Soft-deprecate the top-level HashWithIndifferentAccess class

Since using a `ActiveSupport::Deprecation::DeprecatedConstantProxy`
would prevent people from inheriting this class and extending it
from the `ActiveSupport::HashWithIndifferentAccess` one would break
the ancestors chain, that's the best option we have here.

3 files changed, 12 insertions, 0 deletions

diff --git a/activesupport/CHANGELOG.md b/activesupport/CHANGELOG.md
index 0f43b1256f..d43927967f 100644
--- a/activesupport/CHANGELOG.md
+++ b/activesupport/CHANGELOG.md
@@ -1,3 +1,9 @@
+*   Soft-deprecated the top-level `HashWithIndifferentAcces` constant.
+    `ActiveSupport::HashWithIndifferentAccess` should be used instead.
+
+    *Robin Dupret* (#28157)
+
+
 ## Rails 5.1.0.beta1 (February 23, 2017) ##
 
 *   Cache `ActiveSupport::TimeWithZone#to_datetime` before freezing.
diff --git a/activesupport/lib/active_support/hash_with_indifferent_access.rb b/activesupport/lib/active_support/hash_with_indifferent_access.rb
index f9b269ad69..1927cddf34 100644
--- a/activesupport/lib/active_support/hash_with_indifferent_access.rb
+++ b/activesupport/lib/active_support/hash_with_indifferent_access.rb
@@ -316,4 +316,6 @@ module ActiveSupport
   end
 end
 
+# :stopdoc:
+
 HashWithIndifferentAccess = ActiveSupport::HashWithIndifferentAccess
diff --git a/activesupport/test/core_ext/hash_ext_test.rb b/activesupport/test/core_ext/hash_ext_test.rb
index a6e3e59433..efe211677e 100644
--- a/activesupport/test/core_ext/hash_ext_test.rb
+++ b/activesupport/test/core_ext/hash_ext_test.rb
@@ -8,6 +8,8 @@ require "active_support/core_ext/object/deep_dup"
 require "active_support/inflections"
 
 class HashExtTest < ActiveSupport::TestCase
+  HashWithIndifferentAccess = ActiveSupport::HashWithIndifferentAccess
+
   class IndifferentHash < ActiveSupport::HashWithIndifferentAccess
   end
 
@@ -1133,6 +1135,8 @@ class HashExtToParamTests < ActiveSupport::TestCase
 end
 
 class HashToXmlTest < ActiveSupport::TestCase
+  HashWithIndifferentAccess = ActiveSupport::HashWithIndifferentAccess
+
   def setup
     @xml_options = { root: :person, skip_instruct: true, indent: 0 }
   end