Merge branch 'master' into pr/18316

Conflicts:
	activerecord/CHANGELOG.md

1 files changed, 16 insertions, 6 deletions

diff --git a/activerecord/lib/active_record/associations/has_many_association.rb b/activerecord/lib/active_record/associations/has_many_association.rb
index d7f655d00c..b574185561 100644
--- a/activerecord/lib/active_record/associations/has_many_association.rb
+++ b/activerecord/lib/active_record/associations/has_many_association.rb
@@ -17,7 +17,7 @@ module ActiveRecord
           unless empty?
             record = klass.human_attribute_name(reflection.name).downcase
             owner.errors.add(:base, :"restrict_dependent_destroy.many", record: record)
-            false
+            throw(:abort)
           end
 
         else
@@ -101,7 +101,7 @@ module ActiveRecord
         end
 
         def update_counter_in_memory(difference, reflection = reflection())
-          if has_cached_counter?(reflection)
+          if counter_must_be_updated_by_has_many?(reflection)
             counter = cached_counter_attribute_name(reflection)
             owner[counter] += difference
             owner.send(:clear_attribute_changes, counter) # eww
@@ -118,18 +118,28 @@ module ActiveRecord
         #     it will be decremented twice.
         #
         # Hence this method.
-        def inverse_updates_counter_cache?(reflection = reflection())
+        def inverse_which_updates_counter_cache(reflection = reflection())
           counter_name = cached_counter_attribute_name(reflection)
-          inverse_updates_counter_named?(counter_name, reflection)
+          inverse_which_updates_counter_named(counter_name, reflection)
         end
+        alias inverse_updates_counter_cache? inverse_which_updates_counter_cache
 
-        def inverse_updates_counter_named?(counter_name, reflection = reflection())
-          reflection.klass._reflections.values.any? { |inverse_reflection|
+        def inverse_which_updates_counter_named(counter_name, reflection)
+          reflection.klass._reflections.values.find { |inverse_reflection|
             inverse_reflection.belongs_to? &&
             inverse_reflection.counter_cache_column == counter_name
           }
         end
 
+        def inverse_updates_counter_in_memory?(reflection)
+          inverse = inverse_which_updates_counter_cache(reflection)
+          inverse && inverse == reflection.inverse_of
+        end
+
+        def counter_must_be_updated_by_has_many?(reflection)
+          !inverse_updates_counter_in_memory?(reflection) && has_cached_counter?(reflection)
+        end
+
         def delete_count(method, scope)
           if method == :delete_all
             scope.delete_all