From df69e4a12efaf6b21c08f57d9cc7512a6aed8674 Mon Sep 17 00:00:00 2001
From: Alexander Momchilov <alexandermomchilov@gmail.com>
Date: Mon, 18 Dec 2023 04:00:48 -0500
Subject: [PATCH 1/2] Use `compare_by_identity` instead of `object_id`

Object IDs became more expensive in Ruby 2.7. Using `Hash#compare_by_identity` let's us get the same effect, without needing to force all these objects to have object_ids assigned to them.
---
 lib/psych/visitors/yaml_tree.rb | 13 ++++++-------
 1 file changed, 6 insertions(+), 7 deletions(-)

diff --git a/lib/psych/visitors/yaml_tree.rb b/lib/psych/visitors/yaml_tree.rb
index 51491783..1dd4094c 100644
--- a/lib/psych/visitors/yaml_tree.rb
+++ b/lib/psych/visitors/yaml_tree.rb
@@ -15,30 +15,29 @@ module Visitors
     class YAMLTree < Psych::Visitors::Visitor
       class Registrar # :nodoc:
         def initialize
-          @obj_to_id   = {}
-          @obj_to_node = {}
+          @obj_to_id   = {}.compare_by_identity
+          @obj_to_node = {}.compare_by_identity
           @targets     = []
           @counter     = 0
         end
 
         def register target, node
-          return unless target.respond_to? :object_id
           @targets << target
-          @obj_to_node[target.object_id] = node
+          @obj_to_node[target] = node
         end
 
         def key? target
-          @obj_to_node.key? target.object_id
+          @obj_to_node.key? target
         rescue NoMethodError
           false
         end
 
         def id_for target
-          @obj_to_id[target.object_id] ||= (@counter += 1)
+          @obj_to_id[target] ||= (@counter += 1)
         end
 
         def node_for target
-          @obj_to_node[target.object_id]
+          @obj_to_node[target]
         end
       end
 

From 0dc25a9d6ae28a24bb8a8168f4ac2c27e413dc7c Mon Sep 17 00:00:00 2001
From: Alexander Momchilov <alexandermomchilov@gmail.com>
Date: Mon, 18 Dec 2023 04:01:01 -0500
Subject: [PATCH 2/2] Use `assert_same` in tests where applicable

---
 test/psych/test_object_references.rb | 8 ++++----
 test/psych/visitors/test_to_ruby.rb  | 2 +-
 2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/test/psych/test_object_references.rb b/test/psych/test_object_references.rb
index 269d7224..86bb9034 100644
--- a/test/psych/test_object_references.rb
+++ b/test/psych/test_object_references.rb
@@ -39,7 +39,7 @@ def assert_reference_trip obj
       rescue Psych::DisallowedClass
         data = Psych.unsafe_load yml
       end
-      assert_equal data.first.object_id, data.last.object_id
+      assert_same data.first, data.last
     end
 
     def test_float_references
@@ -49,7 +49,7 @@ def test_float_references
 - *name
       eoyml
       assert_equal data.first, data.last
-      assert_equal data.first.object_id, data.last.object_id
+      assert_same data.first, data.last
     end
 
     def test_binary_references
@@ -60,7 +60,7 @@ def test_binary_references
 - *name
       eoyml
       assert_equal data.first, data.last
-      assert_equal data.first.object_id, data.last.object_id
+      assert_same data.first, data.last
     end
 
     def test_regexp_references
@@ -70,7 +70,7 @@ def test_regexp_references
 - *name
       eoyml
       assert_equal data.first, data.last
-      assert_equal data.first.object_id, data.last.object_id
+      assert_same data.first, data.last
     end
   end
 end
diff --git a/test/psych/visitors/test_to_ruby.rb b/test/psych/visitors/test_to_ruby.rb
index 3d4608b9..89c36766 100644
--- a/test/psych/visitors/test_to_ruby.rb
+++ b/test/psych/visitors/test_to_ruby.rb
@@ -319,7 +319,7 @@ def test_alias
 
         list = seq.to_ruby
         assert_equal %w{ foo foo }, list
-        assert_equal list[0].object_id, list[1].object_id
+        assert_same list[0], list[1]
       end
 
       def test_mapping_with_str_tag