Lint against case where a variable name could be a flag

[KSXGitHub]

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

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

#!/bin/bash
set -o errexit -o pipefail -o nounset

printf '%s' 'Enter file name to delete... '
read -r filename
rm "$filename"

Here's what shellcheck currently says:

Nothing.

Here's what I wanted or expected to see:

Warns that $filename in the rm command could be a flag, and suggests inserting -- in between rm and $filename.