UnboundMethod only refer defined_class

UnboundMethod records caller's class, like `D` or `E` on the
following case:

```ruby
class C
  def foo = :foo
end

class D < C
end

class E < C
end

d = D.instance_method(:foo)
e = E.instance_method(:foo)
```

But `d` and `e` only refers `C#foo` so that UnboundMethod doesn't
record `D` or `E`. This behavior changes the following methods:

* `UnboundMethod#inspect` (doesn't show caller's class)
* `UnboundMethod#==` (`d == e` for example)

fix https://bugs.ruby-lang.org/issues/18798

2 files changed, 42 insertions, 13 deletions

diff --git a/spec/ruby/core/unboundmethod/equal_value_spec.rb b/spec/ruby/core/unboundmethod/equal_value_spec.rb
index b21677687e..036c6b7f8c 100644
--- a/spec/ruby/core/unboundmethod/equal_value_spec.rb
+++ b/spec/ruby/core/unboundmethod/equal_value_spec.rb
@@ -76,19 +76,38 @@ describe "UnboundMethod#==" do
     (@identical_body == @original_body).should == false
   end
 
-  it "returns false if same method but one extracted from a subclass" do
-    (@parent == @child1).should == false
-    (@child1 == @parent).should == false
-  end
+  ruby_version_is ""..."3.2" do
+    it "returns false if same method but one extracted from a subclass" do
+      (@parent == @child1).should == false
+      (@child1 == @parent).should == false
+    end
 
-  it "returns false if same method but extracted from two different subclasses" do
-    (@child2 == @child1).should == false
-    (@child1 == @child2).should == false
+    it "returns false if same method but extracted from two different subclasses" do
+      (@child2 == @child1).should == false
+      (@child1 == @child2).should == false
+    end
+
+    it "returns false if methods are the same but added from an included Module" do
+      (@includee == @includer).should == false
+      (@includer == @includee).should == false
+    end
   end
 
-  it "returns false if methods are the same but added from an included Module" do
-    (@includee == @includer).should == false
-    (@includer == @includee).should == false
+  ruby_version_is "3.2" do
+    it "returns true if same method but one extracted from a subclass" do
+      (@parent == @child1).should == true
+      (@child1 == @parent).should == true
+    end
+
+    it "returns false if same method but extracted from two different subclasses" do
+      (@child2 == @child1).should == true
+      (@child1 == @child2).should == true
+    end
+
+    it "returns true if methods are the same but added from an included Module" do
+      (@includee == @includer).should == true
+      (@includer == @includee).should == true
+    end
   end
 
   it "returns false if both have same Module, same name, identical body but not the same" do
diff --git a/spec/ruby/core/unboundmethod/shared/to_s.rb b/spec/ruby/core/unboundmethod/shared/to_s.rb
index 38503c3c60..b92bb0b207 100644
--- a/spec/ruby/core/unboundmethod/shared/to_s.rb
+++ b/spec/ruby/core/unboundmethod/shared/to_s.rb
@@ -20,12 +20,22 @@ describe :unboundmethod_to_s, shared: true do
   it "the String shows the method name, Module defined in and Module extracted from" do
     @from_module.send(@method).should =~ /\bfrom_mod\b/
     @from_module.send(@method).should =~ /\bUnboundMethodSpecs::Mod\b/
-    @from_method.send(@method).should =~ /\bUnboundMethodSpecs::Methods\b/
+
+    ruby_version_is ""..."3.2" do
+      @from_method.send(@method).should =~ /\bUnboundMethodSpecs::Methods\b/
+    end
   end
 
   it "returns a String including all details" do
-    @from_module.send(@method).should.start_with? "#<UnboundMethod: UnboundMethodSpecs::Methods(UnboundMethodSpecs::Mod)#from_mod"
-    @from_method.send(@method).should.start_with? "#<UnboundMethod: UnboundMethodSpecs::Methods(UnboundMethodSpecs::Mod)#from_mod"
+    ruby_version_is ""..."3.2" do
+      @from_module.send(@method).should.start_with? "#<UnboundMethod: UnboundMethodSpecs::Methods(UnboundMethodSpecs::Mod)#from_mod"
+      @from_method.send(@method).should.start_with? "#<UnboundMethod: UnboundMethodSpecs::Methods(UnboundMethodSpecs::Mod)#from_mod"
+    end
+
+    ruby_version_is "3.2" do
+      @from_module.send(@method).should.start_with? "#<UnboundMethod: UnboundMethodSpecs::Mod#from_mod"
+      @from_method.send(@method).should.start_with? "#<UnboundMethod: UnboundMethodSpecs::Mod#from_mod"
+    end
   end
 
   it "does not show the defining module if it is the same as the origin" do