we don't need to to_s the column
stop exposing the underlying alias datastructure
Remove deprecation messages about protected_attributes and rails-observers
Removed deprecated options for assocations

Deprecated options `delete_sql`, `insert_sql`, `finder_sql` and `counter_sql`
have been deleted.
build an AST rather than slapping strings together
Merge pull request #11222 from neerajdotname/removed-deprecation-for-sql

Removed deprecated options for assocations
only deal with strings internally
make the identity type a singleton to save on object creation
avoid intermediate zipped array
Remove deprecated constants from Action Controller

  ActionController::AbstractRequest  => ActionDispatch::Request
  ActionController::Request          => ActionDispatch::Request
  ActionController::AbstractResponse => ActionDispatch::Response
  ActionController::Response         => ActionDispatch::Response
  ActionController::Routing          => ActionDispatch::Routing
  ActionController::Integration      => ActionDispatch::Integration
  ActionController::IntegrationTest  => ActionDispatch::IntegrationTest
Remove deprecated AS::BasicObject, use AS::ProxyObject instead
Remove deprecated Array#uniq_by and Array#uniq_by!

Use native Array#uniq and Array#uniq! instead.
Remove deprecated `Proc#bind` with no replacement.
Removed deprecated method type_cast_code from Column
Remove deprecated AR::Connection#clear_stale_cached_connections! method
Merge pull request #11231 from neerajdotname/deprecated-type-cast-code

Removed deprecated method type_cast_code from Column
Merge pull request #11230 from frodsan/remove_deprecated_clear_stale_cached_connections_method

Remove AR::Connection#clear_stale_cached_connections! deprecated method
calling default_scope without a proc will raise ArgumentError

Calling default_scope without a proc will now raise `ArgumentError`.
Merge pull request #11229 from neerajdotname/deprecated-default-scope

calling default_scope without a proc will raise ArgumentError
Merge pull request #10604 from neerajdotname/delete_all_should_not_call_callbacks

Do not invoke callbacks when delete_all is called

Conflicts:
	activerecord/CHANGELOG.md