Warn in verbose mode on defining a finalizer that captures the object

[Feature #15974]

Closes: https://github.com/ruby/ruby/pull/2264

1 files changed, 26 insertions, 0 deletions

diff --git a/spec/ruby/core/objectspace/define_finalizer_spec.rb b/spec/ruby/core/objectspace/define_finalizer_spec.rb
index b7e47473a0..3a9132ef93 100644
--- a/spec/ruby/core/objectspace/define_finalizer_spec.rb
+++ b/spec/ruby/core/objectspace/define_finalizer_spec.rb
@@ -65,4 +65,30 @@ describe "ObjectSpace.define_finalizer" do
 
     ruby_exe(code).lines.sort.should == ["finalized1\n", "finalized2\n"]
   end
+
+  it "warns in verbose mode if it is self-referencing" do
+    code = <<-RUBY
+      obj = "Test"
+      handler = Proc.new { puts "finalized" }
+      ObjectSpace.define_finalizer(obj, handler)
+      exit 0
+    RUBY
+
+    ruby_exe(code, :options => "-w", :args => "2>&1").should include("warning: object is reachable from finalizer - it may never be run")
+  end
+
+  it "warns in verbose mode if it is indirectly self-referencing" do
+    code = <<-RUBY
+      def scoped(indirect)
+        Proc.new { puts "finalized" }
+      end
+      obj = "Test"
+      indirect = [obj]
+      handler = scoped(indirect)
+      ObjectSpace.define_finalizer(obj, handler)
+      exit 0
+    RUBY
+
+    ruby_exe(code, :options => "-w", :args => "2>&1").should include("warning: object is reachable from finalizer - it may never be run")
+  end
 end