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From: Bize Ma <binaryzebra@gmail.com>
Newsgroups: gnu.bash.bug
Subject: Error on arithmetic evaluation of `~0`.
Date: Wed, 19 Dec 2018 22:31:36 -0500
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Xref: csiph.com gnu.bash.bug:14931

This is the third time I am reporting this issue.

This fails:

var=(hello); echo "${var[~0]}"
syntax error: operand expected ...

While this works:

var=(hello); echo "${var[ ~0]}"
hello

It is also interesting that this fails:

var=hello; echo "${var[ ~0]}"
bash: var: bad array subscript

Isn't `var[0]` valid and equivalent to `var` ?

This was "supposed" to be resolved in a dev version,
but is still present on bash 5.