From c69111ba5fde8445237f682c88b927bcde1588d4 Mon Sep 17 00:00:00 2001
From: Jon Leighton <j@jonathanleighton.com>
Date: Wed, 25 May 2011 00:07:38 +0100
Subject: Fix infinite recursion where a lazy default scope references a scope.
 Fixes #1264.

---
 activerecord/lib/active_record/base.rb           | 15 ++++++++++++---
 activerecord/lib/active_record/relation.rb       |  2 +-
 activerecord/test/cases/relation_scoping_test.rb |  8 ++++++++
 activerecord/test/models/developer.rb            | 15 +++++++++++++++
 4 files changed, 36 insertions(+), 4 deletions(-)

diff --git a/activerecord/lib/active_record/base.rb b/activerecord/lib/active_record/base.rb
index 19a7965429..99930e7697 100644
--- a/activerecord/lib/active_record/base.rb
+++ b/activerecord/lib/active_record/base.rb
@@ -428,6 +428,10 @@ module ActiveRecord #:nodoc:
     class_attribute :default_scopes, :instance_writer => false
     self.default_scopes = []
 
+    # Boolean flag to prevent infinite recursion when evaluating default scopes
+    class_attribute :apply_default_scope, :instance_writer => false
+    self.apply_default_scope = true
+
     # Returns a hash of all the attributes that have been specified for serialization as
     # keys and their class restriction as values.
     class_attribute :serialized_attributes
@@ -1261,11 +1265,14 @@ MSG
           self.default_scopes = default_scopes + [scope]
         end
 
+        # The apply_default_scope flag is used to prevent an infinite recursion situation where
+        # a default scope references a scope which has a default scope which references a scope...
         def build_default_scope #:nodoc:
+          return unless apply_default_scope
+          self.apply_default_scope = false
+
           if method(:default_scope).owner != Base.singleton_class
-            # Use relation.scoping to ensure we ignore whatever the current value of
-            # self.current_scope may be.
-            relation.scoping { default_scope }
+            default_scope
           elsif default_scopes.any?
             default_scopes.inject(relation) do |default_scope, scope|
               if scope.is_a?(Hash)
@@ -1277,6 +1284,8 @@ MSG
               end
             end
           end
+        ensure
+          self.apply_default_scope = true
         end
 
         # Returns the class type of the record using the current module as a prefix. So descendants of
diff --git a/activerecord/lib/active_record/relation.rb b/activerecord/lib/active_record/relation.rb
index a3f4a6fe94..65e2ad0963 100644
--- a/activerecord/lib/active_record/relation.rb
+++ b/activerecord/lib/active_record/relation.rb
@@ -424,7 +424,7 @@ module ActiveRecord
     end
 
     def with_default_scope #:nodoc:
-      if default_scoped? && default_scope = @klass.send(:build_default_scope)
+      if default_scoped? && default_scope = klass.send(:build_default_scope)
         default_scope = default_scope.merge(self)
         default_scope.default_scoped = false
         default_scope
diff --git a/activerecord/test/cases/relation_scoping_test.rb b/activerecord/test/cases/relation_scoping_test.rb
index c215602567..8f8e72f052 100644
--- a/activerecord/test/cases/relation_scoping_test.rb
+++ b/activerecord/test/cases/relation_scoping_test.rb
@@ -312,6 +312,14 @@ class DefaultScopingTest < ActiveRecord::TestCase
     assert_equal [developers(:david).becomes(ClassMethodDeveloperCalledDavid)], ClassMethodDeveloperCalledDavid.all
   end
 
+  def test_default_scope_as_class_method_referencing_scope
+    assert_equal [developers(:david).becomes(ClassMethodReferencingScopeDeveloperCalledDavid)], ClassMethodReferencingScopeDeveloperCalledDavid.all
+  end
+
+  def test_default_scope_as_block_referencing_scope
+    assert_equal [developers(:david).becomes(LazyBlockReferencingScopeDeveloperCalledDavid)], LazyBlockReferencingScopeDeveloperCalledDavid.all
+  end
+
   def test_default_scope_with_lambda
     assert_equal [developers(:david).becomes(LazyLambdaDeveloperCalledDavid)], LazyLambdaDeveloperCalledDavid.all
   end
diff --git a/activerecord/test/models/developer.rb b/activerecord/test/models/developer.rb
index a2aa8ae664..41c52f7df0 100644
--- a/activerecord/test/models/developer.rb
+++ b/activerecord/test/models/developer.rb
@@ -127,6 +127,21 @@ class ClassMethodDeveloperCalledDavid < ActiveRecord::Base
   end
 end
 
+class ClassMethodReferencingScopeDeveloperCalledDavid < ActiveRecord::Base
+  self.table_name = 'developers'
+  scope :david, where(:name => 'David')
+
+  def self.default_scope
+    david
+  end
+end
+
+class LazyBlockReferencingScopeDeveloperCalledDavid < ActiveRecord::Base
+  self.table_name = 'developers'
+  scope :david, where(:name => 'David')
+  default_scope { david }
+end
+
 class DeveloperCalledJamis < ActiveRecord::Base
   self.table_name = 'developers'
 
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