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

[Chet Ramey]

On 1/14/21 10:31 AM, Léa Gris wrote:
> Le 14/01/2021 à 16:15, Chet Ramey écrivait :
> > On 1/13/21 4:40 PM, Léa Gris wrote:
> > > Le 13/01/2021 à 22:13, Chet Ramey écrivait :
> > > > The `-i' forces arithmetic evaluation, which makes this expand to the 
> > > > equivalent of `declare -n b=1'. That's an invalid name for a nameref,
> > > > which you'd see if you used `declare -n b=1' instead. The assignment
> > > > error causes `declare' to return an non-zero status, but the error
> > > > message checks the original value, not the result of arithmetic
> > > > evaluation, and the `a[0]' is valid.
> > > >
> > > > I guess I never thought people would try to use integer variables as
> > > > namerefs, since nameref values can't be digits.
> > >
> > >
> > > Sorry Chet, this does not make sense to me. There is no error message.
> >
> > OK, let's be clear that this sequence of commands from your message is what
> > we're talking about:
> >
> > unset a b
> > declare -ai a=(1)
> > declare -in b="a[0]"
> > declare -p a b
> >
> > I get this result:
> >
> > declare -ai a=([0]="1")
> > x4: line 4: declare: b: not found
> >
> > and I explained why there is no variable `b'.
>
>
> Not the same issue and not exactly same sequence of commands:

OK, so this is a new question.

> unset a; unset -n b
> declare -ai a=(1)
> declare -n b="a[0]" # No i flag at that point for b
> typeset -ni b # Now b also has a int flag alongside the nameref

Yeah, that probably shouldn't be allowed, but it currently is.

> b+=2 # This is only allowed if b has the int flag

https://lists.gnu.org/archive/html/bug-bash/2021-01/msg00094.html


> As Oğuz wrote:
> > Seems to be another bug. `bind_variable_internal' calls both
> > `assign_array_element' and `make_variable_value' with ASS_APPEND in flags (
> > https://git.savannah.gnu.org/cgit/bash.git/tree/variables.c#n3140 ), the
> > latter returns 6 (4 + 2), the former adds it to a[0]'s value.

It's all the same problem. That code has been in bash since 2012.

--
``The lyf so short, the craft so long to lerne.'' - Chaucer
                 ``Ars longa, vita brevis'' - Hippocrates
Chet Ramey, UTech, CWRU    chet@case.edu    http://tiswww.cwru.edu/~chet/