Fully separate positional arguments and keyword arguments

This removes the warnings added in 2.7, and changes the behavior
so that a final positional hash is not treated as keywords or
vice-versa.

To handle the arg_setup_block splat case correctly with keyword
arguments, we need to check if we are taking a keyword hash.
That case didn't have a test, but it affects real-world code,
so add a test for it.

This removes rb_empty_keyword_given_p() and related code, as
that is not needed in Ruby 3.  The empty keyword case is the
same as the no keyword case in Ruby 3.

This changes rb_scan_args to implement keyword argument
separation for C functions when the : character is used.
For backwards compatibility, it returns a duped hash.
This is a bad idea for performance, but not duping the hash
breaks at least Enumerator::ArithmeticSequence#inspect.

Instead of having RB_PASS_CALLED_KEYWORDS be a number,
simplify the code by just making it be rb_keyword_given_p().

1 files changed, 10 insertions, 0 deletions

diff --git a/test/ruby/test_proc.rb b/test/ruby/test_proc.rb
index 1f84b2eb84..fce1bd4a87 100644
--- a/test/ruby/test_proc.rb
+++ b/test/ruby/test_proc.rb
@@ -1087,6 +1087,16 @@ class TestProc < Test::Unit::TestCase
     assert_equal([1,2,[3],4,5], r, "[ruby-core:19485]")
   end
 
+  def test_proc_single_arg_with_keywords_accepted_and_yielded
+    def self.a
+      yield [], **{a: 1}
+    end
+    res = a do |arg, **opts|
+      [arg, opts]
+    end
+    assert_equal([[], {a: 1}], res)
+  end
+
   def test_parameters
     assert_equal([], proc {}.parameters)
     assert_equal([], proc {||}.parameters)