Add new Style/RedundantArrayConstructor cop

[koic]

Follow up #11874 (comment).

Checks for the instantiation of array using redundant Array constructor. Autocorrect replaces to array literal which is the simplest and fastest.

# bad
Array.new([])
Array[]
Array([])
Array.new(['foo', 'foo', 'foo'])
Array['foo', 'foo', 'foo']
Array(['foo', 'foo', 'foo'])

# good
[]
['foo', 'foo', 'foo']
Array.new(3, 'foo')
Array.new(3) { 'foo' }

---

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.

[fatkodima]

I think a similar cop can be created for a string too?

# bad
String.new("string")

[bbatsov]

Btw, for arrays the constructor is redundant also when you're just enumerating some elements, as you can use a literal directly then. Not sure if it's worth covering this here or separately, though.

[koic]

Btw, for arrays the constructor is redundant also when you're just enumerating some elements, as you can use a literal directly then.

My understanding hasn't quite caught up 💦 Can you provide an example code?

[koic]

I think a similar cop can be created for a string too?

It seems like that case would be handled by Performance/UnfreezeString.
https://docs.rubocop.org/rubocop-performance/cops_performance.html#performanceunfreezestring

[bbatsov]

@koic I was thinking of:

arr = Array[1, 2, 3]

Not exactly a classic constructor, but I guess you get the idea.

[koic]

Ah I didn't realize that. I think Array([1, 2, 3]) can be handled similarly. I updated this PR to handle them.

[bbatsov]

Looks great now. Thanks!