[GR-18163] Repair serialising Data instances into Marshal format

CHANGELOG.md

@@ -29,6 +29,7 @@ Compatibility:
 * Add `IO#{pread, pwrite}` methods (#3718, @andrykonchin).
 * Add `rb_io_closed_p()` (#3681, @andrykonchin).
 * Add `rb_io_open_descriptor()` (#3681, @andrykonchin).
+* Support serializing of `Data` instances into Marshal format (#3726, @andrykonchin).
 
 Performance:
 

spec/ruby/core/marshal/dump_spec.rb

@@ -283,6 +283,28 @@ def _dump(level)
     end
   end
 
+  ruby_version_is "3.2" do
+    describe "with a Data" do
+      it "dumps a Data" do
+        Marshal.dump(MarshalSpec::DataSpec::Measure.new(100, 'km')).should == "\x04\bS:#MarshalSpec::DataSpec::Measure\a:\vamountii:\tunit\"\akm"
+      end
+
+      it "dumps an extended Data" do
+        obj = MarshalSpec::DataSpec::MeasureExtended.new(100, "km")
+        Marshal.dump(obj).should == "\x04\bS:+MarshalSpec::DataSpec::MeasureExtended\a:\vamountii:\tunit\"\akm"
+      end
+
+      it "ignores overridden name method" do
+        obj = MarshalSpec::DataSpec::MeasureWithOverriddenName.new(100, "km")
+        Marshal.dump(obj).should == "\x04\bS:5MarshalSpec::DataSpec::MeasureWithOverriddenName\a:\vamountii:\tunit\"\akm"
+      end
+
+      it "raises TypeError with an anonymous Struct" do
+        -> { Marshal.dump(Data.define(:a).new(1)) }.should raise_error(TypeError, /can't dump anonymous class/)
+      end
+    end
+  end
+
   describe "with a String" do
     it "dumps a blank String" do
       Marshal.dump("".dup.force_encoding("binary")).should == "\004\b\"\000"

spec/ruby/core/marshal/fixtures/marshal_data.rb

@@ -486,6 +486,22 @@ class ObjectWithoutFreeze < Object
                  "\004\bS:\024Struct::Pyramid\000"],
     "Random" => random_data,
   }
+
+  if defined? Data # TODO: remove the condition when minimal supported version is 3.2
+    module DataSpec
+      Measure = Data.define(:amount, :unit)
+      Empty = Data.define
+
+      MeasureExtended = Class.new(Measure)
+      MeasureExtended.extend(Enumerable)
+
+      class MeasureWithOverriddenName < Measure
+        def self.name
+          "Foo"
+        end
+      end
+    end
+  end
 end
 
 class ArraySub < Array

spec/ruby/core/marshal/shared/load.rb

@@ -749,6 +749,34 @@ def io.binmode; raise "binmode"; end
     end
   end
 
+  ruby_version_is "3.2" do
+    describe "for a Data" do
+      it "loads a Data" do
+        obj = MarshalSpec::DataSpec::Measure.new(100, 'km')
+        dumped = "\x04\bS:#MarshalSpec::DataSpec::Measure\a:\vamountii:\tunit\"\akm"
+        Marshal.dump(obj).should == dumped
+
+        Marshal.send(@method, dumped).should == obj
+      end
+
+      it "loads an extended Data" do
+        obj = MarshalSpec::DataSpec::MeasureExtended.new(100, "km")
+        dumped = "\x04\bS:+MarshalSpec::DataSpec::MeasureExtended\a:\vamountii:\tunit\"\akm"
+        Marshal.dump(obj).should == dumped
+
+        Marshal.send(@method, dumped).should == obj
+      end
+
+      it "returns a frozen object" do
+        obj = MarshalSpec::DataSpec::Measure.new(100, 'km')
+        dumped = "\x04\bS:#MarshalSpec::DataSpec::Measure\a:\vamountii:\tunit\"\akm"
+        Marshal.dump(obj).should == dumped
+
+        Marshal.send(@method, dumped).should.frozen?
+      end
+    end
+  end
+
   describe "for an Exception" do
     it "loads a marshalled exception with no message" do
       obj = Exception.new

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

@@ -437,6 +437,39 @@ class Struct
   end
 end
 
+class Data
+  # Data is serialized like Struct with the same type 'S'
+  private def __marshal__(ms)
+    # Data instances are frozen so no instance variables could be set (with #instance_variable_set).
+    # But when Data class has no members - then its instances are allowed to be assigned instance variables.
+    #   Foo = Data.define
+    #   f = Foo.new
+    #   f.instance_variable_set(:@a, 42) # => 42
+    # So keep the logic of serializing instance variables for now.
+    out =  ms.serialize_instance_variables_prefix(self)
+    Primitive.string_binary_append out, ms.serialize_extended_object(self)
+
+    Primitive.string_binary_append out, 'S'
+
+    cls = Primitive.class self
+    if Primitive.module_anonymous?(cls)
+      raise TypeError, "can't dump anonymous class #{cls}"
+    end
+    class_name = Primitive.module_name cls
+    Primitive.string_binary_append out, ms.serialize(class_name.to_sym)
+    Primitive.string_binary_append out, ms.serialize_integer(self.members.length)
+
+    self.to_h.each_pair do |name, value|
+      Primitive.string_binary_append out, ms.serialize(name)
+      Primitive.string_binary_append out, ms.serialize(value)
+    end
+
+    Primitive.string_binary_append out, ms.serialize_instance_variables_suffix(self)
+
+    out
+  end
+end
+
 class Array
   private def __marshal__(ms)
     out =  ms.serialize_instance_variables_prefix(self)
@@ -952,6 +985,7 @@ def construct_regexp(ivar_index)
       store_unique_object obj
     end
 
+    # handle both Struct and Data classes
     def construct_struct
       name = get_symbol
 
@@ -970,6 +1004,8 @@ def construct_struct
         Primitive.object_hidden_var_set obj, slot, construct
       end
 
+      obj.freeze if Primitive.is_a?(obj, Data)
+
       obj
     end