[ruby/delegate] Fix DelegateClass block "method redefined" warning

This commit prevents "method redefined" warnings when overriding methods
within a `DelegateClass` block, such as in the following example:

  ```ruby
  Base = Class.new do
    def foo
      "foo"
    end
  end

  Overridden = DelegateClass(Base) do
    def foo
      super + "!"
    end
  end
  ```

Fixes https://bugs.ruby-lang.org/issues/19047.

https://github.com/ruby/delegate/commit/214fae86de

1 files changed, 2 insertions, 0 deletions

diff --git a/lib/delegate.rb b/lib/delegate.rb
index 70d4e4ad1d..af95c866f3 100644
--- a/lib/delegate.rb
+++ b/lib/delegate.rb
@@ -412,10 +412,12 @@ def DelegateClass(superclass, &block)
     end
     protected_instance_methods.each do |method|
       define_method(method, Delegator.delegating_block(method))
+      alias_method(method, method)
       protected method
     end
     public_instance_methods.each do |method|
       define_method(method, Delegator.delegating_block(method))
+      alias_method(method, method)
     end
   end
   klass.define_singleton_method :public_instance_methods do |all=true|