Implement Kernel#extend(Refinement) semantics

Author: eregon

spec/ruby/core/refinement/extend_object_spec.rb

@@ -11,8 +11,10 @@
       Module.new do
         refine c do
           called = false
-          define_method(:extend_object){called = true}
-          proc{c.extend(self)}.should raise_error(TypeError)
+          define_method(:extend_object) { called = true }
+          -> {
+            c.extend(self)
+          }.should raise_error(TypeError)
           called.should == false
         end
       end

src/main/ruby/truffleruby/core/kernel.rb

@@ -327,6 +327,8 @@ def extend(*modules)
     modules.reverse_each do |mod|
       if !Primitive.is_a?(mod, Module) or Primitive.is_a?(mod, Class)
         raise TypeError, "wrong argument type #{Primitive.class(mod)} (expected Module)"
+      elsif Primitive.is_a?(mod, Refinement)
+        raise TypeError, 'Cannot extend object with refinement'
       end
 
       mod.__send__ :extend_object, self