1 files changed, 46 insertions, 0 deletions
diff --git a/activesupport/lib/active_support/deprecation.rb b/activesupport/lib/active_support/deprecation.rb
new file mode 100644
index 0000000000..7271ab565b
--- /dev/null
+++ b/activesupport/lib/active_support/deprecation.rb
@@ -0,0 +1,46 @@
+# frozen_string_literal: true
+
+require "singleton"
+
+module ActiveSupport
+  # \Deprecation specifies the API used by Rails to deprecate methods, instance
+  # variables, objects and constants.
+  class Deprecation
+    # active_support.rb sets an autoload for ActiveSupport::Deprecation.
+    #
+    # If these requires were at the top of the file the constant would not be
+    # defined by the time their files were loaded. Since some of them reopen
+    # ActiveSupport::Deprecation its autoload would be triggered, resulting in
+    # a circular require warning for active_support/deprecation.rb.
+    #
+    # So, we define the constant first, and load dependencies later.
+    require "active_support/deprecation/instance_delegator"
+    require "active_support/deprecation/behaviors"
+    require "active_support/deprecation/reporting"
+    require "active_support/deprecation/constant_accessor"
+    require "active_support/deprecation/method_wrappers"
+    require "active_support/deprecation/proxy_wrappers"
+    require "active_support/core_ext/module/deprecation"
+
+    include Singleton
+    include InstanceDelegator
+    include Behavior
+    include Reporting
+    include MethodWrapper
+
+    # The version number in which the deprecated behavior will be removed, by default.
+    attr_accessor :deprecation_horizon
+
+    # It accepts two parameters on initialization. The first is a version of library
+    # and the second is a library name.
+    #
+    #   ActiveSupport::Deprecation.new('2.0', 'MyLibrary')
+    def initialize(deprecation_horizon = "6.1", gem_name = "Rails")
+      self.gem_name = gem_name
+      self.deprecation_horizon = deprecation_horizon
+      # By default, warnings are not silenced and debugging is off.
+      self.silenced = false
+      self.debug = false
+    end
+  end
+end