Add spec for keyword argument caller to allocate a new hash object

in Ruby versions <3.0.0

Author: wildmaples

spec/ruby/language/method_spec.rb

@@ -777,7 +777,18 @@ def m(a, **k) [a, k] end
           m("a" => 1, b: 2).should == [{"a" => 1, b: 2}, {}]
         end
       end
+
+      evaluate <<-ruby do
+        def m(a)
+          a.delete(:one); a
+        end
+      ruby
+      h = { one: 1, two: 2 }
+
+      m(**h).should == { two: 2 }
+      m(**h).should_not equal(h)
     end
+  end
 
     ruby_version_is "3.0" do
       evaluate <<-ruby do

spec/tags/language/method_tags.txt

@@ -1,5 +1,6 @@
 fails:A method assigns local variables from method parameters for definition 'def m() end'
 fails:A method assigns local variables from method parameters for definition 'def m(*a) a end'
+fails:"A method assigns local variables from method parameters for definition \n    def m(a)\n      a.delete(:one); a\n    end"
 fails:A method assigns local variables from method parameters for definition 'def m(a = nil, **k) [a, k] end'
 fails:A method assigns local variables from method parameters for definition 'def m(*a, **k) [a, k] end'
 fails:A method assigns local variables from method parameters for definition 'def m(a, **nil); a end;'