merge revision(s) f6d5de8f33fe715d939e3e77b8ef73d88bcd6c9f: [Backport #17659]

	[ruby/io-wait] Declare as Ractor-safe

	Fixes https://bugs.ruby-lang.org/issues/17659

	https://github.com/ruby/io-wait/commit/ba338b4764
	---
	 ext/io/wait/wait.c          |  4 ++++
	 test/io/wait/test_ractor.rb | 22 ++++++++++++++++++++++
	 2 files changed, 26 insertions(+)
	 create mode 100644 test/io/wait/test_ractor.rb

1 files changed, 22 insertions, 0 deletions

diff --git a/test/io/wait/test_ractor.rb b/test/io/wait/test_ractor.rb
new file mode 100644
index 0000000000..3d286af77f
--- /dev/null
+++ b/test/io/wait/test_ractor.rb
@@ -0,0 +1,22 @@
+# frozen_string_literal: true
+require 'test/unit'
+require 'rbconfig'
+require 'io/wait'
+
+class TestIOWaitInRactor < Test::Unit::TestCase
+  def setup
+    omit unless defined? Ractor
+  end
+
+  def test_ractor
+    ext = "/io/wait.#{RbConfig::CONFIG['DLEXT']}"
+    path = $".find {|path| path.end_with?(ext)}
+    assert_in_out_err(%W[-r#{path}], <<-"end;", ["true"], [])
+      $VERBOSE = nil
+      r = Ractor.new do
+        $stdout.equal?($stdout.wait_writable)
+      end
+      puts r.take
+    end;
+  end
+end