[BUG] dash uses $* instead of $@ in variable assignments

[BUG] dash uses $* instead of $@ in variable assignments

[Gioele Barabucci]

Hello,

I am forwarding a bug [1] reported by a Debian user: dash incorrectly
uses `$*` instead of the requested `$@` inside variable assignments.
The current version of dash is affected by this bug.

A simple test from the original reporter:

    $ dash -c 'IFS=:$IFS ; set -- a b c ; echo "$@" ; x="$@" ; echo "$x"'
    a b c
    a:b:c

    $ bash --posix -c 'IFS=:$IFS ; set -- a b c ; echo "$@" ; x="$@" ;
echo "$x"'
    a b c
    a b c

This error is reproducible with dash 0.5.7 and with the current master
git master branch, commit 2e5842258bd5b252ffdaa630db09c9a19a9717ca.

[1] https://bugs.debian.org/764365

--
Gioele Barabucci <gioele@svario.it>

Re: [BUG] dash uses $* instead of $@ in variable assignments

[Harald van Dijk]

On 26/11/2015 20:44, Gioele Barabucci wrote:
> Hello,
>
> I am forwarding a bug [1] reported by a Debian user: dash incorrectly
> uses `$*` instead of the requested `$@` inside variable assignments.
> The current version of dash is affected by this bug.
>
> A simple test from the original reporter:
>
>      $ dash -c 'IFS=:$IFS ; set -- a b c ; echo "$@" ; x="$@" ; echo "$x"'
>      a b c
>      a:b:c
>
>      $ bash --posix -c 'IFS=:$IFS ; set -- a b c ; echo "$@" ; x="$@" ;
> echo "$x"'
>      a b c
>      a b c

The behaviour for "$@" is underspecified except for very specific 
situations. Both behaviours are very defensible. There is an attempt to 
clear up the requirements for the future, but even with the cleared up 
wording, the behaviour of var=$@ and var="$@" would remain unspecified. 
See <http://austingroupbugs.net/view.php?id=888> for details.

Cheers,
Harald van Dijk

> This error is reproducible with dash 0.5.7 and with the current master
> git master branch, commit 2e5842258bd5b252ffdaa630db09c9a19a9717ca.
>
> [1] https://bugs.debian.org/764365
>
> --
> Gioele Barabucci <gioele@svario.it>
>
> --
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Re: [BUG] dash uses $* instead of $@ in variable assignments

[Stephane Chazelas]

2015-11-26 20:44:26 +0100, Gioele Barabucci:
> Hello,
> 
> I am forwarding a bug [1] reported by a Debian user: dash incorrectly
> uses `$*` instead of the requested `$@` inside variable assignments.
> The current version of dash is affected by this bug.
> 
> A simple test from the original reporter:
> 
>     $ dash -c 'IFS=:$IFS ; set -- a b c ; echo "$@" ; x="$@" ; echo "$x"'
>     a b c
>     a:b:c
[...]

This behaviour is what I expect and is common to other shells as
well.

$* and $@ are the concatenation of the positional parameters
with the first character of $IFS, but "$@" in list contexts
expands to all the position parameters as separate words. That's
a logical continuation to the Bourne behaviour (which
concatenated on space instead of the first character of $IFS).

POSIX used to be unclear about it. I had raised the issue some
time ago and I beleive there's a new wording. See the longish
discussion at
http://thread.gmane.org/gmane.comp.standards.posix.austin.general/9972

In any case, you should only use $@ quoted and in list contexts.
$* may be used quoted in non-list contexts.

IIRC the proposed new wording for the POSIX spec would make this
behaviour of dash non-conformant:

$ dash -c 'set a b c; IFS=; echo $*'
abc

(even though I'd argue it's a logical design choice).

-- 
Stephane

Re: [BUG] dash uses $* instead of $@ in variable assignments

[Gioele Barabucci]

On 26/11/2015 22:37, Stephane Chazelas wrote:
> 2015-11-26 20:44:26 +0100, Gioele Barabucci:
>> Hello,
>>
>> I am forwarding a bug [1] reported by a Debian user: dash incorrectly
>> uses `$*` instead of the requested `$@` inside variable assignments.
>> The current version of dash is affected by this bug.
>>
>> A simple test from the original reporter:
>>
>>     $ dash -c 'IFS=:$IFS ; set -- a b c ; echo "$@" ; x="$@" ; echo "$x"'
>>     a b c
>>     a:b:c
> [...]
> 
> This behaviour is what I expect and is common to other shells as
> well.

Hi,

so from the answers I got this looks like an intended behaviour. Fair
enough. :) For the sake of triage I will then mark the Debian bug as
wontfix.

Regards,

--
Gioele Barabucci <gioele@svario.it>