Re: bash exorcism experiment ('bug' 762923 & 763012)
>> Array variables practically imply arithmetic evaluation, amd this is
>> shell feature which is rather difficult to use correctly because
>> compatibility with other shell encourages both recursive evaluation
>> and access to the full shell language in a few corners.
I think the idea here was not "use correctly" as in "yielding the result you expect" but as in "guard against wreaking havoc":
foo='x[$(rm -rf /)]'
echo $(( foo ))
Guess when the array index is evaluated? Now mind that it could be user-provided.