negation of SC2055, [[ $1 = foo && $1 = bar ]], is not detected

[e-kwsm]

For bugs

• Rule Id (if any, e.g. SC1000): SC2055?
• My shellcheck version (shellcheck --version or 'online'): online
• I tried on shellcheck.net and verified that this is still a problem on the latest commit
• It's not reproducible on shellcheck.net, but I think that's because it's an OS, configuration or encoding issue

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
# ! [[ $1 != foo || $1 != bar ]]  # SC2055 is issued
if [[ $1 = foo && $1 = bar ]]
then
  echo "$1 is foo or bar"
fi

Here's what shellcheck currently says:

Nothing.

Here's what I wanted or expected to see:

Line 3:
if [[ $1 = foo && $1 = bar ]]
               ^-- SC2055 (warning): You probably wanted || here, otherwise it's always false.