Delete Ractor#close_incoming

Author: soutaro

core/ractor.rbs

@@ -424,22 +424,6 @@ class Ractor
   %a{deprecated: Use Ractor.[]= instead}
   def []=: [T] (interned sym, T val) -> T
 
-  # <!--
-  #   rdoc-file=ractor.rb
-  #   - ractor.close_incoming -> true | false
-  # -->
-  # Closes the incoming port and returns whether it was already closed. All
-  # further attempts to Ractor.receive in the ractor, and #send to the ractor will
-  # fail with Ractor::ClosedError.
-  #
-  #     r = Ractor.new {sleep(500)}
-  #     r.close_incoming  #=> false
-  #     r.close_incoming  #=> true
-  #     r.send('test')
-  #     # Ractor::ClosedError (The incoming-port is already closed)
-  #
-  def close_incoming: () -> bool
-
   # <!--
   #   rdoc-file=ractor.rb
   #   - ractor.close_outgoing -> true | false

test/stdlib/Ractor_test.rb

@@ -93,14 +93,6 @@ class RactorInstanceTest < Test::Unit::TestCase
 
   testing "::Ractor"
 
-  def test_close_incoming
-    omit "Ractor#close_incoming is not implemented" if RUBY_VERSION >= "3.5"
-
-    r = Ractor.new {}
-    assert_send_type "() -> bool",
-                     r, :close_incoming
-  end
-
   def test_close_outgoing
     omit "Ractor#close_outgoing is not implemented" if RUBY_VERSION >= "3.5"