Merge pull request #10303 from ahorner/3-2-stable

Preserve context for joins while merging relations

2 files changed, 7 insertions, 2 deletions

diff --git a/activerecord/lib/active_record/associations/join_dependency.rb b/activerecord/lib/active_record/associations/join_dependency.rb
index cd366ac8b7..e3d8356f49 100644
--- a/activerecord/lib/active_record/associations/join_dependency.rb
+++ b/activerecord/lib/active_record/associations/join_dependency.rb
@@ -109,7 +109,7 @@ module ActiveRecord
         case associations
         when Symbol, String
           reflection = parent.reflections[associations.to_s.intern] or
-          raise ConfigurationError, "Association named '#{ associations }' was not found; perhaps you misspelled it?"
+          raise ConfigurationError, "Association named '#{ associations }' was not found on #{parent.active_record.name}; perhaps you misspelled it?"
           unless join_association = find_join_association(reflection, parent)
             @reflections << reflection
             join_association = build_join_association(reflection, parent)
diff --git a/activerecord/lib/active_record/associations/join_dependency/join_association.rb b/activerecord/lib/active_record/associations/join_dependency/join_association.rb
index 03963ab060..becf1a3f62 100644
--- a/activerecord/lib/active_record/associations/join_dependency/join_association.rb
+++ b/activerecord/lib/active_record/associations/join_dependency/join_association.rb
@@ -55,7 +55,12 @@ module ActiveRecord
 
         def find_parent_in(other_join_dependency)
           other_join_dependency.join_parts.detect do |join_part|
-            parent == join_part
+            case parent
+            when JoinBase
+              parent.active_record == join_part.active_record
+            else
+              parent == join_part
+            end
           end
         end