Allow extra scoping in callbacks when create on association relation

#37523 has a regression that ignore extra scoping in callbacks when
create on association relation.

It should respect `klass.current_scope` even when create on association
relation to allow extra scoping in callbacks.

Fixes #38741.

activerecord/lib/active_record/association_relation.rb

@@ -17,24 +17,18 @@ def ==(other)
 
     def build(attributes = nil, &block)
       block = _deprecated_scope_block("new", &block)
-      @association.scoping(self) do
-        @association.build(attributes, &block)
-      end
+      scoping { @association.build(attributes, &block) }
     end
     alias new build
 
     def create(attributes = nil, &block)
       block = _deprecated_scope_block("create", &block)
-      @association.scoping(self) do
-        @association.create(attributes, &block)
-      end
+      scoping { @association.create(attributes, &block) }
     end
 
     def create!(attributes = nil, &block)
       block = _deprecated_scope_block("create!", &block)
-      @association.scoping(self) do
-        @association.create!(attributes, &block)
-      end
+      scoping { @association.create!(attributes, &block) }
     end
 
     private

activerecord/lib/active_record/associations/association.rb

@@ -41,7 +41,6 @@ def initialize(owner, reflection)
         reflection.check_validity!
 
         @owner, @reflection = owner, reflection
-        @_scope = nil
 
         reset
         reset_scope
@@ -98,7 +97,11 @@ def target=(target)
       end
 
       def scope
-        @_scope&.spawn || target_scope.merge!(association_scope)
+        if (scope = klass.current_scope) && scope.try(:proxy_association) == self
+          scope.spawn
+        else
+          target_scope.merge!(association_scope)
+        end
       end
 
       def reset_scope
@@ -198,13 +201,6 @@ def create!(attributes = nil, &block)
         _create_record(attributes, true, &block)
       end
 
-      def scoping(relation, &block)
-        @_scope = relation
-        relation.scoping(&block)
-      ensure
-        @_scope = nil
-      end
-
       private
         def find_target
           if owner.strict_loading?

activerecord/test/cases/associations/has_many_associations_test.rb

@@ -224,6 +224,18 @@ def test_create_from_association_should_respect_default_scope
   def test_build_and_create_from_association_should_respect_passed_attributes_over_default_scope
     car = Car.create(name: "honda")
 
+    bulb = car.bulbs.where(name: "exotic").build
+    assert_equal "exotic", bulb.name
+    assert_nil bulb.count_after_create
+
+    bulb = car.bulbs.where(name: "exotic").create
+    assert_equal "exotic", bulb.name
+    assert_equal 1, bulb.count_after_create
+
+    bulb = car.bulbs.where(name: "exotic").create!
+    assert_equal "exotic", bulb.name
+    assert_equal 2, bulb.count_after_create
+
     bulb = car.bulbs.build(name: "exotic")
     assert_equal "exotic", bulb.name
 

activerecord/test/models/bulb.rb

@@ -5,7 +5,7 @@ class Bulb < ActiveRecord::Base
   belongs_to :car, touch: true
   scope :awesome, -> { where(frickinawesome: true) }
 
-  attr_reader :scope_after_initialize, :attributes_after_initialize
+  attr_reader :scope_after_initialize, :attributes_after_initialize, :count_after_create
 
   after_initialize :record_scope_after_initialize
   def record_scope_after_initialize
@@ -17,6 +17,13 @@ def record_attributes_after_initialize
     @attributes_after_initialize = attributes.dup
   end
 
+  after_create :record_count_after_create
+  def record_count_after_create
+    @count_after_create = Bulb.unscoped do
+      car&.bulbs&.count
+    end
+  end
+
   def color=(color)
     self[:color] = color.upcase + "!"
   end