Bug ? SC2086 - false positiv due to bash arithmetic ?!

[PeterPitterling]

For bugs

• Rule Id SC2086
• My shellcheck version (shellcheck --version or "online"): online
• The rule's wiki page does not already cover this (e.g. https://shellcheck.net/wiki/SC2086)
• I tried on https://www.shellcheck.net/ and verified that this is still a problem on the latest commit

For new checks and feature suggestions

• https://www.shellcheck.net/ (i.e. the latest commit) currently gives no useful warnings about this
• I searched through https://github.com/koalaman/shellcheck/issues and didn't find anything related

Maybe similar to "retryLimit appears unused" but its used.

Here's a snippet or screenshot that shows the problem:

#!/usr/bin/env bash

declare -i prefix_length=0

(( prefix_length += 17 ))                      #triggers SC2086 in next line

printf '%-*b\n' ${prefix_length} 'same string with long prefix'

Here's what shellcheck currently says:

Line 7:
printf '%-*b\n' ${prefix_length} 'same string with long prefix'
                ^-- SC2086 (info): Double quote to prevent globbing and word splitting.

Did you mean: (apply this, apply all SC2086)
printf '%-*b\n' "${prefix_length}" 'same string with long prefix'

Here's what I wanted or expected to see:

No error message

[koalaman]

ShellCheck really needs to start understanding declare -i, but that's a bigger job. For now I just updated this naive logic to realize that arithmetic assignments will cause the value not to contain spaces. Thanks!

[PeterPitterling]

how long does it take to materialize on shellcheck.net ?

[koalaman]

Huh, the tests passed locally but not on the host so it didn't update. I'll have a look later today.

[PeterPitterling]

same issue with

((prefix_length++))

while this is accepted now ...
((prefix_length+=1))

[ramses0]

(please disregard reference from #2687, it was a typo of 2346 v. 2364)