From b342234a1ab4e72c1b5eaf92b09361a78a607509 Mon Sep 17 00:00:00 2001
From: ksss <co000ri@gmail.com>
Date: Mon, 28 Sep 2026 18:15:29 +0900
Subject: [PATCH] Always return `nil`

---
 core/thread.rbs            | 2 +-
 test/stdlib/Thread_test.rb | 4 ++++
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/core/thread.rbs b/core/thread.rbs
index 1410f47e4..59b2c6957 100644
--- a/core/thread.rbs
+++ b/core/thread.rbs
@@ -1015,7 +1015,7 @@ class Thread < Object
   # Give the thread scheduler a hint to pass execution to another thread. A
   # running thread may or may not switch, it depends on OS and processor.
   #
-  def self.pass: () -> untyped
+  def self.pass: () -> nil
 
   # <!--
   #   rdoc-file=thread.c
diff --git a/test/stdlib/Thread_test.rb b/test/stdlib/Thread_test.rb
index 3b702103f..cb1752ff8 100644
--- a/test/stdlib/Thread_test.rb
+++ b/test/stdlib/Thread_test.rb
@@ -65,6 +65,10 @@ def test_each_caller_location
   def test_list
     assert_send_type "() -> Array[Thread]", Thread, :list
   end
+
+  def test_pass
+    assert_send_type "() -> nil", Thread, :pass
+  end
 end
 
 class ThreadTest < Test::Unit::TestCase