backport #8176, `#pluck` can be used on a relation with `select` clause.

Conflicts:

	activerecord/CHANGELOG.md
	activerecord/lib/active_record/relation/calculations.rb
	activerecord/test/cases/calculations_test.rb

1 files changed, 6 insertions, 0 deletions

diff --git a/activerecord/test/cases/calculations_test.rb b/activerecord/test/cases/calculations_test.rb
index cf1181e829..63383bded9 100644
--- a/activerecord/test/cases/calculations_test.rb
+++ b/activerecord/test/cases/calculations_test.rb
@@ -487,4 +487,10 @@ class CalculationsTest < ActiveRecord::TestCase
   def test_pluck_with_qualified_column_name
     assert_equal [1,2,3,4], Topic.order(:id).pluck("topics.id")
   end
+
+  def test_pluck_replaces_select_clause
+    taks_relation = Topic.select([:approved, :id]).order(:id)
+    assert_equal [1,2,3,4], taks_relation.pluck(:id)
+    assert_equal [false, true, true, true], taks_relation.pluck(:approved)
+  end
 end