--- rspec-support-3.8.2/spec/rspec/support/spec/stderr_splitter_spec.rb	2022-02-16 21:22:44.095853100 +0800
+++ rspec-support-3.8.2_bak/spec/rspec/support/spec/stderr_splitter_spec.rb	2022-02-16 21:21:29.934595730 +0800
@@ -88,7 +88,7 @@
 
   unless defined?(RUBY_ENGINE) && RUBY_ENGINE == 'rbx'
     it 'will fail an example which generates a warning' do
-      true unless @undefined
+      true unless $undefined
       expect { splitter.verify_no_warnings! }.to raise_error(/Warnings were generated:/)
     end
   end