Feature: detect return values other than 0-225 (like strings) in functions when used via variables

[mika]

For new checks and feature suggestions

• 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

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

#!/bin/bash
foo() {
  local file="/usr/bin/foo"
  return "$file"
}
foo

Here's what shellcheck currently says:

No issues detected!

Here's what I wanted or expected to see:

SC2152: Can only return 0-255. Other data should be written to stdout.

JFTR, shellcheck detects it when used without a variable but a plain string already:

#!/bin/bash
foo() {
  return bar                                                                                                                                                                                                                                 
}
foo

This is reported as SC2152: Can only return 0-255. Other data should be written to stdout..

Thanks for shellcheck!