Shellcheck: getopts: detect option letters handled in case statement but missing from optstring

[phagara]

For new checks and feature suggestions

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

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

#!/bin/sh

usage() {
        echo "$0 [-a text] [-b]"
        exit 1
}

while getopts a: opt; do
        case "$opt" in
                a) foo=$OPTARG ;;
                b) alias bar=true ;;
                *) usage ;;
        esac
 done

echo "$foo"

Here's what shellcheck currently says:

No issues detected!

Here's what I wanted or expected to see:

Something along the lines of Attempting to handle option "b" not present in getopts' optstring.

[koalaman]

This feature has been added in 4243c6a. It only works for getopts (not getopt) in strictly canonical while loops like this one.

Great suggestion. It's high frequency so it'll actually trigger, high precision so it won't be noisy, and high level so you'll be impressed when it's caught ^^

[brother]

Incorrect commit link.
I think this is the correct one https://github.com/koalaman/shellcheck/commit/070a465b64f07600

[koalaman]

Oops! Yes, that's the one

[phagara]

Awesome, thanks!