Fix wrong offense in Style/SymbolProc

[tdeo]

While upgrading to rubocop 1.6.1, I noticed that the Style/SymbolProc was registering an offense on the following code:

array.map { _2.first }

And suggesting to autocorrect to array.map(&:first), which is incorrect in such case.

I believe this was introduced in #9127

I suggest changing the cop to only register offenses for the _1 numbered block argument.

---

Before submitting the PR make sure the following are checked:

• The PR relates to only one subject with a clear title and description in grammatically correct, complete sentences.
• Wrote good commit messages.
• Commit message starts with [Fix #issue-number] (if the related issue exists).
• Feature branch is up-to-date with master (if not - rebase it).
• Squashed related commits together.
• Added tests.
• Ran bundle exec rake default. It executes all tests and runs RuboCop on its own code.
• Added an entry (file) to the changelog folder named {change_type}_{change_description}.md if the new code introduces user-observable changes. See changelog entry format for details.

[dvandersluis]

Thanks for catching this!

https://github.com/rubocop-hq/rubocop/blob/701468b5dfea527d991fba5ebd7b181d6750a1a8/lib/rubocop/cop/style/symbol_proc.rb#L25-L30

You can fix this more simply by changing line 28 to ${(args (arg _)) 1} (ie. match only numblocks with 1 numeric arg). Then the rest of the code doesn't need to be changed.

[tdeo]

You can fix this more simply by changing line 28 to ${(args (arg _)) 1} (ie. match only numblocks with 1 numeric arg). Then the rest of the code doesn't need to be changed.

This is indeed a much better solution, thanks

[bbatsov]

You misplaced this changelog entry. Now they go under the changelog dir and this file is auto-generated on release.

[tdeo]

Indeed, read the checklist a bit too fast and assumed it still was the same, I amended the commit

[marcandre]

Great, thanks!