Issue #11382 has been reported by Milovan Zogovic.

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Bug #11382: Keyword arguments nullified on inheritance
https://bugs.ruby-lang.org/issues/11382

* Author: Milovan Zogovic
* Status: Open
* Priority: Normal
* Assignee: 
* ruby -v: 2.2.2
* Backport: 
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Here is the example:

~~~
class Parent
  def initialize(a: nil, b: nil, **properties)
    puts("parent: { a: #{a.inspect}, b: #{b.inspect}, properties: #{properties}")
  end
end


class Child < Parent
  def initialize(args={})
    puts("child: #{args}")
    super
  end
end

require "yaml"
Child.new(a: "A", **YAML.load("---\n:b: B\n:x: X"))   # ok
Child.new(a: "A", **YAML.load("---\n:b: B\n:xx: XX")) # bug: ":a" gets nullified
~~~


The output is:

~~~
child: {:a=>"A", :b=>"B", :x=>"X"}
parent: { a: "A", b: "B", properties: {:x=>"X"}

child: {:a=>"A", :b=>"B", :xx=>"XX"}
parent: { a: "A", b: nil, properties: {:xx=>"XX"}
~~~

The only difference between first and second example is that the second one uses :xx as extra argument, while the first one uses :x. 
The bug will appear randomly based on the argument name.
Also, this only happens when  when the arguments are loaded from somewhere else (e.g. YAML.load).
If i put `{ b: "B", xx: "XX" }` just anywhere in the code, the bug won't happen, which is extra weird.

It works with ruby 2.1, and 2.0.





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