Check invalid operations for -k

[gdhameeja]

#6822 KeywordMapping returns a bool on lookup which when passed to eval
fail on certain operations such as index access and attribute access.
Check has been added to raise a UsageError if such operations are passed
to -k

[gdhameeja]

The change is very simple check to see if '.' or '[' exists in the keywordexpr, a UsageError is raised.
Please let me know if there is a better way to do this. Also kindly guide me on how I can write a test for this and if I need to add this information to the documentation that attribute access and indexing is not allowed in -k inputs.

[nicoddemus]

Thanks a lot @gdhameeja, we appreciate the PR!

I replied here #6822 (comment) because I think we should discuss the approach further. 👍

[gdhameeja]

@nicoddemus I checked out the comment #6822 (comment) and I understand why checking for '.' isn't such a great idea. I can reference a new PR for changing the expression so it passes eval.
As far as reporting is concerned, I did check for TypeError and raise the appropriate message. Can I just remove the checking for this PR and let the reporting be?

[bluetech]

I think this is a good measure to fix the problem at least while we're still using eval.

I agree with @nicoddemus in the issue that we might as well do a full except Exception to catch all cases.

[bluetech]

So this seems like a good thing to have for now, until/if the eval goes away.

[nicoddemus]

Anybody up for backporting this? 😁

[gdhameeja]

Anybody up for backporting this?

I'm up. Although I don't understand what you mean by backporting it and would need a little guidance.

[bluetech]

I'm up. Although I don't understand what you mean by backporting it and would need a little guidance.

Since this change just missed the 5.4.0 release, it is merged to master which means it will only be included in 5.5.0 which can be some time from now. "Backporting" means applying the same change to the 5.4.x release series, which means it will be included also in the next 5.4.x patch release (e.g. 5.4.2).

In practice, you want to:

• git fetch --all
• git checkout 5.4.x
• git checkout -B Fix-6822-backport
• git cherry-pick 599bf075dbf1c1afb1a59b521dca52155c157488
• Submit this Fix-6822-backport branch as a PR against the 5.4.x branch

We intend to automate this, but haven't yet...