Merge pull request rails#41892 from kamipo/fix_default_scope_table_alias

Fix user-defined `self.default_scope` to respect table alias

Author: kamipo

activerecord/lib/active_record/scoping/default.rb

@@ -146,9 +146,7 @@ def build_default_scope(relation = relation(), all_queries: nil)
             if default_scope_override
               # The user has defined their own default scope method, so call that
               evaluate_default_scope do
-                if scope = default_scope
-                  relation.merge!(scope)
-                end
+                relation.scoping { default_scope }
               end
             elsif default_scopes.any?
               evaluate_default_scope do

activerecord/test/cases/adapters/postgresql/schema_test.rb

@@ -76,6 +76,7 @@ class Song < ActiveRecord::Base
   class Album < ActiveRecord::Base
     self.table_name = "music.albums"
     has_and_belongs_to_many :songs
+    def self.default_scope; where(deleted: false); end
   end
 
   def setup
@@ -149,14 +150,14 @@ def test_habtm_table_name_with_schema
     ActiveRecord::Base.connection.drop_schema "music", if_exists: true
     ActiveRecord::Base.connection.create_schema "music"
     ActiveRecord::Base.connection.execute <<~SQL
-      CREATE TABLE music.albums (id serial primary key);
+      CREATE TABLE music.albums (id serial primary key, deleted boolean default false);
       CREATE TABLE music.songs (id serial primary key);
       CREATE TABLE music.albums_songs (album_id integer, song_id integer);
     SQL
 
     song = Song.create
-    Album.create
-    assert_equal song, Song.includes(:albums).references(:albums).first
+    album = song.albums.create
+    assert_equal song, Song.includes(:albums).where("albums.id": album.id).first
   ensure
     ActiveRecord::Base.connection.drop_schema "music", if_exists: true
   end