Cop idea: Referencing named capture with a number

[pocke]

Is your feature request related to a problem? Please describe.

Regexp's named capture can be referenced with a number, but referencing with a name is preferred.

# bad
'str'.match(/(?<X>s)/)[1]
# => "s"

# good
'str'.match(/(?<X>s)/)[:X]
# => "s"

# also good
'str'.match(/(?<X>s)/)['X']
# => "s"

Describe the solution you'd like

Add a cop to detect the problem.

Describe alternatives you've considered

Nothing

Additional context

We will be able to the cop with regexp_parser gem. ref: #7746

[choosen]

should we detect also following example? :

match_data = 'str'.match /(?<X>s)/
match_data[1]

[pocke]

I think the cop should detect the problem ideally, but I guess it is difficult with the current RuboCop implementation.Because RuboCop's analysis for local variable assigments is not enougth.
I think a simple implementation, which detects no-assignment cases only, is enough for the first step.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contribution and understanding!

[stale]

This issues been automatically closed due to lack of activity. Feel free to re-open it if you ever come back to it.