Merge pull request #21302 from theunraveler/delegate_reserved_argument_names

ActiveSupport: Fixing issue when delegating to methods named "block", "args", or "arg"

activesupport/lib/active_support/core_ext/module/delegation.rb

@@ -5,10 +5,11 @@ class Module
   # 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)
+  DELEGATION_RESERVED_METHOD_NAMES = Set.new(
+    %w(_ arg args alias and BEGIN begin block 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'
@@ -171,7 +172,7 @@ def delegate(*methods)
     line = line.to_i
 
     to = to.to_s
-    to = "self.#{to}" if RUBY_RESERVED_WORDS.include?(to)
+    to = "self.#{to}" if DELEGATION_RESERVED_METHOD_NAMES.include?(to)
 
     methods.each do |method|
       # Attribute writer methods only accept one argument. Makes sure []=

activesupport/test/core_ext/module_test.rb

@@ -83,6 +83,16 @@ def type
   end
 end
 
+class Block
+  def hello?
+    true
+  end
+end
+
+HasBlock = Struct.new(:block) do
+  delegate :hello?, to: :block
+end
+
 class ParameterSet
   delegate :[], :[]=, :to => :@params
 
@@ -301,6 +311,11 @@ def test_delegation_doesnt_mask_nested_no_method_error_on_nil_receiver
     assert_raise(NoMethodError) { product.type_name }
   end
 
+  def test_delegation_with_method_arguments
+    has_block = HasBlock.new(Block.new)
+    assert has_block.hello?
+  end
+
   def test_parent
     assert_equal Yz::Zy, Yz::Zy::Cd.parent
     assert_equal Yz, Yz::Zy.parent