Association scope's own order should be prioritized over through scope's order

3acc5d6e was changed the order of scope evaluation from through scope to
the association's own scope to be prioritized over the through scope.
But the sorting order will be prioritized that is evaluated first. It is
unintentional effect, association scope's sorting order should be
prioritized as well.

Fixes #32008.

activerecord/lib/active_record/associations/association_scope.rb

@@ -135,7 +135,7 @@ def add_constraints(scope, owner, chain)
               item = eval_scope(reflection, scope_chain_item, owner)
 
               if scope_chain_item == chain_head.scope
-                scope.merge! item.except(:where, :includes)
+                scope.merge! item.except(:where, :includes, :unscope, :order)
               end
 
               reflection.all_includes do
@@ -144,7 +144,7 @@ def add_constraints(scope, owner, chain)
 
               scope.unscope!(*item.unscope_values)
               scope.where_clause += item.where_clause
-              scope.order_values |= item.order_values
+              scope.order_values = item.order_values | scope.order_values
             end
           end
 

activerecord/test/cases/associations/has_many_associations_test.rb

@@ -1842,6 +1842,13 @@ def test_modifying_a_through_a_has_many_should_raise
     ].each { |block| assert_raise(ActiveRecord::HasManyThroughCantAssociateThroughHasOneOrManyReflection, &block) }
   end
 
+  def test_associations_order_should_be_priority_over_throughs_order
+    david = authors(:david)
+    expected = [12, 10, 9, 8, 7, 6, 5, 3, 2, 1]
+    assert_equal expected, david.comments_desc.map(&:id)
+    assert_equal expected, Author.includes(:comments_desc).find(david.id).comments_desc.map(&:id)
+  end
+
   def test_dynamic_find_should_respect_association_order_for_through
     assert_equal Comment.find(10), authors(:david).comments_desc.where("comments.type = 'SpecialComment'").first
     assert_equal Comment.find(10), authors(:david).comments_desc.find_by_type("SpecialComment")

activerecord/test/models/author.rb

@@ -8,6 +8,7 @@ class Author < ActiveRecord::Base
   has_many :posts_with_comments, -> { includes(:comments) }, class_name: "Post"
   has_many :popular_grouped_posts, -> { includes(:comments).group("type").having("SUM(comments_count) > 1").select("type") }, class_name: "Post"
   has_many :posts_with_comments_sorted_by_comment_id, -> { includes(:comments).order("comments.id") }, class_name: "Post"
+  has_many :posts_sorted_by_id, -> { order(:id) }, class_name: "Post"
   has_many :posts_sorted_by_id_limited, -> { order("posts.id").limit(1) }, class_name: "Post"
   has_many :posts_with_categories, -> { includes(:categories) }, class_name: "Post"
   has_many :posts_with_comments_and_categories, -> { includes(:comments, :categories).order("posts.id") }, class_name: "Post"
@@ -40,7 +41,7 @@ def ratings
            -> { where(title: "Welcome to the weblog").where(Post.arel_table[:comments_count].gt(0)) },
            class_name: "Post"
 
-  has_many :comments_desc, -> { order("comments.id DESC") }, through: :posts, source: :comments
+  has_many :comments_desc, -> { order("comments.id DESC") }, through: :posts_sorted_by_id, source: :comments
   has_many :unordered_comments, -> { unscope(:order).distinct }, through: :posts_sorted_by_id_limited, source: :comments
   has_many :funky_comments, through: :posts, source: :comments
   has_many :ordered_uniq_comments, -> { distinct.order("comments.id") }, through: :posts, source: :comments