Re: [gentoo-portage-dev] Fix all misc. bash errors.

[R0b0t1]

On Sun, Feb 4, 2018 at 10:45 PM, Zac Medico <zmedico@g.o> wrote:
> On 02/04/2018 07:22 PM, R0b0t1 wrote:
>> This is everything that shellcheck reported as an error. They are not
>> as serious as the globbing issue, but it would be a good idea to
>> change them. They are generally "type" issues (e.g. ">" instead of
>> "-gt").
>>
>> Some changes are shellcheck annotations. Very interesting was:
>>
>> eval "$x=(\"\${$x[@]}\" ${QA_PREBUILT//\*/.*})"
>>
>> Which looks like a bad array expansion ("$x[@]").
>
> I don't see a shellcheck error for that, using shellcheck-0.4.7. Maybe a
> false positive with an older version?
>

0.4.6, I will see if I can check.

>> diff --git a/bin/isolated-functions.sh b/bin/isolated-functions.sh
>> index b28e44f18..377b32d90 100644
>> --- a/bin/isolated-functions.sh
>> +++ b/bin/isolated-functions.sh
>> @@ -82,7 +82,7 @@ __dump_trace() {
>>          lineno=${BASH_LINENO[${n} - 1]}
>>          # Display function arguments
>>          args=
>> -        if [[ -n "${BASH_ARGV[@]}" ]]; then
>> +        if [[ -n "${BASH_ARGV[*]}" ]]; then
>
> I feel like the shellcheck authors might be willing to accept [[ -n
> ${BASH_ARGV[@]} ]] or [[ ${BASH_ARGV[@]} ]] as correct, since the
> "Problematic code" that they cite involves an incorrect comparison:
>
> https://github.com/koalaman/shellcheck/wiki/SC2199#problematic-code
>

This example might be more illustrative:

argc () {
    echo $#
}

argc "${BASH_ARGV[*]}"
argc "${BASH_ARGV[@]}"


Output (./test.sh a b):

1
2


Which changes the semantics of the tests in which it is present. It is
hard to know what [[ is doing; if the same is attempted with [ it
would be an error for the same reason that globbing produces errors.
See:

[  "${BASH_ARGV[*]}"  ]
[  "${BASH_ARGV[@]}"  ] # Fails; [: b: unary operator expected
[[ "${BASH_ARGV[*]}" ]]
[[ "${BASH_ARGV[@]}" ]]


It is possible [[ ignores the extra elements. I can't think of a
reason where this would make the results of the test different. At the
same time, it might give people the wrong impression of the operation
of [.

In the sense that [ and [[ represent test(1), anything but the "[*]"
expansion is incorrect, as the error message indicates. That [[ treats
its arguments specially because it is a feature of the syntax just
makes the situation more confusing.

Cheers,
     R0b0t1