Remove `AttributeSet#initialized_keys`

This method doesn't need to be lazy, as it is never called from reads.
The only time it is called are in write cases, where we're about to loop
through the results of it, and build the attribute objects anyway. So we
don't gain anything by dodging the instantiation here. This is the only
method that coupled `AttributeSet` to `LazyAttributeHash`, so removing
it puts us back in a place where we can use a normal hash instead.

2 files changed, 2 insertions, 6 deletions

diff --git a/activerecord/lib/active_record/attribute_set.rb b/activerecord/lib/active_record/attribute_set.rb
index fdce68ce45..0c9793d470 100644
--- a/activerecord/lib/active_record/attribute_set.rb
+++ b/activerecord/lib/active_record/attribute_set.rb
@@ -24,7 +24,7 @@ module ActiveRecord
     end
 
     def keys
-      attributes.initialized_keys
+      attributes.each_key.select { |name| self[name].initialized? }
     end
 
     def fetch_value(name)
diff --git a/activerecord/lib/active_record/attribute_set/builder.rb b/activerecord/lib/active_record/attribute_set/builder.rb
index 3a76f5262d..0f3c285a80 100644
--- a/activerecord/lib/active_record/attribute_set/builder.rb
+++ b/activerecord/lib/active_record/attribute_set/builder.rb
@@ -20,7 +20,7 @@ module ActiveRecord
   end
 
   class LazyAttributeHash # :nodoc:
-    delegate :select, :transform_values, to: :materialize
+    delegate :select, :transform_values, :each_key, to: :materialize
 
     def initialize(types, values, additional_types)
       @types = types
@@ -45,10 +45,6 @@ module ActiveRecord
       delegate_hash[key] = value
     end
 
-    def initialized_keys
-      delegate_hash.keys | values.keys
-    end
-
     def initialize_dup(_)
       @delegate_hash = delegate_hash.transform_values(&:dup)
       super