I gave a shot to the implementation of this new feature and although all existing tests (and the new ones exercising this change) in test/mri/ruby/test_struct.rb are passing, I'm probably missing something here.

I decided to test if inheritance work as expected and I wrote the following test to verify but I found out some assertions are failing:

  def test_struct_new_with_keyword_init_and_inheritance
    klass = @Struct.new(:a, keyword_init: true)
    klass2 = Class.new(klass)
    assert_raise(ArgumentError) { klass2.new(1) } # broken, nothing is raised: => #<struct a=1>
    assert_nothing_raised { klass2.new(a: 5) }    # nothing is raised but is wrong as well: => #<struct a={:a=>5}>
    o = klass2.new(a: 5)                          # wrong => #<struct a={:a=>5}>
    assert_equal(5, o.a)                          # broken: o.a => {:a=>5}
  end

Where should I look to get this working?

BTW, do you see worthwhile to contribute that extra test to MRI or ruby/spec?

Thank you for the PR!

Regarding your test:

• Contribute it to ruby/spec, ideally. It will filter back to JRuby whenever we update. ruby/spec is structured better and should always be the first place you look to contribute tests.
• If you want to try to fix it, look at RubyStruct.createStructClass and newInstance and compare with CRuby's logic. It's possible they changed the class structure surrounding Struct and we missed it.
• You can also defer and file a separate bug for the failing assertions, so we can get the PR in. We'll collab on fixing it in-place then.

@headius Thanks for the pointer, I just saw what's the problem with the inheritance in this case. I'll update the PR soon.

@headius The issue I pointed out in my previous comment is now fixed. I'll try to submit my extra test to ruby/spec later.