SG2086: useless to double quote exit

[mcollica]

For bugs

• Rule Id (if any, e.g. SC1000): SC2086
• My shellcheck version (shellcheck --version or "online"): 0.7.1
• [V] The rule's wiki page does not already cover this (e.g. https://shellcheck.net/wiki/SC2086)
• [V] I tried on shellcheck.net and verified that this is still a problem on the latest commit

For new checks and feature suggestions

• [V] shellcheck.net (i.e. the latest commit) currently gives no useful warnings about this
• [V] 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
exit $1

Here's what shellcheck currently says:

In snippet.sh line 2:
exit $1
^-- SC2086: Double quote to prevent globbing and word splitting.

Did you mean:
exit "$1"

For more information:
https://www.shellcheck.net/wiki/SC2086 -- Double quote to prevent globbing ...

Here's what I wanted or expected to see:

Nothing, that's useless to double quote a single number

[koalaman]

ShellCheck is correct in this case. Since this value comes from whatever invokes the script, there is no guarantee that it's a single number.