Emit `warn` event for duplicated hash keys on ripper

Need to use `rb_warn` macro instead of calling `rb_compile_warn`
directly to emit `warn` event on ripper.

1 files changed, 6 insertions, 0 deletions

diff --git a/test/ripper/test_parser_events.rb b/test/ripper/test_parser_events.rb
index 0bad60b259..cbae6e7ed5 100644
--- a/test/ripper/test_parser_events.rb
+++ b/test/ripper/test_parser_events.rb
@@ -1686,6 +1686,12 @@ class TestRipper::ParserEvents < Test::Unit::TestCase
     assert_equal([3], args)
   end
 
+  def test_warn_duplicated_hash_keys
+    fmt, *args = warn("{ a: 1, a: 2 }")
+    assert_match(/is duplicated and overwritten on line/, fmt)
+    assert_equal([:a, 1], args)
+  end
+
   def test_warn_cr_in_middle
     fmt = nil
     assert_warn("") {fmt, = warn("\r;")}