1 files changed, 141 insertions, 10 deletions

diff --git a/test/ruby/test_variable.rb b/test/ruby/test_variable.rb
index 4943449204..a305ad6b2a 100644
--- a/test/ruby/test_variable.rb
+++ b/test/ruby/test_variable.rb
@@ -50,6 +50,11 @@ class TestVariable < Test::Unit::TestCase
   end
 
   Zeus = Gods.clone
+  class Zeus
+    def ruler5
+      @@rule
+    end
+  end
 
   def test_cloned_allows_setting_cvar
     Zeus.class_variable_set(:@@rule, "Athena")
@@ -58,8 +63,12 @@ class TestVariable < Test::Unit::TestCase
     zeus = Zeus.new.ruler0
 
     assert_equal "Cronus", god
-    assert_equal "Athena", zeus
-    assert_not_equal god.object_id, zeus.object_id
+    assert_equal "Cronus", zeus
+
+    assert_equal "Athena", Zeus.new.ruler5
+
+    assert_equal "Cronus", Gods.class_variable_get(:@@rule)
+    assert_equal "Athena", Zeus.class_variable_get(:@@rule)
   end
 
   def test_singleton_class_included_class_variable
@@ -120,6 +129,34 @@ class TestVariable < Test::Unit::TestCase
     TestVariable.send(:remove_const, :Parent) rescue nil
   end
 
+  def test_cvar_cache_invalidated_by_parent_class_variable_set
+    m = Module.new { class_variable_set(:@@x, 1) }
+    a = Class.new
+    b = Class.new(a) do
+      include m
+      class_eval "def self.x; @@x; end"
+    end
+    assert_equal 1, b.x # warm cache
+    a.class_variable_set(:@@x, 2)
+    error = assert_raise(RuntimeError) { b.x }
+    assert_match(/class variable @@x of .+ is overtaken by .+/, error.message)
+  end
+
+  def test_cvar_cache_invalidated_by_module_class_variable_set
+    m = Module.new
+    n = Module.new
+    b = Class.new do
+      include m
+      include n
+      class_eval "def self.x; @@x; end"
+    end
+    m.class_variable_set(:@@x, 1)
+    assert_equal 1, b.x # warm cache
+    n.class_variable_set(:@@x, 2)
+    error = assert_raise(RuntimeError) { b.x }
+    assert_match(/class variable @@x of .+ is overtaken by .+/, error.message)
+  end
+
   def test_cvar_overtaken_by_module
     error = eval <<~EORB
       class ParentForModule
@@ -388,27 +425,77 @@ class TestVariable < Test::Unit::TestCase
     end
   end
 
+  class RemoveIvar
+    class << self
+      attr_reader :ivar
+
+      def add_ivar
+        @ivar = 1
+      end
+    end
+
+    attr_reader :ivar
+
+    def add_ivar
+      @ivar = 1
+    end
+  end
+
+  def add_and_remove_ivar(obj)
+    assert_nil obj.ivar
+    assert_equal 1, obj.add_ivar
+    assert_equal 1, obj.instance_variable_get(:@ivar)
+    assert_equal 1, obj.ivar
+
+    obj.remove_instance_variable(:@ivar)
+    assert_nil obj.ivar
+
+    assert_raise NameError do
+      obj.remove_instance_variable(:@ivar)
+    end
+  end
+
+  def test_remove_instance_variables_object
+    obj = RemoveIvar.new
+    add_and_remove_ivar(obj)
+    add_and_remove_ivar(obj)
+  end
+
+  def test_remove_instance_variables_class
+    add_and_remove_ivar(RemoveIvar)
+    add_and_remove_ivar(RemoveIvar)
+  end
+
+  class RemoveIvarGeneric < Array
+    attr_reader :ivar
+
+    def add_ivar
+      @ivar = 1
+    end
+  end
+
+  def test_remove_instance_variables_generic
+    obj = RemoveIvarGeneric.new
+    add_and_remove_ivar(obj)
+    add_and_remove_ivar(obj)
+  end
+
   class ExIvar < Hash
     def initialize
       @a = 1
       @b = 2
       @c = 3
-      @d = 4
-      @e = 5
-      @f = 6
-      @g = 7
-      @h = 8
     end
 
     def ivars
-      [@a, @b, @c, @d, @e, @f, @g, @h]
+      [@a, @b, @c]
     end
   end
 
   def test_external_ivars
     3.times{
       # check inline cache for external ivar access
-      assert_equal [1, 2, 3, 4, 5, 6, 7, 8], ExIvar.new.ivars
+      assert_equal [1, 2, 3], ExIvar.new.ivars
     }
   end
 
@@ -424,6 +511,7 @@ class TestVariable < Test::Unit::TestCase
         x
       end
     end
+    objs or flunk
   end
 
   def test_local_variables_with_kwarg
@@ -445,12 +533,55 @@ class TestVariable < Test::Unit::TestCase
   end
 
   def test_local_variables_encoding
-    α = 1
+    α = 1 or flunk
     b = binding
     b.eval("".encode("us-ascii"))
     assert_equal(%i[α b], b.local_variables)
   end
 
+  def test_genivar_cache
+    bug21547 = '[Bug #21547]'
+    klass = Class.new(Array)
+    instance = klass.new
+    instance.instance_variable_set(:@a1, 1)
+    instance.instance_variable_set(:@a2, 2)
+    Fiber.new do
+      instance.instance_variable_set(:@a3, 3)
+      instance.instance_variable_set(:@a4, 4)
+    end.resume
+    assert_equal 4, instance.instance_variable_get(:@a4), bug21547
+  end
+
+  def test_genivar_cache_free
+    str = +"hello"
+    str.instance_variable_set(:@x, :old_value)
+
+    str.instance_variable_get(:@x) # populate cache
+
+    Fiber.new {
+      str.remove_instance_variable(:@x)
+      str.instance_variable_set(:@x, :new_value)
+    }.resume
+
+    assert_equal :new_value, str.instance_variable_get(:@x)
+  end
+
+  def test_genivar_cache_invalidated_by_gc
+    str = +"hello"
+    str.instance_variable_set(:@x, :old_value)
+
+    str.instance_variable_get(:@x) # populate cache
+
+    Fiber.new {
+      str.remove_instance_variable(:@x)
+      str.instance_variable_set(:@x, :new_value)
+    }.resume
+
+    GC.start
+
+    assert_equal :new_value, str.instance_variable_get(:@x)
+  end
+
   private
   def with_kwargs_11(v1:, v2:, v3:, v4:, v5:, v6:, v7:, v8:, v9:, v10:, v11:)
     local_variables