Update to ruby/spec@41bf282

75 files changed, 851 insertions, 143 deletions

diff --git a/spec/ruby/CONTRIBUTING.md b/spec/ruby/CONTRIBUTING.md
index 1ec6f0ff4b..d0924867fa 100644
--- a/spec/ruby/CONTRIBUTING.md
+++ b/spec/ruby/CONTRIBUTING.md
@@ -53,6 +53,8 @@ which indicates the file was generated but the method unspecified.
 Here is a list of frequently-used matchers, which should be enough for most specs.
 There are a few extra specific matchers used in the couple specs that need it.
 
+#### Comparison matchers
+
 ```ruby
 (1 + 2).should == 3 # Calls #==
 (1 + 2).should_not == 5
@@ -66,7 +68,11 @@ File.should equal(File) # Calls #equal? (tests identity)
 4.should > 3
 
 "Hello".should =~ /l{2}/ # Calls #=~ (Regexp match)
+```
 
+#### Predicate matchers
+
+```ruby
 [].should be_empty # Calls #empty?
 [1,2,3].should include(2) # Calls #include?
 
@@ -82,8 +88,13 @@ Numeric.should be_ancestor_of(Float) # Float.ancestors.include?(Numeric)
 3.14.should respond_to(:to_i) # Calls #respond_to?
 Fixnum.should have_instance_method(:+)
 Array.should have_method(:new)
-# Also have_constant, have_private_instance_method, have_singleton_method, etc
+```
+
+Also `have_constant`, `have_private_instance_method`, `have_singleton_method`, etc.
 
+#### Exception matchers
+
+```ruby
 -> {
   raise "oops"
 }.should raise_error(RuntimeError, /oops/)
@@ -95,11 +106,20 @@ Array.should have_method(:new)
   e.message.should include("oops")
   e.cause.should == nil
 }
+```
+
+##### should_not raise_error
 
-# To avoid! Instead, use an expectation testing what the code in the lambda does.
-# If an exception is raised, it will fail the example anyway.
+**To avoid!** Instead, use an expectation testing what the code in the lambda does.
+If an exception is raised, it will fail the example anyway.
+
+```ruby
 -> { ... }.should_not raise_error
+```
+
+#### Warning matcher
 
+```ruby
 -> {
   Fixnum
 }.should complain(/constant ::Fixnum is deprecated/) # Expect a warning
@@ -110,6 +130,8 @@ Array.should have_method(:new)
 Different guards are available as defined by mspec.
 Here is a list of the most commonly-used guards:
 
+#### Version guards
+
 ```ruby
 ruby_version_is ""..."2.4" do
   # Specs for RUBY_VERSION < 2.4
@@ -118,7 +140,11 @@ end
 ruby_version_is "2.4" do
   # Specs for RUBY_VERSION >= 2.4
 end
+```
 
+#### Platform guards
+
+```ruby
 platform_is :windows do
   # Specs only valid on Windows
 end
@@ -140,18 +166,25 @@ end
 big_endian do
   # Big-endian platform
 end
+```
+
+#### Guard for bug
+
+In case there is a bug in MRI but the expected behavior is obvious.
+First, file a bug at https://bugs.ruby-lang.org/.
+It is better to use a `ruby_version_is` guard if there was a release with the fix.
 
-# In case there is a bug in MRI but the expected behavior is obvious
-# First file a bug at https://bugs.ruby-lang.org/
-# It is better to use a ruby_version_is guard if there was a release with the fix
+```ruby
 ruby_bug '#13669', ''...'2.5' do
   it "works like this" do
     # Specify the expected behavior here, not the bug
   end
 end
+```
 
+#### Combining guards
 
-# Combining guards
+```ruby
 guard -> { platform_is :windows and ruby_version_is ""..."2.5" } do
   # Windows and RUBY_VERSION < 2.5
 end
@@ -159,8 +192,11 @@ end
 guard_not -> { platform_is :windows and ruby_version_is ""..."2.5" } do
   # The opposite
 end
+```
 
-# Custom guard
+#### Custom guard
+
+```ruby
 max_uint = (1 << 32) - 1
 guard -> { max_uint <= fixnum_max } do
 end
@@ -168,6 +204,8 @@ end
 
 Custom guards are better than a simple `if` as they allow [mspec commands](https://github.com/ruby/mspec/issues/30#issuecomment-312487779) to work properly.
 
+#### Implementation-specific behaviors
+
 In general, the usage of guards should be minimized as possible.
 
 There are no guards to define implementation-specific behavior because
diff --git a/spec/ruby/README.md b/spec/ruby/README.md
index b34e6681b1..e6c7153c3d 100644
--- a/spec/ruby/README.md
+++ b/spec/ruby/README.md
@@ -1,7 +1,6 @@
 # The Ruby Spec Suite
 
-[![Actions Build Status](https://github.com/ruby/spec/workflows/CI/badge.svg?branch=master)](https://github.com/ruby/spec/actions)
-[![Windows Actions Build Status](https://github.com/ruby/spec/workflows/Windows/badge.svg?branch=master)](https://github.com/ruby/spec/actions)
+[![Actions Build Status](https://github.com/ruby/spec/workflows/CI/badge.svg)](https://github.com/ruby/spec/actions)
 [![Gitter](https://badges.gitter.im/ruby/spec.svg)](https://gitter.im/ruby/spec)
 
 The Ruby Spec Suite, abbreviated `ruby/spec`, is a test suite for the behavior of the Ruby programming language.
diff --git a/spec/ruby/command_line/dash_l_spec.rb b/spec/ruby/command_line/dash_l_spec.rb
new file mode 100644
index 0000000000..51d924edc1
--- /dev/null
+++ b/spec/ruby/command_line/dash_l_spec.rb
@@ -0,0 +1,33 @@
+require_relative '../spec_helper'
+
+describe "The -l command line option" do
+  before :each do
+    @names  = fixture __FILE__, "full_names.txt"
+  end
+
+  it "chomps lines with default separator" do
+    ruby_exe('puts $_.end_with?("\n")', options: "-n -l", escape: true,
+             args: " < #{@names}").should ==
+        "false\nfalse\nfalse\n"
+  end
+
+  ruby_version_is "2.5" do
+    it "chomps last line based on $/" do
+      ruby_exe('BEGIN { $/ = "ones\n" }; puts $_', options: "-W0 -n -l", escape: true,
+               args: " < #{@names}").should ==
+          "alice j\nbob field\njames grey\n"
+    end
+  end
+
+  it "sets $\\ to the value of $/" do
+    ruby_exe("puts $\\ == $/", options: "-W0 -n -l", escape: true,
+             args: " < #{@names}").should ==
+        "true\ntrue\ntrue\n"
+  end
+
+  it "sets $-l" do
+    ruby_exe("puts $-l", options: "-n -l", escape: true,
+                         args: " < #{@names}").should ==
+      "true\ntrue\ntrue\n"
+  end
+end
diff --git a/spec/ruby/core/array/shared/slice.rb b/spec/ruby/core/array/shared/slice.rb
index 1e7fdf934a..d6b4547b2b 100644
--- a/spec/ruby/core/array/shared/slice.rb
+++ b/spec/ruby/core/array/shared/slice.rb
@@ -461,7 +461,7 @@ describe :array_slice, shared: true do
   it "raises a RangeError when the start index is out of range of Fixnum" do
     array = [1, 2, 3, 4, 5, 6]
     obj = mock('large value')
-    obj.should_receive(:to_int).and_return(0x8000_0000_0000_0000_0000)
+    obj.should_receive(:to_int).and_return(bignum_value)
     -> { array.send(@method, obj) }.should raise_error(RangeError)
 
     obj = 8e19
@@ -471,10 +471,19 @@ describe :array_slice, shared: true do
   it "raises a RangeError when the length is out of range of Fixnum" do
     array = [1, 2, 3, 4, 5, 6]
     obj = mock('large value')
-    obj.should_receive(:to_int).and_return(0x8000_0000_0000_0000_0000)
+    obj.should_receive(:to_int).and_return(bignum_value)
     -> { array.send(@method, 1, obj) }.should raise_error(RangeError)
 
     obj = 8e19
     -> { array.send(@method, 1, obj) }.should raise_error(RangeError)
   end
+
+  it "raises a type error if a range is passed with a length" do
+    ->{ [1, 2, 3].send(@method, 1..2, 1) }.should raise_error(TypeError)
+  end
+
+  it "raises a RangeError if passed a range with a bound that is too large" do
+    -> { "hello".send(@method, bignum_value..(bignum_value + 1)) }.should raise_error(RangeError)
+    -> { "hello".send(@method, 0..bignum_value) }.should raise_error(RangeError)
+  end
 end
diff --git a/spec/ruby/core/binding/eval_spec.rb b/spec/ruby/core/binding/eval_spec.rb
index 84096f8a91..224bce4c33 100644
--- a/spec/ruby/core/binding/eval_spec.rb
+++ b/spec/ruby/core/binding/eval_spec.rb
@@ -131,4 +131,10 @@ describe "Binding#eval" do
     bind, meth = obj.get_binding_with_send_and_method
     bind.eval("__method__").should == meth
   end
+
+  it "reflects refinements activated in the binding scope" do
+    bind = BindingSpecs::Refined.refined_binding
+
+    bind.eval("'bar'.foo").should == "foo"
+  end
 end
diff --git a/spec/ruby/core/binding/fixtures/classes.rb b/spec/ruby/core/binding/fixtures/classes.rb
index 43e32cacf6..b5f3ce9008 100644
--- a/spec/ruby/core/binding/fixtures/classes.rb
+++ b/spec/ruby/core/binding/fixtures/classes.rb
@@ -49,4 +49,18 @@ module BindingSpecs
       end
     end
   end
+
+  module AddFooToString
+    refine(String) do
+      def foo
+        "foo"
+      end
+    end
+  end
+  class Refined
+    using AddFooToString
+    def self.refined_binding
+      binding
+    end
+  end
 end
diff --git a/spec/ruby/core/file/realpath_spec.rb b/spec/ruby/core/file/realpath_spec.rb
index 0c5d19287a..bd27e09da6 100644
--- a/spec/ruby/core/file/realpath_spec.rb
+++ b/spec/ruby/core/file/realpath_spec.rb
@@ -67,6 +67,12 @@ platform_is_not :windows do
     it "raises Errno::ENOENT if the symlink points to an absent file" do
       -> { File.realpath(@fake_link) }.should raise_error(Errno::ENOENT)
     end
+
+    it "converts the argument with #to_path" do
+      path = mock("path")
+      path.should_receive(:to_path).and_return(__FILE__)
+      File.realpath(path).should == File.realpath(__FILE__ )
+    end
   end
 end
 
diff --git a/spec/ruby/core/file/stat_spec.rb b/spec/ruby/core/file/stat_spec.rb
index 31f9dc58af..76b0becbf0 100644
--- a/spec/ruby/core/file/stat_spec.rb
+++ b/spec/ruby/core/file/stat_spec.rb
@@ -41,5 +41,14 @@ platform_is_not :windows do
       st.file?.should == true
       st.symlink?.should == false
     end
+
+    it "returns an error when given missing non-ASCII path" do
+      missing_path = "/missingfilepath\xE3E4".force_encoding("ASCII-8BIT")
+      -> {
+        File.stat(missing_path)
+      }.should raise_error(Errno::ENOENT) { |e|
+        e.message.should include(missing_path)
+      }
+    end
   end
 end
diff --git a/spec/ruby/core/integer/lte_spec.rb b/spec/ruby/core/integer/lte_spec.rb
index 3d843a5dd9..40a89f094a 100644
--- a/spec/ruby/core/integer/lte_spec.rb
+++ b/spec/ruby/core/integer/lte_spec.rb
@@ -46,6 +46,11 @@ describe "Integer#<=" do
       (@bignum <= (@bignum + 0.5)).should == false
     end
 
+    it "returns true for bignums compare to a bigger float" do
+      (18446744073709551616 <= 1.8446744073709552e+19).should == true
+      (@bignum <= (@bignum + 9999.0)).should == true
+    end
+
     it "raises an ArgumentError when given a non-Integer" do
       -> { @bignum <= "4" }.should raise_error(ArgumentError)
       -> { @bignum <= mock('str') }.should raise_error(ArgumentError)
diff --git a/spec/ruby/core/kernel/caller_locations_spec.rb b/spec/ruby/core/kernel/caller_locations_spec.rb
index 8f9429845d..cb344e16a0 100644
--- a/spec/ruby/core/kernel/caller_locations_spec.rb
+++ b/spec/ruby/core/kernel/caller_locations_spec.rb
@@ -28,6 +28,14 @@ describe 'Kernel#caller_locations' do
     locations1[2..4].map(&:to_s).should == locations2.map(&:to_s)
   end
 
+  ruby_version_is "2.6" do
+    it "works with endless ranges" do
+      locations1 = caller_locations(0)
+      locations2 = caller_locations(eval("(2..)"))
+      locations2.map(&:to_s).should == locations1[2..-1].map(&:to_s)
+    end
+  end
+
   it "can be called with a range whose end is negative" do
     locations1 = caller_locations(0)
     locations2 = caller_locations(2..-1)
diff --git a/spec/ruby/core/kernel/caller_spec.rb b/spec/ruby/core/kernel/caller_spec.rb
index 8469319c94..e943e36dc2 100644
--- a/spec/ruby/core/kernel/caller_spec.rb
+++ b/spec/ruby/core/kernel/caller_spec.rb
@@ -43,4 +43,12 @@ describe 'Kernel#caller' do
       "#{path}:2:in `block in <main>'\n"
     ]
   end
+
+  ruby_version_is "2.6" do
+    it "works with endless ranges" do
+      locations1 = KernelSpecs::CallerTest.locations(0)
+      locations2 = KernelSpecs::CallerTest.locations(eval("(2..)"))
+      locations2.map(&:to_s).should == locations1[2..-1].map(&:to_s)
+    end
+  end
 end
diff --git a/spec/ruby/core/kernel/eval_spec.rb b/spec/ruby/core/kernel/eval_spec.rb
index 09ccb9dc62..783009ac01 100644
--- a/spec/ruby/core/kernel/eval_spec.rb
+++ b/spec/ruby/core/kernel/eval_spec.rb
@@ -373,4 +373,44 @@ CODE
       EvalSpecs.send :remove_const, :Vπstring_not_frozen
     end
   end
+
+  it "activates refinements from the eval scope" do
+    refinery = Module.new do
+      refine EvalSpecs::A do
+        def foo
+          "bar"
+        end
+      end
+    end
+
+    result = nil
+
+    Module.new do
+      using refinery
+
+      result = eval "EvalSpecs::A.new.foo"
+    end
+
+    result.should == "bar"
+  end
+
+  it "activates refinements from the binding" do
+    refinery = Module.new do
+      refine EvalSpecs::A do
+        def foo
+          "bar"
+        end
+      end
+    end
+
+    b = nil
+    m = Module.new do
+      using refinery
+      b = binding
+    end
+
+    result = eval "EvalSpecs::A.new.foo", b
+
+    result.should == "bar"
+  end
 end
diff --git a/spec/ruby/core/module/name_spec.rb b/spec/ruby/core/module/name_spec.rb
index 36a91f5be5..9a4730313f 100644
--- a/spec/ruby/core/module/name_spec.rb
+++ b/spec/ruby/core/module/name_spec.rb
@@ -18,6 +18,12 @@ describe "Module#name" do
     m::N.name.should =~ /\A#<Module:0x[0-9a-f]+>::N\z/
   end
 
+  it "returns nil for a singleton class" do
+    Module.new.singleton_class.name.should be_nil
+    String.singleton_class.name.should be_nil
+    Object.new.singleton_class.name.should be_nil
+  end
+
   it "changes when the module is reachable through a constant path" do
     m = Module.new
     module m::N; end
diff --git a/spec/ruby/core/module/shared/class_eval.rb b/spec/ruby/core/module/shared/class_eval.rb
index 08f8ff7597..224078ae54 100644
--- a/spec/ruby/core/module/shared/class_eval.rb
+++ b/spec/ruby/core/module/shared/class_eval.rb
@@ -112,4 +112,48 @@ describe :module_class_eval, shared: true do
     a.attribute.should == "A"
     b.attribute.should == "B"
   end
+
+  it "activates refinements from the eval scope" do
+    refinery = Module.new do
+      refine ModuleSpecs::NamedClass do
+        def foo
+          "bar"
+        end
+      end
+    end
+
+    mid = @method
+    result = nil
+
+    Class.new do
+      using refinery
+
+      result = send(mid, "ModuleSpecs::NamedClass.new.foo")
+    end
+
+    result.should == "bar"
+  end
+
+  it "activates refinements from the eval scope with block" do
+    refinery = Module.new do
+      refine ModuleSpecs::NamedClass do
+        def foo
+          "bar"
+        end
+      end
+    end
+
+    mid = @method
+    result = nil
+
+    Class.new do
+      using refinery
+
+      result = send(mid) do
+        ModuleSpecs::NamedClass.new.foo
+      end
+    end
+
+    result.should == "bar"
+  end
 end
diff --git a/spec/ruby/core/nil/match_spec.rb b/spec/ruby/core/nil/match_spec.rb
index 3f69312bfe..27646e9749 100644
--- a/spec/ruby/core/nil/match_spec.rb
+++ b/spec/ruby/core/nil/match_spec.rb
@@ -15,5 +15,9 @@ ruby_version_is "2.6" do
         (o =~ true).should       be_nil
       end
     end
+
+    it "should not warn" do
+      -> { nil =~ /a/ }.should_not complain(verbose: true)
+    end
   end
 end
diff --git a/spec/ruby/core/string/shared/slice.rb b/spec/ruby/core/string/shared/slice.rb
index b192005369..1c438bc48d 100644
--- a/spec/ruby/core/string/shared/slice.rb
+++ b/spec/ruby/core/string/shared/slice.rb
@@ -121,6 +121,8 @@ describe :string_slice_index_length, shared: true do
 
     "x".send(@method, -2,0).should == nil
     "x".send(@method, -2,1).should == nil
+
+    "x".send(@method, fixnum_max, 1).should == nil
   end
 
   it "returns nil if the length is negative" do
@@ -293,6 +295,24 @@ describe :string_slice_range, shared: true do
     "hello world".send(@method, 6..5).send(@method, -1..-1).should == nil
     "hello world".send(@method, 6..5).send(@method, 1..1).should == nil
   end
+
+  it "raises a type error if a range is passed with a length" do
+    ->{ "hello".send(@method, 1..2, 1) }.should raise_error(TypeError)
+  end
+
+  it "raises a RangeError if one of the bound is too big" do
+    -> { "hello".send(@method, bignum_value..(bignum_value + 1)) }.should raise_error(RangeError)
+    -> { "hello".send(@method, 0..bignum_value) }.should raise_error(RangeError)
+  end
+
+  ruby_version_is "2.6" do
+    it "works with endless ranges" do
+      "hello there".send(@method, eval("(2..)")).should == "llo there"
+      "hello there".send(@method, eval("(2...)")).should == "llo there"
+      "hello there".send(@method, eval("(-4..)")).should == "here"
+      "hello there".send(@method, eval("(-4...)")).should == "here"
+    end
+  end
 end
 
 describe :string_slice_regexp, shared: true do
diff --git a/spec/ruby/core/struct/new_spec.rb b/spec/ruby/core/struct/new_spec.rb
index 564c49af01..071aa38d25 100644
--- a/spec/ruby/core/struct/new_spec.rb
+++ b/spec/ruby/core/struct/new_spec.rb
@@ -15,7 +15,7 @@ describe "Struct.new" do
     second = nil
     -> {
       second = Struct.new('Person', :hair, :sex)
-    }.should complain(/redefining constant/)
+    }.should complain(/constant/)
     second.should == Struct::Person
 
     first.members.should_not == second.members
diff --git a/spec/ruby/core/thread/backtrace_locations_spec.rb b/spec/ruby/core/thread/backtrace_locations_spec.rb
index 211858899c..ead4be2d8c 100644
--- a/spec/ruby/core/thread/backtrace_locations_spec.rb
+++ b/spec/ruby/core/thread/backtrace_locations_spec.rb
@@ -22,28 +22,33 @@ describe "Thread#backtrace_locations" do
   it "can be called with a number of locations to omit" do
     locations1 = Thread.current.backtrace_locations
     locations2 = Thread.current.backtrace_locations(2)
-    locations1[2..-1].length.should == locations2.length
-    locations1[2..-1].map(&:to_s).should == locations2.map(&:to_s)
+    locations2.length.should == locations1[2..-1].length
+    locations2.map(&:to_s).should == locations1[2..-1].map(&:to_s)
   end
 
   it "can be called with a maximum number of locations to return as second parameter" do
     locations1 = Thread.current.backtrace_locations
     locations2 = Thread.current.backtrace_locations(2, 3)
-    locations1[2..4].map(&:to_s).should == locations2.map(&:to_s)
+    locations2.map(&:to_s).should == locations1[2..4].map(&:to_s)
   end
 
   it "can be called with a range" do
     locations1 = Thread.current.backtrace_locations
     locations2 = Thread.current.backtrace_locations(2..4)
-    locations1[2..4].map(&:to_s).should == locations2.map(&:to_s)
+    locations2.map(&:to_s).should == locations1[2..4].map(&:to_s)
   end
 
   it "can be called with a range whose end is negative" do
-    locations1 = Thread.current.backtrace_locations
-    locations2 = Thread.current.backtrace_locations(2..-1)
-    locations3 = Thread.current.backtrace_locations(2..-2)
-    locations1[2..-1].map(&:to_s).should == locations2.map(&:to_s)
-    locations1[2..-2].map(&:to_s).should == locations3.map(&:to_s)
+    Thread.current.backtrace_locations(2..-1).map(&:to_s).should == Thread.current.backtrace_locations[2..-1].map(&:to_s)
+    Thread.current.backtrace_locations(2..-2).map(&:to_s).should == Thread.current.backtrace_locations[2..-2].map(&:to_s)
+  end
+
+  ruby_version_is "2.6" do
+    it "can be called with an endless range" do
+      locations1 = Thread.current.backtrace_locations(0)
+      locations2 = Thread.current.backtrace_locations(eval("(2..)"))
+      locations2.map(&:to_s).should == locations1[2..-1].map(&:to_s)
+    end
   end
 
   it "returns nil if omitting more locations than available" do
diff --git a/spec/ruby/core/thread/backtrace_spec.rb b/spec/ruby/core/thread/backtrace_spec.rb
index 84ed574d5c..9001b1b7eb 100644
--- a/spec/ruby/core/thread/backtrace_spec.rb
+++ b/spec/ruby/core/thread/backtrace_spec.rb
@@ -32,4 +32,38 @@ describe "Thread#backtrace" do
     t.join
     backtrace.should be_kind_of(Array)
   end
+
+  it "can be called with a number of locations to omit" do
+    locations1 = Thread.current.backtrace
+    locations2 = Thread.current.backtrace(2)
+    locations1[2..-1].length.should == locations2.length
+    locations1[2..-1].map(&:to_s).should == locations2.map(&:to_s)
+  end
+
+  it "can be called with a maximum number of locations to return as second parameter" do
+    locations1 = Thread.current.backtrace
+    locations2 = Thread.current.backtrace(2, 3)
+    locations1[2..4].map(&:to_s).should == locations2.map(&:to_s)
+  end
+
+  it "can be called with a range" do
+    locations1 = Thread.current.backtrace
+    locations2 = Thread.current.backtrace(2..4)
+    locations1[2..4].map(&:to_s).should == locations2.map(&:to_s)
+  end
+
+  it "can be called with a range whose end is negative" do
+    Thread.current.backtrace(2..-1).should == Thread.current.backtrace[2..-1]
+    Thread.current.backtrace(2..-2).should == Thread.current.backtrace[2..-2]
+  end
+
+  it "returns nil if omitting more locations than available" do
+    Thread.current.backtrace(100).should == nil
+    Thread.current.backtrace(100..-1).should == nil
+  end
+
+  it "returns [] if omitting exactly the number of locations available" do
+    omit = Thread.current.backtrace.length
+    Thread.current.backtrace(omit).should == []
+  end
 end
diff --git a/spec/ruby/core/time/ceil_spec.rb b/spec/ruby/core/time/ceil_spec.rb
index 29dcec5d72..86029554db 100644
--- a/spec/ruby/core/time/ceil_spec.rb
+++ b/spec/ruby/core/time/ceil_spec.rb
@@ -36,10 +36,11 @@ ruby_version_is "2.7" do
     it "copies own timezone to the returning value" do
       @time.zone.should == @time.ceil.zone
 
-      with_timezone "JST-9" do
-        time = Time.at 0, 1
-        time.zone.should == time.ceil.zone
+      time = with_timezone "JST-9" do
+        Time.at 0, 1
       end
+
+      time.zone.should == time.ceil.zone
     end
   end
 end
diff --git a/spec/ruby/core/time/floor_spec.rb b/spec/ruby/core/time/floor_spec.rb
index 763ed1ba51..a19585b787 100644
--- a/spec/ruby/core/time/floor_spec.rb
+++ b/spec/ruby/core/time/floor_spec.rb
@@ -28,10 +28,11 @@ ruby_version_is "2.7" do
     it "copies own timezone to the returning value" do
       @time.zone.should == @time.floor.zone
 
-      with_timezone "JST-9" do
-        time = Time.at 0, 1
-        time.zone.should == time.floor.zone
+      time = with_timezone "JST-9" do
+        Time.at 0, 1
       end
+
+      time.zone.should == time.floor.zone
     end
   end
 end
diff --git a/spec/ruby/language/delegation_spec.rb b/spec/ruby/language/delegation_spec.rb
new file mode 100644
index 0000000000..4063ad457e
--- /dev/null
+++ b/spec/ruby/language/delegation_spec.rb
@@ -0,0 +1,41 @@
+require_relative '../spec_helper'
+require_relative 'fixtures/delegation'
+
+ruby_version_is "2.7" do
+  describe "delegation with def(...)" do
+    it "delegates rest and kwargs" do
+      a = Class.new(DelegationSpecs::Target)
+      a.class_eval(<<-RUBY)
+        def delegate(...)
+          target(...)
+        end
+      RUBY
+
+      a.new.delegate(1, b: 2).should == [[1], {b: 2}]
+    end
+
+    it "delegates block" do
+      a = Class.new(DelegationSpecs::Target)
+      a.class_eval(<<-RUBY)
+        def delegate_block(...)
+          target_block(...)
+        end
+      RUBY
+
+      a.new.delegate_block(1, b: 2) { |x| x }.should == [{b: 2}, [1]]
+    end
+
+    it "parses as open endless Range when brackets are ommitted" do
+      a = Class.new(DelegationSpecs::Target)
+      suppress_warning do
+        a.class_eval(<<-RUBY)
+          def delegate(...)
+            target ...
+          end
+         RUBY
+       end
+
+       a.new.delegate(1, b: 2).should == Range.new([[], {}], nil, true)
+    end
+  end
+end
diff --git a/spec/ruby/language/fixtures/delegation.rb b/spec/ruby/language/fixtures/delegation.rb
new file mode 100644
index 0000000000..527d928390
--- /dev/null
+++ b/spec/ruby/language/fixtures/delegation.rb
@@ -0,0 +1,11 @@
+module DelegationSpecs
+  class Target
+    def target(*args, **kwargs)
+      [args, kwargs]
+    end
+
+    def target_block(*args, **kwargs)
+      yield [kwargs, args]
+    end
+  end
+end
diff --git a/spec/ruby/language/pattern_matching_spec.rb b/spec/ruby/language/pattern_matching_spec.rb
index 6a6de506ff..f84d84c241 100644
--- a/spec/ruby/language/pattern_matching_spec.rb
+++ b/spec/ruby/language/pattern_matching_spec.rb
@@ -402,6 +402,17 @@ ruby_version_is "2.7" do
           RUBY
         }.should raise_error(SyntaxError, /illegal variable in alternative pattern/)
       end
+
+      it "support undescore prefixed variables in alternation" do
+        eval(<<~RUBY).should == true
+          case [0, 1]
+            in [1, _]
+              false
+            in [0, 0] | [0, _a]
+              true
+          end
+        RUBY
+      end
     end
 
     describe "AS pattern" do
@@ -962,5 +973,79 @@ ruby_version_is "2.7" do
         RUBY
       end
     end
+
+    describe "refinements" do
+      it "are used for #deconstruct" do
+        refinery = Module.new do
+          refine Array do
+            def deconstruct
+              [0]
+            end
+          end
+        end
+
+        result = nil
+        Module.new do
+          using refinery
+
+          result = eval(<<~RUBY)
+            case []
+              in [0]
+                true
+            end
+          RUBY
+        end
+
+        result.should == true
+      end
+
+      it "are used for #deconstruct_keys" do
+        refinery = Module.new do
+          refine Hash do
+            def deconstruct_keys(_)
+              {a: 0}
+            end
+          end
+        end
+
+        result = nil
+        Module.new do
+          using refinery
+
+          result = eval(<<~RUBY)
+            case {}
+              in a: 0
+                true
+            end
+          RUBY
+        end
+
+        result.should == true
+      end
+
+      it "are used for #=== in constant pattern" do
+        refinery = Module.new do
+          refine Array.singleton_class do
+            def ===(obj)
+              obj.is_a?(Hash)
+            end
+          end
+        end
+
+        result = nil
+        Module.new do
+          using refinery
+
+          result = eval(<<~RUBY)
+            case {}
+              in Array
+                true
+            end
+          RUBY
+        end
+
+        result.should == true
+      end
+    end
   end
 end
diff --git a/spec/ruby/language/variables_spec.rb b/spec/ruby/language/variables_spec.rb
index 868603eb88..7c2c7889f1 100644
--- a/spec/ruby/language/variables_spec.rb
+++ b/spec/ruby/language/variables_spec.rb
@@ -354,6 +354,16 @@ describe "Multiple assignment" do
       a.should be_an_instance_of(Array)
     end
 
+    it "unfreezes the array returned from calling 'to_a' on the splatted value" do
+      obj = Object.new
+      def obj.to_a
+        [1,2].freeze
+      end
+      res = *obj
+      res.should == [1,2]
+      res.frozen?.should == false
+    end
+
     it "consumes values for an anonymous splat" do
       a = 1
       (* = *a).should == [1]
diff --git a/spec/ruby/library/cgi/escapeHTML_spec.rb b/spec/ruby/library/cgi/escapeHTML_spec.rb
index dcbfebe720..421aac5d4a 100644
--- a/spec/ruby/library/cgi/escapeHTML_spec.rb
+++ b/spec/ruby/library/cgi/escapeHTML_spec.rb
@@ -6,6 +6,10 @@ describe "CGI.escapeHTML" do
     CGI.escapeHTML(%[& < > " ']).should == '&amp; &lt; &gt; &quot; &#39;'
   end
 
+  it "escapes invalid encoding" do
+    CGI.escapeHTML(%[<\xA4??>]).should == "&lt;\xA4??&gt;"
+  end
+
   it "does not escape any other characters" do
     chars = " !\#$%()*+,-./0123456789:;=?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_`abcdefghijklmnopqrstuvwxyz{|}~"
     CGI.escapeHTML(chars).should == chars
diff --git a/spec/ruby/library/stringio/binmode_spec.rb b/spec/ruby/library/stringio/binmode_spec.rb
index 5d9a8c41df..83178787f3 100644
--- a/spec/ruby/library/stringio/binmode_spec.rb
+++ b/spec/ruby/library/stringio/binmode_spec.rb
@@ -6,4 +6,18 @@ describe "StringIO#binmode" do
     io = StringIO.new("example")
     io.binmode.should equal(io)
   end
+
+  it "changes external encoding to BINARY" do
+    io = StringIO.new
+    io.external_encoding.should == Encoding.find('locale')
+    io.binmode
+    io.external_encoding.should == Encoding::BINARY
+  end
+
+  it "does not set internal encoding" do
+    io = StringIO.new
+    io.internal_encoding.should == nil
+    io.binmode
+    io.internal_encoding.should == nil
+  end
 end
diff --git a/spec/ruby/library/stringio/inspect_spec.rb b/spec/ruby/library/stringio/inspect_spec.rb
new file mode 100644
index 0000000000..7c02f8d360
--- /dev/null
+++ b/spec/ruby/library/stringio/inspect_spec.rb
@@ -0,0 +1,19 @@
+require_relative '../../spec_helper'
+require "stringio"
+
+describe "StringIO#inspect" do
+  it "returns the same as #to_s" do
+    io = StringIO.new("example")
+    io.inspect.should == io.to_s
+  end
+
+  it "does not include the contents" do
+    io = StringIO.new("contents")
+    io.inspect.should_not include("contents")
+  end
+
+  it "uses the regular Object#inspect without any instance variable" do
+    io = StringIO.new("example")
+    io.inspect.should =~ /\A#<StringIO:0x\h+>\z/
+  end
+end
diff --git a/spec/ruby/library/yaml/add_builtin_type_spec.rb b/spec/ruby/library/yaml/add_builtin_type_spec.rb
deleted file mode 100644
index 44c820940f..0000000000
--- a/spec/ruby/library/yaml/add_builtin_type_spec.rb
+++ /dev/null
@@ -1,2 +0,0 @@
-require_relative '../../spec_helper'
-require_relative 'fixtures/common'
diff --git a/spec/ruby/library/yaml/add_domain_type_spec.rb b/spec/ruby/library/yaml/add_domain_type_spec.rb
deleted file mode 100644
index 44c820940f..0000000000
--- a/spec/ruby/library/yaml/add_domain_type_spec.rb
+++ /dev/null
@@ -1,2 +0,0 @@
-require_relative '../../spec_helper'
-require_relative 'fixtures/common'
diff --git a/spec/ruby/library/yaml/add_private_type_spec.rb b/spec/ruby/library/yaml/add_private_type_spec.rb
deleted file mode 100644
index 44c820940f..0000000000
--- a/spec/ruby/library/yaml/add_private_type_spec.rb
+++ /dev/null
@@ -1,2 +0,0 @@
-require_relative '../../spec_helper'
-require_relative 'fixtures/common'
diff --git a/spec/ruby/library/yaml/add_ruby_type_spec.rb b/spec/ruby/library/yaml/add_ruby_type_spec.rb
deleted file mode 100644
index 44c820940f..0000000000
--- a/spec/ruby/library/yaml/add_ruby_type_spec.rb
+++ /dev/null
@@ -1,2 +0,0 @@
-require_relative '../../spec_helper'
-require_relative 'fixtures/common'
diff --git a/spec/ruby/library/yaml/detect_implicit_spec.rb b/spec/ruby/library/yaml/detect_implicit_spec.rb
deleted file mode 100644
index 44c820940f..0000000000
--- a/spec/ruby/library/yaml/detect_implicit_spec.rb
+++ /dev/null
@@ -1,2 +0,0 @@
-require_relative '../../spec_helper'
-require_relative 'fixtures/common'
diff --git a/spec/ruby/library/yaml/each_node_spec.rb b/spec/ruby/library/yaml/each_node_spec.rb
deleted file mode 100644
index 44c820940f..0000000000
--- a/spec/ruby/library/yaml/each_node_spec.rb
+++ /dev/null
@@ -1,2 +0,0 @@
-require_relative '../../spec_helper'
-require_relative 'fixtures/common'
diff --git a/spec/ruby/library/yaml/emitter_spec.rb b/spec/ruby/library/yaml/emitter_spec.rb
deleted file mode 100644
index 44c820940f..0000000000
--- a/spec/ruby/library/yaml/emitter_spec.rb
+++ /dev/null
@@ -1,2 +0,0 @@
-require_relative '../../spec_helper'
-require_relative 'fixtures/common'
diff --git a/spec/ruby/library/yaml/generic_parser_spec.rb b/spec/ruby/library/yaml/generic_parser_spec.rb
deleted file mode 100644
index 44c820940f..0000000000
--- a/spec/ruby/library/yaml/generic_parser_spec.rb
+++ /dev/null
@@ -1,2 +0,0 @@
-require_relative '../../spec_helper'
-require_relative 'fixtures/common'
diff --git a/spec/ruby/library/yaml/object_maker_spec.rb b/spec/ruby/library/yaml/object_maker_spec.rb
deleted file mode 100644
index 44c820940f..0000000000
--- a/spec/ruby/library/yaml/object_maker_spec.rb
+++ /dev/null
@@ -1,2 +0,0 @@
-require_relative '../../spec_helper'
-require_relative 'fixtures/common'
diff --git a/spec/ruby/library/yaml/parse_documents_spec.rb b/spec/ruby/library/yaml/parse_documents_spec.rb
deleted file mode 100644
index 44c820940f..0000000000
--- a/spec/ruby/library/yaml/parse_documents_spec.rb
+++ /dev/null
@@ -1,2 +0,0 @@
-require_relative '../../spec_helper'
-require_relative 'fixtures/common'
diff --git a/spec/ruby/library/yaml/parser_spec.rb b/spec/ruby/library/yaml/parser_spec.rb
deleted file mode 100644
index 44c820940f..0000000000
--- a/spec/ruby/library/yaml/parser_spec.rb
+++ /dev/null
@@ -1,2 +0,0 @@
-require_relative '../../spec_helper'
-require_relative 'fixtures/common'
diff --git a/spec/ruby/library/yaml/quick_emit_spec.rb b/spec/ruby/library/yaml/quick_emit_spec.rb
deleted file mode 100644
index 44c820940f..0000000000
--- a/spec/ruby/library/yaml/quick_emit_spec.rb
+++ /dev/null
@@ -1,2 +0,0 @@
-require_relative '../../spec_helper'
-require_relative 'fixtures/common'
diff --git a/spec/ruby/library/yaml/read_type_class_spec.rb b/spec/ruby/library/yaml/read_type_class_spec.rb
deleted file mode 100644
index 44c820940f..0000000000
--- a/spec/ruby/library/yaml/read_type_class_spec.rb
+++ /dev/null
@@ -1,2 +0,0 @@
-require_relative '../../spec_helper'
-require_relative 'fixtures/common'
diff --git a/spec/ruby/library/yaml/transfer_spec.rb b/spec/ruby/library/yaml/transfer_spec.rb
deleted file mode 100644
index 44c820940f..0000000000
--- a/spec/ruby/library/yaml/transfer_spec.rb
+++ /dev/null
@@ -1,2 +0,0 @@
-require_relative '../../spec_helper'
-require_relative 'fixtures/common'
diff --git a/spec/ruby/library/yaml/try_implicit_spec.rb b/spec/ruby/library/yaml/try_implicit_spec.rb
deleted file mode 100644
index 44c820940f..0000000000
--- a/spec/ruby/library/yaml/try_implicit_spec.rb
+++ /dev/null
@@ -1,2 +0,0 @@
-require_relative '../../spec_helper'
-require_relative 'fixtures/common'
diff --git a/spec/ruby/optional/capi/README b/spec/ruby/optional/capi/README
index 57b0c51f01..069ca3c106 100644
--- a/spec/ruby/optional/capi/README
+++ b/spec/ruby/optional/capi/README
@@ -8,9 +8,6 @@ specs:
     optional/capi/array_spec.rb
 2.  Put the C file containing the C functions for array_spec.rb in
     optional/capi/ext/array_spec.c
-3.  Add a '#define HAVE_RB_ARY_NEW  1' to rubyspec.h
-4.  Name the C extension class 'CApiArraySpecs'.
-5.  Name the C functions 'array_spec_rb_ary_new'.
-6.  Wrap the code in the optional/capi/ext/array_spec.c in
-    '#ifdef HAVE_RB_ARY_NEW'
-7.  Attach the C function to the class using the name 'rb_ary_new'
+3.  Name the C extension class 'CApiArraySpecs'.
+4.  Name the C functions 'array_spec_rb_ary_new'.
+5.  Attach the C function to the class using the name 'rb_ary_new'
diff --git a/spec/ruby/optional/capi/array_spec.rb b/spec/ruby/optional/capi/array_spec.rb
index cf65bc19b6..6bb20e5921 100644
--- a/spec/ruby/optional/capi/array_spec.rb
+++ b/spec/ruby/optional/capi/array_spec.rb
@@ -272,6 +272,16 @@ describe "C-API Array function" do
     end
   end
 
+  describe "RARRAY_ASET" do
+    # This macro does NOT do any bounds checking!
+    it "writes an element in the array" do
+      ary = [1, 2, 3]
+      @s.RARRAY_ASET(ary, 0, 0)
+      @s.RARRAY_ASET(ary, 2, 42)
+      ary.should == [0, 2, 42]
+    end
+  end
+
   describe "rb_assoc_new" do
     it "returns an array containing the two elements" do
       @s.rb_assoc_new(1, 2).should == [1, 2]
diff --git a/spec/ruby/optional/capi/ext/array_spec.c b/spec/ruby/optional/capi/ext/array_spec.c
index 454cf03303..afd6aeef15 100644
--- a/spec/ruby/optional/capi/ext/array_spec.c
+++ b/spec/ruby/optional/capi/ext/array_spec.c
@@ -54,6 +54,11 @@ static VALUE array_spec_RARRAY_AREF(VALUE self, VALUE array, VALUE index) {
   return RARRAY_AREF(array, FIX2INT(index));
 }
 
+static VALUE array_spec_RARRAY_ASET(VALUE self, VALUE array, VALUE index, VALUE value) {
+  RARRAY_ASET(array, FIX2INT(index), value);
+  return value;
+}
+
 static VALUE array_spec_rb_ary_aref(int argc, VALUE *argv, VALUE self) {
   VALUE ary, args;
   rb_scan_args(argc, argv, "1*", &ary, &args);
@@ -244,6 +249,7 @@ void Init_array_spec(void) {
   rb_define_method(cls, "RARRAY_PTR_assign", array_spec_RARRAY_PTR_assign, 2);
   rb_define_method(cls, "RARRAY_PTR_memcpy", array_spec_RARRAY_PTR_memcpy, 2);
   rb_define_method(cls, "RARRAY_AREF", array_spec_RARRAY_AREF, 2);
+  rb_define_method(cls, "RARRAY_ASET", array_spec_RARRAY_ASET, 3);
   rb_define_method(cls, "rb_ary_aref", array_spec_rb_ary_aref, -1);
   rb_define_method(cls, "rb_ary_clear", array_spec_rb_ary_clear, 1);
   rb_define_method(cls, "rb_ary_delete", array_spec_rb_ary_delete, 2);
diff --git a/spec/ruby/optional/capi/ext/bignum_spec.c b/spec/ruby/optional/capi/ext/bignum_spec.c
index 14a51f5099..a950d8b16f 100644
--- a/spec/ruby/optional/capi/ext/bignum_spec.c
+++ b/spec/ruby/optional/capi/ext/bignum_spec.c
@@ -65,7 +65,7 @@ static VALUE bignum_spec_rb_big_pack_array(VALUE self, VALUE val, VALUE len) {
   long long_len = NUM2LONG(len);
 
   VALUE ary = rb_ary_new_capa(long_len);
-  unsigned long *buf = malloc(long_len * SIZEOF_LONG);
+  unsigned long *buf = (unsigned long*) malloc(long_len * SIZEOF_LONG);
 
   /* The array should be filled with recognisable junk so we can check
      it is all cleared properly. */
@@ -102,5 +102,5 @@ void Init_bignum_spec(void) {
 }
 
 #ifdef __cplusplus
-extern "C" {
+}
 #endif
diff --git a/spec/ruby/optional/capi/ext/boolean_spec.c b/spec/ruby/optional/capi/ext/boolean_spec.c
index 7bb6fe569d..081cffa103 100644
--- a/spec/ruby/optional/capi/ext/boolean_spec.c
+++ b/spec/ruby/optional/capi/ext/boolean_spec.c
@@ -29,5 +29,5 @@ void Init_boolean_spec(void) {
 }
 
 #ifdef __cplusplus
-extern "C" {
+}
 #endif
diff --git a/spec/ruby/optional/capi/ext/class_id_under_autoload_spec.c b/spec/ruby/optional/capi/ext/class_id_under_autoload_spec.c
index 64393a9397..cc5550f041 100644
--- a/spec/ruby/optional/capi/ext/class_id_under_autoload_spec.c
+++ b/spec/ruby/optional/capi/ext/class_id_under_autoload_spec.c
@@ -1,5 +1,13 @@
 #include "ruby.h"
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 void Init_class_id_under_autoload_spec(void) {
   rb_define_class_id_under(rb_cObject, rb_intern("ClassIdUnderAutoload"), rb_cObject);
 }
+
+#ifdef __cplusplus
+}
+#endif
diff --git a/spec/ruby/optional/capi/ext/class_spec.c b/spec/ruby/optional/capi/ext/class_spec.c
index 6e5c02e657..e62b9efe2e 100644
--- a/spec/ruby/optional/capi/ext/class_spec.c
+++ b/spec/ruby/optional/capi/ext/class_spec.c
@@ -45,7 +45,7 @@ static VALUE class_spec_rb_class_new_instance(VALUE self,
                                       VALUE nargs, VALUE args,
                                       VALUE klass) {
   int c_nargs = FIX2INT(nargs);
-  VALUE *c_args = alloca(sizeof(VALUE) * c_nargs);
+  VALUE *c_args = (VALUE*)alloca(sizeof(VALUE) * c_nargs);
   int i;
 
   for (i = 0; i < c_nargs; i++)
diff --git a/spec/ruby/optional/capi/ext/class_under_autoload_spec.c b/spec/ruby/optional/capi/ext/class_under_autoload_spec.c
index 120dec7327..e0b1f249c0 100644
--- a/spec/ruby/optional/capi/ext/class_under_autoload_spec.c
+++ b/spec/ruby/optional/capi/ext/class_under_autoload_spec.c
@@ -1,5 +1,13 @@
 #include "ruby.h"
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 void Init_class_under_autoload_spec(void) {
   rb_define_class_under(rb_cObject, "ClassUnderAutoload", rb_cObject);
 }
+
+#ifdef __cplusplus
+}
+#endif
diff --git a/spec/ruby/optional/capi/ext/data_spec.c b/spec/ruby/optional/capi/ext/data_spec.c
index a41666f655..109bded1d1 100644
--- a/spec/ruby/optional/capi/ext/data_spec.c
+++ b/spec/ruby/optional/capi/ext/data_spec.c
@@ -19,7 +19,7 @@ void sample_wrapped_struct_mark(void* st) {
 }
 
 VALUE sdaf_alloc_func(VALUE klass) {
-  struct sample_wrapped_struct* bar = malloc(sizeof(struct sample_wrapped_struct));
+  struct sample_wrapped_struct* bar = (struct sample_wrapped_struct*) malloc(sizeof(struct sample_wrapped_struct));
   bar->foo = 42;
   return Data_Wrap_Struct(klass, &sample_wrapped_struct_mark, &sample_wrapped_struct_free, bar);
 }
@@ -32,7 +32,7 @@ VALUE sdaf_get_struct(VALUE self) {
 }
 
 VALUE sws_wrap_struct(VALUE self, VALUE val) {
-  struct sample_wrapped_struct* bar = malloc(sizeof(struct sample_wrapped_struct));
+  struct sample_wrapped_struct* bar = (struct sample_wrapped_struct*) malloc(sizeof(struct sample_wrapped_struct));
   bar->foo = FIX2INT(val);
   return Data_Wrap_Struct(rb_cObject, &sample_wrapped_struct_mark, &sample_wrapped_struct_free, bar);
 }
@@ -58,9 +58,9 @@ VALUE sws_get_struct_data_ptr(VALUE self, VALUE obj) {
 
 VALUE sws_change_struct(VALUE self, VALUE obj, VALUE new_val) {
   struct sample_wrapped_struct *old_struct, *new_struct;
-  new_struct = malloc(sizeof(struct sample_wrapped_struct));
+  new_struct = (struct sample_wrapped_struct*) malloc(sizeof(struct sample_wrapped_struct));
   new_struct->foo = FIX2INT(new_val);
-  old_struct = RDATA(obj)->data;
+  old_struct = (struct sample_wrapped_struct*) RDATA(obj)->data;
   free(old_struct);
   RDATA(obj)->data = new_struct;
   return Qnil;
diff --git a/spec/ruby/optional/capi/ext/gc_spec.c b/spec/ruby/optional/capi/ext/gc_spec.c
index 983b021df9..4611617c18 100644
--- a/spec/ruby/optional/capi/ext/gc_spec.c
+++ b/spec/ruby/optional/capi/ext/gc_spec.c
@@ -16,15 +16,15 @@ static VALUE registered_reference_address(VALUE self) {
   return registered_reference_value;
 }
 
-static VALUE gc_spec_rb_gc_enable() {
+static VALUE gc_spec_rb_gc_enable(VALUE self) {
   return rb_gc_enable();
 }
 
-static VALUE gc_spec_rb_gc_disable() {
+static VALUE gc_spec_rb_gc_disable(VALUE self) {
   return rb_gc_disable();
 }
 
-static VALUE gc_spec_rb_gc() {
+static VALUE gc_spec_rb_gc(VALUE self) {
   rb_gc();
   return Qnil;
 }
diff --git a/spec/ruby/optional/capi/ext/globals_spec.c b/spec/ruby/optional/capi/ext/globals_spec.c
index f70622f66c..75860d3774 100644
--- a/spec/ruby/optional/capi/ext/globals_spec.c
+++ b/spec/ruby/optional/capi/ext/globals_spec.c
@@ -7,12 +7,16 @@ extern "C" {
 
 VALUE g_hooked_var;
 
+VALUE var_2x_getter(ID id, VALUE *data) {
+  return *data;
+}
+
 void var_2x_setter(VALUE val, ID id, VALUE *var) {
-    *var = INT2NUM(NUM2INT(val) * 2);
+  *var = INT2NUM(NUM2INT(val) * 2);
 }
 
 static VALUE sb_define_hooked_variable(VALUE self, VALUE var_name) {
-  rb_define_hooked_variable(StringValuePtr(var_name), &g_hooked_var, 0, var_2x_setter);
+  rb_define_hooked_variable(StringValuePtr(var_name), &g_hooked_var, var_2x_getter, var_2x_setter);
   return Qnil;
 }
 
diff --git a/spec/ruby/optional/capi/ext/integer_spec.c b/spec/ruby/optional/capi/ext/integer_spec.c
index 7e9e8b26bd..124591e231 100644
--- a/spec/ruby/optional/capi/ext/integer_spec.c
+++ b/spec/ruby/optional/capi/ext/integer_spec.c
@@ -30,5 +30,5 @@ void Init_integer_spec(void) {
 }
 
 #ifdef __cplusplus
-extern "C" {
+}
 #endif
diff --git a/spec/ruby/optional/capi/ext/io_spec.c b/spec/ruby/optional/capi/ext/io_spec.c
index 45f57810db..59613c110f 100644
--- a/spec/ruby/optional/capi/ext/io_spec.c
+++ b/spec/ruby/optional/capi/ext/io_spec.c
@@ -43,7 +43,7 @@ VALUE io_spec_rb_io_addstr(VALUE self, VALUE io, VALUE str) {
 
 VALUE io_spec_rb_io_printf(VALUE self, VALUE io, VALUE ary) {
   long argc = RARRAY_LEN(ary);
-  VALUE *argv = alloca(sizeof(VALUE) * argc);
+  VALUE *argv = (VALUE*) alloca(sizeof(VALUE) * argc);
   int i;
 
   for (i = 0; i < argc; i++) {
@@ -55,7 +55,7 @@ VALUE io_spec_rb_io_printf(VALUE self, VALUE io, VALUE ary) {
 
 VALUE io_spec_rb_io_print(VALUE self, VALUE io, VALUE ary) {
   long argc = RARRAY_LEN(ary);
-  VALUE *argv = alloca(sizeof(VALUE) * argc);
+  VALUE *argv = (VALUE*) alloca(sizeof(VALUE) * argc);
   int i;
 
   for (i = 0; i < argc; i++) {
@@ -67,7 +67,7 @@ VALUE io_spec_rb_io_print(VALUE self, VALUE io, VALUE ary) {
 
 VALUE io_spec_rb_io_puts(VALUE self, VALUE io, VALUE ary) {
   long argc = RARRAY_LEN(ary);
-  VALUE *argv = alloca(sizeof(VALUE) * argc);
+  VALUE *argv = (VALUE*) alloca(sizeof(VALUE) * argc);
   int i;
 
   for (i = 0; i < argc; i++) {
diff --git a/spec/ruby/optional/capi/ext/kernel_spec.c b/spec/ruby/optional/capi/ext/kernel_spec.c
index c5bb4a1d9a..13d9598125 100644
--- a/spec/ruby/optional/capi/ext/kernel_spec.c
+++ b/spec/ruby/optional/capi/ext/kernel_spec.c
@@ -68,7 +68,7 @@ VALUE rb_block_call_extra_data(VALUE self, VALUE object) {
 }
 
 VALUE kernel_spec_rb_block_call_no_func(VALUE self, VALUE ary) {
-  return rb_block_call(ary, rb_intern("map"), 0, NULL, NULL, Qnil);
+  return rb_block_call(ary, rb_intern("map"), 0, NULL, (rb_block_call_func_t)NULL, Qnil);
 }
 
 
@@ -153,6 +153,10 @@ VALUE kernel_spec_rb_rescue(VALUE self, VALUE main_proc, VALUE arg,
   rb_ary_push(main_array, main_proc);
   rb_ary_push(main_array, arg);
 
+  if (raise_proc == Qnil) {
+    return rb_rescue(kernel_spec_call_proc, main_array, NULL, arg2);
+  }
+
   raise_array = rb_ary_new();
   rb_ary_push(raise_array, raise_proc);
   rb_ary_push(raise_array, arg2);
diff --git a/spec/ruby/optional/capi/ext/language_spec.c b/spec/ruby/optional/capi/ext/language_spec.c
new file mode 100644
index 0000000000..5aeac63f53
--- /dev/null
+++ b/spec/ruby/optional/capi/ext/language_spec.c
@@ -0,0 +1,34 @@
+#include "ruby.h"
+#include "rubyspec.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+static VALUE language_spec_switch(VALUE self, VALUE value) {
+  if (value == ID2SYM(rb_intern("undef"))) {
+    value = Qundef;
+  }
+
+  switch (value) {
+    case Qtrue:
+      return ID2SYM(rb_intern("true"));
+    case Qfalse:
+      return ID2SYM(rb_intern("false"));
+    case Qnil:
+      return ID2SYM(rb_intern("nil"));
+    case Qundef:
+      return ID2SYM(rb_intern("undef"));
+    default:
+      return ID2SYM(rb_intern("default"));
+  }
+}
+
+void Init_language_spec(void) {
+  VALUE cls = rb_define_class("CApiLanguageSpecs", rb_cObject);
+  rb_define_method(cls, "switch", language_spec_switch, 1);
+}
+
+#ifdef __cplusplus
+}
+#endif
diff --git a/spec/ruby/optional/capi/ext/module_under_autoload_spec.c b/spec/ruby/optional/capi/ext/module_under_autoload_spec.c
index c8f19a287b..b19466e555 100644
--- a/spec/ruby/optional/capi/ext/module_under_autoload_spec.c
+++ b/spec/ruby/optional/capi/ext/module_under_autoload_spec.c
@@ -1,7 +1,15 @@
 #include "ruby.h"
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 void Init_module_under_autoload_spec(void) {
   VALUE specs = rb_const_get(rb_cObject, rb_intern("CApiModuleSpecs"));
   rb_define_module_under(specs, "ModuleUnderAutoload");
   rb_define_module_under(specs, "RubyUnderAutoload");
 }
+
+#ifdef __cplusplus
+}
+#endif
diff --git a/spec/ruby/optional/capi/ext/numeric_spec.c b/spec/ruby/optional/capi/ext/numeric_spec.c
index 556c71a587..33f3a18c00 100644
--- a/spec/ruby/optional/capi/ext/numeric_spec.c
+++ b/spec/ruby/optional/capi/ext/numeric_spec.c
@@ -61,6 +61,10 @@ static VALUE numeric_spec_NUM2LONG(VALUE self, VALUE num) {
   return LONG2NUM(NUM2LONG(num));
 }
 
+static VALUE numeric_spec_NUM2SHORT(VALUE self, VALUE num) {
+  return LONG2NUM(NUM2SHORT(num));
+}
+
 static VALUE numeric_spec_NUM2UINT(VALUE self, VALUE num) {
   return ULONG2NUM(NUM2UINT(num));
 }
@@ -109,6 +113,7 @@ void Init_numeric_spec(void) {
   rb_define_method(cls, "NUM2DBL", numeric_spec_NUM2DBL, 1);
   rb_define_method(cls, "NUM2INT", numeric_spec_NUM2INT, 1);
   rb_define_method(cls, "NUM2LONG", numeric_spec_NUM2LONG, 1);
+  rb_define_method(cls, "NUM2SHORT", numeric_spec_NUM2SHORT, 1);
   rb_define_method(cls, "INT2NUM", numeric_spec_INT2NUM, 1);
   rb_define_method(cls, "NUM2UINT", numeric_spec_NUM2UINT, 1);
   rb_define_method(cls, "NUM2ULONG", numeric_spec_NUM2ULONG, 1);
diff --git a/spec/ruby/optional/capi/ext/object_spec.c b/spec/ruby/optional/capi/ext/object_spec.c
index 2151e37e5c..c95e1b553f 100644
--- a/spec/ruby/optional/capi/ext/object_spec.c
+++ b/spec/ruby/optional/capi/ext/object_spec.c
@@ -102,7 +102,7 @@ static VALUE so_rb_obj_dup(VALUE self, VALUE klass) {
 static VALUE so_rb_obj_call_init(VALUE self, VALUE object,
                                  VALUE nargs, VALUE args) {
   int c_nargs = FIX2INT(nargs);
-  VALUE *c_args = alloca(sizeof(VALUE) * c_nargs);
+  VALUE *c_args = (VALUE*) alloca(sizeof(VALUE) * c_nargs);
   int i;
 
   for (i = 0; i < c_nargs; i++)
diff --git a/spec/ruby/optional/capi/ext/proc_spec.c b/spec/ruby/optional/capi/ext/proc_spec.c
index 18fd1997ee..e0bd8b1bbc 100644
--- a/spec/ruby/optional/capi/ext/proc_spec.c
+++ b/spec/ruby/optional/capi/ext/proc_spec.c
@@ -23,6 +23,10 @@ VALUE proc_spec_rb_proc_call(VALUE self, VALUE prc, VALUE args) {
   return rb_proc_call(prc, args);
 }
 
+VALUE proc_spec_rb_obj_is_proc(VALUE self, VALUE prc) {
+  return rb_obj_is_proc(prc);
+}
+
 /* This helper is not strictly necessary but reflects the code in wxRuby that
  * originally exposed issues with this Proc.new behavior.
  */
@@ -61,6 +65,7 @@ void Init_proc_spec(void) {
   rb_define_method(cls, "rb_proc_arity", proc_spec_rb_proc_arity, 1);
   rb_define_method(cls, "rb_proc_call", proc_spec_rb_proc_call, 2);
   rb_define_method(cls, "rb_Proc_new", proc_spec_rb_Proc_new, 1);
+  rb_define_method(cls, "rb_obj_is_proc", proc_spec_rb_obj_is_proc, 1);
 }
 
 #ifdef __cplusplus
diff --git a/spec/ruby/optional/capi/ext/rubyspec.h b/spec/ruby/optional/capi/ext/rubyspec.h
index 78e298fddb..cce3af22f2 100644
--- a/spec/ruby/optional/capi/ext/rubyspec.h
+++ b/spec/ruby/optional/capi/ext/rubyspec.h
@@ -23,6 +23,10 @@
    (RUBY_VERSION_MAJOR == (major) && RUBY_VERSION_MINOR < (minor)) || \
    (RUBY_VERSION_MAJOR == (major) && RUBY_VERSION_MINOR == (minor) && RUBY_VERSION_TEENY < (teeny)))
 
+#if RUBY_VERSION_MAJOR > 2 || (RUBY_VERSION_MAJOR == 2 && RUBY_VERSION_MINOR >= 7)
+#define RUBY_VERSION_IS_2_7
+#endif
+
 #if RUBY_VERSION_MAJOR > 2 || (RUBY_VERSION_MAJOR == 2 && RUBY_VERSION_MINOR >= 6)
 #define RUBY_VERSION_IS_2_6
 #endif
@@ -31,4 +35,26 @@
 #define RUBY_VERSION_IS_2_4
 #endif
 
+#if defined(__cplusplus) && !defined(RUBY_VERSION_IS_2_7)
+/* Ruby < 2.7 needs this to let these function with callbacks and compile in C++ code */
+#define rb_define_method(mod, name, func, argc) rb_define_method(mod, name, RUBY_METHOD_FUNC(func), argc)
+#define rb_define_protected_method(mod, name, func, argc) rb_define_protected_method(mod, name, RUBY_METHOD_FUNC(func), argc)
+#define rb_define_private_method(mod, name, func, argc) rb_define_private_method(mod, name, RUBY_METHOD_FUNC(func), argc)
+#define rb_define_singleton_method(mod, name, func, argc) rb_define_singleton_method(mod, name, RUBY_METHOD_FUNC(func), argc)
+#define rb_define_module_function(mod, name, func, argc) rb_define_module_function(mod, name, RUBY_METHOD_FUNC(func), argc)
+#define rb_define_global_function(name, func, argc) rb_define_global_function(name, RUBY_METHOD_FUNC(func), argc)
+#define rb_iterate(function, arg1, block, arg2) rb_iterate(function, arg1, RUBY_METHOD_FUNC(block), arg2)
+#define rb_hash_foreach(hash, func, farg) rb_hash_foreach(hash, (int (*)(...))func, farg)
+#define st_foreach(tab, func, arg) st_foreach(tab, (int (*)(...))func, arg)
+#define rb_block_call(object, name, args_count, args, block_call_func, data) rb_block_call(object, name, args_count, args, RUBY_METHOD_FUNC(block_call_func), data)
+#define rb_ensure(b_proc, data1, e_proc, data2) rb_ensure(RUBY_METHOD_FUNC(b_proc), data1, RUBY_METHOD_FUNC(e_proc), data2)
+#define rb_rescue(b_proc, data1, e_proc, data2) rb_rescue(RUBY_METHOD_FUNC(b_proc), data1, RUBY_METHOD_FUNC(e_proc), data2)
+#define rb_rescue2(b_proc, data1, e_proc, data2, ...) rb_rescue2(RUBY_METHOD_FUNC(b_proc), data1, RUBY_METHOD_FUNC(e_proc), data2, __VA_ARGS__)
+#define rb_catch(tag, func, data) rb_catch(tag, RUBY_METHOD_FUNC(func), data)
+#define rb_catch_obj(tag, func, data) rb_catch_obj(tag, RUBY_METHOD_FUNC(func), data)
+#define rb_proc_new(fn, arg) rb_proc_new(RUBY_METHOD_FUNC(fn), arg)
+#define rb_thread_create(fn, arg) rb_thread_create(RUBY_METHOD_FUNC(fn), arg)
+#define rb_define_hooked_variable(name, var, getter, setter) rb_define_hooked_variable(name, var, RUBY_METHOD_FUNC(getter), (void (*)(...))setter)
+#endif
+
 #endif
diff --git a/spec/ruby/optional/capi/ext/string_spec.c b/spec/ruby/optional/capi/ext/string_spec.c
index a44e437bba..97f6b031ef 100644
--- a/spec/ruby/optional/capi/ext/string_spec.c
+++ b/spec/ruby/optional/capi/ext/string_spec.c
@@ -284,6 +284,26 @@ VALUE string_spec_RSTRING_PTR_iterate(VALUE self, VALUE str) {
   return Qnil;
 }
 
+VALUE string_spec_RSTRING_PTR_iterate_uint32(VALUE self, VALUE str) {
+  int i;
+  uint32_t* ptr;
+  int l = RSTRING_LEN(str) / sizeof(uint32_t);
+
+  ptr = (uint32_t *)RSTRING_PTR(str);
+  for(i = 0; i < l; i++) {
+    rb_yield(UINT2NUM(ptr[i]));
+  }
+  return Qnil;
+}
+
+VALUE string_spec_RSTRING_PTR_short_memcpy(VALUE self, VALUE str) {
+  // Short memcpy operations may be optimised by the compiler to a single write.
+  if (RSTRING_LEN(str) >= 8) {
+    memcpy(RSTRING_PTR(str), "Infinity", 8);
+  }
+  return str;
+}
+
 VALUE string_spec_RSTRING_PTR_assign(VALUE self, VALUE str, VALUE chr) {
   int i;
   char c;
@@ -362,11 +382,11 @@ static VALUE string_spec_rb_sprintf2(VALUE self, VALUE str, VALUE repl1, VALUE r
 }
 
 static VALUE string_spec_rb_sprintf3(VALUE self, VALUE str) {
-  return rb_sprintf("Result: %"PRIsVALUE".", str);
+  return rb_sprintf("Result: %" PRIsVALUE ".", str);
 }
 
 static VALUE string_spec_rb_sprintf4(VALUE self, VALUE str) {
-  return rb_sprintf("Result: %+"PRIsVALUE".", str);
+  return rb_sprintf("Result: %+" PRIsVALUE ".", str);
 }
 
 static VALUE string_spec_rb_vsprintf_worker(char* fmt, ...) {
@@ -477,6 +497,8 @@ void Init_string_spec(void) {
   rb_define_method(cls, "RSTRING_LEN", string_spec_RSTRING_LEN, 1);
   rb_define_method(cls, "RSTRING_LENINT", string_spec_RSTRING_LENINT, 1);
   rb_define_method(cls, "RSTRING_PTR_iterate", string_spec_RSTRING_PTR_iterate, 1);
+  rb_define_method(cls, "RSTRING_PTR_iterate_uint32", string_spec_RSTRING_PTR_iterate_uint32, 1);
+  rb_define_method(cls, "RSTRING_PTR_short_memcpy", string_spec_RSTRING_PTR_short_memcpy, 1);
   rb_define_method(cls, "RSTRING_PTR_assign", string_spec_RSTRING_PTR_assign, 2);
   rb_define_method(cls, "RSTRING_PTR_set", string_spec_RSTRING_PTR_set, 3);
   rb_define_method(cls, "RSTRING_PTR_after_funcall", string_spec_RSTRING_PTR_after_funcall, 2);
diff --git a/spec/ruby/optional/capi/ext/symbol_spec.c b/spec/ruby/optional/capi/ext/symbol_spec.c
index 27732ae58f..d2ca62d81e 100644
--- a/spec/ruby/optional/capi/ext/symbol_spec.c
+++ b/spec/ruby/optional/capi/ext/symbol_spec.c
@@ -7,6 +7,10 @@
 extern "C" {
 #endif
 
+VALUE symbol_spec_SYMBOL_P(VALUE self, VALUE obj) {
+  return SYMBOL_P(obj) ? Qtrue : Qfalse;
+}
+
 VALUE symbol_spec_rb_intern(VALUE self, VALUE string) {
   return ID2SYM(rb_intern(RSTRING_PTR(string)));
 }
@@ -73,6 +77,7 @@ VALUE symbol_spec_rb_sym2str(VALUE self, VALUE sym) {
 
 void Init_symbol_spec(void) {
   VALUE cls = rb_define_class("CApiSymbolSpecs", rb_cObject);
+  rb_define_method(cls, "SYMBOL_P", symbol_spec_SYMBOL_P, 1);
   rb_define_method(cls, "rb_intern", symbol_spec_rb_intern, 1);
   rb_define_method(cls, "rb_intern2", symbol_spec_rb_intern2, 2);
   rb_define_method(cls, "rb_intern_const", symbol_spec_rb_intern_const, 1);
diff --git a/spec/ruby/optional/capi/ext/thread_spec.c b/spec/ruby/optional/capi/ext/thread_spec.c
index 139652e326..743828b523 100644
--- a/spec/ruby/optional/capi/ext/thread_spec.c
+++ b/spec/ruby/optional/capi/ext/thread_spec.c
@@ -15,7 +15,7 @@
 extern "C" {
 #endif
 
-static VALUE thread_spec_rb_thread_alone() {
+static VALUE thread_spec_rb_thread_alone(VALUE self) {
   return rb_thread_alone() ? Qtrue : Qfalse;
 }
 
@@ -89,7 +89,7 @@ static VALUE thread_spec_rb_thread_call_without_gvl_with_ubf_io(VALUE self) {
   return (VALUE)ret;
 }
 
-static VALUE thread_spec_rb_thread_current() {
+static VALUE thread_spec_rb_thread_current(VALUE self) {
   return rb_thread_current();
 }
 
diff --git a/spec/ruby/optional/capi/ext/typed_data_spec.c b/spec/ruby/optional/capi/ext/typed_data_spec.c
index a2cc53f54d..6eb91b76bf 100644
--- a/spec/ruby/optional/capi/ext/typed_data_spec.c
+++ b/spec/ruby/optional/capi/ext/typed_data_spec.c
@@ -8,7 +8,7 @@ extern "C" {
 #endif
 
 struct sample_typed_wrapped_struct_parent {
-    int foo;
+  int foo;
 };
 
 void sample_typed_wrapped_struct_parent_free(void* st) {
@@ -32,7 +32,7 @@ static const rb_data_type_t sample_typed_wrapped_struct_parent_data_type = {
 };
 
 struct sample_typed_wrapped_struct {
-    int foo;
+  int foo;
 };
 
 void sample_typed_wrapped_struct_free(void* st) {
@@ -61,7 +61,7 @@ static const rb_data_type_t sample_typed_wrapped_struct_data_type = {
 };
 
 struct sample_typed_wrapped_struct_other {
-    int foo;
+  int foo;
 };
 
 void sample_typed_wrapped_struct_other_free(void* st) {
@@ -86,43 +86,45 @@ static const rb_data_type_t sample_typed_wrapped_struct_other_data_type = {
 
 
 VALUE sdaf_alloc_typed_func(VALUE klass) {
-    struct sample_typed_wrapped_struct* bar = (struct sample_typed_wrapped_struct *)malloc(sizeof(struct sample_typed_wrapped_struct));
-    bar->foo = 42;
-    return TypedData_Wrap_Struct(klass, &sample_typed_wrapped_struct_data_type, bar);
+  struct sample_typed_wrapped_struct* bar;
+  bar = (struct sample_typed_wrapped_struct *) malloc(sizeof(struct sample_typed_wrapped_struct));
+  bar->foo = 42;
+  return TypedData_Wrap_Struct(klass, &sample_typed_wrapped_struct_data_type, bar);
 }
 
 VALUE sdaf_typed_get_struct(VALUE self) {
-    struct sample_typed_wrapped_struct* bar;
-    TypedData_Get_Struct(self, struct sample_typed_wrapped_struct, &sample_typed_wrapped_struct_data_type, bar);
+  struct sample_typed_wrapped_struct* bar;
+  TypedData_Get_Struct(self, struct sample_typed_wrapped_struct, &sample_typed_wrapped_struct_data_type, bar);
 
-    return INT2FIX((*bar).foo);
+  return INT2FIX((*bar).foo);
 }
 
 VALUE sws_typed_wrap_struct(VALUE self, VALUE val) {
-    struct sample_typed_wrapped_struct* bar = (struct sample_typed_wrapped_struct *)malloc(sizeof(struct sample_typed_wrapped_struct));
-    bar->foo = FIX2INT(val);
-    return TypedData_Wrap_Struct(rb_cObject, &sample_typed_wrapped_struct_data_type, bar);
+  struct sample_typed_wrapped_struct* bar;
+  bar = (struct sample_typed_wrapped_struct *) malloc(sizeof(struct sample_typed_wrapped_struct));
+  bar->foo = FIX2INT(val);
+  return TypedData_Wrap_Struct(rb_cObject, &sample_typed_wrapped_struct_data_type, bar);
 }
 
 VALUE sws_typed_get_struct(VALUE self, VALUE obj) {
-    struct sample_typed_wrapped_struct* bar;
-    TypedData_Get_Struct(obj, struct sample_typed_wrapped_struct, &sample_typed_wrapped_struct_data_type, bar);
+  struct sample_typed_wrapped_struct* bar;
+  TypedData_Get_Struct(obj, struct sample_typed_wrapped_struct, &sample_typed_wrapped_struct_data_type, bar);
 
-    return INT2FIX((*bar).foo);
+  return INT2FIX((*bar).foo);
 }
 
 VALUE sws_typed_get_struct_different_type(VALUE self, VALUE obj) {
-    struct sample_typed_wrapped_struct_other* bar;
-    TypedData_Get_Struct(obj, struct sample_typed_wrapped_struct_other, &sample_typed_wrapped_struct_other_data_type, bar);
+  struct sample_typed_wrapped_struct_other* bar;
+  TypedData_Get_Struct(obj, struct sample_typed_wrapped_struct_other, &sample_typed_wrapped_struct_other_data_type, bar);
 
-    return INT2FIX((*bar).foo);
+  return INT2FIX((*bar).foo);
 }
 
 VALUE sws_typed_get_struct_parent_type(VALUE self, VALUE obj) {
-    struct sample_typed_wrapped_struct_parent* bar;
-    TypedData_Get_Struct(obj, struct sample_typed_wrapped_struct_parent, &sample_typed_wrapped_struct_parent_data_type, bar);
+  struct sample_typed_wrapped_struct_parent* bar;
+  TypedData_Get_Struct(obj, struct sample_typed_wrapped_struct_parent, &sample_typed_wrapped_struct_parent_data_type, bar);
 
-    return INT2FIX((*bar).foo);
+  return INT2FIX((*bar).foo);
 }
 
 VALUE sws_typed_get_struct_rdata(VALUE self, VALUE obj) {
@@ -138,11 +140,10 @@ VALUE sws_typed_get_struct_data_ptr(VALUE self, VALUE obj) {
 }
 
 VALUE sws_typed_change_struct(VALUE self, VALUE obj, VALUE new_val) {
-  struct sample_typed_wrapped_struct *old_struct, *new_struct;
-  new_struct = (struct sample_typed_wrapped_struct *)malloc(sizeof(struct sample_typed_wrapped_struct));
+  struct sample_typed_wrapped_struct *new_struct;
+  new_struct = (struct sample_typed_wrapped_struct *) malloc(sizeof(struct sample_typed_wrapped_struct));
   new_struct->foo = FIX2INT(new_val);
-  old_struct = RTYPEDDATA(obj)->data;
-  free(old_struct);
+  free(RTYPEDDATA(obj)->data);
   RTYPEDDATA(obj)->data = new_struct;
   return Qnil;
 }
diff --git a/spec/ruby/optional/capi/ext/util_spec.c b/spec/ruby/optional/capi/ext/util_spec.c
index f3c6a1ba58..f7b45de6b6 100644
--- a/spec/ruby/optional/capi/ext/util_spec.c
+++ b/spec/ruby/optional/capi/ext/util_spec.c
@@ -60,8 +60,8 @@ static VALUE util_spec_rb_get_kwargs(VALUE self, VALUE keyword_hash, VALUE keys,
   int values_len = req + (opt < 0 ? -1 - opt : opt);
   int i = 0;
 
-  ID *ids = malloc(sizeof(VALUE) * len);
-  VALUE *results = malloc(sizeof(VALUE) * values_len);
+  ID *ids = (ID*) malloc(sizeof(VALUE) * len);
+  VALUE *results = (VALUE*) malloc(sizeof(VALUE) * values_len);
   int extracted = 0;
   VALUE ary = Qundef;
 
diff --git a/spec/ruby/optional/capi/kernel_spec.rb b/spec/ruby/optional/capi/kernel_spec.rb
index c6fddc3f64..5c272947ab 100644
--- a/spec/ruby/optional/capi/kernel_spec.rb
+++ b/spec/ruby/optional/capi/kernel_spec.rb
@@ -261,28 +261,28 @@ describe "C-API Kernel function" do
   describe "rb_protect" do
     it "will run a function with an argument" do
       proof = [] # Hold proof of work performed after the yield.
-      res = @s.rb_protect_yield(7, proof) { |x| x + 1 }
-      res.should == 8
+      res = @s.rb_protect_yield(77, proof) { |x| x + 1 }
+      res.should == 78
       proof[0].should == 23
     end
 
     it "will allow cleanup code to run after break" do
       proof = [] # Hold proof of work performed after the yield.
-      @s.rb_protect_yield(7, proof) { |x| break }
+      @s.rb_protect_yield(77, proof) { |x| break }
       proof[0].should == 23
     end
 
     it "will allow cleanup code to run after break with value" do
       proof = [] # Hold proof of work performed after the yield.
-      res = @s.rb_protect_yield(7, proof) { |x| break x + 1 }
-      res.should == 8
+      res = @s.rb_protect_yield(77, proof) { |x| break x + 1 }
+      res.should == 78
       proof[0].should == 23
     end
 
     it "will allow cleanup code to run after a raise" do
       proof = [] # Hold proof of work performed after the yield.
       -> do
-        @s.rb_protect_yield(7, proof) { |x| raise NameError}
+        @s.rb_protect_yield(77, proof) { |x| raise NameError}
       end.should raise_error(NameError)
       proof[0].should == 23
     end
@@ -290,7 +290,7 @@ describe "C-API Kernel function" do
     it "will return nil if an error was raised" do
       proof = [] # Hold proof of work performed after the yield.
       -> do
-        @s.rb_protect_yield(7, proof) { |x| raise NameError}
+        @s.rb_protect_yield(77, proof) { |x| raise NameError}
       end.should raise_error(NameError)
       proof[0].should == 23
       proof[1].should == nil
@@ -316,47 +316,47 @@ describe "C-API Kernel function" do
   describe "rb_rescue" do
     before :each do
       @proc = -> x { x }
-      @raise_proc_returns_sentinel = -> *_ { :raise_proc_executed }
-      @raise_proc_returns_arg = -> *a { a }
+      @rescue_proc_returns_sentinel = -> *_ { :rescue_proc_executed }
+      @rescue_proc_returns_arg = -> *a { a }
       @arg_error_proc = -> *_ { raise ArgumentError, '' }
       @std_error_proc = -> *_ { raise StandardError, '' }
       @exc_error_proc = -> *_ { raise Exception, '' }
     end
 
     it "executes passed function" do
-      @s.rb_rescue(@proc, :no_exc, @raise_proc_returns_arg, :exc).should == :no_exc
+      @s.rb_rescue(@proc, :no_exc, @rescue_proc_returns_arg, :exc).should == :no_exc
     end
 
-    it "executes passed 'raise function' if a StandardError exception is raised" do
-      @s.rb_rescue(@arg_error_proc, nil, @raise_proc_returns_sentinel, :exc).should == :raise_proc_executed
-      @s.rb_rescue(@std_error_proc, nil, @raise_proc_returns_sentinel, :exc).should == :raise_proc_executed
+    it "executes the passed 'rescue function' if a StandardError exception is raised" do
+      @s.rb_rescue(@arg_error_proc, nil, @rescue_proc_returns_sentinel, :exc).should == :rescue_proc_executed
+      @s.rb_rescue(@std_error_proc, nil, @rescue_proc_returns_sentinel, :exc).should == :rescue_proc_executed
     end
 
-    it "passes the user supplied argument to the 'raise function' if a StandardError exception is raised" do
-      arg1, _ = @s.rb_rescue(@arg_error_proc, nil, @raise_proc_returns_arg, :exc1)
+    it "passes the user supplied argument to the 'rescue function' if a StandardError exception is raised" do
+      arg1, _ = @s.rb_rescue(@arg_error_proc, nil, @rescue_proc_returns_arg, :exc1)
       arg1.should == :exc1
 
-      arg2, _ = @s.rb_rescue(@std_error_proc, nil, @raise_proc_returns_arg, :exc2)
+      arg2, _ = @s.rb_rescue(@std_error_proc, nil, @rescue_proc_returns_arg, :exc2)
       arg2.should == :exc2
     end
 
-    it "passes the raised exception to the 'raise function' if a StandardError exception is raised" do
-      _, exc1 = @s.rb_rescue(@arg_error_proc, nil, @raise_proc_returns_arg, :exc)
+    it "passes the raised exception to the 'rescue function' if a StandardError exception is raised" do
+      _, exc1 = @s.rb_rescue(@arg_error_proc, nil, @rescue_proc_returns_arg, :exc)
       exc1.class.should == ArgumentError
 
-      _, exc2 = @s.rb_rescue(@std_error_proc, nil, @raise_proc_returns_arg, :exc)
+      _, exc2 = @s.rb_rescue(@std_error_proc, nil, @rescue_proc_returns_arg, :exc)
       exc2.class.should == StandardError
     end
 
     it "raises an exception if passed function raises an exception other than StandardError" do
-      -> { @s.rb_rescue(@exc_error_proc, nil, @raise_proc_returns_arg, nil) }.should raise_error(Exception)
+      -> { @s.rb_rescue(@exc_error_proc, nil, @rescue_proc_returns_arg, nil) }.should raise_error(Exception)
     end
 
-    it "raises an exception if any exception is raised inside 'raise function'" do
+    it "raises an exception if any exception is raised inside the 'rescue function'" do
       -> { @s.rb_rescue(@std_error_proc, nil, @std_error_proc, nil) }.should raise_error(StandardError)
     end
 
-    it "makes $! available only during 'raise function' execution" do
+    it "makes $! available only during the 'rescue function' execution" do
       @s.rb_rescue(@std_error_proc, nil, -> *_ { $! }, nil).class.should == StandardError
       $!.should == nil
     end
@@ -368,6 +368,10 @@ describe "C-API Kernel function" do
 
       proc_caller { break :value }.should == :value
     end
+
+    it "returns nil if the 'rescue function' is null" do
+      @s.rb_rescue(@std_error_proc, nil, nil, nil).should == nil
+    end
   end
 
   describe "rb_rescue2" do
diff --git a/spec/ruby/optional/capi/language_spec.rb b/spec/ruby/optional/capi/language_spec.rb
new file mode 100644
index 0000000000..7605332fbd
--- /dev/null
+++ b/spec/ruby/optional/capi/language_spec.rb
@@ -0,0 +1,31 @@
+require_relative 'spec_helper'
+
+load_extension("language")
+
+describe "C language construct" do
+  before :each do
+    @s = CApiLanguageSpecs.new
+  end
+
+  describe "switch (VALUE)" do
+    it "works for Qtrue" do
+      @s.switch(true).should == :true
+    end
+
+    it "works for Qfalse" do
+      @s.switch(false).should == :false
+    end
+
+    it "works for Qnil" do
+      @s.switch(nil).should == :nil
+    end
+
+    it "works for Qundef" do
+      @s.switch(:undef).should == :undef
+    end
+
+    it "works for the default case" do
+      @s.switch(Object.new).should == :default
+    end
+  end
+end
diff --git a/spec/ruby/optional/capi/numeric_spec.rb b/spec/ruby/optional/capi/numeric_spec.rb
index d76f353850..de7e180414 100644
--- a/spec/ruby/optional/capi/numeric_spec.rb
+++ b/spec/ruby/optional/capi/numeric_spec.rb
@@ -143,6 +143,34 @@ describe "CApiNumericSpecs" do
     end
   end
 
+  describe "NUM2SHORT" do
+    it "raises a TypeError if passed nil" do
+      -> { @s.NUM2SHORT(nil) }.should raise_error(TypeError)
+    end
+
+    it "converts a Float" do
+      @s.NUM2SHORT(4.2).should == 4
+    end
+
+    it "converts a Fixnum" do
+      @s.NUM2SHORT(5).should == 5
+    end
+
+    it "converts -1 to an signed number" do
+      @s.NUM2SHORT(-1).should == -1
+    end
+
+    it "raises a RangeError if the value is more than 32bits" do
+      -> { @s.NUM2SHORT(0xffff_ffff+1) }.should raise_error(RangeError)
+    end
+
+    it "calls #to_int to coerce the value" do
+      obj = mock("number")
+      obj.should_receive(:to_int).and_return(2)
+      @s.NUM2SHORT(obj).should == 2
+    end
+  end
+
   describe "INT2NUM" do
     it "raises a TypeError if passed nil" do
       -> { @s.INT2NUM(nil) }.should raise_error(TypeError)
diff --git a/spec/ruby/optional/capi/proc_spec.rb b/spec/ruby/optional/capi/proc_spec.rb
index 9f9a37cc98..ff119416f6 100644
--- a/spec/ruby/optional/capi/proc_spec.rb
+++ b/spec/ruby/optional/capi/proc_spec.rb
@@ -54,6 +54,25 @@ describe "C-API Proc function" do
       @p.rb_proc_call(prc, [6, 7]).should == 42
     end
   end
+
+  describe "rb_obj_is_proc" do
+    it "returns true for Proc" do
+      prc = Proc.new {|a,b| a * b }
+      @p.rb_obj_is_proc(prc).should be_true
+    end
+
+    it "returns true for subclass of Proc" do
+      prc = Class.new(Proc).new {}
+      @p.rb_obj_is_proc(prc).should be_true
+    end
+
+    it "returns false for non Proc instances" do
+      @p.rb_obj_is_proc("aoeui").should be_false
+      @p.rb_obj_is_proc(123).should be_false
+      @p.rb_obj_is_proc(true).should be_false
+      @p.rb_obj_is_proc([]).should be_false
+    end
+  end
 end
 
 describe "C-API when calling Proc.new from a C function" do
diff --git a/spec/ruby/optional/capi/spec_helper.rb b/spec/ruby/optional/capi/spec_helper.rb
index eda4964b69..30e6196d05 100644
--- a/spec/ruby/optional/capi/spec_helper.rb
+++ b/spec/ruby/optional/capi/spec_helper.rb
@@ -8,12 +8,17 @@ require 'rbconfig'
 OBJDIR ||= File.expand_path("../../../ext/#{RUBY_ENGINE}/#{RUBY_VERSION}", __FILE__)
 
 def object_path
-  mkdir_p(OBJDIR)
-  OBJDIR
+  path = OBJDIR
+  if ENV['SPEC_CAPI_CXX'] == 'true'
+    path = "#{path}/cxx"
+  end
+  mkdir_p(path)
+  path
 end
 
 def compile_extension(name)
   debug = false
+  cxx = ENV['SPEC_CAPI_CXX'] == 'true'
   run_mkmf_in_process = RUBY_ENGINE == 'truffleruby'
 
   core_ext_dir = File.expand_path("../ext", __FILE__)
@@ -54,7 +59,11 @@ def compile_extension(name)
   Dir.mkdir(tmpdir)
   begin
     ["#{core_ext_dir}/rubyspec.h", "#{spec_ext_dir}/#{ext}.c"].each do |file|
-      cp file, "#{tmpdir}/#{File.basename(file)}"
+      if cxx and file.end_with?('.c')
+        cp file, "#{tmpdir}/#{File.basename(file, '.c')}.cpp"
+      else
+        cp file, "#{tmpdir}/#{File.basename(file)}"
+      end
     end
 
     Dir.chdir(tmpdir) do
@@ -64,11 +73,13 @@ def compile_extension(name)
         init_mkmf unless required
         create_makefile(ext, tmpdir)
       else
-        File.write("extconf.rb", "require 'mkmf'\n" +
-          "$ruby = ENV.values_at('RUBY_EXE', 'RUBY_FLAGS').join(' ')\n" +
+        File.write("extconf.rb", <<-RUBY)
+          require 'mkmf'
+          $ruby = ENV.values_at('RUBY_EXE', 'RUBY_FLAGS').join(' ')
           # MRI magic to consider building non-bundled extensions
-          "$extout = nil\n" +
-          "create_makefile(#{ext.inspect})\n")
+          $extout = nil
+          create_makefile(#{ext.inspect})
+        RUBY
         output = ruby_exe("extconf.rb")
         raise "extconf failed:\n#{output}" unless $?.success?
         $stderr.puts output if debug
diff --git a/spec/ruby/optional/capi/string_spec.rb b/spec/ruby/optional/capi/string_spec.rb
index 1ad35b9e8a..243765cdbe 100644
--- a/spec/ruby/optional/capi/string_spec.rb
+++ b/spec/ruby/optional/capi/string_spec.rb
@@ -513,6 +513,24 @@ describe "C-API String function" do
       end
       chars.should == [55, 48, 227, 131, 145, 227, 130, 175]
     end
+
+    it "returns a pointer which can be cast and used as another type" do
+      s = "70パク".
+        encode(Encoding::UTF_16LE).
+        force_encoding(Encoding::UTF_16LE).
+        encode(Encoding::UTF_8)
+
+      ints = []
+      @s.RSTRING_PTR_iterate_uint32(s) do |i|
+        ints << i
+      end
+      ints.should == s.unpack('LL')
+    end
+
+    it "allows a short memcpy to the string which may be converted to a single write operation by the compiler" do
+      str = "        "
+      @s.RSTRING_PTR_short_memcpy(str).should == "Infinity"
+    end
   end
 
   describe "RSTRING_LEN" do
diff --git a/spec/ruby/optional/capi/symbol_spec.rb b/spec/ruby/optional/capi/symbol_spec.rb
index 7f345f879f..0d71c1c711 100644
--- a/spec/ruby/optional/capi/symbol_spec.rb
+++ b/spec/ruby/optional/capi/symbol_spec.rb
@@ -8,6 +8,16 @@ describe "C-API Symbol function" do
     @s = CApiSymbolSpecs.new
   end
 
+  describe "SYMBOL_P" do
+    it "returns true for a Symbol" do
+      @s.SYMBOL_P(:foo).should == true
+    end
+
+    it "returns false for non-Symbols" do
+      @s.SYMBOL_P('bar').should == false
+    end
+  end
+
   describe "rb_intern" do
     it "converts a string to a symbol, uniquely" do
       @s.rb_intern("test_symbol").should == :test_symbol