Restore splitting of hashes into positional and keyword arguments, add warning

This restores compatibility with Ruby 2.6, splitting the last
positional hash into positional and keyword arguments if it
contains both symbol and non-symbol keys.  However, in this case
it will warn, as the behavior in Ruby 3 will be to not split the
hash and keep it as a positional argument.

This does not affect the handling of mixed symbol and non-symbol
keys in bare keywords.  Those are still treated as keywords now,
as they were before this patch.  This results in different
behavior than Ruby 2.6, which would split the bare keywords and
use the non-Symbol keys as a positional arguments.

1 files changed, 24 insertions, 0 deletions

diff --git a/test/ruby/test_keyword.rb b/test/ruby/test_keyword.rb
index d0d64520e4..791d60b70a 100644
--- a/test/ruby/test_keyword.rb
+++ b/test/ruby/test_keyword.rb
@@ -284,6 +284,30 @@ class TestKeywordArguments < Test::Unit::TestCase
     assert_equal(expect.values_at(0, -1), pr.call(expect), bug8463)
   end
 
+  def opt_plus_keyword(x=1, **h)
+    [x, h]
+  end
+
+  def splat_plus_keyword(*a, **h)
+    [a, h]
+  end
+
+  def test_keyword_split
+    assert_equal([1, {:a=>1}], opt_plus_keyword(:a=>1))
+    assert_equal([1, {"a"=>1}], opt_plus_keyword("a"=>1))
+    assert_equal([1, {"a"=>1, :a=>1}], opt_plus_keyword("a"=>1, :a=>1))
+    assert_equal([1, {:a=>1}], opt_plus_keyword({:a=>1}))
+    assert_equal([{"a"=>1}, {}], opt_plus_keyword({"a"=>1}))
+    assert_equal([{"a"=>1}, {:a=>1}], opt_plus_keyword({"a"=>1, :a=>1}))
+
+    assert_equal([[], {:a=>1}], splat_plus_keyword(:a=>1))
+    assert_equal([[], {"a"=>1}], splat_plus_keyword("a"=>1))
+    assert_equal([[], {"a"=>1, :a=>1}], splat_plus_keyword("a"=>1, :a=>1))
+    assert_equal([[], {:a=>1}], splat_plus_keyword({:a=>1}))
+    assert_equal([[{"a"=>1}], {}], splat_plus_keyword({"a"=>1}))
+    assert_equal([[{"a"=>1}], {:a=>1}], splat_plus_keyword({"a"=>1, :a=>1}))
+  end
+
   def test_bare_kwrest
     # valid syntax, but its semantics is undefined
     assert_valid_syntax("def bug7662(**) end")