1 files changed, 9 insertions, 1 deletions
diff --git a/activesupport/lib/active_support/cache.rb b/activesupport/lib/active_support/cache.rb
index 402a35e198..5011014e96 100644
--- a/activesupport/lib/active_support/cache.rb
+++ b/activesupport/lib/active_support/cache.rb
@@ -8,6 +8,7 @@ require 'active_support/core_ext/numeric/bytes'
 require 'active_support/core_ext/numeric/time'
 require 'active_support/core_ext/object/to_param'
 require 'active_support/core_ext/string/inflections'
+require 'active_support/core_ext/string/strip'
 
 module ActiveSupport
   # See ActiveSupport::Cache::Store for documentation.
@@ -536,7 +537,14 @@ module ActiveSupport
           key = "#{prefix}:#{key}" if prefix
           key
         end
-        alias namespaced_key normalize_key
+
+        def namespaced_key(*args)
+          ActiveSupport::Deprecation.warn(<<-MESSAGE.strip_heredoc)
+            `namespaced_key` is deprecated and will be removed from Rails 5.1.
+            Please use `normalize_key` which will return a fully resolved key.
+          MESSAGE
+          normalize_key(*args)
+        end
 
         def instrument(operation, key, options = nil)
           log { "Cache #{operation}: #{normalize_key(key, options)}#{options.blank? ? "" : " (#{options.inspect})"}" }