -- Pinski
--
Gabriel Dos Reis
gdr@integrable-solutions.net
^ permalink raw reply [flat|nested] 4+ messages in thread
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