diff --git a/core/binding/fixtures/irb.rb b/core/binding/fixtures/irb.rb
deleted file mode 100644
index 5f305f2d5d..0000000000
--- a/core/binding/fixtures/irb.rb
+++ /dev/null
@@ -1,3 +0,0 @@
-a = 10
-
-binding.irb
diff --git a/core/dir/chdir_spec.rb b/core/dir/chdir_spec.rb
index 69a8b40415..015386a902 100644
--- a/core/dir/chdir_spec.rb
+++ b/core/dir/chdir_spec.rb
@@ -95,10 +95,10 @@ def to_str;  DirSpecs.mock_dir; end
   end
 
   it "raises an Errno::ENOENT if the original directory no longer exists" do
-    dir1 = tmp('/testdir1')
-    dir2 = tmp('/testdir2')
-    File.should_not.exist?(dir1)
-    File.should_not.exist?(dir2)
+    dir1 = tmp('testdir1')
+    dir2 = tmp('testdir2')
+    Dir.should_not.exist?(dir1)
+    Dir.should_not.exist?(dir2)
     Dir.mkdir dir1
     Dir.mkdir dir2
     begin
@@ -108,8 +108,8 @@ def to_str;  DirSpecs.mock_dir; end
         end
       }.should raise_error(Errno::ENOENT)
     ensure
-      Dir.unlink dir1 if File.exist?(dir1)
-      Dir.unlink dir2 if File.exist?(dir2)
+      Dir.unlink dir1 if Dir.exist?(dir1)
+      Dir.unlink dir2 if Dir.exist?(dir2)
     end
   end
 
@@ -177,28 +177,29 @@ def to_str;  DirSpecs.mock_dir; end
       dir.close
     end
 
-    it "raises an Errno::ENOENT if the original directory no longer exists" do
-      dir_name1 = tmp('/testdir1')
-      dir_name2 = tmp('/testdir2')
-      File.should_not.exist?(dir_name1)
-      File.should_not.exist?(dir_name2)
-      Dir.mkdir dir_name1
-      Dir.mkdir dir_name2
+    platform_is_not :windows do
+      it "does not raise an Errno::ENOENT if the original directory no longer exists" do
+        dir_name1 = tmp('testdir1')
+        dir_name2 = tmp('testdir2')
+        Dir.should_not.exist?(dir_name1)
+        Dir.should_not.exist?(dir_name2)
+        Dir.mkdir dir_name1
+        Dir.mkdir dir_name2
 
-      dir1 = Dir.new(dir_name1)
+        dir2 = Dir.new(dir_name2)
 
-      begin
-        -> {
-          dir1.chdir do
-            Dir.chdir(dir_name2) { Dir.unlink dir_name1 }
+        begin
+          Dir.chdir(dir_name1) do
+            dir2.chdir { Dir.unlink dir_name1 }
           end
-        }.should raise_error(Errno::ENOENT)
+          Dir.pwd.should == @original
+        ensure
+          Dir.unlink dir_name1 if Dir.exist?(dir_name1)
+          Dir.unlink dir_name2 if Dir.exist?(dir_name2)
+        end
       ensure
-        Dir.unlink dir_name1 if File.exist?(dir_name1)
-        Dir.unlink dir_name2 if File.exist?(dir_name2)
+        dir2.close
       end
-    ensure
-      dir1.close
     end
 
     it "always returns to the original directory when given a block" do
diff --git a/core/dir/for_fd_spec.rb b/core/dir/for_fd_spec.rb
index eeda26754a..3afcc7e949 100644
--- a/core/dir/for_fd_spec.rb
+++ b/core/dir/for_fd_spec.rb
@@ -1,6 +1,7 @@
 require_relative '../../spec_helper'
 require_relative 'fixtures/common'
 
+quarantine! do # leads to "Errno::EBADF: Bad file descriptor - closedir" in DirSpecs.delete_mock_dirs
 ruby_version_is '3.3' do
   guard -> { Dir.respond_to? :for_fd } do
     describe "Dir.for_fd" do
@@ -42,8 +43,8 @@
 
       it "calls #to_int to convert a value to an Integer" do
         dir = Dir.new(DirSpecs.mock_dir)
-        obj = Object.new
-        obj.singleton_class.define_method(:to_int) { dir.fileno }
+        obj = mock("fd")
+        obj.should_receive(:to_int).and_return(dir.fileno)
 
         dir_new = Dir.for_fd(obj)
         dir_new.fileno.should == dir.fileno
@@ -75,3 +76,4 @@
     end
   end
 end
+end
diff --git a/core/exception/fixtures/common.rb b/core/exception/fixtures/common.rb
index 1e243098bd..3d8a3c3430 100644
--- a/core/exception/fixtures/common.rb
+++ b/core/exception/fixtures/common.rb
@@ -84,6 +84,9 @@ class NoMethodErrorD; end
 
   class InstanceException < Exception
   end
+
+  class AClass; end
+  module AModule; end
 end
 
 class NameErrorSpecs
diff --git a/core/exception/no_method_error_spec.rb b/core/exception/no_method_error_spec.rb
index 26df3338e9..772c569f67 100644
--- a/core/exception/no_method_error_spec.rb
+++ b/core/exception/no_method_error_spec.rb
@@ -67,7 +67,7 @@
   end
 
   ruby_version_is ""..."3.3" do
-    it "calls receiver.inspect only when calling Exception#message" do
+    it "calls #inspect when calling Exception#message" do
       ScratchPad.record []
       test_class = Class.new do
         def inspect
@@ -76,19 +76,163 @@ def inspect
         end
       end
       instance = test_class.new
+
       begin
         instance.bar
-      rescue Exception => e
-        e.name.should == :bar
-        ScratchPad.recorded.should == []
-        e.message.should =~ /undefined method.+\bbar\b/
+      rescue NoMethodError => error
+        error.message.should =~ /\Aundefined method [`']bar' for <inspect>:#<Class:0x\h+>$/
         ScratchPad.recorded.should == [:inspect_called]
       end
     end
+
+    it "fallbacks to a simpler representation of the receiver when receiver.inspect raises an exception" do
+      test_class = Class.new do
+        def inspect
+          raise NoMethodErrorSpecs::InstanceException
+        end
+      end
+      instance = test_class.new
+
+      begin
+        instance.bar
+      rescue NoMethodError => error
+        message = error.message
+        message.should =~ /undefined method.+\bbar\b/
+        message.should include test_class.inspect
+      end
+    end
+
+    it "uses #name to display the receiver if it is a class" do
+      klass = Class.new { def self.name; "MyClass"; end }
+
+      begin
+        klass.foo
+      rescue NoMethodError => error
+        error.message.should =~ /\Aundefined method [`']foo' for MyClass:Class$/
+      end
+    end
+
+    it "uses #name to display the receiver if it is a module" do
+      mod = Module.new { def self.name; "MyModule"; end }
+
+      begin
+        mod.foo
+      rescue NoMethodError => error
+        error.message.should =~ /\Aundefined method [`']foo' for MyModule:Module$/
+      end
+    end
   end
 
   ruby_version_is "3.3" do
-    it "does not call receiver.inspect even when calling Exception#message" do
+    it "uses a literal name when receiver is nil" do
+      begin
+        nil.foo
+      rescue NoMethodError => error
+        error.message.should =~ /\Aundefined method [`']foo' for nil\Z/
+      end
+    end
+
+    it "uses a literal name when receiver is true" do
+      begin
+        true.foo
+      rescue NoMethodError => error
+        error.message.should =~ /\Aundefined method [`']foo' for true\Z/
+      end
+    end
+
+    it "uses a literal name when receiver is false" do
+      begin
+        false.foo
+      rescue NoMethodError => error
+        error.message.should =~ /\Aundefined method [`']foo' for false\Z/
+      end
+    end
+
+    it "uses #name when receiver is a class" do
+      klass = Class.new { def self.name; "MyClass"; end }
+
+      begin
+        klass.foo
+      rescue NoMethodError => error
+        error.message.should =~ /\Aundefined method [`']foo' for class MyClass\Z/
+      end
+    end
+
+    it "uses class' string representation when receiver is an anonymous class" do
+      klass = Class.new
+
+      begin
+        klass.foo
+      rescue NoMethodError => error
+        error.message.should =~ /\Aundefined method [`']foo' for class #<Class:0x\h+>\Z/
+      end
+    end
+
+    it "uses class' string representation when receiver is a singleton class" do
+      obj = Object.new
+      singleton_class = obj.singleton_class
+
+      begin
+        singleton_class.foo
+      rescue NoMethodError => error
+        error.message.should =~ /\Aundefined method [`']foo' for class #<Class:#<Object:0x\h+>>\Z/
+      end
+    end
+
+    it "uses #name when receiver is a module" do
+      mod = Module.new { def self.name; "MyModule"; end }
+
+      begin
+        mod.foo
+      rescue NoMethodError => error
+        error.message.should =~ /\Aundefined method [`']foo' for module MyModule\Z/
+      end
+    end
+
+    it "uses module's string representation when receiver is an anonymous module" do
+      m = Module.new
+
+      begin
+        m.foo
+      rescue NoMethodError => error
+        error.message.should =~ /\Aundefined method [`']foo' for module #<Module:0x\h+>\Z/
+      end
+    end
+
+    it "uses class #name when receiver is an ordinary object" do
+      klass = Class.new { def self.name; "MyClass"; end }
+      instance = klass.new
+
+      begin
+        instance.bar
+      rescue NoMethodError => error
+        error.message.should =~ /\Aundefined method [`']bar' for an instance of MyClass\Z/
+      end
+    end
+
+    it "uses class string representation when receiver is an instance of anonymous class" do
+      klass = Class.new
+      instance = klass.new
+
+      begin
+        instance.bar
+      rescue NoMethodError => error
+        error.message.should =~ /\Aundefined method [`']bar' for an instance of #<Class:0x\h+>\Z/
+      end
+    end
+
+    it "uses class name when receiver has a singleton class" do
+      instance = NoMethodErrorSpecs::NoMethodErrorA.new
+      def instance.foo; end
+
+      begin
+        instance.bar
+      rescue NoMethodError => error
+        error.message.should =~ /\Aundefined method [`']bar' for #<NoMethodErrorSpecs::NoMethodErrorA:0x\h+>\Z/
+      end
+    end
+
+    it "does not call #inspect when calling Exception#message" do
       ScratchPad.record []
       test_class = Class.new do
         def inspect
@@ -97,47 +241,29 @@ def inspect
         end
       end
       instance = test_class.new
+
       begin
         instance.bar
-      rescue Exception => e
-        e.name.should == :bar
-        ScratchPad.recorded.should == []
-        e.message.should =~ /undefined method.+\bbar\b/
+      rescue NoMethodError => error
+        error.message.should =~ /\Aundefined method [`']bar' for an instance of #<Class:0x\h+>\Z/
         ScratchPad.recorded.should == []
       end
     end
-  end
 
-  it "fallbacks to a simpler representation of the receiver when receiver.inspect raises an exception" do
-    test_class = Class.new do
-      def inspect
-        raise NoMethodErrorSpecs::InstanceException
-      end
-    end
-    instance = test_class.new
-    begin
-      instance.bar
-    rescue Exception => e
-      e.name.should == :bar
-      message = e.message
-      message.should =~ /undefined method.+\bbar\b/
-      message.should include test_class.inspect
-    end
-  end
+    it "does not truncate long class names" do
+      class_name = 'ExceptionSpecs::A' + 'a'*100
 
-  it "uses #name to display the receiver if it is a class or a module" do
-    klass = Class.new { def self.name; "MyClass"; end }
-    begin
-      klass.foo
-    rescue NoMethodError => error
-      error.message.lines.first.chomp.should =~ /^undefined method [`']foo' for /
-    end
+      begin
+        eval <<~RUBY
+          class #{class_name}
+          end
 
-    mod = Module.new { def self.name; "MyModule"; end }
-    begin
-      mod.foo
-    rescue NoMethodError => error
-      error.message.lines.first.chomp.should =~ /^undefined method [`']foo' for /
+          obj = #{class_name}.new
+          obj.foo
+        RUBY
+      rescue NoMethodError => error
+        error.message.should =~ /\Aundefined method [`']foo' for an instance of #{class_name}\Z/
+      end
     end
   end
 end
diff --git a/core/integer/divide_spec.rb b/core/integer/divide_spec.rb
index a878c4668c..665f4d57be 100644
--- a/core/integer/divide_spec.rb
+++ b/core/integer/divide_spec.rb
@@ -12,6 +12,17 @@
 
     it "supports dividing negative numbers" do
       (-1 / 10).should == -1
+      (-1 / 10**10).should == -1
+      (-1 / 10**20).should == -1
+    end
+
+    it "preservers sign correctly" do
+      (4 / 3).should == 1
+      (4 / -3).should == -2
+      (-4 / 3).should == -2
+      (-4 / -3).should == 1
+      (0 / -3).should == 0
+      (0 / 3).should == 0
     end
 
     it "returns result the same class as the argument" do
@@ -58,6 +69,15 @@
       ((10**50) / -(10**40 + 1)).should == -10000000000
     end
 
+    it "preservers sign correctly" do
+      (4 / bignum_value).should == 0
+      (4 / -bignum_value).should == -1
+      (-4 / bignum_value).should == -1
+      (-4 / -bignum_value).should == 0
+      (0 / bignum_value).should == 0
+      (0 / -bignum_value).should == 0
+    end
+
     it "returns self divided by Float" do
       not_supported_on :opal do
         (bignum_value(88) / 4294967295.0).should be_close(4294967297.0, TOLERANCE)
diff --git a/core/kernel/Float_spec.rb b/core/kernel/Float_spec.rb
index 0f83cb5824..6cedfe0617 100644
--- a/core/kernel/Float_spec.rb
+++ b/core/kernel/Float_spec.rb
@@ -157,6 +157,24 @@ def to_f() 1.2 end
     @object.send(:Float, "1\t\n").should == 1.0
   end
 
+  ruby_version_is ""..."3.4" do
+    it "raises ArgumentError if a fractional part is missing" do
+      -> { @object.send(:Float, "1.") }.should raise_error(ArgumentError)
+      -> { @object.send(:Float, "+1.") }.should raise_error(ArgumentError)
+      -> { @object.send(:Float, "-1.") }.should raise_error(ArgumentError)
+      -> { @object.send(:Float, "1.e+0") }.should raise_error(ArgumentError)
+    end
+  end
+
+  ruby_version_is "3.4" do
+    it "allows String representation without a fractional part" do
+      @object.send(:Float, "1.").should == 1.0
+      @object.send(:Float, "+1.").should == 1.0
+      @object.send(:Float, "-1.").should == -1.0
+      @object.send(:Float, "1.e+0").should == 1.0
+    end
+  end
+
   %w(e E).each do |e|
     it "raises an ArgumentError if #{e} is the trailing character" do
       -> { @object.send(:Float, "2#{e}") }.should raise_error(ArgumentError)
@@ -280,7 +298,7 @@ def to_f() 1.2 end
     nan2.should equal(nan)
   end
 
-  it "returns the identical Infinity if to_f is called and it returns Infinity" do
+  it "returns the identical Infinity if #to_f is called and it returns Infinity" do
     infinity = infinity_value
     (infinity_to_f = mock('Infinity')).should_receive(:to_f).once.and_return(infinity)
     infinity2 = @object.send(:Float, infinity_to_f)
diff --git a/core/marshal/dump_spec.rb b/core/marshal/dump_spec.rb
index 05e473c64e..716ba0e946 100644
--- a/core/marshal/dump_spec.rb
+++ b/core/marshal/dump_spec.rb
@@ -47,6 +47,11 @@
         Marshal.dump(-2**31 - 1).should == "\x04\bl-\a\x01\x00\x00\x80"
       end
     end
+
+    it "does not use object links for objects repeatedly dumped" do
+      Marshal.dump([0, 0]).should == "\x04\b[\ai\x00i\x00"
+      Marshal.dump([2**16, 2**16]).should == "\x04\b[\ai\x03\x00\x00\x01i\x03\x00\x00\x01"
+    end
   end
 
   describe "with a Symbol" do
@@ -93,6 +98,11 @@
       value = [*value, value[0]]
       Marshal.dump(value).should == "\x04\b[\b#{symbol1}#{symbol2};\x00"
     end
+
+    it "uses symbol links for objects repeatedly dumped" do
+      symbol = :foo
+      Marshal.dump([symbol, symbol]).should == "\x04\b[\a:\bfoo;\x00" # ;\x00 is a link to the symbol object
+    end
   end
 
   describe "with an object responding to #marshal_dump" do
@@ -108,6 +118,20 @@
     it "raises TypeError if an Object is an instance of an anonymous class" do
       -> { Marshal.dump(Class.new(UserMarshal).new) }.should raise_error(TypeError, /can't dump anonymous class/)
     end
+
+    it "uses object links for objects repeatedly dumped" do
+      obj = UserMarshal.new
+      Marshal.dump([obj, obj]).should == "\x04\b[\aU:\x10UserMarshal:\tdata@\x06" # @\x06 is a link to the object
+    end
+
+    it "adds instance variables of a dumped object after the object itself into the objects table" do
+      value = "<foo>"
+      obj = MarshalSpec::UserMarshalDumpWithIvar.new("string", value)
+
+      # expect a link to the object (@\x06, that means Integer 1) is smaller than a link
+      # to the instance variable value (@\t, that means Integer 4)
+      Marshal.dump([obj, obj, value]).should == "\x04\b[\bU:)MarshalSpec::UserMarshalDumpWithIvarI[\x06\"\vstring\x06:\t@foo\"\n<foo>@\x06@\t"
+    end
   end
 
   describe "with an object responding to #_dump" do
@@ -166,6 +190,20 @@ def _dump(level)
       Marshal.dump([a, a]).should == "\x04\b[\aIu:\x17MarshalSpec::M1::A\v<dump>\x06:\t@foo\"\bbar#{reference}"
     end
 
+    it "uses object links for objects repeatedly dumped" do
+      obj = UserDefined.new
+      Marshal.dump([obj, obj]).should == "\x04\b[\au:\x10UserDefined\x12\x04\b[\a:\nstuff;\x00@\x06" # @\x06 is a link to the object
+    end
+
+    it "adds instance variables of a dumped String before the object itself into the objects table" do
+      value = "<foo>"
+      obj = MarshalSpec::UserDefinedDumpWithIVars.new(+"string", value)
+
+      # expect a link to the object (@\a, that means Integer 2) is greater than a link
+      # to the instance variable value (@\x06, that means Integer 1)
+      Marshal.dump([obj, obj, value]).should == "\x04\b[\bIu:*MarshalSpec::UserDefinedDumpWithIVars\vstring\x06:\t@foo\"\n<foo>@\a@\x06"
+    end
+
     describe "Core library classes with #_dump returning a String with instance variables" do
       it "indexes instance variables and then a Time object itself" do
         t = Time.utc(2022)
@@ -198,6 +236,10 @@ def _dump(level)
       Marshal.dump(source_object).should == "\x04\bc,MarshalSpec::Multibyte\xE3\x81\x81\xE3\x81\x82\xE3\x81\x83\xE3\x81\x84Class"
     end
 
+    it "uses object links for objects repeatedly dumped" do
+      Marshal.dump([String, String]).should == "\x04\b[\ac\vString@\x06" # @\x06 is a link to the object
+    end
+
     it "raises TypeError with an anonymous Class" do
       -> { Marshal.dump(Class.new) }.should raise_error(TypeError, /can't dump anonymous class/)
     end
@@ -221,6 +263,10 @@ def _dump(level)
       Marshal.dump(source_object).should == "\x04\bm-MarshalSpec::Multibyte\xE3\x81\x91\xE3\x81\x92\xE3\x81\x93\xE3\x81\x94Module"
     end
 
+    it "uses object links for objects repeatedly dumped" do
+      Marshal.dump([Marshal, Marshal]).should == "\x04\b[\am\fMarshal@\x06" # @\x06 is a link to the object
+    end
+
     it "raises TypeError with an anonymous Module" do
       -> { Marshal.dump(Module.new) }.should raise_error(TypeError, /can't dump anonymous module/)
     end
@@ -239,6 +285,10 @@ def _dump(level)
         [Marshal,  nan_value,      "\004\bf\bnan"],
       ].should be_computed_by(:dump)
     end
+
+    it "uses object links for objects repeatedly dumped" do
+      Marshal.dump([0.0, 0.0]).should == "\x04\b[\af\x060@\x06" # @\x06 is a link to the float value
+    end
   end
 
   describe "with a Bignum" do
@@ -256,6 +306,11 @@ def _dump(level)
       ].should be_computed_by(:dump)
     end
 
+    it "uses object links for objects repeatedly dumped" do
+      n = 2**64
+      Marshal.dump([n, n]).should == "\x04\b[\al+\n\x00\x00\x00\x00\x00\x00\x00\x00\x01\x00@\x06" # @\x06 is a link to the object
+    end
+
     it "increases the object links counter" do
       obj = Object.new
       object_1_link = "\x06" # representing of (0-based) index=1 (by adding 5 for small Integers)
@@ -275,12 +330,22 @@ def _dump(level)
     it "dumps a Rational" do
       Marshal.dump(Rational(2, 3)).should == "\x04\bU:\rRational[\ai\ai\b"
     end
+
+    it "uses object links for objects repeatedly dumped" do
+      r = Rational(2, 3)
+      Marshal.dump([r, r]).should == "\x04\b[\aU:\rRational[\ai\ai\b@\x06" # @\x06 is a link to the object
+    end
   end
 
   describe "with a Complex" do
     it "dumps a Complex" do
       Marshal.dump(Complex(2, 3)).should == "\x04\bU:\fComplex[\ai\ai\b"
     end
+
+    it "uses object links for objects repeatedly dumped" do
+      c = Complex(2, 3)
+      Marshal.dump([c, c]).should == "\x04\b[\aU:\fComplex[\ai\ai\b@\x06" # @\x06 is a link to the object
+    end
   end
 
   ruby_version_is "3.2" do
@@ -299,6 +364,11 @@ def _dump(level)
         Marshal.dump(obj).should == "\x04\bS:5MarshalSpec::DataSpec::MeasureWithOverriddenName\a:\vamountii:\tunit\"\akm"
       end
 
+      it "uses object links for objects repeatedly dumped" do
+        d = MarshalSpec::DataSpec::Measure.new(100, 'km')
+        Marshal.dump([d, d]).should == "\x04\b[\aS:#MarshalSpec::DataSpec::Measure\a:\vamountii:\tunit\"\akm@\x06" # @\x06 is a link to the object
+      end
+
       it "raises TypeError with an anonymous Struct" do
         -> { Marshal.dump(Data.define(:a).new(1)) }.should raise_error(TypeError, /can't dump anonymous class/)
       end
@@ -360,6 +430,21 @@ def _dump(level)
     it "dumps multiple strings using symlinks for the :E (encoding) symbol" do
       Marshal.dump(["".encode("us-ascii"), "".encode("utf-8")]).should == "\x04\b[\aI\"\x00\x06:\x06EFI\"\x00\x06;\x00T"
     end
+
+    it "uses object links for objects repeatedly dumped" do
+      s = "string"
+      Marshal.dump([s, s]).should == "\x04\b[\a\"\vstring@\x06" # @\x06 is a link to the object
+    end
+
+    it "adds instance variables after the object itself into the objects table" do
+      obj = +"string"
+      value = "<foo>"
+      obj.instance_variable_set :@foo, value
+
+      # expect a link to the object (@\x06, that means Integer 1) is smaller than a link
+      # to the instance variable value (@\a, that means Integer 2)
+      Marshal.dump([obj, obj, value]).should == "\x04\b[\bI\"\vstring\x06:\t@foo\"\n<foo>@\x06@\a"
+    end
   end
 
   describe "with a Regexp" do
@@ -427,6 +512,11 @@ def _dump(level)
       obj = MarshalSpec::RegexpWithOverriddenName.new("")
       Marshal.dump(obj).should == "\x04\bIC:*MarshalSpec::RegexpWithOverriddenName/\x00\x00\x06:\x06EF"
     end
+
+    it "uses object links for objects repeatedly dumped" do
+      r = /\A.\Z/
+      Marshal.dump([r, r]).should == "\x04\b[\aI/\n\\A.\\Z\x00\x06:\x06EF@\x06" # @\x06 is a link to the object
+    end
   end
 
   describe "with an Array" do
@@ -462,6 +552,21 @@ def _dump(level)
       obj = MarshalSpec::ArrayWithOverriddenName.new
       Marshal.dump(obj).should == "\x04\bC:)MarshalSpec::ArrayWithOverriddenName[\x00"
     end
+
+    it "uses object links for objects repeatedly dumped" do
+      a = [1]
+      Marshal.dump([a, a]).should == "\x04\b[\a[\x06i\x06@\x06" # @\x06 is a link to the object
+    end
+
+    it "adds instance variables after the object itself into the objects table" do
+      obj = []
+      value = "<foo>"
+      obj.instance_variable_set :@foo, value
+
+      # expect a link to the object (@\x06, that means Integer 1) is smaller than a link
+      # to the instance variable value (@\a, that means Integer 2)
+      Marshal.dump([obj, obj, value]).should == "\x04\b[\bI[\x00\x06:\t@foo\"\n<foo>@\x06@\a"
+    end
   end
 
   describe "with a Hash" do
@@ -519,6 +624,21 @@ def _dump(level)
       obj = MarshalSpec::HashWithOverriddenName.new
       Marshal.dump(obj).should == "\x04\bC:(MarshalSpec::HashWithOverriddenName{\x00"
     end
+
+    it "uses object links for objects repeatedly dumped" do
+      h = {a: 1}
+      Marshal.dump([h, h]).should == "\x04\b[\a{\x06:\x06ai\x06@\x06" # @\x06 is a link to the object
+    end
+
+    it "adds instance variables after the object itself into the objects table" do
+      obj = {}
+      value = "<foo>"
+      obj.instance_variable_set :@foo, value
+
+      # expect a link to the object (@\x06, that means Integer 1) is smaller than a link
+      # to the instance variable value (@\a, that means Integer 2)
+      Marshal.dump([obj, obj, value]).should == "\x04\b[\bI{\x00\x06:\t@foo\"\n<foo>@\x06@\a"
+    end
   end
 
   describe "with a Struct" do
@@ -553,9 +673,24 @@ def _dump(level)
       Marshal.dump(obj).should == "\x04\bS:*MarshalSpec::StructWithOverriddenName\x06:\x06a\"\vmember"
     end
 
+    it "uses object links for objects repeatedly dumped" do
+      s = Struct::Pyramid.new
+      Marshal.dump([s, s]).should == "\x04\b[\aS:\x14Struct::Pyramid\x00@\x06" # @\x06 is a link to the object
+    end
+
     it "raises TypeError with an anonymous Struct" do
       -> { Marshal.dump(Struct.new(:a).new(1)) }.should raise_error(TypeError, /can't dump anonymous class/)
     end
+
+    it "adds instance variables after the object itself into the objects table" do
+      obj = Struct::Pyramid.new
+      value = "<foo>"
+      obj.instance_variable_set :@foo, value
+
+      # expect a link to the object (@\x06, that means Integer 1) is smaller than a link
+      # to the instance variable value (@\a, that means Integer 2)
+      Marshal.dump([obj, obj, value]).should == "\x04\b[\bIS:\x14Struct::Pyramid\x00\x06:\t@foo\"\n<foo>@\x06@\a"
+    end
   end
 
   describe "with an Object" do
@@ -645,21 +780,45 @@ def finalizer.noop(_)
       ObjectSpace.define_finalizer(obj, finalizer.method(:noop))
       Marshal.load(Marshal.dump(obj)).class.should == Object
     end
+
+    it "uses object links for objects repeatedly dumped" do
+      obj = Object.new
+      Marshal.dump([obj, obj]).should == "\x04\b[\ao:\vObject\x00@\x06" # @\x06 is a link to the object
+    end
+
+    it "adds instance variables after the object itself into the objects table" do
+      obj = Object.new
+      value = "<foo>"
+      obj.instance_variable_set :@foo, value
+
+      # expect a link to the object (@\x06, that means Integer 1) is smaller than a link
+      # to the instance variable value (@\a, that means Integer 2)
+      Marshal.dump([obj, obj, value]).should == "\x04\b[\bo:\vObject\x06:\t@foo\"\n<foo>@\x06@\a"
+    end
   end
 
   describe "with a Range" do
-    it "dumps a Range inclusive of end (with indeterminant order)" do
+    it "dumps a Range inclusive of end" do
       dump = Marshal.dump(1..2)
+      dump.should == "\x04\bo:\nRange\b:\texclF:\nbegini\x06:\bendi\a"
+
       load = Marshal.load(dump)
       load.should == (1..2)
     end
 
-    it "dumps a Range exclusive of end (with indeterminant order)" do
+    it "dumps a Range exclusive of end" do
       dump = Marshal.dump(1...2)
+      dump.should == "\x04\bo:\nRange\b:\texclT:\nbegini\x06:\bendi\a"
+
       load = Marshal.load(dump)
       load.should == (1...2)
     end
 
+    it "uses object links for objects repeatedly dumped" do
+      r = 1..2
+      Marshal.dump([r, r]).should == "\x04\b[\ao:\nRange\b:\texclF:\nbegini\x06:\bendi\a@\x06" # @\x06 is a link to the object
+    end
+
     it "raises TypeError with an anonymous Range subclass" do
       -> { Marshal.dump(Class.new(Range).new(1, 2)) }.should raise_error(TypeError, /can't dump anonymous class/)
     end
@@ -711,6 +870,26 @@ def finalizer.noop(_)
       Marshal.dump(source_object).should == "\x04\bc+MarshalSpec::Multibyte\xE3\x81\x81\xE3\x81\x82\xE3\x81\x83\xE3\x81\x84Time"
     end
 
+    it "uses object links for objects repeatedly dumped" do
+      # order of the offset and zone instance variables is a subject to change
+      # and may be different on different CRuby versions
+      base = Regexp.quote("\x04\b[\aIu:\tTime\r\xF5\xEF\e\x80\x00\x00\x00\x00\a")
+      offset = Regexp.quote(":\voffseti\x020*:\tzoneI\"\bAST\x06:\x06EF")
+      zone = Regexp.quote(":\tzoneI\"\bAST\x06:\x06EF:\voffseti\x020*")
+      instance_variables = /#{offset}|#{zone}/
+      Marshal.dump([@t, @t]).should =~ /\A#{base}#{instance_variables}@\a\Z/ # @\a is a link to the object
+    end
+
+    it "adds instance variables before the object itself into the objects table" do
+      obj = @utc
+      value = "<foo>"
+      obj.instance_variable_set :@foo, value
+
+      # expect a link to the object (@\b, that means Integer 3) is greater than a link
+      # to the instance variable value (@\x06, that means Integer 1)
+      Marshal.dump([obj, obj, value]).should == "\x04\b[\bIu:\tTime\r \x00\x1C\xC0\x00\x00\x00\x00\a:\t@foo\"\n<foo>:\tzoneI\"\bUTC\x06:\x06EF@\b@\x06"
+    end
+
     it "raises TypeError with an anonymous Time subclass" do
       -> { Marshal.dump(Class.new(Time).now) }.should raise_error(TypeError)
     end
@@ -765,6 +944,21 @@ def finalizer.noop(_)
       Marshal.dump(e).should =~ /undefined method [`']foo' for ("":String|an instance of String)/
     end
 
+    it "uses object links for objects repeatedly dumped" do
+      e = Exception.new
+      Marshal.dump([e, e]).should == "\x04\b[\ao:\x0EException\a:\tmesg0:\abt0@\x06" # @\x\a is a link to the object
+    end
+
+    it "adds instance variables after the object itself into the objects table" do
+      obj = Exception.new
+      value = "<foo>"
+      obj.instance_variable_set :@foo, value
+
+      # expect a link to the object (@\x06, that means Integer 1) is smaller than a link
+      # to the instance variable value (@\a, that means Integer 2)
+      Marshal.dump([obj, obj, value]).should == "\x04\b[\bo:\x0EException\b:\tmesg0:\abt0:\t@foo\"\n<foo>@\x06@\a"
+    end
+
     it "raises TypeError if an Object is an instance of an anonymous class" do
       anonymous_class = Class.new(Exception)
       obj = anonymous_class.new
diff --git a/core/marshal/fixtures/marshal_data.rb b/core/marshal/fixtures/marshal_data.rb
index 97fd78b2d7..3ba85aa6eb 100644
--- a/core/marshal/fixtures/marshal_data.rb
+++ b/core/marshal/fixtures/marshal_data.rb
@@ -97,6 +97,25 @@ def self._load(data)
   end
 end
 
+module MarshalSpec
+  class UserDefinedDumpWithIVars
+    attr_reader :string
+
+    def initialize(string, ivar_value)
+      @string = string
+      @string.instance_variable_set(:@foo, ivar_value)
+    end
+
+    def _dump(depth)
+      @string
+    end
+
+    def self._load(data)
+      new(data)
+    end
+  end
+end
+
 class UserPreviouslyDefinedWithInitializedIvar
   attr_accessor :field1, :field2
 end
@@ -139,6 +158,32 @@ def ==(other)
   end
 end
 
+module MarshalSpec
+  class UserMarshalDumpWithIvar
+    attr_reader :data
+
+    def initialize(data, ivar_value)
+      @data = data
+      @ivar_value = ivar_value
+    end
+
+    def marshal_dump
+      obj = [data]
+      obj.instance_variable_set(:@foo, @ivar_value)
+      obj
+    end
+
+    def marshal_load(o)
+      @data = o[0]
+    end
+
+    def ==(other)
+      self.class === other and
+        @data = other.data
+    end
+  end
+end
+
 class UserArray < Array
 end
 
diff --git a/core/method/source_location_spec.rb b/core/method/source_location_spec.rb
index c5b296f6e2..23d956ebec 100644
--- a/core/method/source_location_spec.rb
+++ b/core/method/source_location_spec.rb
@@ -11,23 +11,23 @@
   end
 
   it "sets the first value to the path of the file in which the method was defined" do
-    file = @method.source_location.first
+    file = @method.source_location[0]
     file.should be_an_instance_of(String)
     file.should == File.realpath('fixtures/classes.rb', __dir__)
   end
 
   it "sets the last value to an Integer representing the line on which the method was defined" do
-    line = @method.source_location.last
+    line = @method.source_location[1]
     line.should be_an_instance_of(Integer)
     line.should == 5
   end
 
   it "returns the last place the method was defined" do
-    MethodSpecs::SourceLocation.method(:redefined).source_location.last.should == 13
+    MethodSpecs::SourceLocation.method(:redefined).source_location[1].should == 13
   end
 
   it "returns the location of the original method even if it was aliased" do
-    MethodSpecs::SourceLocation.new.method(:aka).source_location.last.should == 17
+    MethodSpecs::SourceLocation.new.method(:aka).source_location[1].should == 17
   end
 
   it "works for methods defined with a block" do
@@ -108,7 +108,13 @@ def f
     c = Class.new do
       eval('def self.m; end', nil, "foo", 100)
     end
-    c.method(:m).source_location.should == ["foo", 100]
+    location = c.method(:m).source_location
+    ruby_version_is(""..."3.5") do
+      location.should == ["foo", 100]
+    end
+    ruby_version_is("3.5") do
+      location.should == ["foo", 100, 0, 100, 15]
+    end
   end
 
   describe "for a Method generated by respond_to_missing?" do
diff --git a/core/module/fixtures/set_temporary_name.rb b/core/module/fixtures/set_temporary_name.rb
new file mode 100644
index 0000000000..901b3b94d1
--- /dev/null
+++ b/core/module/fixtures/set_temporary_name.rb
@@ -0,0 +1,4 @@
+module ModuleSpecs
+  module SetTemporaryNameSpec
+  end
+end
diff --git a/core/module/set_temporary_name_spec.rb b/core/module/set_temporary_name_spec.rb
index f5886a3398..12541374ae 100644
--- a/core/module/set_temporary_name_spec.rb
+++ b/core/module/set_temporary_name_spec.rb
@@ -1,4 +1,5 @@
 require_relative '../../spec_helper'
+require_relative 'fixtures/set_temporary_name'
 
 ruby_version_is "3.3" do
   describe "Module#set_temporary_name" do
@@ -13,13 +14,34 @@
       m.name.should be_nil
     end
 
+    it "returns self" do
+      m = Module.new
+      m.set_temporary_name("fake_name").should.equal? m
+    end
+
     it "can assign a temporary name which is not a valid constant path" do
       m = Module.new
-      m.set_temporary_name("a::B")
-      m.name.should == "a::B"
+
+      m.set_temporary_name("name")
+      m.name.should == "name"
 
       m.set_temporary_name("Template['foo.rb']")
       m.name.should == "Template['foo.rb']"
+
+      m.set_temporary_name("a::B")
+      m.name.should == "a::B"
+
+      m.set_temporary_name("A::b")
+      m.name.should == "A::b"
+
+      m.set_temporary_name("A::B::")
+      m.name.should == "A::B::"
+
+      m.set_temporary_name("A::::B")
+      m.name.should == "A::::B"
+
+      m.set_temporary_name("A=")
+      m.name.should == "A="
     end
 
     it "can't assign empty string as name" do
@@ -43,7 +65,7 @@
       -> { Object.set_temporary_name("fake_name") }.should raise_error(RuntimeError, "can't change permanent name")
     end
 
-    it "can assign a temporary name to a nested module" do
+    it "can assign a temporary name to a module nested into an anonymous module" do
       m = Module.new
       module m::N; end
       m::N.name.should =~ /\A#<Module:0x\h+>::N\z/
@@ -55,6 +77,17 @@ module m::N; end
       m::N.name.should be_nil
     end
 
+    it "discards a temporary name when an outer anonymous module gets a permanent name" do
+      m = Module.new
+      module m::N; end
+
+      m::N.set_temporary_name("fake_name")
+      m::N.name.should == "fake_name"
+
+      ModuleSpecs::SetTemporaryNameSpec::M = m
+      m::N.name.should == "ModuleSpecs::SetTemporaryNameSpec::M::N"
+    end
+
     it "can update the name when assigned to a constant" do
       m = Module.new
       m::N = Module.new
@@ -64,5 +97,45 @@ module m::N; end
       m::M = m::N
       m::M.name.should =~ /\A#<Module:0x\h+>::M\z/m
     end
+
+    it "can reassign a temporary name repeatedly" do
+      m = Module.new
+
+      m.set_temporary_name("fake_name")
+      m.name.should == "fake_name"
+
+      m.set_temporary_name("fake_name_2")
+      m.name.should == "fake_name_2"
+    end
+
+    it "does not affect a name of a module nested into an anonymous module with a temporary name" do
+      m = Module.new
+      m::N = Module.new
+      m::N.name.should =~ /\A#<Module:0x\h+>::N\z/
+
+      m.set_temporary_name("foo")
+      m::N.name.should =~ /\A#<Module:0x\h+>::N\z/
+    end
+
+    it "keeps temporary name when assigned in an anonymous module" do
+      outer = Module.new
+      m = Module.new
+      m.set_temporary_name "m"
+      m.name.should == "m"
+      outer::M = m
+      m.name.should == "m"
+      m.inspect.should == "m"
+    end
+
+    it "keeps temporary name when assigned in an anonymous module and nested before" do
+      outer = Module.new
+      m = Module.new
+      outer::A = m
+      m.set_temporary_name "m"
+      m.name.should == "m"
+      outer::M = m
+      m.name.should == "m"
+      m.inspect.should == "m"
+    end
   end
 end
diff --git a/core/proc/clone_spec.rb b/core/proc/clone_spec.rb
index 26f031334f..730dc421a8 100644
--- a/core/proc/clone_spec.rb
+++ b/core/proc/clone_spec.rb
@@ -15,7 +15,7 @@
   end
 
   ruby_version_is "3.3" do
-    it "calls #initialize_copy on subclass" do
+    it "calls #initialize_clone on subclass" do
       obj = ProcSpecs::MyProc2.new(:a, 2) { }
       dup = obj.clone
 
@@ -24,7 +24,7 @@
 
       dup.first.should == :a
       dup.second.should == 2
-      dup.initializer.should == :copy
+      dup.initializer.should == :clone
     end
   end
 end
diff --git a/core/proc/fixtures/common.rb b/core/proc/fixtures/common.rb
index 204acde597..dfe67d7ba8 100644
--- a/core/proc/fixtures/common.rb
+++ b/core/proc/fixtures/common.rb
@@ -47,6 +47,13 @@ def initialize_dup(other)
       @first = other.first
       @second = other.second
     end
+
+    def initialize_clone(other, **options)
+      super
+      @initializer = :clone
+      @first = other.first
+      @second = other.second
+    end
   end
 
   class Arity
diff --git a/core/proc/source_location_spec.rb b/core/proc/source_location_spec.rb
index a8b99287d5..484466f577 100644
--- a/core/proc/source_location_spec.rb
+++ b/core/proc/source_location_spec.rb
@@ -17,57 +17,64 @@
   end
 
   it "sets the first value to the path of the file in which the proc was defined" do
-    file = @proc.source_location.first
+    file = @proc.source_location[0]
     file.should be_an_instance_of(String)
     file.should == File.realpath('fixtures/source_location.rb', __dir__)
 
-    file = @proc_new.source_location.first
+    file = @proc_new.source_location[0]
     file.should be_an_instance_of(String)
     file.should == File.realpath('fixtures/source_location.rb', __dir__)
 
-    file = @lambda.source_location.first
+    file = @lambda.source_location[0]
     file.should be_an_instance_of(String)
     file.should == File.realpath('fixtures/source_location.rb', __dir__)
 
-    file = @method.source_location.first
+    file = @method.source_location[0]
     file.should be_an_instance_of(String)
     file.should == File.realpath('fixtures/source_location.rb', __dir__)
   end
 
-  it "sets the last value to an Integer representing the line on which the proc was defined" do
-    line = @proc.source_location.last
+  it "sets the second value to an Integer representing the line on which the proc was defined" do
+    line = @proc.source_location[1]
     line.should be_an_instance_of(Integer)
     line.should == 4
 
-    line = @proc_new.source_location.last
+    line = @proc_new.source_location[1]
     line.should be_an_instance_of(Integer)
     line.should == 12
 
-    line = @lambda.source_location.last
+    line = @lambda.source_location[1]
     line.should be_an_instance_of(Integer)
     line.should == 8
 
-    line = @method.source_location.last
+    line = @method.source_location[1]
     line.should be_an_instance_of(Integer)
     line.should == 15
   end
 
   it "works even if the proc was created on the same line" do
-    proc { true }.source_location.should == [__FILE__, __LINE__]
-    Proc.new { true }.source_location.should == [__FILE__, __LINE__]
-    -> { true }.source_location.should == [__FILE__, __LINE__]
+    ruby_version_is(""..."3.5") do
+      proc { true }.source_location.should == [__FILE__, __LINE__]
+      Proc.new { true }.source_location.should == [__FILE__, __LINE__]
+      -> { true }.source_location.should == [__FILE__, __LINE__]
+    end
+    ruby_version_is("3.5") do
+      proc { true }.source_location.should == [__FILE__, __LINE__, 11, __LINE__, 19]
+      Proc.new { true }.source_location.should == [__FILE__, __LINE__, 15, __LINE__, 23]
+      -> { true }.source_location.should == [__FILE__, __LINE__, 8, __LINE__, 17]
+    end
   end
 
   it "returns the first line of a multi-line proc (i.e. the line containing 'proc do')" do
-    ProcSpecs::SourceLocation.my_multiline_proc.source_location.last.should == 20
-    ProcSpecs::SourceLocation.my_multiline_proc_new.source_location.last.should == 34
-    ProcSpecs::SourceLocation.my_multiline_lambda.source_location.last.should == 27
+    ProcSpecs::SourceLocation.my_multiline_proc.source_location[1].should == 20
+    ProcSpecs::SourceLocation.my_multiline_proc_new.source_location[1].should == 34
+    ProcSpecs::SourceLocation.my_multiline_lambda.source_location[1].should == 27
   end
 
   it "returns the location of the proc's body; not necessarily the proc itself" do
-    ProcSpecs::SourceLocation.my_detached_proc.source_location.last.should == 41
-    ProcSpecs::SourceLocation.my_detached_proc_new.source_location.last.should == 51
-    ProcSpecs::SourceLocation.my_detached_lambda.source_location.last.should == 46
+    ProcSpecs::SourceLocation.my_detached_proc.source_location[1].should == 41
+    ProcSpecs::SourceLocation.my_detached_proc_new.source_location[1].should == 51
+    ProcSpecs::SourceLocation.my_detached_lambda.source_location[1].should == 46
   end
 
   it "returns the same value for a proc-ified method as the method reports" do
@@ -86,6 +93,12 @@
 
   it "works for eval with a given line" do
     proc = eval('-> {}', nil, "foo", 100)
-    proc.source_location.should == ["foo", 100]
+    location = proc.source_location
+    ruby_version_is(""..."3.5") do
+      location.should == ["foo", 100]
+    end
+    ruby_version_is("3.5") do
+      location.should == ["foo", 100, 2, 100, 5]
+    end
   end
 end
diff --git a/core/range/overlap_spec.rb b/core/range/overlap_spec.rb
new file mode 100644
index 0000000000..9b6fc13493
--- /dev/null
+++ b/core/range/overlap_spec.rb
@@ -0,0 +1,89 @@
+require_relative '../../spec_helper'
+
+ruby_version_is '3.3' do
+  describe "Range#overlap?" do
+    it "returns true if other Range overlaps self" do
+      (0..2).overlap?(1..3).should == true
+      (1..3).overlap?(0..2).should == true
+      (0..2).overlap?(0..2).should == true
+      (0..3).overlap?(1..2).should == true
+      (1..2).overlap?(0..3).should == true
+
+      ('a'..'c').overlap?('b'..'d').should == true
+    end
+
+    it "returns false if other Range does not overlap self" do
+      (0..2).overlap?(3..4).should == false
+      (0..2).overlap?(-4..-1).should == false
+
+      ('a'..'c').overlap?('d'..'f').should == false
+    end
+
+    it "raises TypeError when called with non-Range argument" do
+      -> {
+        (0..2).overlap?(1)
+      }.should raise_error(TypeError, "wrong argument type Integer (expected Range)")
+    end
+
+    it "returns true when beginningless and endless Ranges overlap" do
+      (0..2).overlap?(..3).should == true
+      (0..2).overlap?(..1).should == true
+      (0..2).overlap?(..0).should == true
+
+      (..3).overlap?(0..2).should == true
+      (..1).overlap?(0..2).should == true
+      (..0).overlap?(0..2).should == true
+
+      (0..2).overlap?(-1..).should == true
+      (0..2).overlap?(1..).should == true
+      (0..2).overlap?(2..).should == true
+
+      (-1..).overlap?(0..2).should == true
+      (1..).overlap?(0..2).should == true
+      (2..).overlap?(0..2).should == true
+
+      (0..).overlap?(2..).should == true
+      (..0).overlap?(..2).should == true
+    end
+
+    it "returns false when beginningless and endless Ranges do not overlap" do
+      (0..2).overlap?(..-1).should == false
+      (0..2).overlap?(3..).should == false
+
+      (..-1).overlap?(0..2).should == false
+      (3..).overlap?(0..2).should == false
+    end
+
+    it "returns false when Ranges are not compatible" do
+      (0..2).overlap?('a'..'d').should == false
+    end
+
+    it "return false when self is empty" do
+      (2..0).overlap?(1..3).should == false
+      (2...2).overlap?(1..3).should == false
+      (1...1).overlap?(1...1).should == false
+      (2..0).overlap?(2..0).should == false
+
+      ('c'..'a').overlap?('b'..'d').should == false
+      ('a'...'a').overlap?('b'..'d').should == false
+      ('b'...'b').overlap?('b'...'b').should == false
+      ('c'...'a').overlap?('c'...'a').should == false
+    end
+
+    it "return false when other Range is empty" do
+      (1..3).overlap?(2..0).should == false
+      (1..3).overlap?(2...2).should == false
+
+      ('b'..'d').overlap?('c'..'a').should == false
+      ('b'..'d').overlap?('c'...'c').should == false
+    end
+
+    it "takes into account exclusive end" do
+      (0...2).overlap?(2..4).should == false
+      (2..4).overlap?(0...2).should == false
+
+      ('a'...'c').overlap?('c'..'e').should == false
+      ('c'..'e').overlap?('a'...'c').should == false
+    end
+  end
+end
diff --git a/core/string/modulo_spec.rb b/core/string/modulo_spec.rb
index 8e3853551f..33c2141812 100644
--- a/core/string/modulo_spec.rb
+++ b/core/string/modulo_spec.rb
@@ -749,9 +749,11 @@ def obj.to_s() "obj" end
       (format % "-10.4e-20").should == (format % -10.4e-20)
       (format % ".5").should == (format % 0.5)
       (format % "-.5").should == (format % -0.5)
-      ruby_bug("#20705", ""..."3.4") do
+
+      ruby_version_is "3.4" do
         (format % "10.").should == (format % 10)
       end
+
       # Something's strange with this spec:
       # it works just fine in individual mode, but not when run as part of a group
       (format % "10_1_0.5_5_5").should == (format % 1010.555)
diff --git a/core/time/at_spec.rb b/core/time/at_spec.rb
index 48fb3c6f52..85bb6d7ebf 100644
--- a/core/time/at_spec.rb
+++ b/core/time/at_spec.rb
@@ -228,6 +228,12 @@
       time.utc_offset.should == -9*60*60
       time.zone.should == nil
       time.to_i.should == @epoch_time
+
+      time = Time.at(@epoch_time, in: "-09:00:01")
+
+      time.utc_offset.should == -(9*60*60 + 1)
+      time.zone.should == nil
+      time.to_i.should == @epoch_time
     end
 
     it "could be UTC offset as a number of seconds" do
@@ -280,5 +286,51 @@
       -> { Time.at(@epoch_time, in: "+09:99") }.should raise_error(ArgumentError)
       -> { Time.at(@epoch_time, in: "ABC") }.should raise_error(ArgumentError)
     end
+
+    it "raises ArgumentError if hours greater than 23" do # TODO
+      ruby_version_is ""..."3.1" do
+        -> { Time.at(@epoch_time, in: "+24:00") }.should raise_error(ArgumentError, 'utc_offset out of range')
+        -> { Time.at(@epoch_time, in: "+2400") }.should raise_error(ArgumentError, '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset')
+
+        -> { Time.at(@epoch_time, in: "+99:00") }.should raise_error(ArgumentError, 'utc_offset out of range')
+        -> { Time.at(@epoch_time, in: "+9900") }.should raise_error(ArgumentError, '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset')
+      end
+
+      ruby_version_is "3.1" do
+        -> { Time.at(@epoch_time, in: "+24:00") }.should raise_error(ArgumentError, "utc_offset out of range")
+        -> { Time.at(@epoch_time, in: "+2400") }.should raise_error(ArgumentError, "utc_offset out of range")
+
+        -> { Time.at(@epoch_time, in: "+99:00") }.should raise_error(ArgumentError, "utc_offset out of range")
+        -> { Time.at(@epoch_time, in: "+9900") }.should raise_error(ArgumentError, "utc_offset out of range")
+      end
+    end
+
+    it "raises ArgumentError if minutes greater than 59" do # TODO
+      ruby_version_is ""..."3.1" do
+        -> { Time.at(@epoch_time, in: "+00:60") }.should raise_error(ArgumentError, '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset')
+        -> { Time.at(@epoch_time, in: "+0060") }.should raise_error(ArgumentError, '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset')
+
+        -> { Time.at(@epoch_time, in: "+00:99") }.should raise_error(ArgumentError, '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset')
+        -> { Time.at(@epoch_time, in: "+0099") }.should raise_error(ArgumentError, '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset')
+      end
+
+      ruby_version_is "3.1" do
+        -> { Time.at(@epoch_time, in: "+00:60") }.should raise_error(ArgumentError, '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset: +00:60')
+        -> { Time.at(@epoch_time, in: "+0060") }.should raise_error(ArgumentError, '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset: +0060')
+
+        -> { Time.at(@epoch_time, in: "+00:99") }.should raise_error(ArgumentError, '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset: +00:99')
+        -> { Time.at(@epoch_time, in: "+0099") }.should raise_error(ArgumentError, '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset: +0099')
+      end
+    end
+
+    ruby_bug '#20797', ''...'3.4' do
+      it "raises ArgumentError if seconds greater than 59" do
+        -> { Time.at(@epoch_time, in: "+00:00:60") }.should raise_error(ArgumentError, '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset: +00:00:60')
+        -> { Time.at(@epoch_time, in: "+000060") }.should raise_error(ArgumentError, '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset: +000060')
+
+        -> { Time.at(@epoch_time, in: "+00:00:99") }.should raise_error(ArgumentError, '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset: +00:00:99')
+        -> { Time.at(@epoch_time, in: "+000099") }.should raise_error(ArgumentError, '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset: +000099')
+      end
+    end
   end
 end
diff --git a/core/time/getlocal_spec.rb b/core/time/getlocal_spec.rb
index 926a6dbf45..ff3e3d8dd1 100644
--- a/core/time/getlocal_spec.rb
+++ b/core/time/getlocal_spec.rb
@@ -59,12 +59,24 @@
     t.utc_offset.should == 3600
   end
 
+  it "returns a Time with a UTC offset specified as +HH:MM:SS" do
+    t = Time.gm(2007, 1, 9, 12, 0, 0).getlocal("+01:00:01")
+    t.should == Time.new(2007, 1, 9, 13, 0, 1, 3601)
+    t.utc_offset.should == 3601
+  end
+
   it "returns a Time with a UTC offset specified as -HH:MM" do
     t = Time.gm(2007, 1, 9, 12, 0, 0).getlocal("-01:00")
     t.should == Time.new(2007, 1, 9, 11, 0, 0, -3600)
     t.utc_offset.should == -3600
   end
 
+  it "returns a Time with a UTC offset specified as -HH:MM:SS" do
+    t = Time.gm(2007, 1, 9, 12, 0, 0).getlocal("-01:00:01")
+    t.should == Time.new(2007, 1, 9, 10, 59, 59, -3601)
+    t.utc_offset.should == -3601
+  end
+
   describe "with an argument that responds to #to_str" do
     it "coerces using #to_str" do
       o = mock('string')
@@ -97,6 +109,52 @@
     -> { t.getlocal(86400) }.should raise_error(ArgumentError)
   end
 
+  it "raises ArgumentError if String argument and hours greater than 23" do
+    ruby_version_is ""..."3.1" do
+      -> { Time.now.getlocal("+24:00") }.should raise_error(ArgumentError, "utc_offset out of range")
+      -> { Time.now.getlocal("+2400") }.should raise_error(ArgumentError, '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset')
+
+      -> { Time.now.getlocal("+99:00") }.should raise_error(ArgumentError, "utc_offset out of range")
+      -> { Time.now.getlocal("+9900") }.should raise_error(ArgumentError, '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset')
+    end
+
+    ruby_version_is "3.1" do
+      -> { Time.now.getlocal("+24:00") }.should raise_error(ArgumentError, "utc_offset out of range")
+      -> { Time.now.getlocal("+2400") }.should raise_error(ArgumentError, "utc_offset out of range")
+
+      -> { Time.now.getlocal("+99:00") }.should raise_error(ArgumentError, "utc_offset out of range")
+      -> { Time.now.getlocal("+9900") }.should raise_error(ArgumentError, "utc_offset out of range")
+    end
+  end
+
+  it "raises ArgumentError if String argument and minutes greater than 59" do
+    ruby_version_is ""..."3.1" do
+      -> { Time.now.getlocal("+00:60") }.should raise_error(ArgumentError, '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset')
+      -> { Time.now.getlocal("+0060") }.should raise_error(ArgumentError, '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset')
+
+      -> { Time.now.getlocal("+00:99") }.should raise_error(ArgumentError, '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset')
+      -> { Time.now.getlocal("+0099") }.should raise_error(ArgumentError, '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset')
+    end
+
+    ruby_version_is "3.1" do
+      -> { Time.now.getlocal("+00:60") }.should raise_error(ArgumentError, '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset: +00:60')
+      -> { Time.now.getlocal("+0060") }.should raise_error(ArgumentError, '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset: +0060')
+
+      -> { Time.now.getlocal("+00:99") }.should raise_error(ArgumentError, '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset: +00:99')
+      -> { Time.now.getlocal("+0099") }.should raise_error(ArgumentError, '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset: +0099')
+    end
+  end
+
+  ruby_bug '#20797', ''...'3.4' do
+    it "raises ArgumentError if String argument and seconds greater than 59" do
+      -> { Time.now.getlocal("+00:00:60") }.should raise_error(ArgumentError, '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset: +00:00:60')
+      -> { Time.now.getlocal("+000060") }.should raise_error(ArgumentError, '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset: +000060')
+
+      -> { Time.now.getlocal("+00:00:99") }.should raise_error(ArgumentError, '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset: +00:00:99')
+      -> { Time.now.getlocal("+000099") }.should raise_error(ArgumentError, '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset: +000099')
+    end
+  end
+
   describe "with a timezone argument" do
     it "returns a Time in the timezone" do
       zone = TimeSpecs::Timezone.new(offset: (5*3600+30*60))
diff --git a/core/time/localtime_spec.rb b/core/time/localtime_spec.rb
index 609b6532a1..5badba9fb2 100644
--- a/core/time/localtime_spec.rb
+++ b/core/time/localtime_spec.rb
@@ -72,6 +72,13 @@
     t.utc_offset.should == 3600
   end
 
+  it "returns a Time with a UTC offset specified as +HH:MM:SS" do
+    t = Time.gm(2007, 1, 9, 12, 0, 0)
+    t.localtime("+01:00:01")
+    t.should == Time.new(2007, 1, 9, 13, 0, 1, 3601)
+    t.utc_offset.should == 3601
+  end
+
   it "returns a Time with a UTC offset specified as -HH:MM" do
     t = Time.gm(2007, 1, 9, 12, 0, 0)
     t.localtime("-01:00")
@@ -79,6 +86,13 @@
     t.utc_offset.should == -3600
   end
 
+  it "returns a Time with a UTC offset specified as -HH:MM:SS" do
+    t = Time.gm(2007, 1, 9, 12, 0, 0)
+    t.localtime("-01:00:01")
+    t.should == Time.new(2007, 1, 9, 10, 59, 59, -3601)
+    t.utc_offset.should == -3601
+  end
+
   it "returns a Time with a UTC offset specified as UTC" do
     t = Time.new(2007, 1, 9, 12, 0, 0, 3600)
     t.localtime("UTC")
@@ -91,6 +105,52 @@
     t.utc_offset.should == 3600 * 2
   end
 
+  it "raises ArgumentError if String argument and hours greater than 23" do
+    ruby_version_is ""..."3.1" do
+      -> { Time.now.localtime("+24:00") }.should raise_error(ArgumentError, "utc_offset out of range")
+      -> { Time.now.localtime("+2400") }.should raise_error(ArgumentError, '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset')
+
+      -> { Time.now.localtime("+99:00") }.should raise_error(ArgumentError, "utc_offset out of range")
+      -> { Time.now.localtime("+9900") }.should raise_error(ArgumentError, '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset')
+    end
+
+    ruby_version_is "3.1" do
+      -> { Time.now.localtime("+24:00") }.should raise_error(ArgumentError, "utc_offset out of range")
+      -> { Time.now.localtime("+2400") }.should raise_error(ArgumentError, "utc_offset out of range")
+
+      -> { Time.now.localtime("+99:00") }.should raise_error(ArgumentError, "utc_offset out of range")
+      -> { Time.now.localtime("+9900") }.should raise_error(ArgumentError, "utc_offset out of range")
+    end
+  end
+
+  it "raises ArgumentError if String argument and minutes greater than 59" do
+    ruby_version_is ""..."3.1" do
+      -> { Time.now.localtime("+00:60") }.should raise_error(ArgumentError, '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset')
+      -> { Time.now.localtime("+0060") }.should raise_error(ArgumentError, '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset')
+
+      -> { Time.now.localtime("+00:99") }.should raise_error(ArgumentError, '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset')
+      -> { Time.now.localtime("+0099") }.should raise_error(ArgumentError, '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset')
+    end
+
+    ruby_version_is "3.1" do
+      -> { Time.now.localtime("+00:60") }.should raise_error(ArgumentError, '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset: +00:60')
+      -> { Time.now.localtime("+0060") }.should raise_error(ArgumentError, '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset: +0060')
+
+      -> { Time.now.localtime("+00:99") }.should raise_error(ArgumentError, '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset: +00:99')
+      -> { Time.now.localtime("+0099") }.should raise_error(ArgumentError, '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset: +0099')
+    end
+  end
+
+  ruby_bug '#20797', ''...'3.4' do
+    it "raises ArgumentError if String argument and seconds greater than 59" do
+      -> { Time.now.localtime("+00:00:60") }.should raise_error(ArgumentError, '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset: +00:00:60')
+      -> { Time.now.localtime("+000060") }.should raise_error(ArgumentError, '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset: +000060')
+
+      -> { Time.now.localtime("+00:00:99") }.should raise_error(ArgumentError, '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset: +00:00:99')
+      -> { Time.now.localtime("+000099") }.should raise_error(ArgumentError, '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset: +000099')
+    end
+  end
+
   platform_is_not :windows do
     it "changes the timezone according to the set one" do
       t = Time.new(2005, 2, 27, 22, 50, 0, -3600)
diff --git a/core/time/new_spec.rb b/core/time/new_spec.rb
index 24bb9fde0c..1a743b485e 100644
--- a/core/time/new_spec.rb
+++ b/core/time/new_spec.rb
@@ -415,6 +415,11 @@ def zone.local_to_utc(t)
 
         time.utc_offset.should == -9*60*60
         time.zone.should == nil
+
+        time = Time.new(2000, 1, 1, 12, 0, 0, in: "-09:00:01")
+
+        time.utc_offset.should == -(9*60*60 + 1)
+        time.zone.should == nil
       end
 
       it "could be UTC offset as a number of seconds" do
@@ -659,7 +664,7 @@ def obj.to_int; 3; end
 
         -> {
           Time.new("2020-12-25 00:56:17 +23:61")
-        }.should raise_error(ArgumentError, /utc_offset|can't parse:/)
+        }.should raise_error(ArgumentError, /utc_offset/)
 
         ruby_bug '#20797', ''...'3.4' do
           -> {
@@ -668,6 +673,28 @@ def obj.to_int; 3; end
         end
       end
 
+      it "raises ArgumentError if utc offset parts are not valid" do
+        -> { Time.new("2020-12-25 00:56:17 +24:00") }.should raise_error(ArgumentError, "utc_offset out of range")
+        -> { Time.new("2020-12-25 00:56:17 +2400") }.should raise_error(ArgumentError, "utc_offset out of range")
+
+        -> { Time.new("2020-12-25 00:56:17 +99:00") }.should raise_error(ArgumentError, "utc_offset out of range")
+        -> { Time.new("2020-12-25 00:56:17 +9900") }.should raise_error(ArgumentError, "utc_offset out of range")
+
+        -> { Time.new("2020-12-25 00:56:17 +00:60") }.should raise_error(ArgumentError, '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset: +00:60')
+        -> { Time.new("2020-12-25 00:56:17 +0060") }.should raise_error(ArgumentError, '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset: +0060')
+
+        -> { Time.new("2020-12-25 00:56:17 +00:99") }.should raise_error(ArgumentError, '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset: +00:99')
+        -> { Time.new("2020-12-25 00:56:17 +0099") }.should raise_error(ArgumentError, '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset: +0099')
+
+        ruby_bug '#20797', ''...'3.4' do
+          -> { Time.new("2020-12-25 00:56:17 +00:00:60") }.should raise_error(ArgumentError, '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset: +00:00:60')
+          -> { Time.new("2020-12-25 00:56:17 +000060") }.should raise_error(ArgumentError, '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset: +000060')
+
+          -> { Time.new("2020-12-25 00:56:17 +00:00:99") }.should raise_error(ArgumentError, '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset: +00:00:99')
+          -> { Time.new("2020-12-25 00:56:17 +000099") }.should raise_error(ArgumentError, '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset: +000099')
+        end
+      end
+
       it "raises ArgumentError if string has not ascii-compatible encoding" do
         -> {
           Time.new("2021-11-31 00:00:60 +09:00".encode("utf-32le"))
diff --git a/core/time/now_spec.rb b/core/time/now_spec.rb
index d47f00723e..7c2425411a 100644
--- a/core/time/now_spec.rb
+++ b/core/time/now_spec.rb
@@ -16,6 +16,11 @@
 
         time.utc_offset.should == -9*60*60
         time.zone.should == nil
+
+        time = Time.now(in: "-09:00:01")
+
+        time.utc_offset.should == -(9*60*60 + 1)
+        time.zone.should == nil
       end
 
       it "could be UTC offset as a number of seconds" do
@@ -52,6 +57,32 @@
         -> { Time.now(in: "+09:99") }.should raise_error(ArgumentError)
         -> { Time.now(in: "ABC") }.should raise_error(ArgumentError)
       end
+
+      it "raises ArgumentError if String argument and hours greater than 23" do
+        -> { Time.now(in: "+24:00") }.should raise_error(ArgumentError, "utc_offset out of range")
+        -> { Time.now(in: "+2400") }.should raise_error(ArgumentError, "utc_offset out of range")
+
+        -> { Time.now(in: "+99:00") }.should raise_error(ArgumentError, "utc_offset out of range")
+        -> { Time.now(in: "+9900") }.should raise_error(ArgumentError, "utc_offset out of range")
+      end
+
+      it "raises ArgumentError if String argument and minutes greater than 59" do
+        -> { Time.now(in: "+00:60") }.should raise_error(ArgumentError, '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset: +00:60')
+        -> { Time.now(in: "+0060") }.should raise_error(ArgumentError, '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset: +0060')
+
+        -> { Time.now(in: "+00:99") }.should raise_error(ArgumentError, '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset: +00:99')
+        -> { Time.now(in: "+0099") }.should raise_error(ArgumentError, '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset: +0099')
+      end
+
+      ruby_bug '#20797', ''...'3.4' do
+        it "raises ArgumentError if String argument and seconds greater than 59" do
+          -> { Time.now(in: "+00:00:60") }.should raise_error(ArgumentError, '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset: +00:00:60')
+          -> { Time.now(in: "+000060") }.should raise_error(ArgumentError, '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset: +000060')
+
+          -> { Time.now(in: "+00:00:99") }.should raise_error(ArgumentError, '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset: +00:00:99')
+          -> { Time.now(in: "+000099") }.should raise_error(ArgumentError, '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset: +000099')
+        end
+      end
     end
   end
 end
diff --git a/core/unboundmethod/source_location_spec.rb b/core/unboundmethod/source_location_spec.rb
index 5c2f14362c..45bd69438c 100644
--- a/core/unboundmethod/source_location_spec.rb
+++ b/core/unboundmethod/source_location_spec.rb
@@ -7,23 +7,23 @@
   end
 
   it "sets the first value to the path of the file in which the method was defined" do
-    file = @method.source_location.first
+    file = @method.source_location[0]
     file.should be_an_instance_of(String)
     file.should == File.realpath('fixtures/classes.rb', __dir__)
   end
 
-  it "sets the last value to an Integer representing the line on which the method was defined" do
-    line = @method.source_location.last
+  it "sets the second value to an Integer representing the line on which the method was defined" do
+    line = @method.source_location[1]
     line.should be_an_instance_of(Integer)
     line.should == 5
   end
 
   it "returns the last place the method was defined" do
-    UnboundMethodSpecs::SourceLocation.method(:redefined).unbind.source_location.last.should == 13
+    UnboundMethodSpecs::SourceLocation.method(:redefined).unbind.source_location[1].should == 13
   end
 
   it "returns the location of the original method even if it was aliased" do
-    UnboundMethodSpecs::SourceLocation.instance_method(:aka).source_location.last.should == 17
+    UnboundMethodSpecs::SourceLocation.instance_method(:aka).source_location[1].should == 17
   end
 
   it "works for define_method methods" do
@@ -54,6 +54,12 @@
     c = Class.new do
       eval('def m; end', nil, "foo", 100)
     end
-    c.instance_method(:m).source_location.should == ["foo", 100]
-  end
+    location = c.instance_method(:m).source_location
+    ruby_version_is(""..."3.5") do
+      location.should == ["foo", 100]
+    end
+    ruby_version_is("3.5") do
+      location.should == ["foo", 100, 0, 100, 10]
+    end
+ end
 end
diff --git a/library/irb/fixtures/irb.rb b/library/irb/fixtures/irb.rb
new file mode 100644
index 0000000000..8d386dfda1
--- /dev/null
+++ b/library/irb/fixtures/irb.rb
@@ -0,0 +1,3 @@
+a = 10
+
+binding.irb # rubocop:disable Lint/Debugger
diff --git a/core/binding/irb_spec.rb b/library/irb/irb_spec.rb
similarity index 100%
rename from core/binding/irb_spec.rb
rename to library/irb/irb_spec.rb
diff --git a/library/rubygems/gem/bin_path_spec.rb b/library/rubygems/gem/bin_path_spec.rb
index 67b3e042c2..0b8c4db08b 100644
--- a/library/rubygems/gem/bin_path_spec.rb
+++ b/library/rubygems/gem/bin_path_spec.rb
@@ -22,6 +22,7 @@
       end
 
       skip "Could not find the default gemspecs" unless Dir.exist?(default_specifications_dir)
+      skip "default_specifications_dir mismatch with GEM_HOME" if ENV["GEM_HOME"] && !default_specifications_dir.start_with?(ENV['GEM_HOME'])
 
       Gem::Specification.each_spec([default_specifications_dir]) do |spec|
         spec.executables.each do |exe|
diff --git a/library/socket/basicsocket/recv_nonblock_spec.rb b/library/socket/basicsocket/recv_nonblock_spec.rb
index df42c116fb..5bdbbfe688 100644
--- a/library/socket/basicsocket/recv_nonblock_spec.rb
+++ b/library/socket/basicsocket/recv_nonblock_spec.rb
@@ -99,3 +99,68 @@
     end
   end
 end
+
+describe "Socket::BasicSocket#recv_nonblock" do
+  context "when recvfrom(2) returns 0 (if no messages are available to be received and the peer has performed an orderly shutdown)" do
+    describe "stream socket" do
+      before :each do
+        @server = TCPServer.new('127.0.0.1', 0)
+        @port = @server.addr[1]
+      end
+
+      after :each do
+        @server.close unless @server.closed?
+      end
+
+      ruby_version_is ""..."3.3" do
+        quarantine! do # May fail with "IO::EAGAINWaitReadable: Resource temporarily unavailable - recvfrom(2) would block" error
+        it "returns an empty String on a closed stream socket" do
+          ready = false
+
+          t = Thread.new do
+            client = @server.accept
+
+            Thread.pass while !ready
+            client.recv_nonblock(10)
+          ensure
+            client.close if client
+          end
+
+          Thread.pass while t.status and t.status != "sleep"
+          t.status.should_not be_nil
+
+          socket = TCPSocket.new('127.0.0.1', @port)
+          socket.close
+          ready = true
+
+          t.value.should == ""
+        end
+        end
+      end
+
+      ruby_version_is "3.3" do
+        it "returns nil on a closed stream socket" do
+          ready = false
+
+          t = Thread.new do
+            client = @server.accept
+
+            Thread.pass while !ready
+            client.recv_nonblock(10)
+          ensure
+            client.close if client
+          end
+
+          Thread.pass while t.status and t.status != "sleep"
+          t.status.should_not be_nil
+
+          socket = TCPSocket.new('127.0.0.1', @port)
+          socket.close
+          ready = true
+
+          t.value.should be_nil
+        end
+      end
+    end
+  end
+end
diff --git a/library/socket/basicsocket/recv_spec.rb b/library/socket/basicsocket/recv_spec.rb
index e82a357d3d..e20c571922 100644
--- a/library/socket/basicsocket/recv_spec.rb
+++ b/library/socket/basicsocket/recv_spec.rb
@@ -32,25 +32,6 @@
     ScratchPad.recorded.should == 'hello'
   end
 
-  ruby_version_is "3.3" do
-    it "returns nil on a closed stream socket" do
-      t = Thread.new do
-        client = @server.accept
-        packet = client.recv(10)
-        client.close
-        packet
-      end
-
-      Thread.pass while t.status and t.status != "sleep"
-      t.status.should_not be_nil
-
-      socket = TCPSocket.new('127.0.0.1', @port)
-      socket.close
-
-      t.value.should be_nil
-    end
-  end
-
   platform_is_not :solaris do
     it "accepts flags to specify unusual receiving behaviour" do
       t = Thread.new do
@@ -192,3 +173,80 @@
     end
   end
 end
+
+describe "BasicSocket#recv" do
+  context "when recvfrom(2) returns 0 (if no messages are available to be received and the peer has performed an orderly shutdown)" do
+    describe "stream socket" do
+      before :each do
+        @server = TCPServer.new('127.0.0.1', 0)
+        @port = @server.addr[1]
+      end
+
+      after :each do
+        @server.close unless @server.closed?
+      end
+
+      ruby_version_is ""..."3.3" do
+        it "returns an empty String on a closed stream socket" do
+          t = Thread.new do
+            client = @server.accept
+            client.recv(10)
+          ensure
+            client.close if client
+          end
+
+          Thread.pass while t.status and t.status != "sleep"
+          t.status.should_not be_nil
+
+          socket = TCPSocket.new('127.0.0.1', @port)
+          socket.close
+
+          t.value.should == ""
+        end
+      end
+
+      ruby_version_is "3.3" do
+        it "returns nil on a closed stream socket" do
+          t = Thread.new do
+            client = @server.accept
+            client.recv(10)
+          ensure
+            client.close if client
+          end
+
+          Thread.pass while t.status and t.status != "sleep"
+          t.status.should_not be_nil
+
+          socket = TCPSocket.new('127.0.0.1', @port)
+          socket.close
+
+          t.value.should be_nil
+        end
+      end
+    end
+
+    describe "datagram socket" do
+      SocketSpecs.each_ip_protocol do |family, ip_address|
+        before :each do
+          @server = UDPSocket.new(family)
+          @client = UDPSocket.new(family)
+        end
+
+        after :each do
+          @server.close unless @server.closed?
+          @client.close unless @client.closed?
+        end
+
+        it "returns empty String" do
+          @server.bind(ip_address, 0)
+          addr = @server.connect_address
+          @client.connect(addr.ip_address, addr.ip_port)
+
+          @client.send('', 0)
+
+          @server.recv(1).should == ""
+        end
+      end
+    end
+  end
+end
diff --git a/library/socket/basicsocket/recvmsg_nonblock_spec.rb b/library/socket/basicsocket/recvmsg_nonblock_spec.rb
index cc4275c417..8d5f541a8e 100644
--- a/library/socket/basicsocket/recvmsg_nonblock_spec.rb
+++ b/library/socket/basicsocket/recvmsg_nonblock_spec.rb
@@ -222,3 +222,71 @@
     end
   end
 end
+
+describe 'BasicSocket#recvmsg_nonblock' do
+  context "when recvfrom(2) returns 0 (if no messages are available to be received and the peer has performed an orderly shutdown)" do
+    describe "stream socket" do
+      before :each do
+        @server = TCPServer.new('127.0.0.1', 0)
+        @port = @server.addr[1]
+      end
+
+      after :each do
+        @server.close unless @server.closed?
+      end
+
+      ruby_version_is ""..."3.3" do
+        quarantine! do # May fail with "IO::EAGAINWaitReadable: Resource temporarily unavailable - recvfrom(2) would block" error
+        it "returns an empty String as received data on a closed stream socket" do
+          ready = false
+
+          t = Thread.new do
+            client = @server.accept
+
+            Thread.pass while !ready
+            client.recvmsg_nonblock(10)
+          ensure
+            client.close if client
+          end
+
+          Thread.pass while t.status and t.status != "sleep"
+          t.status.should_not be_nil
+
+          socket = TCPSocket.new('127.0.0.1', @port)
+          socket.close
+          ready = true
+
+          t.value.should.is_a? Array
+          t.value[0].should == ""
+        end
+        end
+      end
+
+      ruby_version_is "3.3" do
+        platform_is_not :windows do
+          it "returns nil on a closed stream socket" do
+            ready = false
+
+            t = Thread.new do
+              client = @server.accept
+
+              Thread.pass while !ready
+              client.recvmsg_nonblock(10)
+            ensure
+              client.close if client
+            end
+
+            Thread.pass while t.status and t.status != "sleep"
+            t.status.should_not be_nil
+
+            socket = TCPSocket.new('127.0.0.1', @port)
+            socket.close
+            ready = true
+
+            t.value.should be_nil
+          end
+        end
+      end
+    end
+  end
+end
diff --git a/library/socket/basicsocket/recvmsg_spec.rb b/library/socket/basicsocket/recvmsg_spec.rb
index 8063723701..04ba1d74c7 100644
--- a/library/socket/basicsocket/recvmsg_spec.rb
+++ b/library/socket/basicsocket/recvmsg_spec.rb
@@ -195,3 +195,87 @@
     end
   end
 end
+
+describe 'BasicSocket#recvmsg' do
+  context "when recvfrom(2) returns 0 (if no messages are available to be received and the peer has performed an orderly shutdown)" do
+    describe "stream socket" do
+      before :each do
+        @server = TCPServer.new('127.0.0.1', 0)
+        @port = @server.addr[1]
+      end
+
+      after :each do
+        @server.close unless @server.closed?
+      end
+
+      ruby_version_is ""..."3.3" do
+        platform_is_not :windows do
+          it "returns an empty String as received data on a closed stream socket" do
+            t = Thread.new do
+              client = @server.accept
+              client.recvmsg(10)
+            ensure
+              client.close if client
+            end
+
+            Thread.pass while t.status and t.status != "sleep"
+            t.status.should_not be_nil
+
+            socket = TCPSocket.new('127.0.0.1', @port)
+            socket.close
+
+            t.value.should.is_a? Array
+            t.value[0].should == ""
+          end
+        end
+      end
+
+      ruby_version_is "3.3" do
+        platform_is_not :windows do
+          it "returns nil on a closed stream socket" do
+            t = Thread.new do
+              client = @server.accept
+              client.recvmsg(10)
+            ensure
+              client.close if client
+            end
+
+            Thread.pass while t.status and t.status != "sleep"
+            t.status.should_not be_nil
+
+            socket = TCPSocket.new('127.0.0.1', @port)
+            socket.close
+
+            t.value.should be_nil
+          end
+        end
+      end
+    end
+
+    describe "datagram socket" do
+      SocketSpecs.each_ip_protocol do |family, ip_address|
+        before :each do
+          @server = UDPSocket.new(family)
+          @client = UDPSocket.new(family)
+        end
+
+        after :each do
+          @server.close unless @server.closed?
+          @client.close unless @client.closed?
+        end
+
+        it "returns an empty String as received data" do
+          @server.bind(ip_address, 0)
+          addr = @server.connect_address
+          @client.connect(addr.ip_address, addr.ip_port)
+
+          @client.send('', 0)
+          message = @server.recvmsg(1)
+
+          message.should.is_a? Array
+          message[0].should == ""
+        end
+      end
+    end
+  end
+end
diff --git a/library/socket/ipsocket/recvfrom_spec.rb b/library/socket/ipsocket/recvfrom_spec.rb
index 2af86ea70d..b58903df23 100644
--- a/library/socket/ipsocket/recvfrom_spec.rb
+++ b/library/socket/ipsocket/recvfrom_spec.rb
@@ -69,6 +69,88 @@
   end
 end
 
+describe "Socket::IPSocket#recvfrom" do
+  context "when recvfrom(2) returns 0 (if no messages are available to be received and the peer has performed an orderly shutdown)" do
+    describe "stream socket" do
+      before :each do
+        @server = TCPServer.new("127.0.0.1", 0)
+        port = @server.addr[1]
+        @client = TCPSocket.new("127.0.0.1", port)
+      end
+
+      after :each do
+        @server.close unless @server.closed?
+        @client.close unless @client.closed?
+      end
+
+      ruby_version_is ""..."3.3" do
+        it "returns an empty String as received data on a closed stream socket" do
+          t = Thread.new do
+            client = @server.accept
+            message = client.recvfrom(10)
+            message
+          ensure
+            client.close if client
+          end
+
+          Thread.pass while t.status and t.status != "sleep"
+          t.status.should_not be_nil
+
+          @client.close
+
+          t.value.should.is_a? Array
+          t.value[0].should == ""
+        end
+      end
+
+      ruby_version_is "3.3" do
+        it "returns nil on a closed stream socket" do
+          t = Thread.new do
+            client = @server.accept
+            message = client.recvfrom(10)
+            message
+          ensure
+            client.close if client
+          end
+
+          Thread.pass while t.status and t.status != "sleep"
+          t.status.should_not be_nil
+
+          @client.close
+
+          t.value.should be_nil
+        end
+      end
+    end
+
+    describe "datagram socket" do
+      SocketSpecs.each_ip_protocol do |family, ip_address|
+        before :each do
+          @server = UDPSocket.new(family)
+          @client = UDPSocket.new(family)
+        end
+
+        after :each do
+          @server.close unless @server.closed?
+          @client.close unless @client.closed?
+        end
+
+        it "returns an empty String as received data" do
+          @server.bind(ip_address, 0)
+          addr = @server.connect_address
+          @client.connect(addr.ip_address, addr.ip_port)
+
+          @client.send('', 0)
+          message = @server.recvfrom(1)
+
+          message.should.is_a? Array
+          message[0].should == ""
+        end
+      end
+    end
+  end
+end
+
 describe 'Socket::IPSocket#recvfrom' do
   SocketSpecs.each_ip_protocol do |family, ip_address, family_name|
     before do
diff --git a/library/socket/socket/gethostname_spec.rb b/library/socket/socket/gethostname_spec.rb
index 4b79747b27..89e1ed496f 100644
--- a/library/socket/socket/gethostname_spec.rb
+++ b/library/socket/socket/gethostname_spec.rb
@@ -2,7 +2,15 @@
 require_relative '../fixtures/classes'
 
 describe "Socket.gethostname" do
+  def system_hostname
+    # Most platforms implement this POSIX standard:
+    `uname -n`.strip
+  rescue
+    # Only really required for Windows without MSYS/MinGW/Cygwin etc:
+    `hostname`.strip
+  end
+
   it "returns the host name" do
-    Socket.gethostname.should == `hostname`.strip
+    Socket.gethostname.should == system_hostname
   end
 end
diff --git a/library/socket/socket/recvfrom_nonblock_spec.rb b/library/socket/socket/recvfrom_nonblock_spec.rb
index 5596f91bb8..ade655e443 100644
--- a/library/socket/socket/recvfrom_nonblock_spec.rb
+++ b/library/socket/socket/recvfrom_nonblock_spec.rb
@@ -137,3 +137,79 @@
     end
   end
 end
+
+describe 'Socket#recvfrom_nonblock' do
+  context "when recvfrom(2) returns 0 (if no messages are available to be received and the peer has performed an orderly shutdown)" do
+    describe "stream socket" do
+      before :each do
+        @server = Socket.new Socket::AF_INET, :STREAM, 0
+        @sockaddr = Socket.sockaddr_in(0, "127.0.0.1")
+        @server.bind(@sockaddr)
+        @server.listen(1)
+
+        server_ip    = @server.local_address.ip_port
+        @server_addr = Socket.sockaddr_in(server_ip, "127.0.0.1")
+
+        @client = Socket.new(Socket::AF_INET, :STREAM, 0)
+      end
+
+      after :each do
+        @server.close unless @server.closed?
+        @client.close unless @client.closed?
+      end
+
+      ruby_version_is ""..."3.3" do
+        quarantine! do # May fail with "IO::EAGAINWaitReadable: Resource temporarily unavailable - recvfrom(2) would block" error
+        it "returns an empty String as received data on a closed stream socket" do
+          ready = false
+
+          t = Thread.new do
+            client, _ = @server.accept
+
+            Thread.pass while !ready
+            client.recvfrom_nonblock(10)
+          ensure
+            client.close if client
+          end
+
+          Thread.pass while t.status and t.status != "sleep"
+          t.status.should_not be_nil
+
+          @client.connect(@server_addr)
+          @client.close
+          ready = true
+
+          t.value.should.is_a? Array
+          t.value[0].should == ""
+        end
+        end
+      end
+
+      ruby_version_is "3.3" do
+        quarantine! do # May fail with "IO::EAGAINWaitReadable: Resource temporarily unavailable - recvfrom(2) would block" error
+        it "returns nil on a closed stream socket" do
+          ready = false
+
+          t = Thread.new do
+            client, _ = @server.accept
+
+            Thread.pass while !ready
+            client.recvfrom_nonblock(10)
+          ensure
+            client.close if client
+          end
+
+          Thread.pass while t.status and t.status != "sleep"
+          t.status.should_not be_nil
+
+          @client.connect(@server_addr)
+          @client.close
+          ready = true
+
+          t.value.should be_nil
+        end
+        end
+      end
+    end
+  end
+end
diff --git a/library/socket/socket/recvfrom_spec.rb b/library/socket/socket/recvfrom_spec.rb
index faf161e4a5..6ba39ffcaf 100644
--- a/library/socket/socket/recvfrom_spec.rb
+++ b/library/socket/socket/recvfrom_spec.rb
@@ -90,3 +90,90 @@
     end
   end
 end
+
+describe 'Socket#recvfrom' do
+  context "when recvfrom(2) returns 0 (if no messages are available to be received and the peer has performed an orderly shutdown)" do
+    describe "stream socket" do
+      before :each do
+        @server = Socket.new Socket::AF_INET, :STREAM, 0
+        sockaddr = Socket.sockaddr_in(0, "127.0.0.1")
+        @server.bind(sockaddr)
+        @server.listen(1)
+
+        server_ip    = @server.local_address.ip_port
+        @server_addr = Socket.sockaddr_in(server_ip, "127.0.0.1")
+
+        @client = Socket.new(Socket::AF_INET, :STREAM, 0)
+      end
+
+      after :each do
+        @server.close unless @server.closed?
+        @client.close unless @client.closed?
+      end
+
+      ruby_version_is ""..."3.3" do
+        it "returns an empty String as received data on a closed stream socket" do
+          t = Thread.new do
+            client, _ = @server.accept
+            client.recvfrom(10)
+          ensure
+            client.close if client
+          end
+
+          Thread.pass while t.status and t.status != "sleep"
+          t.status.should_not be_nil
+
+          @client.connect(@server_addr)
+          @client.close
+
+          t.value.should.is_a? Array
+          t.value[0].should == ""
+        end
+      end
+
+      ruby_version_is "3.3" do
+        it "returns nil on a closed stream socket" do
+          t = Thread.new do
+            client, _ = @server.accept
+            client.recvfrom(10)
+          ensure
+            client.close if client
+          end
+
+          Thread.pass while t.status and t.status != "sleep"
+          t.status.should_not be_nil
+
+          @client.connect(@server_addr)
+          @client.close
+
+          t.value.should be_nil
+        end
+      end
+    end
+
+    describe "datagram socket" do
+      SocketSpecs.each_ip_protocol do |family, ip_address|
+        before :each do
+          @server = Socket.new(family, :DGRAM)
+          @client = Socket.new(family, :DGRAM)
+        end
+
+        after :each do
+          @server.close unless @server.closed?
+          @client.close unless @client.closed?
+        end
+
+        it "returns an empty String as received data" do
+          @server.bind(Socket.sockaddr_in(0, ip_address))
+          @client.connect(@server.getsockname)
+
+          @client.send('', 0)
+          message = @server.recvfrom(1)
+
+          message.should.is_a? Array
+          message[0].should == ""
+        end
+      end
+    end
+  end
+end
diff --git a/library/yaml/dump_spec.rb b/library/yaml/dump_spec.rb
index ea94b2f856..97b665d6a5 100644
--- a/library/yaml/dump_spec.rb
+++ b/library/yaml/dump_spec.rb
@@ -39,7 +39,11 @@
   end
 
   it "dumps an OpenStruct" do
-    require "ostruct"
+    begin
+      require "ostruct"
+    rescue LoadError
+      skip "OpenStruct is not available"
+    end
     os = OpenStruct.new("age" => 20, "name" => "John")
     yaml_dump = YAML.dump(os)
 
diff --git a/library/yaml/shared/load.rb b/library/yaml/shared/load.rb
index bd55332fe5..b8bb605b0a 100644
--- a/library/yaml/shared/load.rb
+++ b/library/yaml/shared/load.rb
@@ -123,7 +123,11 @@
   end
 
   it "loads an OpenStruct" do
-    require "ostruct"
+    begin
+      require "ostruct"
+    rescue LoadError
+      skip "OpenStruct is not available"
+    end
     os = OpenStruct.new("age" => 20, "name" => "John")
     loaded = YAML.send(@method, "--- !ruby/object:OpenStruct\ntable:\n  :age: 20\n  :name: John\n")
     loaded.should == os
diff --git a/optional/capi/ext/io_spec.c b/optional/capi/ext/io_spec.c
index d1cc861e21..3b7e8c4481 100644
--- a/optional/capi/ext/io_spec.c
+++ b/optional/capi/ext/io_spec.c
@@ -377,16 +377,14 @@ static VALUE io_spec_rb_io_closed_p(VALUE self, VALUE io) {
 }
 
 static VALUE io_spec_rb_io_open_descriptor(VALUE self, VALUE klass, VALUE descriptor, VALUE mode, VALUE path, VALUE timeout, VALUE internal_encoding, VALUE external_encoding, VALUE ecflags, VALUE ecopts) {
-  struct rb_io_encoding *io_encoding;
+  struct rb_io_encoding io_encoding;
 
-  io_encoding = (struct rb_io_encoding *) malloc(sizeof(struct rb_io_encoding));
+  io_encoding.enc = rb_to_encoding(internal_encoding);
+  io_encoding.enc2 = rb_to_encoding(external_encoding);
+  io_encoding.ecflags = FIX2INT(ecflags);
+  io_encoding.ecopts = ecopts;
 
-  io_encoding->enc = rb_to_encoding(internal_encoding);
-  io_encoding->enc2 = rb_to_encoding(external_encoding);
-  io_encoding->ecflags = FIX2INT(ecflags);
-  io_encoding->ecopts = ecopts;
-
-  return rb_io_open_descriptor(klass, FIX2INT(descriptor), FIX2INT(mode), path, timeout, io_encoding);
+  return rb_io_open_descriptor(klass, FIX2INT(descriptor), FIX2INT(mode), path, timeout, &io_encoding);
 }
 
 static VALUE io_spec_rb_io_open_descriptor_without_encoding(VALUE self, VALUE klass, VALUE descriptor, VALUE mode, VALUE path, VALUE timeout) {
diff --git a/optional/capi/ext/struct_spec.c b/optional/capi/ext/struct_spec.c
index 9c45bd5672..413249e828 100644
--- a/optional/capi/ext/struct_spec.c
+++ b/optional/capi/ext/struct_spec.c
@@ -28,7 +28,7 @@ static VALUE struct_spec_rb_struct_aset(VALUE self, VALUE st, VALUE key, VALUE v
 }
 
 /* Only allow setting three attributes, should be sufficient for testing. */
-static VALUE struct_spec_struct_define(VALUE self, VALUE name,
+static VALUE struct_spec_rb_struct_define(VALUE self, VALUE name,
   VALUE attr1, VALUE attr2, VALUE attr3) {
 
   const char *a1 = StringValuePtr(attr1);
@@ -42,7 +42,7 @@ static VALUE struct_spec_struct_define(VALUE self, VALUE name,
 }
 
 /* Only allow setting three attributes, should be sufficient for testing. */
-static VALUE struct_spec_struct_define_under(VALUE self, VALUE outer,
+static VALUE struct_spec_rb_struct_define_under(VALUE self, VALUE outer,
   VALUE name, VALUE attr1, VALUE attr2, VALUE attr3) {
 
   const char *nm = StringValuePtr(name);
@@ -62,6 +62,23 @@ static VALUE struct_spec_rb_struct_size(VALUE self, VALUE st) {
   return rb_struct_size(st);
 }
 
+#if defined(RUBY_VERSION_IS_3_3)
+/* Only allow setting three attributes, should be sufficient for testing. */
+static VALUE struct_spec_rb_data_define(VALUE self, VALUE superclass,
+  VALUE attr1, VALUE attr2, VALUE attr3) {
+
+  const char *a1 = StringValuePtr(attr1);
+  const char *a2 = StringValuePtr(attr2);
+  const char *a3 = StringValuePtr(attr3);
+
+  if (superclass == Qnil) {
+    superclass = 0;
+  }
+
+  return rb_data_define(superclass, a1, a2, a3, NULL);
+}
+#endif
+
 void Init_struct_spec(void) {
   VALUE cls = rb_define_class("CApiStructSpecs", rb_cObject);
   rb_define_method(cls, "rb_struct_aref", struct_spec_rb_struct_aref, 2);
@@ -69,10 +86,13 @@ void Init_struct_spec(void) {
   rb_define_method(cls, "rb_struct_s_members", struct_spec_rb_struct_s_members, 1);
   rb_define_method(cls, "rb_struct_members", struct_spec_rb_struct_members, 1);
   rb_define_method(cls, "rb_struct_aset", struct_spec_rb_struct_aset, 3);
-  rb_define_method(cls, "rb_struct_define", struct_spec_struct_define, 4);
-  rb_define_method(cls, "rb_struct_define_under", struct_spec_struct_define_under, 5);
+  rb_define_method(cls, "rb_struct_define", struct_spec_rb_struct_define, 4);
+  rb_define_method(cls, "rb_struct_define_under", struct_spec_rb_struct_define_under, 5);
   rb_define_method(cls, "rb_struct_new", struct_spec_rb_struct_new, 4);
   rb_define_method(cls, "rb_struct_size", struct_spec_rb_struct_size, 1);
+#if defined(RUBY_VERSION_IS_3_3)
+  rb_define_method(cls, "rb_data_define", struct_spec_rb_data_define, 4);
+#endif
 }
 
 #ifdef __cplusplus
diff --git a/optional/capi/struct_spec.rb b/optional/capi/struct_spec.rb
index 0e9e366908..474c397956 100644
--- a/optional/capi/struct_spec.rb
+++ b/optional/capi/struct_spec.rb
@@ -209,3 +209,52 @@
     end
   end
 end
+
+ruby_version_is "3.3" do
+  describe "C-API Data function" do
+    before :each do
+      @s = CApiStructSpecs.new
+    end
+
+    describe "rb_data_define" do
+      it "returns a subclass of Data class when passed nil as the first argument" do
+        klass = @s.rb_data_define(nil, "a", "b", "c")
+
+        klass.should.is_a? Class
+        klass.superclass.should == Data
+      end
+
+      it "returns a subclass of a class when passed as the first argument" do
+        superclass = Class.new(Data)
+        klass = @s.rb_data_define(superclass, "a", "b", "c")
+
+        klass.should.is_a? Class
+        klass.superclass.should == superclass
+      end
+
+      it "creates readers for the members" do
+        klass = @s.rb_data_define(nil, "a", "b", "c")
+        obj = klass.new(1, 2, 3)
+
+        obj.a.should == 1
+        obj.b.should == 2
+        obj.c.should == 3
+      end
+
+      it "returns the member names as Symbols" do
+        klass = @s.rb_data_define(nil, "a", "b", "c")
+        obj = klass.new(0, 0, 0)
+
+        obj.members.should == [:a, :b, :c]
+      end
+
+      it "raises an ArgumentError if arguments contain duplicate member name" do
+        -> { @s.rb_data_define(nil, "a", "b", "a") }.should raise_error(ArgumentError)
+      end
+
+      it "raises when first argument is not a class" do
+        -> { @s.rb_data_define([], "a", "b", "c") }.should raise_error(TypeError, "wrong argument type Array (expected Class)")
+      end
+    end
+  end
+end
diff --git a/security/cve_2024_49761_spec.rb b/security/cve_2024_49761_spec.rb
new file mode 100644
index 0000000000..54ede39032
--- /dev/null
+++ b/security/cve_2024_49761_spec.rb
@@ -0,0 +1,9 @@
+require_relative '../spec_helper'
+
+ruby_version_is "3.2" do
+  describe "CVE-2024-49761 is resisted by" do
+    it "the Regexp implementation handling that regular expression in linear time" do
+      Regexp.linear_time?(/&#0*((?:\d+)|(?:x[a-fA-F0-9]+));/).should == true
+    end
+  end
+end