Delegation works with reserved words passed to `:to`

Fixes #16956.

1 files changed, 9 insertions, 1 deletions

diff --git a/activesupport/lib/active_support/core_ext/module/delegation.rb b/activesupport/lib/active_support/core_ext/module/delegation.rb
index e926392952..570585b89a 100644
--- a/activesupport/lib/active_support/core_ext/module/delegation.rb
+++ b/activesupport/lib/active_support/core_ext/module/delegation.rb
@@ -1,8 +1,16 @@
+require 'set'
+
 class Module
   # Error generated by +delegate+ when a method is called on +nil+ and +allow_nil+
   # option is not used.
   class DelegationError < NoMethodError; end
 
+  RUBY_RESERVED_WORDS = Set.new(
+    %w(alias and BEGIN begin break case class def defined? do else elsif END
+       end ensure false for if in module next nil not or redo rescue retry
+       return self super then true undef unless until when while yield)
+  ).freeze
+
   # Provides a +delegate+ class method to easily expose contained objects'
   # public methods as your own.
   #
@@ -163,7 +171,7 @@ class Module
     line = line.to_i
 
     to = to.to_s
-    to = 'self.class' if to == 'class'
+    to = "self.#{to}" if RUBY_RESERVED_WORDS.include?(to)
 
     methods.each do |method|
       # Attribute writer methods only accept one argument. Makes sure []=