Fix where_clause#except with specific where value

Fixes a regression introduced in
22ca710f20c3c656811df006cbf1f4dbc359f7a6 where Relation#unscope with a
specific where value (vs unscoping the entire where clause) could result
in the wrong binds being left on the query.

This was caused by an index variable not being incremented properly.

2 files changed, 10 insertions, 2 deletions

diff --git a/activerecord/lib/active_record/relation/where_clause.rb b/activerecord/lib/active_record/relation/where_clause.rb
index 417b24c7bb..119910ee79 100644
--- a/activerecord/lib/active_record/relation/where_clause.rb
+++ b/activerecord/lib/active_record/relation/where_clause.rb
@@ -148,10 +148,10 @@ module ActiveRecord
               (binds_index...(binds_index + binds_contains)).each do |i|
                 except_binds[i] = true
               end
-
-              binds_index += binds_contains
             end
 
+            binds_index += binds_contains if binds_contains
+
             except
           end
 
diff --git a/activerecord/test/cases/relations_test.rb b/activerecord/test/cases/relations_test.rb
index 73986d2d16..e17cb1795e 100644
--- a/activerecord/test/cases/relations_test.rb
+++ b/activerecord/test/cases/relations_test.rb
@@ -1970,6 +1970,14 @@ class RelationTest < ActiveRecord::TestCase
     assert_equal p2.first.comments, comments
   end
 
+  def test_unscope_specific_where_value
+    posts = Post.where(title: "Welcome to the weblog", body: "Such a lovely day")
+
+    assert_equal 1, posts.count
+    assert_equal 1, posts.unscope(where: :title).count
+    assert_equal 1, posts.unscope(where: :body).count
+  end
+
   def test_unscope_removes_binds
     left = Post.where(id: Arel::Nodes::BindParam.new)
     column = Post.columns_hash["id"]