Re: wrong variable name in error message about unbound variable?

[Grisha Levit]

On Mon, Oct 16, 2023, 22:46 Christoph Anton Mitterer <calestyo@scientia.org>
wrote:

> Hey.
>
> On Mon, 2023-10-16 at 22:05 -0400, Lawrence Velázquez wrote:
> > Under no circumstances should your examples complain about "array"
> > because they do not attempt to expand it.  As I demonstrated, your
> > examples do not even complain about unset scalar variables.
>
> Okay I realise now, why it worked once it was declared an associative
> array.
>
> But why does it even try to evaluate the subscript "key" as arithmetic
> expression?
>
> Yes it's defined for indexed arrays, but shouldn't it already know that
> there is no indexed array of the name "array" and any evaluation of the
> subscript is thus pointless?
>

The array subscript can an arbitrary arithmetic expression with side
effects, so it makes sense to perform the expansion even if the array whose
subscript is being expanded is unset:

$ unset a b; echo "${a[b=2]-X}" "$b"
X 2

Though I do think Bash isn't being very consistent in the case where a side
effects of expanding a subscript of an unset variable ends up making it no
longer unset:

$ unset a; echo "${a[a=0]-X}" "$a"
X 0

$ unset a; declare a; echo "${a[a=0]-X}" "$a"
0 0