Style/YodaCondition: not necessarily safe to autocorrect

[jbodah]

I was reviewing a PR on one of our projects and was surprised to see Style/YodaCondition was marked as safe to autocorrect: https://github.com/rubocop-hq/rubocop/blob/master/manual/cops_style.md#styleyodacondition

It's a gotcha in Ruby that operators are not necessarily commutative. Take the following example:

class MyKlass
  def ==(other)
    true
  end
end

obj = MyKlass.new
obj == 'string'
#=> true
'string' == obj 
#=> false

This is a trivial examples but I have run into several real cases in the wild where this occurs in Rails apps

It seems like some literals are commutative in some cases (e.g. integers will delegate to MyKlass#== even if the integer is the receiver)

[koic]

Sure. I think it depends on the operand whether it can be replaced. So, I think autocorrection can be marked as unsafe.

[knu]

I agree. Reversing operands is an unsafe modification in Ruby and can easily break existing code that is written for a reason.