avoid creating a set if no where values are removed

1 files changed, 12 insertions, 0 deletions

diff --git a/activerecord/test/cases/relations_test.rb b/activerecord/test/cases/relations_test.rb
index 3c1fae78ce..b64ff13d29 100644
--- a/activerecord/test/cases/relations_test.rb
+++ b/activerecord/test/cases/relations_test.rb
@@ -1556,4 +1556,16 @@ class RelationTest < ActiveRecord::TestCase
     merged = left.merge(right)
     assert_equal [], merged.bind_values
   end
+
+  def test_merging_keeps_lhs_bind_parameters
+    column = Post.columns_hash['id']
+    binds = [[column, 20]]
+
+    right  = Post.where(id: Arel::Nodes::BindParam.new('?'))
+    right.bind_values += binds
+    left   = Post.where(id: 10)
+
+    merged = left.merge(right)
+    assert_equal binds, merged.bind_values
+  end
 end