Decrease string allocations on AR#respond_to?

When a symbol is passed in, we call `to_s` on it which allocates a string. The two hardcoded symbols that are used internally are `:to_partial_path` and `:to_model`.

This change buys us 71,136 bytes of memory and 1,777 fewer objects per request.

1 files changed, 9 insertions, 1 deletions

diff --git a/activerecord/lib/active_record/attribute_methods.rb b/activerecord/lib/active_record/attribute_methods.rb
index abe1d465a5..7fb899c242 100644
--- a/activerecord/lib/active_record/attribute_methods.rb
+++ b/activerecord/lib/active_record/attribute_methods.rb
@@ -230,7 +230,15 @@ module ActiveRecord
     #   person.respond_to(:nothing) # => false
     def respond_to?(name, include_private = false)
       return false unless super
-      name = name.to_s
+
+      case name
+      when :to_partial_path
+        name = "to_partial_path".freeze
+      when :to_model
+        name = "to_model".freeze
+      else
+        name = name.to_s
+      end
 
       # If the result is true then check for the select case.
       # For queries selecting a subset of columns, return false for unselected columns.