GNU bug report logs - #17800
seq weirdness with -0

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Rasmus Villemoes <rv <at> rasmusvillemoes.dk>
To: bug-coreutils <at> gnu.org
Subject: seq weirdness with -0
Date: Wed, 18 Jun 2014 11:41:43 +0200

$ ./seq --version | head -1
seq (GNU coreutils) 8.22.119-8a51b

./seq -0 n works fine when n is a single digit:

$ ./seq --separator=, -0 5
-0,1,2,3,4,5

But something weird happens when one uses a number >= 10:

$ ./seq --separator=, -0 10
-0,-1,-2,-3,-4,-5,-6,-7,-8,-9,.0,.1,.2,.3,.4,.5,.6,.7,.8,.9,/0,/1,/2,/3,/4,/5,/6,/7,/8,/9,00,01,02,03,04,05,06,07,08,09,10

[It also happens without the --separator; I just use that to save
vertical space.] This smells of ASCII, and looking at the code, the
problem is very likely to be the seq_fast/incr functions. I don't know
what the simplest fix is, though.

Rasmus

Message #8 received at 17800 <at> debbugs.gnu.org (full text, mbox):

From: Pádraig Brady <P <at> draigBrady.com>
To: Rasmus Villemoes <rv <at> rasmusvillemoes.dk>
Cc: 17800 <at> debbugs.gnu.org
Subject: Re: bug#17800: seq weirdness with -0
Date: Wed, 18 Jun 2014 13:03:37 +0100

On 06/18/2014 10:41 AM, Rasmus Villemoes wrote:
> $ ./seq --version | head -1
> seq (GNU coreutils) 8.22.119-8a51b
> 
> ./seq -0 n works fine when n is a single digit:
> 
> $ ./seq --separator=, -0 5
> -0,1,2,3,4,5
> 
> But something weird happens when one uses a number >= 10:
> 
> $ ./seq --separator=, -0 10
> -0,-1,-2,-3,-4,-5,-6,-7,-8,-9,.0,.1,.2,.3,.4,.5,.6,.7,.8,.9,/0,/1,/2,/3,/4,/5,/6,/7,/8,/9,00,01,02,03,04,05,06,07,08,09,10
> 
> [It also happens without the --separator; I just use that to save
> vertical space.] This smells of ASCII, and looking at the code, the
> problem is very likely to be the seq_fast/incr functions. I don't know
> what the simplest fix is, though.

Ouch. I see the issue. Fix on the way...

thanks!
Pádraig.

Message #13 received at 17800-done <at> debbugs.gnu.org (full text, mbox):

From: Pádraig Brady <P <at> draigBrady.com>
To: Rasmus Villemoes <rv <at> rasmusvillemoes.dk>
Cc: 17800-done <at> debbugs.gnu.org
Subject: Re: bug#17800: seq weirdness with -0
Date: Wed, 18 Jun 2014 14:39:03 +0100

[Message part 1 (text/plain, inline)]

On 06/18/2014 01:03 PM, Pádraig Brady wrote:
> On 06/18/2014 10:41 AM, Rasmus Villemoes wrote:
>> $ ./seq --version | head -1
>> seq (GNU coreutils) 8.22.119-8a51b
>>
>> ./seq -0 n works fine when n is a single digit:
>>
>> $ ./seq --separator=, -0 5
>> -0,1,2,3,4,5
>>
>> But something weird happens when one uses a number >= 10:
>>
>> $ ./seq --separator=, -0 10
>> -0,-1,-2,-3,-4,-5,-6,-7,-8,-9,.0,.1,.2,.3,.4,.5,.6,.7,.8,.9,/0,/1,/2,/3,/4,/5,/6,/7,/8,/9,00,01,02,03,04,05,06,07,08,09,10
>>
>> [It also happens without the --separator; I just use that to save
>> vertical space.] This smells of ASCII, and looking at the code, the
>> problem is very likely to be the seq_fast/incr functions. I don't know
>> what the simplest fix is, though.
> 
> Ouch. I see the issue. Fix on the way...

Fast path avoidance logic updated in the attached.

thanks!
Pádraig.

[seq-0.patch (text/x-patch, attachment)]

Message #16 received at 17800 <at> debbugs.gnu.org (full text, mbox):

From: Bernhard Voelker <mail <at> bernhard-voelker.de>
To: 17800 <at> debbugs.gnu.org, P <at> draigBrady.com, rv <at> rasmusvillemoes.dk
Subject: Re: bug#17800: seq weirdness with -0
Date: Wed, 18 Jun 2014 17:47:34 +0200

On 06/18/2014 03:39 PM, Pádraig Brady wrote:
> Subject: [PATCH] seq: fix incorrect output with start or end of -0

LGTM - although I'm still wondering what's the use case
behind a negative Null "-0". ;-)

Thanks & have a nice day,
Berny

Message #19 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Rasmus Villemoes <rv <at> rasmusvillemoes.dk>
To: bug-coreutils <at> gnu.org
Cc: Bernhard Voelker <mail <at> bernhard-voelker.de>, P <at> draigBrady.com
Subject: Re: bug#17800: seq weirdness with -0
Date: Wed, 18 Jun 2014 21:10:50 +0200

Bernhard Voelker <mail <at> bernhard-voelker.de> writes:

> On 06/18/2014 03:39 PM, Pádraig Brady wrote:
>> Subject: [PATCH] seq: fix incorrect output with start or end of -0
>
> LGTM - although I'm still wondering what's the use case
> behind a negative Null "-0". ;-)

I agree it is unlikely anyone would write -0 explicitly, but one could
imagine a script doing

    seq -$n $m | ...

where the preceding code sets $n and $m to be some non-negative integers.

Thanks for the quick response.

Rasmus

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