According to Q339, arc lint patches don't work with RuboCop because the RuboCop driver doesn't implement it:
To implement, you need to call setOriginalText() and setReplacementText() on the message object with the appropriate patch.
This is a request to implement these methods in the RuboCop driver.
I know very little about RuboCop, but maybe someone who worked on D10738 could help out?
Does RuboCop actually have a mode where it emits errors and replacement text?
RuboCop needs to have some set of flags that work like this for us to offer patching from arc:
$ rubocop --suggest-replacement-text something.rb This text is bad: aaaa Replace it with this: bbbb
I don't see such a mode from looking at the Readme on GitHub:
https://github.com/bbatsov/rubocop
It appears to support autocorrect, but not a mode where it prints the autocorrections without applying them. We can't deduce the corrections from a pre-corrected and post-corrected file because two or more correction ranges may overlap.
Am I just missing this mode?
Assuming this mode does not exist, the clearest pathway forward is for you or someone else to:
If such a mode already exists, you can skip step 1.
I don't know RuboCop well enough to definitively answer the question about whether that mode exists, or to volunteer to maintain the driver. But I opened a parallel issue in the RuboCop repo, so hopefully we'll find out whether RuboCop has this mode soon enough.