Removing empty parenthesis from method call can change behaviour

[davidtaylorhq]

Input:

def string
  "string"
end

string = string()
string += "-appended"

puts string

When run, this prints "string-appended"

After formatting, stree removes the parenthesis:

  def string
    "string"
  end

- string = string()
+ string = string
  string += "-appended"
  
  puts string

The resultant script now throws an "undefined method" error

test.rb:6:in `<main>': undefined method `+' for nil:NilClass (NoMethodError)

string += "-appended"
       ^

(Admittedly this is very strange code, but it is simplified from a real-world case in Discourse)

[kddnewton]

Ahh yeah, I'll fix this.