Merge pull request #6521 from Empact/throw-result

Fix that #exists? can blow up with ThrowResult exception
Conflicts:
	activerecord/lib/active_record/relation/finder_methods.rb

2 files changed, 8 insertions, 1 deletions

diff --git a/activerecord/lib/active_record/relation/finder_methods.rb b/activerecord/lib/active_record/relation/finder_methods.rb
index fa457ae0c6..86f1d6936e 100644
--- a/activerecord/lib/active_record/relation/finder_methods.rb
+++ b/activerecord/lib/active_record/relation/finder_methods.rb
@@ -200,6 +200,8 @@ module ActiveRecord
       end
 
       connection.select_value(relation, "#{name} Exists") ? true : false
+    rescue ThrowResult
+      false
     end
 
     protected
diff --git a/activerecord/test/cases/finder_test.rb b/activerecord/test/cases/finder_test.rb
index 8622a1a295..e3e3a1ca7c 100644
--- a/activerecord/test/cases/finder_test.rb
+++ b/activerecord/test/cases/finder_test.rb
@@ -69,7 +69,12 @@ class FinderTest < ActiveRecord::TestCase
     assert Topic.order(:id).uniq.exists?
   end
 
-  def test_does_not_exist_with_empty_table_and_no_args_given
+  def test_exists_with_includes_limit_and_empty_result
+    assert !Topic.includes(:replies).limit(0).exists?
+    assert !Topic.includes(:replies).limit(1).where('0 = 1').exists?
+  end
+
+  def test_exists_with_empty_table_and_no_args_given
     Topic.delete_all
     assert !Topic.exists?
   end