Bring back the valid_options class accessor

It is need in activerecord-deprecated_finders

activerecord/lib/active_record/associations/builder/association.rb

+require 'active_support/core_ext/module/attribute_accessors'
+
 # This is the parent Association class which defines the variables
 # used by all associations.
 #
@@ -16,7 +18,10 @@ class << self
     end
     self.extensions = []
 
-    VALID_OPTIONS = [:class_name, :class, :foreign_key, :validate]
+    # TODO: This class accessor is needed to make activerecord-deprecated_finders work.
+    # We can move it to a constant in 5.0.
+    cattr_accessor :valid_options, instance_accessor: false
+    self.valid_options = [:class_name, :class, :foreign_key, :validate]
 
     def self.build(model, name, scope, options, &block)
       extension = define_extensions model, name, &block
@@ -63,12 +68,12 @@ def self.macro
       raise NotImplementedError
     end
 
-    def self.valid_options(options)
-      VALID_OPTIONS + Association.extensions.flat_map(&:valid_options)
+    def self.build_valid_options(options)
+      self.valid_options + Association.extensions.flat_map(&:valid_options)
     end
 
     def self.validate_options(options)
-      options.assert_valid_keys(valid_options(options))
+      options.assert_valid_keys(build_valid_options(options))
     end
 
     def self.define_extensions(model, name)

activerecord/lib/active_record/associations/builder/belongs_to.rb

@@ -4,7 +4,7 @@ def self.macro
       :belongs_to
     end
 
-    def self.valid_options(options)
+    def self.build_valid_options(options)
       super + [:foreign_type, :polymorphic, :touch, :counter_cache]
     end
 

activerecord/lib/active_record/associations/builder/collection_association.rb

@@ -7,7 +7,7 @@ class CollectionAssociation < Association #:nodoc:
 
     CALLBACKS = [:before_add, :after_add, :before_remove, :after_remove]
 
-    def self.valid_options(options)
+    def self.build_valid_options(options)
       super + [:table_name, :before_add,
                :after_add, :before_remove, :after_remove, :extend]
     end

activerecord/lib/active_record/associations/builder/has_many.rb

@@ -4,7 +4,7 @@ def self.macro
       :has_many
     end
 
-    def self.valid_options(options)
+    def self.build_valid_options(options)
       super + [:primary_key, :dependent, :as, :through, :source, :source_type, :inverse_of, :counter_cache]
     end
 

activerecord/lib/active_record/associations/builder/has_one.rb

@@ -4,7 +4,7 @@ def self.macro
       :has_one
     end
 
-    def self.valid_options(options)
+    def self.build_valid_options(options)
       valid = super + [:order, :as]
       valid += [:through, :source, :source_type] if options[:through]
       valid

activerecord/lib/active_record/associations/builder/singular_association.rb

@@ -2,7 +2,7 @@
 
 module ActiveRecord::Associations::Builder
   class SingularAssociation < Association #:nodoc:
-    def self.valid_options(options)
+    def self.build_valid_options(options)
       super + [:remote, :dependent, :primary_key, :inverse_of]
     end