Add new Style/OptionalBooleanParameter cop

[fatkodima]

https://rubystyle.guide/#boolean-keyword-arguments

# bad
def some_method(bar = false)
  puts bar
end

# good
def some_method(bar: false)
  puts bar
end

[koic]

I think that this cop is unsafe, just like Style/OptionalArguments cop.

[marcandre]

I'm curious why Style/OptionalArguments is "unsafe", or this one?

For this one, my only concern is if there is a call to super, or super(that_argument), then maybe there should be no offense since this method is just copying the interface it inherits. Maybe there should not be an offense then; the base method will be flagged probably. What other cases are unsafe?

[koic]

I think it means a breaking change to users if the API signature is a published interface.
https://martinfowler.com/bliki/PublishedInterface.html

[fatkodima]

Made it unsafe.

[marcandre]

I love it when a new cop improves our codebase!

Here, I think all of these true/false were clear examples of arguments that can not be understood when called.

[bbatsov]

Seems we've made a mistake with the heading in the style guide - I think the cop should be named OptionalBooleanParameter.

[fatkodima]

Updated with new name.

[bbatsov]

Great cop!