Add workaround and deprecation if the inherited hook is not executed. Closes #4757.

1 files changed, 12 insertions, 0 deletions

diff --git a/activerecord/lib/active_record/attribute_methods.rb b/activerecord/lib/active_record/attribute_methods.rb
index f3200aa78a..399c22fb18 100644
--- a/activerecord/lib/active_record/attribute_methods.rb
+++ b/activerecord/lib/active_record/attribute_methods.rb
@@ -36,6 +36,18 @@ module ActiveRecord
       # Generates all the attribute related methods for columns in the database
       # accessors, mutators and query methods.
       def define_attribute_methods
+        unless defined?(@attribute_methods_mutex)
+          ActiveSupport::Deprecation.warn(
+            "It looks like something (probably a gem/plugin) is removing or overriding the " \
+            "ActiveRecord::Base.inherited method. It is important that this hook executes so " \
+            "that your models are set up correctly. A workaround has been added to stop this " \
+            "causing an error in 3.2, but future versions will simply not work if the hook is " \
+            "overridden."
+          )
+
+          @attribute_methods_mutex = Mutex.new
+        end
+
         # Use a mutex; we don't want two thread simaltaneously trying to define
         # attribute methods.
         @attribute_methods_mutex.synchronize do