Only emit circular dependency warning for owned thread shields

[Bug #19415]

If multiple threads attemps to load the same file concurrently
it's not a circular dependency issue.

So we check that the existing ThreadShield is owner by the current
fiber before warning about circular dependencies.

2 files changed, 15 insertions, 0 deletions

diff --git a/spec/ruby/core/kernel/shared/require.rb b/spec/ruby/core/kernel/shared/require.rb
index 666ca15e11..ae814aa317 100644
--- a/spec/ruby/core/kernel/shared/require.rb
+++ b/spec/ruby/core/kernel/shared/require.rb
@@ -237,6 +237,17 @@ describe :kernel_require, shared: true do
       }.should complain(/circular require considered harmful/, verbose: true)
       ScratchPad.recorded.should == [:loaded]
     end
+
+    ruby_bug "#17340", ''...'3.3' do
+      it "loads a file concurrently" do
+        path = File.expand_path "concurrent_require_fixture.rb", CODE_LOADING_DIR
+        ScratchPad.record(@object)
+        -> {
+          @object.require(path)
+        }.should_not complain(/circular require considered harmful/, verbose: true)
+        ScratchPad.recorded.join
+      end
+    end
   end
 
   describe "(non-extensioned path)" do
diff --git a/spec/ruby/fixtures/code/concurrent_require_fixture.rb b/spec/ruby/fixtures/code/concurrent_require_fixture.rb
new file mode 100644
index 0000000000..ee85e7fb51
--- /dev/null
+++ b/spec/ruby/fixtures/code/concurrent_require_fixture.rb
@@ -0,0 +1,4 @@
+object = ScratchPad.recorded
+thread = Thread.new { object.require(__FILE__) }
+thread.wakeup unless thread.stop?
+ScratchPad.record(thread)