Change how Merging conditions on the same column works

Merging conditions on the same column no longer maintain both conditions,
and will be consistently replaced by the latter condition.

    ```ruby
    # Rails 6.1 (IN clause is replaced by merger side equality condition)
    Author.where(id: [david.id, mary.id]).merge(Author.where(id: bob)) # => [bob]
    # Rails 6.1 (both conflict conditions exists, deprecated)
    Author.where(id: david.id..mary.id).merge(Author.where(id: bob)) # => []
    # Rails 6.1 with rewhere to migrate to Rails 7.0's behavior
    Author.where(id: david.id..mary.id).merge(Author.where(id: bob), rewhere: true) # => [bob]
    # Rails 7.0 (same behavior with IN clause, mergee side condition is consistently replaced)
    Author.where(id: [david.id, mary.id]).merge(Author.where(id: bob)) # => [bob]
    Author.where(id: david.id..mary.id).merge(Author.where(id: bob)) # => [bob]
    ```

Author: rafaelfranca

activerecord/CHANGELOG.md

@@ -1,3 +1,20 @@
+*   Merging conditions on the same column no longer maintain both conditions,
+    and will be consistently replaced by the latter condition.
+
+    ```ruby
+    # Rails 6.1 (IN clause is replaced by merger side equality condition)
+    Author.where(id: [david.id, mary.id]).merge(Author.where(id: bob)) # => [bob]
+    # Rails 6.1 (both conflict conditions exists, deprecated)
+    Author.where(id: david.id..mary.id).merge(Author.where(id: bob)) # => []
+    # Rails 6.1 with rewhere to migrate to Rails 7.0's behavior
+    Author.where(id: david.id..mary.id).merge(Author.where(id: bob), rewhere: true) # => [bob]
+    # Rails 7.0 (same behavior with IN clause, mergee side condition is consistently replaced)
+    Author.where(id: [david.id, mary.id]).merge(Author.where(id: bob)) # => [bob]
+    Author.where(id: david.id..mary.id).merge(Author.where(id: bob)) # => [bob]
+
+    *Rafael Mendonça França*
+
+
 *   Remove deprecated support to `Model.reorder(nil).first` to search using non-deterministic order.
 
     *Rafael Mendonça França*

activerecord/lib/active_record/relation/where_clause.rb

@@ -163,21 +163,8 @@ def predicates_unreferenced_by(other)
             attr = extract_attribute(node) || begin
               node.left if equality_node?(node) && node.left.is_a?(Arel::Predications)
             end
-            next false unless attr
-
-            ref = referenced_columns[attr]
-            next false unless ref
-
-            if equality_node?(node) && equality_node?(ref) || node == ref
-              true
-            else
-              ActiveSupport::Deprecation.warn(<<-MSG.squish)
-                Merging (#{node.to_sql}) and (#{ref.to_sql}) no longer maintain
-                both conditions, and will be replaced by the latter in Rails 7.0.
-                To migrate to Rails 7.0's behavior, use `relation.merge(other, rewhere: true)`.
-              MSG
-              false
-            end
+
+            attr && referenced_columns[attr]
           end
         end
 

activerecord/test/cases/relation/merging_test.rb

@@ -60,38 +60,23 @@ def test_merge_between_clause
     assert_equal [david, mary], david_and_mary
     assert_equal [mary, bob],   mary_and_bob
 
-    author_id = Regexp.escape(Author.connection.quote_table_name("authors.id"))
-    message = %r/Merging \(#{author_id} BETWEEN (\?|\W?\w?\d) AND \g<1>\) and \(#{author_id} (?:= \g<1>|IN \(\g<1>, \g<1>\))\) no longer maintain both conditions, and will be replaced by the latter in Rails 7\.0\./
-
-    assert_deprecated(message) do
-      assert_equal [mary], david_and_mary.merge(Author.where(id: mary))
-    end
+    assert_equal [mary], david_and_mary.merge(Author.where(id: mary))
     assert_equal [mary], david_and_mary.merge(Author.rewhere(id: mary))
     assert_equal [mary], david_and_mary.merge(Author.where(id: mary), rewhere: true)
 
-    assert_deprecated(message) do
-      assert_equal [], david_and_mary.merge(Author.where(id: bob))
-    end
+    assert_equal [bob], david_and_mary.merge(Author.where(id: bob))
     assert_equal [bob],  david_and_mary.merge(Author.rewhere(id: bob))
     assert_equal [bob],  david_and_mary.merge(Author.where(id: bob), rewhere: true)
 
-    assert_deprecated(message) do
-      assert_equal [bob], mary_and_bob.merge(Author.where(id: [david, bob]))
-    end
+    assert_equal [david, bob], mary_and_bob.merge(Author.where(id: [david, bob]))
     assert_equal [david, bob], mary_and_bob.merge(Author.where(id: [david, bob]), rewhere: true)
 
-    message = %r/Merging \(#{author_id} BETWEEN (\?|\W?\w?\d) AND \g<1>\) and \(#{author_id} BETWEEN \g<1> AND \g<1>\) no longer maintain both conditions, and will be replaced by the latter in Rails 7\.0\./
-
-    assert_deprecated(message) do
-      assert_equal [mary], david_and_mary.merge(mary_and_bob)
-    end
+    assert_equal [mary, bob], david_and_mary.merge(mary_and_bob)
     assert_equal [mary, bob], david_and_mary.merge(mary_and_bob, rewhere: true)
     assert_equal [mary], david_and_mary.and(mary_and_bob)
     assert_equal authors, david_and_mary.or(mary_and_bob)
 
-    assert_deprecated(message) do
-      assert_equal [mary], mary_and_bob.merge(david_and_mary)
-    end
+    assert_equal [david, mary], mary_and_bob.merge(david_and_mary)
     assert_equal [david, mary], mary_and_bob.merge(david_and_mary, rewhere: true)
     assert_equal [mary], david_and_mary.and(mary_and_bob)
     assert_equal authors, david_and_mary.or(mary_and_bob)
@@ -113,38 +98,24 @@ def test_merge_or_clause
     assert_equal [david, mary], david_and_mary
     assert_equal [mary, bob],   mary_and_bob
 
-    author_id = Regexp.escape(Author.connection.quote_table_name("authors.id"))
-    message = %r/Merging \(\(#{author_id} = (\?|\W?\w?\d) OR #{author_id} = \g<1>\)\) and \(#{author_id} (?:= \g<1>|IN \(\g<1>, \g<1>\))\) no longer maintain both conditions, and will be replaced by the latter in Rails 7\.0\./
-
-    assert_deprecated(message) do
-      assert_equal [mary], david_and_mary.merge(Author.where(id: mary))
-    end
+    assert_equal [mary], david_and_mary.merge(Author.where(id: mary))
     assert_equal [mary], david_and_mary.merge(Author.rewhere(id: mary))
     assert_equal [mary], david_and_mary.merge(Author.where(id: mary), rewhere: true)
 
-    assert_deprecated(message) do
-      assert_equal [], david_and_mary.merge(Author.where(id: bob))
-    end
+    assert_equal [bob], david_and_mary.merge(Author.where(id: bob))
     assert_equal [bob],  david_and_mary.merge(Author.rewhere(id: bob))
     assert_equal [bob],  david_and_mary.merge(Author.where(id: bob), rewhere: true)
 
-    assert_deprecated(message) do
-      assert_equal [bob], mary_and_bob.merge(Author.where(id: [david, bob]))
-    end
+    assert_equal [david, bob], mary_and_bob.merge(Author.where(id: [david, bob]))
     assert_equal [david, bob], mary_and_bob.merge(Author.where(id: [david, bob]), rewhere: true)
 
-    message = %r/Merging \(\(#{author_id} = (\?|\W?\w?\d) OR #{author_id} = \g<1>\)\) and \(\(#{author_id} = \g<1> OR #{author_id} = \g<1>\)\) no longer maintain both conditions, and will be replaced by the latter in Rails 7\.0\./
 
-    assert_deprecated(message) do
-      assert_equal [mary], david_and_mary.merge(mary_and_bob)
-    end
+    assert_equal [mary, bob], david_and_mary.merge(mary_and_bob)
     assert_equal [mary, bob], david_and_mary.merge(mary_and_bob, rewhere: true)
     assert_equal [mary], david_and_mary.and(mary_and_bob)
     assert_equal authors, david_and_mary.or(mary_and_bob)
 
-    assert_deprecated(message) do
-      assert_equal [mary], mary_and_bob.merge(david_and_mary)
-    end
+    assert_equal [david, mary], mary_and_bob.merge(david_and_mary)
     assert_equal [david, mary], mary_and_bob.merge(david_and_mary, rewhere: true)
     assert_equal [mary], david_and_mary.and(mary_and_bob)
     assert_equal authors, david_and_mary.or(mary_and_bob)
@@ -164,14 +135,10 @@ def test_merge_not_in_clause
 
     assert_equal [david], non_mary_and_bob
 
-    assert_deprecated do
-      assert_equal [david], Author.where(id: david).merge(non_mary_and_bob)
-    end
+    assert_equal [david], Author.where(id: david).merge(non_mary_and_bob)
     assert_equal [david], Author.where(id: david).merge(non_mary_and_bob, rewhere: true)
 
-    assert_deprecated do
-      assert_equal [], Author.where(id: mary).merge(non_mary_and_bob)
-    end
+    assert_equal [david], Author.where(id: mary).merge(non_mary_and_bob)
     assert_equal [david], Author.where(id: mary).merge(non_mary_and_bob, rewhere: true)
   end
 
@@ -182,14 +149,10 @@ def test_merge_not_range_clause
 
     assert_equal [david, mary], less_than_bob
 
-    assert_deprecated do
-      assert_equal [david], Author.where(id: david).merge(less_than_bob)
-    end
+    assert_equal [david, mary], Author.where(id: david).merge(less_than_bob)
     assert_equal [david, mary], Author.where(id: david).merge(less_than_bob, rewhere: true)
 
-    assert_deprecated do
-      assert_equal [mary], Author.where(id: mary).merge(less_than_bob)
-    end
+    assert_equal [david, mary], Author.where(id: mary).merge(less_than_bob)
     assert_equal [david, mary], Author.where(id: mary).merge(less_than_bob, rewhere: true)
   end
 

guides/source/7_0_release_notes.md

@@ -150,6 +150,20 @@ Please refer to the [Changelog][active-record] for detailed changes.
     The problem is that timeouts triggered inside the transaction block was also making the incomplete transaction
     to be committed, so in order to avoid this mistake, the transaction block is rolled back.
 
+*   Merging conditions on the same column no longer maintain both conditions,
+    and will be consistently replaced by the latter condition.
+
+    ```ruby
+    # Rails 6.1 (IN clause is replaced by merger side equality condition)
+    Author.where(id: [david.id, mary.id]).merge(Author.where(id: bob)) # => [bob]
+    # Rails 6.1 (both conflict conditions exists, deprecated)
+    Author.where(id: david.id..mary.id).merge(Author.where(id: bob)) # => []
+    # Rails 6.1 with rewhere to migrate to Rails 7.0's behavior
+    Author.where(id: david.id..mary.id).merge(Author.where(id: bob), rewhere: true) # => [bob]
+    # Rails 7.0 (same behavior with IN clause, mergee side condition is consistently replaced)
+    Author.where(id: [david.id, mary.id]).merge(Author.where(id: bob)) # => [bob]
+    Author.where(id: david.id..mary.id).merge(Author.where(id: bob)) # => [bob]
+
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