From 13660105e225df0a4fc1f91b8c9618261e5761f3 Mon Sep 17 00:00:00 2001
From: Samuel Williams <samuel.williams@oriontransfer.co.nz>
Date: Thu, 1 Oct 2020 13:42:58 +1300
Subject: [PATCH] Don't call `Scheduler#close` if it doesn't exist.

---
 scheduler.c                  | 4 +++-
 test/fiber/test_scheduler.rb | 8 ++++++++
 2 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/scheduler.c b/scheduler.c
index 8ec5039096..f0bb5ee597 100644
--- a/scheduler.c
+++ b/scheduler.c
@@ -39,7 +39,9 @@ Init_Scheduler(void)
 
 VALUE rb_scheduler_close(VALUE scheduler)
 {
-    return rb_funcall(scheduler, id_close, 0);
+    if (rb_respond_to(scheduler, id_close)) {
+        return rb_funcall(scheduler, id_close, 0);
+    }
 }
 
 VALUE
diff --git a/test/fiber/test_scheduler.rb b/test/fiber/test_scheduler.rb
index 23b59c06b0..d85aa7a6ce 100644
--- a/test/fiber/test_scheduler.rb
+++ b/test/fiber/test_scheduler.rb
@@ -49,4 +49,12 @@ class TestFiberScheduler < Test::Unit::TestCase
     end
     RUBY
   end
+
+  def test_optional_close
+    thread = Thread.new do
+      Thread.current.scheduler = Object.new
+    end
+    
+    thread.join
+  end
 end