Re: V+=1 doesn't work if V is a reference to an integer array element

[Ilkka Virta]

On Wed, Jan 13, 2021 at 7:49 PM Greg Wooledge <wooledg@eeg.ccf.org> wrote:

> On Wed, Jan 13, 2021 at 07:00:42PM +0200, Oğuz wrote:
> >     $ declare -n b=a[0]
>
> I can't see any documentation that supports the idea that this should
> be allowed in the first place.
>

It's arguably useful though, and works in 4.4 (with -i or not):

$ ./bash4.4.12 -c 'declare -ai a=1; declare -n b="a[0]"; b+=1; echo $b;
b=123; echo $b; declare -p a b'
2
123
declare -ai a=([0]="123")
declare -n b="a[0]"

Also a simple assignment seems to work, just the += case fails:

$ ./bash5.0 -c 'declare -ai a=(11 22 33); declare -n b="a[1]"; b=123; echo
$b; declare -p a'
123
declare -ai a=([0]="11" [1]="123" [2]="33")

Then again, using a nameref like that in an arithmetic context doesn't seem
to work (in either 4.4 or 5.0) but
silently gives a zero (which is what you get if b pointed to an unset
variable, but here I can't see what the
variable it points to would be):

$ ./bash4.4.12 -c 'declare -a a=(11 22 33); declare -n b="a[1]"; echo
$((b))'
0