Update to ruby/spec@d6921ef

spec/ruby/language/yield_spec.rb

@@ -183,5 +183,33 @@ describe "The yield call" do
   it "uses captured block of a block used in define_method" do
     @y.deep(2).should == 4
   end
-
+end
+
+describe "Using yield in a singleton class literal" do
+  ruby_version_is "2.7"..."3.0" do
+    it 'emits a deprecation warning' do
+      code = <<~RUBY
+        def m
+          class << Object.new
+            yield
+          end
+        end
+        m { :ok }
+      RUBY
+
+      -> { eval(code) }.should complain(/warning: `yield' in class syntax will not be supported from Ruby 3.0/)
+    end
+  end
+
+  ruby_version_is "3.0" do
+    it 'raises a SyntaxError' do
+      code = <<~RUBY
+        class << Object.new
+          yield
+        end
+      RUBY
+
+      -> { eval(code) }.should raise_error(SyntaxError, /Invalid yield/)
+    end
+  end
 end