variable.c: cleanup waitq upon thread death

* variable.c (autoload_reset): use idempotent list_del_init
  (autoload_sleep): moved code from rb_autoload_load
  (autoload_sleep_done): cleanup for use with rb_ensure
  (rb_autoload_load): ensure list delete happens in case the
  thread dies during sleep
* test/ruby/bug-13526.rb: new script for separate execution
* test/ruby/test_autoload.rb (test_bug_13526): new test
  [ruby-core:81016] [Bug #13526]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@58587 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

2 files changed, 25 insertions, 0 deletions

diff --git a/test/ruby/bug-13526.rb b/test/ruby/bug-13526.rb
new file mode 100644
index 0000000000..f42e1913ce
--- /dev/null
+++ b/test/ruby/bug-13526.rb
@@ -0,0 +1,20 @@
+# From https://bugs.ruby-lang.org/issues/13526#note-1
+
+sleep if $load
+$load = true
+
+n = 10
+threads = Array.new(n) do
+  Thread.new do
+    begin
+      autoload :Foo, "#{File.dirname($0)}/#{$0}"
+      Thread.pass
+      Foo
+    ensure
+      Thread.pass
+    end
+  end
+end
+
+Thread.pass while threads.all?(&:stop?)
+100.times { Thread.pass }
diff --git a/test/ruby/test_autoload.rb b/test/ruby/test_autoload.rb
index b2d8d660fe..961825e0d0 100644
--- a/test/ruby/test_autoload.rb
+++ b/test/ruby/test_autoload.rb
@@ -241,6 +241,11 @@ p Foo::Bar
     end
   end
 
+  def test_bug_13526
+    script = File.join(__dir__, 'bug-13526.rb')
+    assert_ruby_status([script], '', '[ruby-core:81016] [Bug #13526]')
+  end
+
   def add_autoload(path)
     (@autoload_paths ||= []) << path
     ::Object.class_eval {autoload(:AutoloadTest, path)}