From 9809d4d21bcb4eae153b354f9c3ac3399af203e4 Mon Sep 17 00:00:00 2001
From: Aaron Frase <afrase91@gmail.com>
Date: Thu, 31 Oct 2019 20:53:49 -0400
Subject: [PATCH] Avoid stack level too deep in predicate builder

Check if the query is different from attributes before recursively
calling `expand_from_hash`
---
 .../lib/active_record/relation/predicate_builder.rb        | 4 +++-
 .../test/cases/associations/has_many_associations_test.rb  | 7 +++++++
 activerecord/test/fixtures/comments.yml                    | 7 +++++++
 activerecord/test/fixtures/companies.yml                   | 5 +++++
 activerecord/test/models/comment.rb                        | 1 +
 activerecord/test/models/company.rb                        | 1 +
 activerecord/test/schema/schema.rb                         | 1 +
 7 files changed, 25 insertions(+), 1 deletion(-)

diff --git a/activerecord/lib/active_record/relation/predicate_builder.rb b/activerecord/lib/active_record/relation/predicate_builder.rb
index 240de3bb693f3..d05edbdf68067 100644
--- a/activerecord/lib/active_record/relation/predicate_builder.rb
+++ b/activerecord/lib/active_record/relation/predicate_builder.rb
@@ -85,7 +85,9 @@ def expand_from_hash(attributes)
 
             klass ||= AssociationQueryValue
             queries = klass.new(associated_table, value).queries.map do |query|
-              expand_from_hash(query).reduce(&:and)
+              # If the query produced is identical to attributes don't go any deeper.
+              # Prevents stack level too deep errors when association and foreign_key are identical.
+              query == attributes ? build(table.arel_attribute(key), value) : expand_from_hash(query).reduce(&:and)
             end
             queries.reduce(&:or)
           elsif table.aggregated_with?(key)
diff --git a/activerecord/test/cases/associations/has_many_associations_test.rb b/activerecord/test/cases/associations/has_many_associations_test.rb
index cb3985a45cbd3..77591c90e6adb 100644
--- a/activerecord/test/cases/associations/has_many_associations_test.rb
+++ b/activerecord/test/cases/associations/has_many_associations_test.rb
@@ -2991,6 +2991,13 @@ def test_has_many_preloading_with_duplicate_records
     assert_equal [1, 2], posts.first.comments.map(&:id)
   end
 
+  def test_has_many_association_with_same_foreign_key_name
+    assert_nothing_raised do
+      firm = Firm.find(15)
+      assert_not_nil(firm.comments.first)
+    end
+  end
+
   private
     def force_signal37_to_load_all_clients_of_firm
       companies(:first_firm).clients_of_firm.load_target
diff --git a/activerecord/test/fixtures/comments.yml b/activerecord/test/fixtures/comments.yml
index ddbb823c49f7a..33dc9462602c8 100644
--- a/activerecord/test/fixtures/comments.yml
+++ b/activerecord/test/fixtures/comments.yml
@@ -63,3 +63,10 @@ sub_special_comment:
   post_id: 4
   body: Sub special comment
   type: SubSpecialComment
+
+recursive_association_comment:
+  id: 13
+  post_id: 5
+  body: afrase
+  type: Comment
+  company: 15
diff --git a/activerecord/test/fixtures/companies.yml b/activerecord/test/fixtures/companies.yml
index ab9d5378ad506..b05997038a5fa 100644
--- a/activerecord/test/fixtures/companies.yml
+++ b/activerecord/test/fixtures/companies.yml
@@ -65,3 +65,8 @@ another_first_firm_client:
   client_of: 1
   name: Apex
   firm_name: 37signals
+
+recursive_association_fk:
+  id: 15
+  type: Firm
+  name: RVshare
diff --git a/activerecord/test/models/comment.rb b/activerecord/test/models/comment.rb
index f0f057670957f..23fa006bc70ef 100644
--- a/activerecord/test/models/comment.rb
+++ b/activerecord/test/models/comment.rb
@@ -14,6 +14,7 @@ class Comment < ActiveRecord::Base
   belongs_to :post, counter_cache: true
   belongs_to :author,   polymorphic: true
   belongs_to :resource, polymorphic: true
+  belongs_to :company, foreign_key: 'company'
 
   has_many :ratings
 
diff --git a/activerecord/test/models/company.rb b/activerecord/test/models/company.rb
index 339b5c8ca88e6..7946818540ea0 100644
--- a/activerecord/test/models/company.rb
+++ b/activerecord/test/models/company.rb
@@ -12,6 +12,7 @@ class Company < AbstractCompany
   has_one :dummy_account, foreign_key: "firm_id", class_name: "Account"
   has_many :contracts
   has_many :developers, through: :contracts
+  has_many :comments, foreign_key: 'company'
 
   attribute :metadata, :json
 
diff --git a/activerecord/test/schema/schema.rb b/activerecord/test/schema/schema.rb
index cae2890c9e1ba..c98b26f28d8dc 100644
--- a/activerecord/test/schema/schema.rb
+++ b/activerecord/test/schema/schema.rb
@@ -213,6 +213,7 @@
     t.datetime :updated_at
     t.datetime :deleted_at
     t.integer :comments
+    t.integer :company
   end
 
   create_table :companies, force: true do |t|