Check that Data members match exactly

lib/psych/visitors/to_ruby.rb

@@ -199,14 +199,15 @@ def visit_Psych_Nodes_Mapping o
 
         when /^!ruby\/data(-with-ivars)?(?::(.*))?$/
           data = register(o, resolve_class($2).allocate) if $2
-          members = {}
+          members = nil
+          values = nil
 
           if $1 # data-with-ivars
             ivars   = {}
             o.children.each_slice(2) do |type, vars|
               case accept(type)
               when 'members'
-                revive_data_members(members, vars)
+                members, values = revive_data_members(vars)
                 data ||= allocate_anon_data(o, members)
               when 'ivars'
                 revive_hash(ivars, vars)
@@ -216,10 +217,12 @@ def visit_Psych_Nodes_Mapping o
               data.instance_variable_set ivar, v
             end
           else
-            revive_data_members(members, o)
+            members, values = revive_data_members(o)
           end
           data ||= allocate_anon_data(o, members)
-          values = data.members.map { |m| members[m] }
+          unless members == data.class.members
+            raise ArgumentError, "Data members in YAML (#{members}) do not match the members of #{data.class} (#{data.class.members})"
+          end
           init_data(data, values)
           data.freeze
           data
@@ -368,17 +371,18 @@ def register_empty object
       end
 
       def allocate_anon_data node, members
-        klass = class_loader.data.define(*members.keys)
+        klass = class_loader.data.define(*members)
         register(node, klass.allocate)
       end
 
-      def revive_data_members hash, o
+      def revive_data_members o
+        keys = []
+        values = []
         o.children.each_slice(2) do |k,v|
-          name  = accept(k)
-          value = accept(v)
-          hash[class_loader.symbolize(name)] = value
+          keys << class_loader.symbolize(accept(k))
+          values << accept(v)
         end
-        hash
+        [keys, values]
       end
 
       def revive_hash hash, o, tagged= false

test/psych/test_data.rb

@@ -64,6 +64,37 @@ def test_load
       assert_equal "hello", obj.bar
       assert_equal "bar",   obj.foo
     end
+
+    def test_members_must_be_identical
+      TestData.const_set :D, Data.define(:a, :b)
+      d = Psych.dump(TestData::D.new(1, 2))
+
+      # more members
+      TestData.send :remove_const, :D
+      TestData.const_set :D, Data.define(:a, :b, :c)
+      e = assert_raise(ArgumentError) { Psych.unsafe_load d }
+      assert_equal 'Data members in YAML ([:a, :b]) do not match the members of Psych::TestData::D ([:a, :b, :c])', e.message
+
+      # less members
+      TestData.send :remove_const, :D
+      TestData.const_set :D, Data.define(:a)
+      e = assert_raise(ArgumentError) { Psych.unsafe_load d }
+      assert_equal 'Data members in YAML ([:a, :b]) do not match the members of Psych::TestData::D ([:a])', e.message
+
+      # completely different members
+      TestData.send :remove_const, :D
+      TestData.const_set :D, Data.define(:foo, :bar)
+      e = assert_raise(ArgumentError) { Psych.unsafe_load d }
+      assert_equal 'Data members in YAML ([:a, :b]) do not match the members of Psych::TestData::D ([:foo, :bar])', e.message
+
+      # different order
+      TestData.send :remove_const, :D
+      TestData.const_set :D, Data.define(:b, :a)
+      e = assert_raise(ArgumentError) { Psych.unsafe_load d }
+      assert_equal 'Data members in YAML ([:a, :b]) do not match the members of Psych::TestData::D ([:b, :a])', e.message
+    ensure
+      TestData.send :remove_const, :D
+    end
   end
 end