Self-alias doesn't suppress the warning on Ruby 2.2

activesupport/lib/active_support/core_ext/module/redefine_method.rb

 # frozen_string_literal: true
 
 class Module
-  # Marks the named method as intended to be redefined, if it exists.
-  # Suppresses the Ruby method redefinition warning. Prefer
-  # #redefine_method where possible.
-  def silence_redefinition_of_method(method)
-    if method_defined?(method) || private_method_defined?(method)
-      # This suppresses the "method redefined" warning; the self-alias
-      # looks odd, but means we don't need to generate a unique name
-      alias_method method, method
+  if RUBY_VERSION >= "2.3"
+    # Marks the named method as intended to be redefined, if it exists.
+    # Suppresses the Ruby method redefinition warning. Prefer
+    # #redefine_method where possible.
+    def silence_redefinition_of_method(method)
+      if method_defined?(method) || private_method_defined?(method)
+        # This suppresses the "method redefined" warning; the self-alias
+        # looks odd, but means we don't need to generate a unique name
+        alias_method method, method
+      end
+    end
+  else
+    def silence_redefinition_of_method(method)
+      if method_defined?(method) || private_method_defined?(method)
+        alias_method :__rails_redefine, method
+        remove_method :__rails_redefine
+      end
     end
   end