Pull in latest class_attribute to fix warnings when not using Rails

lib/sidekiq/core_ext.rb

@@ -2,51 +2,76 @@
 begin
   require 'active_support/core_ext/class/attribute'
 rescue LoadError
-
-  # A dumbed down version of ActiveSupport's
+  # A dumbed down version of ActiveSupport 5.1.0's
   # Class#class_attribute helper.
-  class Class
-    def class_attribute(*attrs)
-      instance_writer = true
-
-      attrs.each do |name|
-        class_eval <<-RUBY, __FILE__, __LINE__ + 1
-          def self.#{name}() nil end
-          def self.#{name}?() !!#{name} end
-
-          def self.#{name}=(val)
-            singleton_class.class_eval do
-              define_method(:#{name}) { val }
-            end
-
-            if singleton_class?
-              class_eval do
-                def #{name}
-                  defined?(@#{name}) ? @#{name} : singleton_class.#{name}
-                end
-              end
-            end
-            val
-          end
-
-          def #{name}
-            defined?(@#{name}) ? @#{name} : self.class.#{name}
-          end
-
-          def #{name}?
-            !!#{name}
-          end
-        RUBY
-
-        attr_writer name if instance_writer
+  class Module
+    # Removes the named method, if it exists.
+    def remove_possible_method(method)
+      if method_defined?(method) || private_method_defined?(method)
+        undef_method(method)
       end
     end
 
-    private
-    def singleton_class?
-      ancestors.first != self
+    # Removes the named singleton method, if it exists.
+    def remove_possible_singleton_method(method)
+      singleton_class.instance_eval do
+        remove_possible_method(method)
+      end
     end
   end
+
+  class Class
+    def class_attribute(*attrs)
+      instance_reader = true
+      instance_writer = true
+
+      attrs.each do |name|
+        remove_possible_singleton_method(name)
+        define_singleton_method(name) { nil }
+
+        ivar = "@#{name}"
+
+        remove_possible_singleton_method("#{name}=")
+        define_singleton_method("#{name}=") do |val|
+          singleton_class.class_eval do
+            remove_possible_method(name)
+            define_method(name) { val }
+          end
+
+          if singleton_class?
+            class_eval do
+              remove_possible_method(name)
+              define_method(name) do
+                if instance_variable_defined? ivar
+                  instance_variable_get ivar
+                else
+                  singleton_class.send name
+                end
+              end
+            end
+          end
+          val
+        end
+
+        if instance_reader
+          remove_possible_method name
+          define_method(name) do
+            if instance_variable_defined?(ivar)
+              instance_variable_get ivar
+            else
+              self.class.public_send name
+            end
+          end
+        end
+
+        if instance_writer
+          remove_possible_method "#{name}="
+          attr_writer name
+        end
+      end
+    end
+
+  end
 end
 
 begin