Add option for --force-exclusion to ruby-rubocop checker?

[mmcnl]

As discussed in rubocop/rubocop#893 (comment) when running rubocop from a linter such as flycheck, it is impossible to ignore a particular file or directory from the usual rubocop.yml config file. To address this, the rubocop project added the --force-exclusion command line option (rubocop/rubocop#922). Would it be possible to add --force-exclusion to flycheck's default invocation of rubocop, or to add a flycheck var to enable that option?
Thanks so much for your work on this great tool!

[fmdkdd]

Would it be possible to add --force-exclusion to flycheck's default invocation of rubocop, or to add a flycheck var to enable that option?

Looking at the discussion in rubocop/rubocop#893 (comment), I get that --force-exclusion will tell rubocop to ignore the files that are specified in your configuration. Is that it?

If you don't want to check a specific file, why run Flycheck on it then? Do you have a specific use case that requires this option?

[mmcnl]

Thanks for the reply, @fmdkdd . My use case (which I believe is common) is to be able to have the rubocop checker globally enabled in my Rails-based project without being swamped with error highlighting when I open the db/schema.rb file. (This file is continually auto-generated and thus it's impossible for me to fix the style offenses that get re-created there). This is the use case (for linters like sublime-linter or atom-linter) for which the rubocop team added the --force-exclusion option.

[cpitclaudel]

This is the use case (for linters like sublime-linter or atom-linter) for which the rubocop team added the --force-exclusion option.

Maybe I'm missing something, but this sounds odd. Why do we need that option to achieve this? Isn't it simpler to just ask Flycheck not to lint these files, using whichever predicate you'd use to turn that option on?

IOW, what does it gain us to run rubocop on some file a.rb with the --force-exclusion a.rb flag? Why is that better than just disabling Flycheck for a.rb?

Maybe it'd help if you can show how you'd set this hypothetical new variable :) Let's assume we add flycheck-rubocop-force-exclusion, taking a list of files. How would you use it?

[cpitclaudel]

Oh, wait, I think I understand now. --force-exclusion doesn't take a file name, right?
This makes a lot more sense now. @fmdkdd, the trick is that that option saves you from duplicating rubocop's exclusion logic in your Flycheck config. Instead you just feed everything to rubocop, and it returns early if you actually fed it an excluded file.
I'm in favor of adding support for that flag :) It should probably be on by default, but maybe we can start by adding the option, and then turn it on by default in a few months when more people have updated?

[mmcnl]

Yes, I think the flag is necessary because when the rubocop the executable is being fed an explicit list of filenames (as is often the case with linters) it by default overrides any exclusions specified in the rubocop.yml config file and always processes the file.

[fmdkdd]

@cpitclaudel I see that the flag is mostly harmless (because if the user is the one editing the rubocop config file, they won't be surprised that Flycheck isn't checking it).

The flag was added in 2014, so I think it should be fine to set as default, since it's a better default experience.

[Simplify]

Yeah, this should just be added after --display-cop-names. Should not be an configurable option IMHO.

[mmcnl]

Thanks all for the quick and thoughtful response to this!

[costa]

Hi, I'm banging my head against walls — for the first time in my quite substantial Spacemacs usage — so I will really appreciate help here.

I'm trying to disable Rubocop by default — and enable it only when its config file is present in a project.
I'm even ready to go as far as to disable flycheck for enh/ruby mode at all, but I can't seem to be able to accomplish even that.
Disabling flycheck mode manually for every Ruby file that I open — works — but this is going too far.

So I wonder if this actually worked, and if it works still, and if anyone on Spacemacs can confirm that.

These are my other issues on the subject:
syl20bnr/spacemacs#15139
rubocop/rubocop-emacs#37

Thanks a lot in advance.